Posts Tagged place constraints

Recent Postings from place constraints

Testing Eistein's gravity and dark energy with growth of matter perturbations: Indications for new Physics? [Cross-Listing]

The growth index of matter fluctuations is computed for ten distinct accelerating cosmological models and confronted to the latest growth rate data via a two-step process. First, we implement a joint statistical analysis in order to place constraints on the free parameters of all models using solely background data. Second, using the observed growth rate of clustering from various galaxy surveys we test the performance of the current cosmological models at the perturbation level while either marginalizing over $\sigma_8$ or having it as a free parameter. As a result, we find that at a statistical level, i.e. after considering the best-fit $\chi^2$ or the value of the Akaike information criterion, most models are in very good agreement with the growth rate data and are practically indistinguishable from $\Lambda$CDM. However, when we also consider the internal consistency of the models by comparing the theoretically predicted values of $(\gamma_0, \gamma_1)$, i.e. the value of the growth index $\gamma(z)$ and its derivative today, with the best-fit ones, we find that the predictions of three out of ten dark energy models are in mild tension with the best-fit ones when $\sigma_8$ is marginalized over. When $\sigma_8$ is free we find that most models are not only in mild tension, but also predict low values for $\sigma_8$. This could be attributed to either a systematic problem with the growth-rate data or the emergence of new physics at low redshifts, with the latter possibly being related to the well-known issue of the lack of power at small scales. Finally, by utilizing mock data based on an LSST-like survey we show that with future surveys and by using the growth index parameterization, it will be possible to resolve the issue of the low $\sigma_8$ but also the tension between the fitted and theoretically predicted values of $(\gamma_0, \gamma_1)$.

Testing Eistein's gravity and dark energy with growth of matter perturbations: Indications for new Physics?

The growth index of matter fluctuations is computed for ten distinct accelerating cosmological models and confronted to the latest growth rate data via a two-step process. First, we implement a joint statistical analysis in order to place constraints on the free parameters of all models using solely background data. Second, using the observed growth rate of clustering from various galaxy surveys we test the performance of the current cosmological models at the perturbation level while either marginalizing over $\sigma_8$ or having it as a free parameter. As a result, we find that at a statistical level, i.e. after considering the best-fit $\chi^2$ or the value of the Akaike information criterion, most models are in very good agreement with the growth rate data and are practically indistinguishable from $\Lambda$CDM. However, when we also consider the internal consistency of the models by comparing the theoretically predicted values of $(\gamma_0, \gamma_1)$, i.e. the value of the growth index $\gamma(z)$ and its derivative today, with the best-fit ones, we find that the predictions of three out of ten dark energy models are in mild tension with the best-fit ones when $\sigma_8$ is marginalized over. When $\sigma_8$ is free we find that most models are not only in mild tension, but also predict low values for $\sigma_8$. This could be attributed to either a systematic problem with the growth-rate data or the emergence of new physics at low redshifts, with the latter possibly being related to the well-known issue of the lack of power at small scales. Finally, by utilizing mock data based on an LSST-like survey we show that with future surveys and by using the growth index parameterization, it will be possible to resolve the issue of the low $\sigma_8$ but also the tension between the fitted and theoretically predicted values of $(\gamma_0, \gamma_1)$.

Testing Eistein's gravity and dark energy with growth of matter perturbations: Indications for new Physics? [Cross-Listing]

The growth index of matter fluctuations is computed for ten distinct accelerating cosmological models and confronted to the latest growth rate data via a two-step process. First, we implement a joint statistical analysis in order to place constraints on the free parameters of all models using solely background data. Second, using the observed growth rate of clustering from various galaxy surveys we test the performance of the current cosmological models at the perturbation level while either marginalizing over $\sigma_8$ or having it as a free parameter. As a result, we find that at a statistical level, i.e. after considering the best-fit $\chi^2$ or the value of the Akaike information criterion, most models are in very good agreement with the growth rate data and are practically indistinguishable from $\Lambda$CDM. However, when we also consider the internal consistency of the models by comparing the theoretically predicted values of $(\gamma_0, \gamma_1)$, i.e. the value of the growth index $\gamma(z)$ and its derivative today, with the best-fit ones, we find that the predictions of three out of ten dark energy models are in mild tension with the best-fit ones when $\sigma_8$ is marginalized over. When $\sigma_8$ is free we find that most models are not only in mild tension, but also predict low values for $\sigma_8$. This could be attributed to either a systematic problem with the growth-rate data or the emergence of new physics at low redshifts, with the latter possibly being related to the well-known issue of the lack of power at small scales. Finally, by utilizing mock data based on an LSST-like survey we show that with future surveys and by using the growth index parameterization, it will be possible to resolve the issue of the low $\sigma_8$ but also the tension between the fitted and theoretically predicted values of $(\gamma_0, \gamma_1)$.

An active, asynchronous companion to a redback millisecond pulsar

PSR\,J1723$-$2837 is a "redback" millisecond pulsar (MSP) with a low-mass companion in a 14.8\,h orbit. The system's properties closely resemble those of "transitional" MSPs that alternate between spin-down and accretion-powered states. In this paper we report on long-term photometry of the 15.5\,mag companion to the pulsar. We use our data to illustrate that the star experiences sporadic activity which we attribute to starspots. We also find that the companion is not tidally locked and infer $P_{\rm s}/P_{\rm b}= 0.9974(7)$ for the ratio between the rotational and orbital periods. We place constraints on various parameters, including the irradiation efficiency and pulsar mass. Finally, we discuss similarities with other redback MSPs and conclude that starspots provide the most likely explanation for the often seen irregular and asymmetric optical lightcurves.

Searching for photon-sector Lorentz violation using gravitational-wave detectors

We study the prospects for using interferometers in gravitational-wave detectors as tools to search for photon-sector violations of Lorentz symmetry. Existing interferometers are shown to be exquisitely sensitive to tiny changes in the effective refractive index of light occurring at frequencies around and below the microhertz range, including at the harmonics of the frequencies of the Earth's sidereal rotation and annual revolution relevant for tests of Lorentz symmetry. We use preliminary data obtained by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2006-2007 to place constraints on coefficients for Lorentz violation in the photon sector exceeding current limits by about four orders of magnitude.

Searching for photon-sector Lorentz violation using gravitational-wave detectors [Cross-Listing]

We study the prospects for using interferometers in gravitational-wave detectors as tools to search for photon-sector violations of Lorentz symmetry. Existing interferometers are shown to be exquisitely sensitive to tiny changes in the effective refractive index of light occurring at frequencies around and below the microhertz range, including at the harmonics of the frequencies of the Earth's sidereal rotation and annual revolution relevant for tests of Lorentz symmetry. We use preliminary data obtained by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2006-2007 to place constraints on coefficients for Lorentz violation in the photon sector exceeding current limits by about four orders of magnitude.

Constraining f(R) Gravity with Planck Sunyaev-Zel'dovich Clusters

Clusters of galaxies have the potential of providing powerful constraints on possible deviations from General Relativity. We use the catalogue of Sunyaev-Zel'dovich sources detected by Planck and consider a correction to the halo mass function for a f(R) class of modified gravity models, which has been recently found to reproduce well results from N-body simulations, to place constraints on the scalaron field amplitude at the present time, $f_{R}^0$. We find that applying this correction to different calibrations of the halo mass function produces upper bounds on $f_{R}^0$ tighter by more than an order of magnitude, ranging from $\log_{10}(-f_{R}^0) < -5.81$ to $\log_{10}(-f_{R}^0) < -4.40$ (95 % confidence level). This sensitivity is due to the different shape of the halo mass function, which is degenerate with the parameters used to calibrate the scaling relations between SZ observables and cluster masses. Any claim of constraints more stringent that the weaker limit above, based on cluster number counts, appear to be premature and must be supported by a careful calibration of the halo mass function and by a robust calibration of the mass scaling relations.

