# Posts Tagged spatial resolution

## Recent Postings from spatial resolution

### Highly Multiplexible Thermal Kinetic Inductance Detectors for X-Ray Imaging Spectroscopy

For X-ray imaging spectroscopy, high spatial resolution over a large field of view is often as important as high energy resolution, but current X-ray detectors do not provide both in the same device. Thermal Kinetic Inductance Detectors (TKIDs) are being developed as they offer a feasible way to combine the energy resolution of transition edge sensors with pixel counts approaching CCDs and thus promise significant improvements for many X-ray spectroscopy applications. TKIDs are a variation of Microwave Kinetic Inductance Detectors (MKIDs) and share their multiplexibility: working MKID arrays with 2024 pixels have recently been demonstrated and much bigger arrays are under development. In this work, we present our first working TKID prototypes which are able to achieve an energy resolution of 75 eV at 5.9 keV, even though their general design still has to be optimized. We further describe TKID fabrication, characterization, multiplexing and working principle and demonstrate the necessity of a data fitting algorithm in order to extract photon energies. With further design optimizations we expect to be able to improve our TKID energy resolution to less than 10 eV at 5.9 keV.

### High resolution imaging of NGC 2346 with GSAOI/GeMS: disentangling the planetary nebula molecular structure to understand its origin and evolution

We present high spatial resolution ($\approx$ 60–90 milliarcseconds) images of the molecular hydrogen emission in the Planetary Nebula (PN) NGC 2346. The data were acquired during the System Verification of the Gemini Multi-Conjugate Adaptive Optics System + Gemini South Adaptive Optics Imager. At the distance of NGC 2346, 700 pc, the physical resolution corresponds to $\approx$ 56 AU, which is slightly higher than that an [N II] image of NGC 2346 obtained with HST/WFPC2. With this unprecedented resolution we were able to study in detail the structure of the H$_2$ gas within the nebula for the first time. We found it to be composed of knots and filaments, which at lower resolution had appeared to be a uniform torus of material. We explain how the formation of the clumps and filaments in this PN is consistent with a mechanism in which a central hot bubble of nebular gas surrounding the central star has been depressurized, and the thermal pressure of the photoionized region drives the fragmentation of the swept-up shell.

### HST/WFC3 Observations of an Off-Nuclear Superbubble in Arp 220

We present a high spatial resolution optical and infrared study of the circumnuclear region in Arp 220, a late-stage galaxy merger. Narrowband imaging using HST/WFC3 has resolved the previously observed peak in H$\alpha$+[NII] emission into a bubble-shaped feature. This feature measures 1.6" in diameter, or 600 pc, and is only 1" northwest of the western nucleus. The bubble is aligned with the western nucleus and the large-scale outflow axis seen in X-rays. We explore several possibilities for the bubble origin, including a jet or outflow from a hidden active galactic nucleus (AGN), outflows from high levels of star formation within the few hundred pc nuclear gas disk, or an ultraluminous X-ray source. An obscured AGN or high levels of star formation within the inner $\sim$100 pc of the nuclei are favored based on the alignment of the bubble and energetics arguments.

### Evolution of Near-surface Flows Inferred from High-resolution Ring-diagram Analysis

Ring-diagram analysis of acoustic waves observed at the photosphere can provide a relatively robust determination of the sub-surface flows at a particular time under a particular region. The depth of penetration of the waves is related to the size of the region, hence the depth extent of the measured flows is inversely proportional to the spatial resolution. Most ring-diagram analysis has focused on regions of extent ~15{\deg} (180 Mm) or more in order to provide reasonable mode sets for inversions. HMI data analysis also provides a set of ring fit parameters on a scale three times smaller. These provide flow estimates for the outer 1% (7 Mm) of the Sun only, with very limited depth resolution, but with spatial resolution adequate to map structures potentially associated with the belts and regions of magnetic activity. There are a number of systematic effects affecting the determination of flows from local helioseismic analysis of regions over different parts of the observable disk, not all well understood. In this study we characterize those systematic effects with higher spatial resolution, so that they may more effectively be accounted for in mapping temporal and spatial evolution of the flows. Leaving open the question of the mean structure of the global meridional circulation and the differential rotation, we describe the near-surface flow anomalies in time and latitude corresponding to the torsional oscillation pattern in differential rotation and analogous patterns in the meridional cell structure as observed by SDO/HMI.

