Search

We present the largest Galactic neutral hydrogen HI absorption survey to date, utilizing the Australian SKA Pathfinder Telescope at an unprecedented spatial resolution of 30''. This survey, GASKAP-HI, unbiasedly targets 2,714 continuum background sources over 250 square degrees in the direction of the Magellanic Clouds, a significant increase compared to a total of 373 sources observed by previous Galactic absorption surveys across the entire Milky Way. We aim to investigate the physical properties of cold (CNM) and warm (WNM) neutral atomic gas in the Milky Way foreground, characterized by two prominent filaments at high Galactic latitudes (between $-45^{\circ}$ and $-25^{\circ}$). We detected strong HI absorption along 462 lines of sight above the 3$\sigma$ threshold, achieving an absorption detection rate of 17%. GASKAP-HI's unprecedented angular resolution allows for simultaneous absorption and emission measurements to sample almost the same gas clouds along a line of sight. A joint Gaussian decomposition is then applied to absorption-emission spectra to provide direct estimates of HI optical depths, temperatures, and column densities for the CNM and WNM components. The thermal properties of CNM components are consistent with those previously observed along a wide range of Solar neighborhood environments, indicating that cold HI properties are widely prevalent throughout the local interstellar medium. Across our region of interest, CNM accounts for ~30% of the total HI gas, with the CNM fraction increasing with column density toward the two filaments. Our analysis reveals an anti-correlation between CNM temperature and its optical depth, which implies that CNM with lower optical depth leads to a higher temperature., Comment: Largest Galactic HI Absorption Survey To Date (GASKAP-HI): Cold Atomic Gas in the Magellanic Cloud foreground using Australian SKA Pathfinder. This paper has 19 pages, 17 figures. This paper has been accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journal

Measuring the properties of the cold neutral medium (CNM) in low-metallicity galaxies provides insight into heating and cooling mechanisms in early Universe-like environments. We report detections of two localized atomic neutral hydrogen (HI) absorption features in NGC 6822, a low-metallicity (0.2 Z$_{\odot}$) dwarf galaxy in the Local Group. These are the first unambiguous CNM detections in a low-metallicity dwarf galaxy outside the Magellanic Clouds. The Local Group L-Band Survey (LGLBS) enabled these detections due to its high spatial (15 pc for HI emission) and spectral (0.4 \kms) resolution. We introduce LGLBS and describe a custom pipeline to search for HI absorption at high angular resolution and extract associated HI emission. A detailed Gaussian decomposition and radiative transfer analysis of the NGC 6822 detections reveals five CNM components, with key properties: a mean spin temperature of 32$\pm$6 K, a mean CNM column density of 3.1$\times$10$^{20}$ cm$^{-2}$, and CNM mass fractions of 0.33 and 0.12 for the two sightlines. Stacking non-detections does not reveal low-level signals below our median optical depth sensitivity of 0.05. One detection intercepts a star-forming region, with the HI absorption profile encompassing the CO (2$-$1) emission, indicating coincident molecular gas and a depression in high-resolution HI emission. We also analyze a nearby sightline with deep, narrow HI self-absorption dips, where the background warm neutral medium is attenuated by intervening CNM. The association of CNM, CO, and H$\alpha$ emissions suggests a close link between the colder, denser HI phase and star formation in NGC 6822., Comment: 20 pages, 11 figures, accepted for publication in ApJ

The structure and dynamics of the star-forming disk of the Small Magellanic Cloud (SMC) have long confounded us. The SMC is widely used as a prototype for galactic physics at low metallicity, and yet we fundamentally lack an understanding of the structure of its interstellar medium (ISM). In this work, we present a new model for the SMC by comparing the kinematics of young, massive stars with the structure of the ISM traced by high-resolution observations of neutral atomic hydrogen (HI) from the Galactic Australian Square Kilometer Array Pathfinder survey (GASKAP-HI). Specifically, we identify thousands of young, massive stars with precise radial velocity constraints from the Gaia and APOGEE surveys and match these stars to the ISM structures in which they likely formed. By comparing the average dust extinction towards these stars, we find evidence that the SMC is composed of two structures with distinct stellar and gaseous chemical compositions. We construct a simple model that successfully reproduces the observations and shows that the ISM of the SMC is arranged into two, superimposed, star-forming systems with similar gas mass separated by ~5 kpc along the line of sight., Comment: ApJ accepted. 20 pages, 18 figures

We probe the neutral circumgalactic medium (CGM) along the major axes of NGC891 and NGC4565 in 21-cm emission out to $\gtrsim 100$kpc using the Green Bank Telescope (GBT), extending our previous minor axes observations. We achieve an unprecedented $5\sigma$ sensitivity of $6.1\times 10^{16}$ cm$^{-2}$ per 20 km s$^{-1}$ velocity channel. We detect HI with diverse spectral shapes, velocity widths, and column densities. We compare our detections to the interferometric maps from the Westerbork Synthesis Radio Telescope (WSRT) obtained as part of the HALOGAS survey. At small impact parameters, $> 31-43\%$ of the emission detected by the GBT cannot be explained by emission seen in the WSRT maps, and it increases to $> 64-73\%$ at large impact parameters. This implies the presence of diffuse circumgalactic HI. The mass ratio between HI in the CGM and HI in the disk is an order of magnitude larger than previous estimates based on shallow GBT mapping. The diffuse HI along the major axes pointings is corotating with the HI disk. The velocity along the minor axes pointings is consistent with an inflow and/or fountain in NGC891 and an inflow/outflow in NGC4565. Including the circumgalactic HI, the depletion time and the accretion rate of NGC4565 are sufficient to sustain its star formation. In NGC891, most of the required accreting material is still missing., Comment: 18 pages, 12 figures, accepted for publication in MNRAS