Constraining f(R) Gravity with Planck Sunyaev-Zel'dovich Clusters [Cross-Listing]

Clusters of galaxies have the potential of providing powerful constraints on possible deviations from General Relativity. We use the catalogue of Sunyaev-Zel'dovich sources detected by Planck and consider a correction to the halo mass function for a f(R) class of modified gravity models, which has been recently found to reproduce well results from N-body simulations, to place constraints on the scalaron field amplitude at the present time, $f_{R}^0$. We find that applying this correction to different calibrations of the halo mass function produces upper bounds on $f_{R}^0$ tighter by more than an order of magnitude, ranging from $\log_{10}(-f_{R}^0) < -5.81$ to $\log_{10}(-f_{R}^0) < -4.40$ (95 % confidence level). This sensitivity is due to the different shape of the halo mass function, which is degenerate with the parameters used to calibrate the scaling relations between SZ observables and cluster masses. Any claim of constraints more stringent that the weaker limit above, based on cluster number counts, appear to be premature and must be supported by a careful calibration of the halo mass function and by a robust calibration of the mass scaling relations.

Hubble parameter measurement constraints on the redshift of the deceleration-acceleration transition, dynamical dark energy, and space curvature

We compile an updated list of 28 independent measurements of the Hubble parameter $H(z)$ between redshifts $0.1 \leq z \leq 2.36$ and use them to place constraints on model parameters of constant and time-varying dark energy cosmological models, both spatially flat and curved. We use five models to measure the redshift of the cosmological deceleration-acceleration transition, $z_{\rm da}$, from these $H(z)$ data. Within the error bars, the measured $z_{\rm da}$ are insensitive to the model used, depending only on the value assumed for the Hubble constant $H_0$. The weighted mean of our measurements is $z_{\rm da} = 0.74 \pm 0.06\ (0.86 \pm 0.04)$ for $H_0 = 68 \pm 2.8\ (73.8 \pm 2.4)$ km s$^{-1}$ Mpc$^{-1}$ and should provide a reasonably model-independent estimate of this cosmological parameter. The $H(z)$ data are consistent with the standard spatially-flat $\Lambda$CDM cosmological model but do not rule out non-flat models or dynamical dark energy models.

Hubble parameter measurement constraints on the redshift of the deceleration-acceleration transition, dynamical dark energy, and space curvature [Cross-Listing]

We compile an updated list of 28 independent measurements of the Hubble parameter $H(z)$ between redshifts $0.1 \leq z \leq 2.36$ and use them to place constraints on model parameters of constant and time-varying dark energy cosmological models, both spatially flat and curved. We use five models to measure the redshift of the cosmological deceleration-acceleration transition, $z_{\rm da}$, from these $H(z)$ data. Within the error bars, the measured $z_{\rm da}$ are insensitive to the model used, depending only on the value assumed for the Hubble constant $H_0$. The weighted mean of our measurements is $z_{\rm da} = 0.74 \pm 0.06\ (0.86 \pm 0.04)$ for $H_0 = 68 \pm 2.8\ (73.8 \pm 2.4)$ km s$^{-1}$ Mpc$^{-1}$ and should provide a reasonably model-independent estimate of this cosmological parameter. The $H(z)$ data are consistent with the standard spatially-flat $\Lambda$CDM cosmological model but do not rule out non-flat models or dynamical dark energy models.

Constraining a halo model for cosmological neutral hydrogen [Replacement]

We describe a combined halo model to constrain the distribution of neutral hydrogen (HI) in the post-reionization universe. We combine constraints from the various probes of HI at different redshifts: the low-redshift 21-cm emission line surveys, intensity mapping experiments at intermediate redshifts, and the Damped Lyman-Alpha (DLA) observations at higher redshifts. We use a Markov Chain Monte Carlo (MCMC) approach to combine the observations and place constraints on the free parameters in the model. Our best-fit model involves a relation between neutral hydrogen mass $M_{\rm HI}$ and halo mass $M$ with a non-unit slope, and an upper and a lower cutoff. We find that the model fits all the observables but leads to an underprediction of the bias parameter of DLAs at $z \sim 2.3$. We also find indications of a possible tension between the HI column density distribution and the mass function of HI-selected galaxies at $z\sim 0$. We provide the central values of the parameters of the best-fit model so derived. We also provide a fitting form for the derived evolution of the concentration parameter of HI in dark matter haloes, and discuss the implications for the redshift evolution of the HI-halo mass relation.

Constraining a halo model for cosmological neutral hydrogen

We describe a combined halo model to constrain the distribution of neutral hydrogen (HI) in the post-reionization universe. We combine constraints from the various probes of HI at different redshifts: the low-redshift 21-cm emission line surveys, intensity mapping experiments at intermediate redshifts, and the Damped Lyman-Alpha (DLA) observations at higher redshifts. We use a Markov Chain Monte Carlo (MCMC) approach to combine the observations and place constraints on the free parameters in the model. Our best-fit model involves a relation between neutral hydrogen mass $M_{\rm HI}$ and halo mass $M$ with a non-unit slope, and an upper and a lower cutoff. We find that the model fits all the observables but leads to an underprediction of the bias parameter of DLAs at $z \sim 2.3$. We also find indications of a possible tension between the HI column density distribution and the mass function of HI-selected galaxies at $z\sim 0$. We provide the central values of the parameters of the best-fit model so derived. We also provide a fitting form for the derived evolution of the concentration parameter of HI in dark matter haloes, and discuss the implications for the redshift evolution of the HI-halo mass relation.

Dynamical analysis of $R\dfrac{1}{\Box^{2}}R$ cosmology: Impact of initial conditions and constraints from supernovae [Replacement]

We discuss the cosmological implications of the $R~\Box^{-2}R$ nonlocal modification to standard gravity. We relax the assumption of special initial conditions in the local formulation of the theory, perform a full phase-space analysis of the system, and show that the late-time cosmology of the model exhibits two distinct evolution paths, on which a large range of values for the present equation of state can be reached. We then compare the general solutions to supernovae data and place constraints on the parameters of the model. In particular, we find that the mass parameter of the theory should be smaller than 1.2 in Hubble units.

Dynamical analysis of $R\dfrac{1}{\Box^{2}}R$ cosmology: Impact of initial conditions and constraints from supernovae [Replacement]

We discuss the cosmological implications of the $R~\Box^{-2}R$ nonlocal modification to standard gravity. We relax the assumption of special initial conditions in the local formulation of the theory, perform a full phase-space analysis of the system, and show that the late-time cosmology of the model exhibits two distinct evolution paths, on which a large range of values for the present equation of state can be reached. We then compare the general solutions to supernovae data and place constraints on the parameters of the model. In particular, we find that the mass parameter of the theory should be smaller than 1.2 in Hubble units.

Dynamical analysis of $R\dfrac{1}{\Box^{2}}R$ cosmology: Impact of initial conditions and constraints from supernovae [Cross-Listing]

We discuss the cosmological implications of the $R~\Box^{-2}R$ nonlocal modification to standard gravity. We relax the assumption of special initial conditions in the local formulation of the theory, perform a full phase-space analysis of the system, and show that the late-time cosmology of the model exhibits two distinct evolution paths, on which a large range of values for the present equation of state can be reached. We then compare the general solutions to supernovae data and place constraints on the parameters of the model. In particular, we find that the mass parameter of the theory should be smaller than 1.2 in Hubble units.