### Resolving structure of the disk around HD100546 at 7 mm with ATCA

There is much evidence that planet formation is occurring in the disk around the Herbig Be star HD100546. To learn more about the processes occurring in this disk we conducted high resolution imaging at 43/45 GHz with the Australia Telescope Compact Array (ATCA). Multiple array configurations were used, providing a best spatial resolution of $\sim$ 0.15 arcsec, or 15 AU at HD100546′s distance of $\sim$ 100 pc. Significant structure is revealed, but its precise form is dependent on the $u-v$ plane sampling used for the image reconstruction. At a resolution of $\leq$ 30 AU we detected an inner gap in the disk with a radius of $\sim$ 25 AU and a position angle approximately along the known disk major axis. With different weighting, and an achieved resolution of $\sim$ 15 AU, emission appears at the centre and the disk takes on the shape of an incomplete ring, much like a horseshoe, again with a gap radius of $\sim$ 25 AU. The position angle of the disk major axis and its inclination from face-on are determined to be $140^{\circ}\pm5^{\circ}$ and $40^{\circ}\pm5^{\circ}$ respectively. The $\sim$ 25 AU gap radius is confirmed by a null in the real part of the binned visibilities at 320$\pm$10 k$\lambda$, whilst the non-axisymmetric nature is also confirmed through significant structure in the imaginary component. The emission mechanism at the central peak is most likely to be free-free emission from a stellar or disk wind. Overall our data support the picture of at least one, but probably several, giant planets orbiting HD100546 within 25 AU.

### Cyclic behavior of solar inter-network magnetic field

Solar inter-network magnetic field is the weakest component of solar magnetism, but contributes most of the solar surface magnetic flux. The study on its origin has been constrained by the inadequate tempo-spatial resolution and sensitivity of polarization observations. With dramatic advances in spatial resolution and detective sensitivity, solar spectro-polarimetry provided by the Solar Optical Telescope aboard Hinode in an interval from solar minimum to maximum of cycle 24 opens an unprecedented opportunity to study the cyclic behavior of solar inter-network magnetic field. More than 1000 Hinode magnetograms observed from 2007 January to 2014 August are selected in the study. It has been found that there is a very slight correlation between sunspot number and magnetic field at the inter-network flux spectrum. From solar minimum to maximum of cycle 24, the flux density of solar inter-network field is invariant, which is 10$\pm1$ G. The observations suggest that the inter-network magnetic field does not arise from the flux diffusion or flux recycling of solar active regions, thereby indicating the existence of a locally small-scale dynamo. Combining the full-disk magnetograms observed by SOHO/MDI and SDO/HMI in the same period, we find that the area ratio of the inter-network region to the full-disk of the Sun apparently decreases from solar minimum to maximum but always exceeds 60\% even though in the phase of solar maximum.