Dynamical analysis of $R\dfrac{1}{\Box^{2}}R$ cosmology: Impact of initial conditions and constraints from supernovae

We discuss the cosmological implications of the $R~\Box^{-2}R$ nonlocal modification to standard gravity. We relax the assumption of special initial conditions in the local formulation of the theory, perform a full phase-space analysis of the system, and show that the late-time cosmology of the model exhibits two distinct evolution paths, on which a large range of values for the present equation of state can be reached. We then compare the general solutions to supernovae data and place constraints on the parameters of the model. In particular, we find that the mass parameter of the theory should be smaller than 1.2 in Hubble units.

Dynamical analysis of $R\dfrac{1}{\Box^{2}}R$ cosmology: Impact of initial conditions and constraints from supernovae [Cross-Listing]

We discuss the cosmological implications of the $R~\Box^{-2}R$ nonlocal modification to standard gravity. We relax the assumption of special initial conditions in the local formulation of the theory, perform a full phase-space analysis of the system, and show that the late-time cosmology of the model exhibits two distinct evolution paths, on which a large range of values for the present equation of state can be reached. We then compare the general solutions to supernovae data and place constraints on the parameters of the model. In particular, we find that the mass parameter of the theory should be smaller than 1.2 in Hubble units.

Dynamical analysis of $R\dfrac{1}{\Box^{2}}R$ cosmology: Impact of initial conditions and constraints from supernovae [Replacement]

We discuss the cosmological implications of the $R~\Box^{-2}R$ nonlocal modification to standard gravity. We relax the assumption of special initial conditions in the local formulation of the theory, perform a full phase-space analysis of the system, and show that the late-time cosmology of the model exhibits two distinct evolution paths, on which a large range of values for the present equation of state can be reached. We then compare the general solutions to supernovae data and place constraints on the parameters of the model. In particular, we find that the mass parameter of the theory should be smaller than 1.2 in Hubble units.

Cosmological Constraints on Decoupled Dark Photons and Dark Higgs [Cross-Listing]

Any neutral boson such as a dark photon or dark Higgs that is part of a non-standard sector of particles can mix with its standard model counterpart. When very weakly mixed with the Standard Model, these particles are produced in the early Universe via the freeze-in mechanism and subsequently decay back to standard model particles. In this work, we place constraints on such mediator decays by considering bounds from Big Bang nucleosynthesis and the cosmic microwave background radiation. We find both nucleosynthesis and CMB can constrain dark photons with a kinetic mixing parameter between log {\epsilon} ~ -10 to -17 for masses between 1 MeV and 100 GeV. Similarly, the dark Higgs mixing angle {\epsilon} with the Standard Model Higgs is constrained between log {\epsilon} ~ -6 to -15. Dramatic improvement on the bounds from CMB spectral distortions can be achieved with proposed experiments such as PIXIE.

Cosmological Constraints on Decoupled Dark Photons and Dark Higgs

Any neutral boson such as a dark photon or dark Higgs that is part of a non-standard sector of particles can mix with its standard model counterpart. When very weakly mixed with the Standard Model, these particles are produced in the early Universe via the freeze-in mechanism and subsequently decay back to standard model particles. In this work, we place constraints on such mediator decays by considering bounds from Big Bang nucleosynthesis and the cosmic microwave background radiation. We find both nucleosynthesis and CMB can constrain dark photons with a kinetic mixing parameter between log {\epsilon} ~ -10 to -17 for masses between 1 MeV and 100 GeV. Similarly, the dark Higgs mixing angle {\epsilon} with the Standard Model Higgs is constrained between log {\epsilon} ~ -6 to -15. Dramatic improvement on the bounds from CMB spectral distortions can be achieved with proposed experiments such as PIXIE.

A search for flavor-changing non-standard neutrino interactions using $\nu_{e}$ appearance in MINOS [Replacement]

We report new constraints on flavor-changing non-standard neutrino interactions from the MINOS long-baseline experiment using $\nu_{e}$ appearance candidate events from a predominantly $\nu_{\mu}$ beam. We used a statistical selection algorithm to separate $\nu_{e}$ candidates from background events, enabling an analysis of the combined MINOS neutrino and antineutrino data. We observe no deviations from standard neutrino mixing, and thus place constraints on the non-standard interaction matter effect, $|\varepsilon_{e\tau}|$, and phase, $(\delta_{CP}+\delta_{e\tau})$, using a thirty-bin likelihood fit.

A search for flavor-changing non-standard neutrino interactions using $\nu_{e}$ appearance in MINOS

We report new constraints on flavor-changing non-standard neutrino interactions from the MINOS long-baseline experiment using $\nu_{e}$ appearance candidate events from a predominantly $\nu_{\mu}$ beam. We used a statistical selection algorithm to separate $\nu_{e}$ candidates from background events, enabling an analysis of the combined MINOS neutrino and antineutrino data. We observe no deviations from standard neutrino mixing, and thus place constraints on the non-standard interaction matter effect, $\varepsilon_{e\tau}$, and phase, $(\delta_{CP}+\delta_{e\tau})$, using a thirty-bin likelihood fit.

Running the running [Cross-Listing]

We use the recent observations of Cosmic Microwave Background temperature and polarization anisotropies provided by the Planck satellite experiment to place constraints on the running $\alpha_\mathrm{s} = \mathrm{d}n_{\mathrm{s}} / \mathrm{d}\log k$ and the running of the running $\beta_{\mathrm{s}} = \mathrm{d}\alpha_{\mathrm{s}} / \mathrm{d}\log k$ of the spectral index $n_{\mathrm{s}}$ of primordial scalar fluctuations. We find $\alpha_\mathrm{s}=0.011\pm0.010$ and $\beta_\mathrm{s}=0.027\pm0.013$ at $68\%\,\mathrm{CL}$, suggesting the presence of a running of the running at the level of two standard deviations. We find no significant correlation between $\beta_{\mathrm{s}}$ and foregrounds parameters, with the exception of the point sources amplitude at $143\,\mathrm{GHz}$, $A^{PS}_{143}$, which shifts by half sigma when the running of the running is considered. We further study the cosmological implications of this anomaly by including in the analysis the lensing amplitude $A_L$, the curvature parameter $\Omega_k$, and the sum of neutrino masses $\sum m_{\nu}$. We find that when the running of the running is considered, Planck data are more compatible with the standard expectations of $A_L = 1$ and $\Omega_k = 0$ but still hint at possible deviations. The indication for $\beta_\mathrm{s} > 0$ survives at two standard deviations when external datasets such as BAO and CFHTLenS are included in the analysis, and persists at $\sim 1.7$ standard deviations when CMB lensing is considered. We discuss the possibility of constraining $\beta_\mathrm{s}$ with current and future measurements of CMB spectral distortions, showing that an experiment like PIXIE could provide strong constraints on $\alpha_\mathrm{s}$ and $\beta_\mathrm{s}$.

Running the running [Replacement]

We use the recent observations of Cosmic Microwave Background temperature and polarization anisotropies provided by the Planck satellite experiment to place constraints on the running $\alpha_\mathrm{s} = \mathrm{d}n_{\mathrm{s}} / \mathrm{d}\log k$ and the running of the running $\beta_{\mathrm{s}} = \mathrm{d}\alpha_{\mathrm{s}} / \mathrm{d}\log k$ of the spectral index $n_{\mathrm{s}}$ of primordial scalar fluctuations. We find $\alpha_\mathrm{s}=0.011\pm0.010$ and $\beta_\mathrm{s}=0.027\pm0.013$ at $68\%\,\mathrm{CL}$, suggesting the presence of a running of the running at the level of two standard deviations. We find no significant correlation between $\beta_{\mathrm{s}}$ and foregrounds parameters, with the exception of the point sources amplitude at $143\,\mathrm{GHz}$, $A^{PS}_{143}$, which shifts by half sigma when the running of the running is considered. We further study the cosmological implications of such preference for $\alpha_\mathrm{s},\beta_\mathrm{s}\sim0.01$ by including in the analysis the lensing amplitude $A_L$, the curvature parameter $\Omega_k$, and the sum of neutrino masses $\sum m_{\nu}$. We find that when the running of the running is considered, Planck data are more compatible with the standard expectations of $A_L = 1$ and $\Omega_k = 0$ but still hint at possible deviations. The indication for $\beta_\mathrm{s} > 0$ survives at two standard deviations when external datasets such as BAO and CFHTLenS are included in the analysis, and persists at $\sim 1.7$ standard deviations when CMB lensing is considered. We discuss the possibility of constraining $\beta_\mathrm{s}$ with current and future measurements of CMB spectral distortions, showing that an experiment like PIXIE could provide strong constraints on $\alpha_\mathrm{s}$ and $\beta_\mathrm{s}$.

Running the running [Replacement]

We use the recent observations of Cosmic Microwave Background temperature and polarization anisotropies provided by the Planck satellite experiment to place constraints on the running $\alpha_\mathrm{s} = \mathrm{d}n_{\mathrm{s}} / \mathrm{d}\log k$ and the running of the running $\beta_{\mathrm{s}} = \mathrm{d}\alpha_{\mathrm{s}} / \mathrm{d}\log k$ of the spectral index $n_{\mathrm{s}}$ of primordial scalar fluctuations. We find $\alpha_\mathrm{s}=0.011\pm0.010$ and $\beta_\mathrm{s}=0.027\pm0.013$ at $68\%\,\mathrm{CL}$, suggesting the presence of a running of the running at the level of two standard deviations. We find no significant correlation between $\beta_{\mathrm{s}}$ and foregrounds parameters, with the exception of the point sources amplitude at $143\,\mathrm{GHz}$, $A^{PS}_{143}$, which shifts by half sigma when the running of the running is considered. We further study the cosmological implications of such preference for $\alpha_\mathrm{s},\beta_\mathrm{s}\sim0.01$ by including in the analysis the lensing amplitude $A_L$, the curvature parameter $\Omega_k$, and the sum of neutrino masses $\sum m_{\nu}$. We find that when the running of the running is considered, Planck data are more compatible with the standard expectations of $A_L = 1$ and $\Omega_k = 0$ but still hint at possible deviations. The indication for $\beta_\mathrm{s} > 0$ survives at two standard deviations when external datasets such as BAO and CFHTLenS are included in the analysis, and persists at $\sim 1.7$ standard deviations when CMB lensing is considered. We discuss the possibility of constraining $\beta_\mathrm{s}$ with current and future measurements of CMB spectral distortions, showing that an experiment like PIXIE could provide strong constraints on $\alpha_\mathrm{s}$ and $\beta_\mathrm{s}$.

Running the running

We use the recent observations of Cosmic Microwave Background temperature and polarization anisotropies provided by the Planck satellite experiment to place constraints on the running $\alpha_\mathrm{s} = \mathrm{d}n_{\mathrm{s}} / \mathrm{d}\log k$ and the running of the running $\beta_{\mathrm{s}} = \mathrm{d}\alpha_{\mathrm{s}} / \mathrm{d}\log k$ of the spectral index $n_{\mathrm{s}}$ of primordial scalar fluctuations. We find $\alpha_\mathrm{s}=0.011\pm0.010$ and $\beta_\mathrm{s}=0.027\pm0.013$ at $68\%\,\mathrm{CL}$, suggesting the presence of a running of the running at the level of two standard deviations. We find no significant correlation between $\beta_{\mathrm{s}}$ and foregrounds parameters, with the exception of the point sources amplitude at $143\,\mathrm{GHz}$, $A^{PS}_{143}$, which shifts by half sigma when the running of the running is considered. We further study the cosmological implications of this anomaly by including in the analysis the lensing amplitude $A_L$, the curvature parameter $\Omega_k$, and the sum of neutrino masses $\sum m_{\nu}$. We find that when the running of the running is considered, Planck data are more compatible with the standard expectations of $A_L = 1$ and $\Omega_k = 0$ but still hint at possible deviations. The indication for $\beta_\mathrm{s} > 0$ survives at two standard deviations when external datasets such as BAO and CFHTLenS are included in the analysis, and persists at $\sim 1.7$ standard deviations when CMB lensing is considered. We discuss the possibility of constraining $\beta_\mathrm{s}$ with current and future measurements of CMB spectral distortions, showing that an experiment like PIXIE could provide strong constraints on $\alpha_\mathrm{s}$ and $\beta_\mathrm{s}$.

Bounds on the local energy density of holographic CFTs from bulk geometry [Cross-Listing]

The stress tensor is a basic local operator in any field theory; in the context of AdS/CFT, it is the operator which is dual to the bulk geometry itself. Here we exploit this feature by using the bulk geometry to place constraints on the local energy density in static states of holographic $(2+1)$-dimensional CFTs living on a closed (but otherwise generally curved) spatial geometry. We allow for the presence of a marginal scalar deformation, dual to a massless scalar field in the bulk. For certain vacuum states in which the bulk geometry is well-behaved at zero temperature, we find that the bulk equations of motion imply that the local energy density integrated over specific boundary domains is negative. In the absence of scalar deformations, we use the inverse mean curvature flow to show that if the CFT spatial geometry has spherical topology but non-constant curvature, the local energy density must be positive somewhere. This result extends to other topologies, but only for certain types of vacuum; in particular, for a generic toroidal boundary, the vacuum's bulk dual must be the zero-temperature limit of a toroidal black hole.

Bounds on the local energy density of holographic CFTs from bulk geometry

The stress tensor is a basic local operator in any field theory; in the context of AdS/CFT, it is the operator which is dual to the bulk geometry itself. Here we exploit this feature by using the bulk geometry to place constraints on the local energy density in static states of holographic $(2+1)$-dimensional CFTs living on a closed (but otherwise generally curved) spatial geometry. We allow for the presence of a marginal scalar deformation, dual to a massless scalar field in the bulk. For certain vacuum states in which the bulk geometry is well-behaved at zero temperature, we find that the bulk equations of motion imply that the local energy density integrated over specific boundary domains is negative. In the absence of scalar deformations, we use the inverse mean curvature flow to show that if the CFT spatial geometry has spherical topology but non-constant curvature, the local energy density must be positive somewhere. This result extends to other topologies, but only for certain types of vacuum; in particular, for a generic toroidal boundary, the vacuum's bulk dual must be the zero-temperature limit of a toroidal black hole.