### Examining the T Tauri system with SPHERE

Context. The prototypical low-mass young stellar object, T Tauri, is a well-studied multiple system with at least three components. Aims. We aim to explore the T Tau system with the highest spatial resolution, study the time evolution of the known components, and re-determine the orbital parameters of the stars. Methods. Near-infrared classical imaging and integral field spectrograph observations were obtained during the Science Verification of SPHERE, the new high-contrast imaging facility at the VLT. The obtained FWHM of the primary star varies between 0.050" and 0.059", making these the highest spatial resolution near-infrared images of the T Tauri system obtained to date. Results. Our near-infrared images confirm the presence of extended emission south of T Tau Sa, reported in the literature. New narrow-band images show, for the first time, that this feature shows strong emission in both the Br-{\gamma} and H2 1-0 S(1) lines. Broadband imaging at 2.27 {\mu}m shows that T Tau Sa is 0.92 mag brighter than T Tau Sb, which is in contrast to observations from Jan. 2014 (when T Tau Sa was fainter than Sb), and demonstrates that T Tau Sa has entered a new period of high variability. The newly obtained astrometric positions of T Tau Sa and Sb agree with orbital fits from previous works. The orbit of T Tau S (the center of gravity of Sa and Sb) around T Tau N is poorly constrained by the available observations and can be fit with a range of orbits ranging from a nearly circular orbit with a period of 475 years to highly eccentric orbits with periods up to 2.7*10^4 years. We also detected a feature south of T Tau N, at a distance of $144 \pm 3$ mas, which shows the properties of a new companion.

### Examining the T Tauri system with SPHERE [Replacement]

Context. The prototypical low-mass young stellar object, T Tauri, is a well-studied multiple system with at least three components. Aims. We aim to explore the T Tau system with the highest spatial resolution, study the time evolution of the known components, and re-determine the orbital parameters of the stars. Methods. Near-infrared classical imaging and integral field spectrograph observations were obtained during the Science Verification of SPHERE, the new high-contrast imaging facility at the VLT. The obtained FWHM of the primary star varies between 0.050" and 0.059", making these the highest spatial resolution near-infrared images of the T Tauri system obtained to date. Results. Our near-infrared images confirm the presence of extended emission south of T Tau Sa, reported in the literature. New narrow-band images show, for the first time, that this feature shows strong emission in both the Br-{\gamma} and H2 1-0 S(1) lines. Broadband imaging at 2.27 {\mu}m shows that T Tau Sa is 0.92 mag brighter than T Tau Sb, which is in contrast to observations from Jan. 2014 (when T Tau Sa was fainter than Sb), and demonstrates that T Tau Sa has entered a new period of high variability. The newly obtained astrometric positions of T Tau Sa and Sb agree with orbital fits from previous works. The orbit of T Tau S (the center of gravity of Sa and Sb) around T Tau N is poorly constrained by the available observations and can be fit with a range of orbits ranging from a nearly circular orbit with a period of 475 years to highly eccentric orbits with periods up to 2.7*10^4 years. We also detected a feature south of T Tau N, at a distance of $144 \pm 3$ mas, which shows the properties of a new companion.

### AGN Reverberation Mapping

Reverberation mapping is now a well-established technique for investigating spatially-unresolved structures in the nuclei of distant galaxies with actively-accreting supermassive black holes. Structural parameters for the broad emission-line region, with angular sizes of microarcseconds, can be constrained through the substitution of time resolution for spatial resolution. Many reverberation experiments over the last 30 years have led to a practical understanding of the requirements necessary for a successful program. With reverberation measurements now in hand for 60 active galaxies, and more on the horizon, we are able to directly constrain black hole masses, derive scaling relationships that allow large numbers of black hole mass estimates throughout the observable Universe, and begin investigating the detailed geometry and kinematics of the broad line region. Reverberation mapping is therefore one of the few techniques available that will allow a deeper understanding of the physical mechanisms involved in AGN feeding and feedback at very small scales, as well as constraints on the growth and evolution of black holes across cosmic time. In this contribution, I will briefly review the background, implementation, and major results derived from this high angular resolution technique.

### Calibration and performance of the STAR Muon Telescope Detector using cosmic rays [Cross-Listing]

We report the timing and spatial resolution from the Muon Telescope Detec- tor (MTD) installed in the STAR experiment at RHIC. Cosmic ray muons traversing the STAR detector have an average transverse momentum of 6 GeV/c. Due to their very small multiple scattering, these cosmic muons pro- vide an ideal tool to calibrate the detectors and measure their timing and spatial resolution. The values obtained were ?100 ps and ?1-2 cm, respec- tively. These values are comparable to those obtained from cosmic-ray bench tests and test beams.