Constraints on dark-matter properties from large-scale structure [Replacement]

We use large-scale cosmological observations to place constraints on the dark-matter pressure, sound speed and viscosity, and infer a limit on the mass of warm-dark-matter particles. Measurements of the cosmic microwave background (CMB) anisotropies constrain the equation of state and sound speed of the dark matter at last scattering at the per mille level. Since the redshifting of collisionless particles universally implies that these quantities scale like $a^{-2}$ absent shell crossing, we infer that today $w_{\rm (DM)}< 10^{-10.0}$, $c_{\rm s,(DM)}^2 < 10^{-10.7}$ and $c_{\rm vis, (DM)}^{2} < 10^{-10.3}$ at the $99\%$ confidence level. This very general bound can be translated to model-dependent constraints on dark-matter models: for warm dark matter these constraints imply $m> 70$ eV, assuming it decoupled while relativistic around the same time as the neutrinos; for a cold relic, we show that $m>100$ eV. We separately constrain the properties of the DM fluid on linear scales at late times, and find upper bounds $c_{\rm s, (DM)}^2<10^{-5.9}$, $c_{\rm vis, (DM)}^{2} < 10^{-5.7}$, with no detection of non-dust properties for the DM.

Constraints on dark-matter properties from large-scale structure

We use large-scale cosmological observations to place constraints on the dark matter pressure, sound speed and viscosity, and infer a limit on the mass of warm dark matter particles. Measurements of the cosmic microwave background (CMB) anisotropies constrain the equation of state and sound speed of the dark matter at last scattering at the per mille level. Since the redshifting of collisionless particles universally implies that these quantities scale like $a^{-2}$ absent shell crossing, we infer that today $w_{\rm (DM)}< 10^{-10.0}$, $c_{\rm s,(DM)}^2 < 10^{-10.7}$ and $c_{\rm vis, (DM)}^{2} < 10^{-10.3}$ at the $99\%$ confidence level. This very general bound can be translated to model-dependent constraints on dark matter models: for warm dark matter these constraints imply $m> 70$ eV, assuming it decoupled while relativistic around the same time as the neutrinos; for a cold relic, we show that $m>100$ eV. We separately constrain the properties of the DM fluid on linear scales at late times, and find upper bounds $c_{\rm s, (DM)}^2<10^{-5.9}$, $c_{\rm vis, (DM)}^{2} < 10^{-5.7}$, with no detection of non-dust properties for the DM.

Constraints on dark-matter properties from large-scale structure [Cross-Listing]

We use large-scale cosmological observations to place constraints on the dark matter pressure, sound speed and viscosity, and infer a limit on the mass of warm dark matter particles. Measurements of the cosmic microwave background (CMB) anisotropies constrain the equation of state and sound speed of the dark matter at last scattering at the per mille level. Since the redshifting of collisionless particles universally implies that these quantities scale like $a^{-2}$ absent shell crossing, we infer that today $w_{\rm (DM)}< 10^{-10.0}$, $c_{\rm s,(DM)}^2 < 10^{-10.7}$ and $c_{\rm vis, (DM)}^{2} < 10^{-10.3}$ at the $99\%$ confidence level. This very general bound can be translated to model-dependent constraints on dark matter models: for warm dark matter these constraints imply $m> 70$ eV, assuming it decoupled while relativistic around the same time as the neutrinos; for a cold relic, we show that $m>100$ eV. We separately constrain the properties of the DM fluid on linear scales at late times, and find upper bounds $c_{\rm s, (DM)}^2<10^{-5.9}$, $c_{\rm vis, (DM)}^{2} < 10^{-5.7}$, with no detection of non-dust properties for the DM.

Constraints on dark-matter properties from large-scale structure [Replacement]

We use large-scale cosmological observations to place constraints on the dark-matter pressure, sound speed and viscosity, and infer a limit on the mass of warm-dark-matter particles. Measurements of the cosmic microwave background (CMB) anisotropies constrain the equation of state and sound speed of the dark matter at last scattering at the per mille level. Since the redshifting of collisionless particles universally implies that these quantities scale like $a^{-2}$ absent shell crossing, we infer that today $w_{\rm (DM)}< 10^{-10.0}$, $c_{\rm s,(DM)}^2 < 10^{-10.7}$ and $c_{\rm vis, (DM)}^{2} < 10^{-10.3}$ at the $99\%$ confidence level. This very general bound can be translated to model-dependent constraints on dark-matter models: for warm dark matter these constraints imply $m> 70$ eV, assuming it decoupled while relativistic around the same time as the neutrinos; for a cold relic, we show that $m>100$ eV. We separately constrain the properties of the DM fluid on linear scales at late times, and find upper bounds $c_{\rm s, (DM)}^2<10^{-5.9}$, $c_{\rm vis, (DM)}^{2} < 10^{-5.7}$, with no detection of non-dust properties for the DM.

Constraining the time evolution of dark energy, curvature and neutrino properties with cosmic chronometers

We use the latest compilation of observational H(z) measurements obtained with cosmic chronometers in the redshift range $0<z<2$ to place constraints on cosmological parameters. We consider the sample alone and in combination with other state-of-the art cosmological probes: CMB data from the latest Planck 2015 release, the most recent estimate of the Hubble constant $H_{0}$, a compilation of recent BAO data, and the latest SNe sample. Since cosmic chronometers are independent of the assumed cosmological model, we are able to provide constraints on the parameters that govern the expansion history of the Universe in a way that can be used to test cosmological models. We show that the H(z) measurements obtained with cosmic chronometer from the BOSS survey provide enough constraining power in combination with CMB data to constrain the time evolution of dark energy, yielding constraints competitive with those obtained using SNe and/or BAO. From late-Universe probes alone we find that $w_0=-0.9\pm0.18$ and $w_a=-0.5\pm1.7$, and when combining also CMB data we obtain $w_0=-0.98\pm0.11$and $w_a=-0.30\pm0.4$. These new constraints imply that nearly all quintessence models are disfavoured, only phantom models or a pure cosmological constant being allowed. For the curvature we find $\Omega_k=0.003\pm0.003$, including CMB data. Cosmic chronometers data are important also to constrain neutrino properties by breaking or reducing degeneracies with other parameters. We find that $N_{eff}=3.17\pm0.15$, thus excluding the possibility of an extra (sterile) neutrino at more than $5\sigma$, and put competitive limits on the sum of neutrino masses, $\Sigma m_{\nu}< 0.27$ eV at 95% confidence level. Finally, we constrain the redshift evolution of dark energy, and find w(z) consistent with the $\Lambda$CDM model at the 40% level over the entire redshift range $0<z<2$. [abridged]

On the seed photon source for Comptonisation in the black hole binary SWIFT J1753.5-0127

Aims. The black hole binary SWIFT J1753.5-0127 is providing a unique data-set to study accretion flows. Various investigations of this system and of other black holes have not, however, led to an agreement on the accretion flow geometry nor on the seed photon source for Comptonisation during different stages of X-ray outbursts. We aim to place constraints on these accretion flow properties by studying long term spectral variations of this source. Methods. We performed phenomenological and self-consistent broad band spectral modeling of SWIFT J1753.5-0127 using quasi-simultaneous archived data from INTEGRAL/ISGRI, Swift/UVOT/XRT/BAT, RXTE/PCA/HEXTE and Maxi/GSC instruments. Results. 1. We identify a critical flux limit, F \sim 1.5 \times 10^{-8} erg/cm^2/s, and show that the spectral properties of SWIFT J1753.5-0127 are markedly different above and below that. Above the limit, during the outburst peak, the hot medium seems to intercept roughly 50 per cent of the disc emission. Below it, in the outburst tail, the contribution of the disc photons reduces significantly and the entire optical-to-X-ray spectrum can be produced by a synchrotron-self-Compton mechanism. 2. The long term variations in the hard X-ray spectra are caused by erratic changes of the electron temperatures in the hot medium. 3. Thermal Comptonization models indicate unreasonably low hot medium optical depths during the short incursions into the soft state after 2010, suggesting that non-thermal electrons produce the Comptonized tail in this state. 4. The soft X-ray excess, likely produced by the accretion disc, shows peculiarly stable temperatures for over an order of magnitude changes in flux. (abridged)

Observational constraints and differential diagnosis for cosmic evolutionary models [Cross-Listing]

In this paper, we have proposed a plotting method based on the " natural plotting rule " (NPR) which can be used to distinguish different cosmological scenarios more efficiently and obtain more useful information. By using the NPR, we have avoided the blindness to use different diagnostics when discovering that some scenarios can be hardly differentiated from each other, and develop a logical line to adopt different diagnostics. As a concrete instance, we take this method based on the NPR to distinguish several Cardassian scenarios from the base cosmology scenario, and one from the other. We place constraints on three Cardassian cosmological scenarios and their flat versions by utilizing the Type Ia supernovae (SNe Ia), baryonic acoustic oscillations (BAO), cosmic microwave background (CMB) radiation, observational Hubble parameter (OHD) data-sets as well as the single data point from the newest event GW150914, and discover that our results are more stringent than previous results for constraining the cosmological parameters of the Cardassian scenarios. We find that the flat original Cardassian (FOC) and original Cardassian (OC) scenarios can only be distinguished in the plane of $\{\Omega_m,S_3^{(1)}\}$ at the present epoch, however, if applying the NPR to plot hierarchically for these Cardassian scenarios in the plane of $\{S_3^{(1)},S_4^{(1)}\}$, we can obtain more detailed information and distinguish the two scenarios better than before. More importantly, from the planes of $\{S_4,S_4^{(2)}\}$, $\{S_5^{(1)},S_5^{(2)}\}$, $\{S_3^{(2)},S_4^{(2)}\}$, $\{\Omega_m,S_3^{(1)}\}$,$\{z,\omega\}$ $\{\epsilon(z),S_3^{(1)}\}$ and $\{z,Om\}$, we dsicover that the flat modified polytropic Cardassian (FMPC) scenario can be directly removed from the possible candidates of dark energy phenomenon, since its evolutional behavior deviates from the base cosmology scenario too much.

Observational constraints and differential diagnosis for cosmic evolutionary models

In this paper, we have proposed a plotting method based on the " natural plotting rule " (NPR) which can be used to distinguish different cosmological scenarios more efficiently and obtain more useful information. By using the NPR, we have avoided the blindness to use different diagnostics when discovering that some scenarios can be hardly differentiated from each other, and develop a logical line to adopt different diagnostics. As a concrete instance, we take this method based on the NPR to distinguish several Cardassian scenarios from the base cosmology scenario, and one from the other. We place constraints on three Cardassian cosmological scenarios and their flat versions by utilizing the Type Ia supernovae (SNe Ia), baryonic acoustic oscillations (BAO), cosmic microwave background (CMB) radiation, observational Hubble parameter (OHD) data-sets as well as the single data point from the newest event GW150914, and discover that our results are more stringent than previous results for constraining the cosmological parameters of the Cardassian scenarios. We find that the flat original Cardassian (FOC) and original Cardassian (OC) scenarios can only be distinguished in the plane of $\{\Omega_m,S_3^{(1)}\}$ at the present epoch, however, if applying the NPR to plot hierarchically for these Cardassian scenarios in the plane of $\{S_3^{(1)},S_4^{(1)}\}$, we can obtain more detailed information and distinguish the two scenarios better than before. More importantly, from the planes of $\{S_4,S_4^{(2)}\}$, $\{S_5^{(1)},S_5^{(2)}\}$, $\{S_3^{(2)},S_4^{(2)}\}$, $\{\Omega_m,S_3^{(1)}\}$,$\{z,\omega\}$ $\{\epsilon(z),S_3^{(1)}\}$ and $\{z,Om\}$, we dsicover that the flat modified polytropic Cardassian (FMPC) scenario can be directly removed from the possible candidates of dark energy phenomenon, since its evolutional behavior deviates from the base cosmology scenario too much.

Observational constraints and differential diagnosis for cosmic evolutionary models [Cross-Listing]

In this paper, we have proposed a plotting method based on the " natural plotting rule " (NPR) which can be used to distinguish different cosmological scenarios more efficiently and obtain more useful information. By using the NPR, we have avoided the blindness to use different diagnostics when discovering that some scenarios can be hardly differentiated from each other, and develop a logical line to adopt different diagnostics. As a concrete instance, we take this method based on the NPR to distinguish several Cardassian scenarios from the base cosmology scenario, and one from the other. We place constraints on three Cardassian cosmological scenarios and their flat versions by utilizing the Type Ia supernovae (SNe Ia), baryonic acoustic oscillations (BAO), cosmic microwave background (CMB) radiation, observational Hubble parameter (OHD) data-sets as well as the single data point from the newest event GW150914, and discover that our results are more stringent than previous results for constraining the cosmological parameters of the Cardassian scenarios. We find that the flat original Cardassian (FOC) and original Cardassian (OC) scenarios can only be distinguished in the plane of $\{\Omega_m,S_3^{(1)}\}$ at the present epoch, however, if applying the NPR to plot hierarchically for these Cardassian scenarios in the plane of $\{S_3^{(1)},S_4^{(1)}\}$, we can obtain more detailed information and distinguish the two scenarios better than before. More importantly, from the planes of $\{S_4,S_4^{(2)}\}$, $\{S_5^{(1)},S_5^{(2)}\}$, $\{S_3^{(2)},S_4^{(2)}\}$, $\{\Omega_m,S_3^{(1)}\}$,$\{z,\omega\}$ $\{\epsilon(z),S_3^{(1)}\}$ and $\{z,Om\}$, we dsicover that the flat modified polytropic Cardassian (FMPC) scenario can be directly removed from the possible candidates of dark energy phenomenon, since its evolutional behavior deviates from the base cosmology scenario too much.

Influence of large local and non-local bispectra on primordial black hole abundance

Primordial black holes represent a unique probe to constrain the early universe on small scales - providing the only constraints on the primordial power spectrum on the majority of scales. However, these constraints are strongly dependent on even small amounts of non-Gaussianity, which is unconstrained on scales significantly smaller than those visible in the CMB. This paper goes beyond previous considerations to consider the effects of a bispectrum of the equilateral, orthogonal and local shapes with arbitrary magnitude upon the abundance of primordial black holes. Non-Gaussian density maps of the early universe are generated from a given bispectrum and used to place constraints on the small scale power spectrum. When small, we show that the skewness provides an accurate estimate for how the constraint depends on non-Gaussianity, independently of the shape of the bispectrum. We show that the orthogonal template of non-Gaussianity has an order of magnitude weaker effect on the constraints than the local and equilateral templates.

Influence of large local and non-local bispectra on primordial black hole abundance [Replacement]

Primordial black holes represent a unique probe to constrain the early universe on small scales - providing the only constraints on the primordial power spectrum on the majority of scales. However, these constraints are strongly dependent on even small amounts of non-Gaussianity, which is unconstrained on scales significantly smaller than those visible in the CMB. This paper goes beyond previous considerations to consider the effects of a bispectrum of the equilateral, orthogonal and local shapes with arbitrary magnitude upon the abundance of primordial black holes. Non-Gaussian density maps of the early universe are generated from a given bispectrum and used to place constraints on the small scale power spectrum. When small, we show that the skewness provides an accurate estimate for how the constraint depends on non-Gaussianity, independently of the shape of the bispectrum. We show that the orthogonal template of non-Gaussianity has an order of magnitude weaker effect on the constraints than the local and equilateral templates.

Constraints on binary neutron star merger product from short GRB observations

Binary neutron star mergers are strong gravitational wave (GW) sources and the leading candidates to interpret short duration gamma-ray bursts (SGRBs). Under the assumptions that SGRBs are produced by double neutron star mergers, we use the statistical observational properties of {\em Swift} SGRBs and the mass distribution of Galactic double neutron star systems to place constraints on the neutron star equation of state (EoS) and the properties of the post-merger product. We show that current observations already put following tight constraints: 1) A neutron star EoS with a maximum mass close to a parameterization of $M_{\rm max} = 2.37\,M_\odot (1+1.58\times10^{-10} P^{-2.84})$ is favored; 2) The fractions for the several outcomes of NS-NS mergers are as follows: $\sim40\%$ prompt BHs, $\sim30\%$ supra-massive NSs that collapse to BHs in a range of delay time scales, and $\sim30\%$ stable NSs that never collapse; 3) The initial spin of the newly born supra-massive NSs should be near the breakup limit ($P_i\sim1 {\rm ms}$), which is consistent with the merger scenario; 4) The surface magnetic field of the merger products is typically $\sim 10^{15}$ G; 5) The ellipticity of the supra-massive NSs is $\epsilon \sim (0.004 - 0.007)$, so that strong GW radiation is released post the merger; 6) Even though the initial spin energy of the merger product is similar, the final energy output of the merger product that goes into the electromagnetic channel varies in a wide range from several $10^{49}$ erg to several $10^{52}$ erg, since a good fraction of spin energy is either released in the form of GW or falls into the black hole as the supra-massive NS collapses.

Growth of matter perturbations in clustered holographic dark energy cosmologies

We investigate the growth of matter fluctuations in holographic dark energy cosmologies. First we use an overall statistical analysis involving the latest observational data in order to place constraints on the cosmological parameters. Then we test the range of validity of the holographic dark energy models at the perturbation level and its variants from the concordance $\Lambda$ cosmology. Specifically, we provide a new analytical approach in order to derive, for the first time, the growth index of matter perturbations. Considering a homogeneous holographic dark energy we find that the growth index is $\gamma \approx \frac{4}{7}$ which is somewhat larger ($\sim 4.8\%$) than that of the usual $\Lambda$ cosmology, $\gamma^{(\Lambda)}\approx \frac{6}{11}$. Finally, if we allow clustering in the holographic dark energy models then the asymptotic value of the growth index is given in terms of the effective sound speed $c_{\rm e}$, namely $\gamma \approx \frac{3(1-c_{\rm e})}{7}$.

Growth of matter perturbations in clustered holographic dark energy cosmologies [Replacement]

We investigate the growth of matter fluctuations in holographic dark energy cosmologies. First we use an overall statistical analysis involving the latest observational data in order to place constraints on the cosmological parameters. Then we test the range of validity of the holographic dark energy models at the perturbation level and its variants from the concordance $\Lambda$ cosmology. Specifically, we provide a new analytical approach in order to derive, for the first time, the growth index of matter perturbations. Considering a homogeneous holographic dark energy we find that the growth index is $\gamma \approx \frac{4}{7}$ which is somewhat larger ($\sim 4.8\%$) than that of the usual $\Lambda$ cosmology, $\gamma^{(\Lambda)}\approx \frac{6}{11}$. Finally, if we allow clustering in the holographic dark energy models then the asymptotic value of the growth index is given in terms of the effective sound speed $c_{\rm eff}^2$, namely $\gamma \approx \frac{3(1-c_{\rm eff}^2)}{7}$.

We present the results from a joint Suzaku/NuSTAR broad-band spectral analysis of 3C 390.3. The high quality data enables us to clearly separate the primary continuum from the reprocessed components allowing us to detect a high energy spectral cut-off ($E_\text{cut}=117_{-14}^{+18}$ keV), and to place constraints on the Comptonization parameters of the primary continuum for the first time. The hard over soft compactness is 69$_{-24}^{+124}$ and the optical depth 4.1$_{-3.6}^{+0.5}$, this leads to an electron temperature of $30_{-8}^{+32}$ keV. Expanding our study of the Comptonization spectrum to the optical/UV by studying the simultaneous Swift-UVOT data, we find indications that the compactness of the corona allows only a small fraction of the total UV/optical flux to be Comptonized. Our analysis of the reprocessed emission show that 3C 390.3 only has a small amount of reflection (R~0.3), and of that the vast majority is from distant neutral matter. However we also discover a soft X-ray excess in the source, which can be described by a weak ionized reflection component from the inner parts of the accretion disk. In addition to the backscattered emission, we also detect the highly ionized iron emission lines Fe XXV and Fe XXVI.

Black hole mergers and blue stragglers from hierarchical triples formed in globular clusters [Replacement]

Hierarchical triple-star systems are expected to form frequently via close binary-binary encounters in the dense cores of globular clusters. In a sufficiently inclined triple, gravitational interactions between the inner and outer binary can cause large-amplitude oscillations in the eccentricity of the inner orbit ("Lidov-Kozai cycles"), which can lead to a collision and merger of the two inner components. In this paper we use Monte Carlo models of dense star clusters to identify all triple systems formed dynamically and we compute their evolution using a highly accurate three-body integrator which incorporates relativistic and tidal effects. We find that a large fraction of these triples evolve through a non-secular dynamical phase which can drive the inner binary to higher eccentricities than predicted by the standard secular perturbation theory (even including octupole-order terms). We place constraints on the importance of Lidov-Kozai-induced mergers for producing: (i) gravitational wave sources detectable by Advanced LIGO (aLIGO), for triples with an inner pair of stellar black holes; and (ii) blue straggler stars, for triples with main-sequence-star components. We find a realistic aLIGO detection rate of black hole mergers due to the Lidov-Kozai mechanism of 2yr^-1, with about 20% of these having a finite eccentricity when they first chirp into the aLIGO frequency band. While rare, these events are likely to dominate among eccentric compact object inspirals that are potentially detectable by aLIGO. For blue stragglers, we find that the Lidov-Kozai mechanism can contribute only up to ~10% of their total numbers in globular clusters.

Black hole mergers and blue stragglers from hierarchical triples formed in globular clusters

Hierarchical triple-star systems are expected to form frequently via close binary-binary encounters in the dense cores of globular clusters. In a sufficiently inclined triple, gravitational interactions between the inner and outer binary can cause large-amplitude oscillations in the eccentricity of the inner orbit ("Lidov-Kozai cycles"), which can lead to a collision and merger of the two inner components. In this paper we use Monte Carlo models of dense star clusters to identify all triple systems formed dynamically and we compute their evolution using a highly accurate three-body integrator which incorporates relativistic and tidal effects. We find that a large fraction of these triples evolve through a non-secular dynamical phase which can drive the inner binary to higher eccentricities than predicted by the standard secular perturbation theory (even including octupole-order terms). We place constraints on the importance of Lidov-Kozai-induced mergers for producing: (i) gravitational wave sources detectable by Advanced LIGO (aLIGO), for triples with an inner pair of stellar black holes; and (ii) blue straggler stars, for triples with main-sequence-star components. We find a realistic aLIGO detection rate of black hole mergers due to the Lidov-Kozai mechanism of 2yr^-1, with about 20% of these having a finite eccentricity when they first chirp into the aLIGO frequency band. While rare, these events are likely to dominate among eccentric compact object inspirals that are potentially detectable by aLIGO. For blue stragglers, we find that the Lidov-Kozai mechanism can contribute up to ~10% of their total numbers in globular clusters. In clusters with low central densities, ~10^{3}-10^{4} M_Sun pc^-3, up to ~40% of binary blue stragglers could have formed in dynamically assembled triples.

Horava Gravity in the Effective Field Theory formalism: from cosmology to observational constraints [Replacement]

We consider Horava gravity within the framework of the effective field theory (EFT) of dark energy and modified gravity. We work out a complete mapping of the theory into the EFT language for an action including all the operators which are relevant for linear perturbations with up to sixth order spatial derivatives. We then employ an updated version of the EFTCAMB/EFTCosmoMC package to study the cosmology of the low-energy limit of Horava gravity and place constraints on its parameters using several cosmological data sets. In particular we use cosmic microwave background (CMB) temperature-temperature and lensing power spectra by Planck 2013, WMAP low-l polarization spectra, WiggleZ galaxy power spectrum, local Hubble measurements, Supernovae data from SNLS, SDSS and HST and the baryon acoustic oscillations measurements from BOSS, SDSS and 6dFGS. We get improved upper bounds, with respect to those from Big Bang Nucleosynthesis, on the deviation of the cosmological gravitational constant from the local Newtonian one. At the level of the background phenomenology, we find a relevant rescaling of the Hubble rate at all epoch, which has a strong impact on the cosmological observables; at the level of perturbations, we discuss in details all the relevant effects on the observables and find that in general the quasi-static approximation is not safe to describe the evolution of perturbations. Overall we find that the effects of the modifications induced by the low-energy Horava gravity action are quite dramatic and current data place tight bounds on the theory parameters.

Horava Gravity in the Effective Field Theory formalism: from cosmology to observational constraints [Replacement]

We consider Horava gravity within the framework of the effective field theory (EFT) of dark energy and modified gravity. We work out a complete mapping of the theory into the EFT language for an action including all the operators which are relevant for linear perturbations with up to sixth order spatial derivatives. We then employ an updated version of the EFTCAMB/EFTCosmoMC package to study the cosmology of the low-energy limit of Horava gravity and place constraints on its parameters using several cosmological data sets. In particular we use cosmic microwave background (CMB) temperature-temperature and lensing power spectra by Planck 2013, WMAP low-l polarization spectra, WiggleZ galaxy power spectrum, local Hubble measurements, Supernovae data from SNLS, SDSS and HST and the baryon acoustic oscillations measurements from BOSS, SDSS and 6dFGS. We get improved upper bounds, with respect to those from Big Bang Nucleosynthesis, on the deviation of the cosmological gravitational constant from the local Newtonian one. At the level of the background phenomenology, we find a relevant rescaling of the Hubble rate at all epoch, which has a strong impact on the cosmological observables; at the level of perturbations, we discuss in details all the relevant effects on the observables and find that in general the quasi-static approximation is not safe to describe the evolution of perturbations. Overall we find that the effects of the modifications induced by the low-energy Horava gravity action are quite dramatic and current data place tight bounds on the theory parameters.

Horava Gravity in the Effective Field Theory formalism: from cosmology to observational constraints

We consider Horava gravity within the framework of the EFT of dark energy and modified gravity. We work out a complete mapping of the theory into the EFT language for an action including all the operators which are relevant for linear perturbations with up to sixth order spatial derivatives. We then employ an updated version of the EFTCAMB/EFTCosmoMC package to study the cosmology of the low-energy limit of Horava gravity and place constraints on its parameters using several cosmological data sets. In particular we consider two cases: the first in which the three parameters of the low-energy theory are all varied and a second case that is tuned to evade PPN constraints, reducing the number of free parameters to two. We employ data sets which include the CMB TT and lensing power spectra by Planck 2013, WMAP low-l polarization spectra, the WiggleZ galaxy power spectrum, the local Hubble measurements, Supernovae data from SNLS, SDSS and HST and the BAO measurements from BOSS, SDSS and 6dFGS. For both cases we estimate the deviation of the cosmological gravitational constant from the local Newtonian one, getting improved upper bounds with respect to the previous ones from BBN data. At the level of the background, we find a relevant rescaling of the Hubble rate at all epoch, which has a strong impact on the cosmological observables; at the level of perturbations, we discuss all the relevant effects that the modifications of gravity induce, ranging from modifications of the late time ISW effect, the growth of matter perturbations, gravitational lensing and differences in the B-modes of the CMB. In general the quasi-static approximation is not safe to describe the evolution of perturbations in Horava gravity. Overall we find that the effects of the modifications induced by the low-energy Horava gravity action are quite dramatic and current data place tight bounds on the theory parameters.

Horava Gravity in the Effective Field Theory formalism: from cosmology to observational constraints [Replacement]

We consider Horava gravity within the framework of the effective field theory (EFT) of dark energy and modified gravity. We work out a complete mapping of the theory into the EFT language for an action including all the operators which are relevant for linear perturbations with up to sixth order spatial derivatives. We then employ an updated version of the EFTCAMB/EFTCosmoMC package to study the cosmology of the low-energy limit of Horava gravity and place constraints on its parameters using several cosmological data sets. In particular we use cosmic microwave background (CMB) temperature-temperature and lensing power spectra by Planck 2013, WMAP low-l polarization spectra, WiggleZ galaxy power spectrum, local Hubble measurements, Supernovae data from SNLS, SDSS and HST and the baryon acoustic oscillations measurements from BOSS, SDSS and 6dFGS. We get improved upper bounds, with respect to those from Big Bang Nucleosynthesis, on the deviation of the cosmological gravitational constant from the local Newtonian one. At the level of the background phenomenology, we find a relevant rescaling of the Hubble rate at all epoch, which has a strong impact on the cosmological observables; at the level of perturbations, we discuss in details all the relevant effects on the observables and find that in general the quasi-static approximation is not safe to describe the evolution of perturbations. Overall we find that the effects of the modifications induced by the low-energy Horava gravity action are quite dramatic and current data place tight bounds on the theory parameters.

Horava Gravity in the Effective Field Theory formalism: from cosmology to observational constraints [Cross-Listing]

We consider Horava gravity within the framework of the EFT of dark energy and modified gravity. We work out a complete mapping of the theory into the EFT language for an action including all the operators which are relevant for linear perturbations with up to sixth order spatial derivatives. We then employ an updated version of the EFTCAMB/EFTCosmoMC package to study the cosmology of the low-energy limit of Horava gravity and place constraints on its parameters using several cosmological data sets. In particular we consider two cases: the first in which the three parameters of the low-energy theory are all varied and a second case that is tuned to evade PPN constraints, reducing the number of free parameters to two. We employ data sets which include the CMB TT and lensing power spectra by Planck 2013, WMAP low-l polarization spectra, the WiggleZ galaxy power spectrum, the local Hubble measurements, Supernovae data from SNLS, SDSS and HST and the BAO measurements from BOSS, SDSS and 6dFGS. For both cases we estimate the deviation of the cosmological gravitational constant from the local Newtonian one, getting improved upper bounds with respect to the previous ones from BBN data. At the level of the background, we find a relevant rescaling of the Hubble rate at all epoch, which has a strong impact on the cosmological observables; at the level of perturbations, we discuss all the relevant effects that the modifications of gravity induce, ranging from modifications of the late time ISW effect, the growth of matter perturbations, gravitational lensing and differences in the B-modes of the CMB. In general the quasi-static approximation is not safe to describe the evolution of perturbations in Horava gravity. Overall we find that the effects of the modifications induced by the low-energy Horava gravity action are quite dramatic and current data place tight bounds on the theory parameters.