Star formation in galaxies is regulated by turbulence, outflows, gas heating and cloud dispersal -- processes which depend sensitively on the properties of the interstellar medium (ISM) into which supernovae (SNe) explode. Unfortunately, direct measurements of ISM environments around SNe remain scarce, as SNe are rare and often distant. Here we demonstrate a new approach: mapping the ISM around the massive stars that are soon to explode. This provides a much larger census of explosion sites than possible with only SNe, and allows comparison with sensitive, high-resolution maps of the atomic and molecular gas from the Jansky VLA and ALMA. In the well-resolved Local Group spiral M33, we specifically observe the environments of red supergiants (RSGs, progenitors of Type II SNe), Wolf-Rayet stars (WRs, tracing stars $>$30 M$_{\odot}$, and possibly future stripped-envelope SNe), and supernova remnants (SNRs, locations where SNe have exploded). We find that massive stars evolve not only in dense, molecular-dominated gas (with younger stars in denser gas), but also a substantial fraction ($\sim$45\% of WRs; higher for RSGs) evolve in lower-density, atomic-gas-dominated, inter-cloud media. We show that these measurements are consistent with expectations from different stellar-age tracer maps, and can be useful for validating SN feedback models in numerical simulations of galaxies. Along with the discovery of a 20-pc diameter molecular gas cavity around a WR, these findings re-emphasize the importance of pre-SN/correlated-SN feedback evacuating the dense gas around massive stars before explosion, and the need for high-resolution (down to pc-scale) surveys of the multi-phase ISM in nearby galaxies., Comment: 34 pages, 14 figures. Submitted to ApJ. Comments welcome! The density distributions will be made publicly available after journal acceptance of manuscript. Please feel free to contact us in the meantime if you would like to use them

Interstellar turbulence shapes the HI distribution in the Milky Way (MW). How this affects large-scale statistical properties of HI column density across the MW remains largely unconstrained. We use approx 13,000 square-degree GALFA-HI survey to map statistical fluctuations of HI over the 40 km s-1 velocity range. We calculate the spatial power spectrum (SPS) of HI column density image by running a 3-degree kernel and measuring SPS slope over a range of angular scales from 16 arcmin to 20 degree. Due to GALFA complex observing and calibration strategy, we construct detailed estimates of the noise contribution and account for GALFA beam effects on SPS. This allows us to systematically analyze HI images that trace a wide range of interstellar environments. We find that SPS slope varies between -2.6 at high Galactic latitudes, and -3.2 close to Galactic plane. The range of SPS slope values becomes tighter when we consider HI optical depth and line-of-sight length caused by the plane-parallel geometry of HI disk. This relatively uniform, large-scale distribution of SPS slope is suggestive of large-scale turbulent driving being a dominant mechanism for shaping HI structures in the MW and/or the stellar feedback turbulence being efficiently dissipated within dense molecular clouds. Only at latitudes above 60 degrees we find evidence for HI SPS slope being consistently more shallow. Those directions are largely within the Local Bubble, suggesting the recent history of this cavity, shaped by multiple supernovae explosions, has modified the turbulent state of HI and/or fractions of HI phases., Comment: Accepted in ApJ

Turbulence plays a crucial role in shaping the structure of the interstellar medium. The ratio of the three-dimensional density contrast ($\sigma_{\rho/\rho_0}$) to the turbulent sonic Mach number ($\mathcal{M}$) of an isothermal, compressible gas describes the ratio of solenoidal to compressive modes in the turbulent acceleration field of the gas, and is parameterised by the turbulence driving parameter: $b=\sigma_{\rho/\rho_0}/\mathcal{M}$. The turbulence driving parameter ranges from $b=1/3$ (purely solenoidal) to $b=1$ (purely compressive), with $b=0.38$ characterising the natural mixture (1/3~compressive, 2/3~solenoidal) of the two driving modes. Here we present a new method for recovering $\sigma_{\rho/\rho_0}$, $\mathcal{M}$, and $b$, from observations on galactic scales, using a roving kernel to produce maps of these quantities from column density and centroid velocity maps. We apply our method to high-resolution HI emission observations of the Small Magellanic Cloud (SMC) from the GASKAP-HI survey. We find that the turbulence driving parameter varies between $b\sim 0.3$ and $b\sim 1.0$ within the main body of the SMC, but the median value converges to $b\sim0.51$, suggesting that the turbulence is overall driven more compressively ($b>0.38$). We observe no correlation between the $b$ parameter and HI or H$\alpha$ intensity, indicating that compressive driving of HI turbulence cannot be determined solely by observing HI or H$\alpha$ emission density, and that velocity information must also be considered. Further investigation is required to link our findings to potential driving mechanisms such as star-formation feedback, gravitational collapse, or cloud-cloud collisions., Comment: 20 pages, 16 figures, accepted to MNRAS

Modern interferometers routinely provide radio-astronomical images down to subarcsecond resolution. However, interferometers filter out spatial scales larger than those sampled by the shortest baselines, which affects the measurement of both spatial and spectral features. Complementary single-dish data are vital for recovering the true flux distribution of spatially resolved astronomical sources with such extended emission. In this work, we provide an overview of the prominent available methods to combine single-dish and interferometric observations. We test each of these methods in the framework of the CASA data analysis software package on both synthetic continuum and observed spectral data sets. We develop a set of new assessment tools that are generally applicable to all radio-astronomical cases of data combination. Applying these new assessment diagnostics, we evaluate the methods' performance and demonstrate the significant improvement of the combined results in comparison to purely interferometric reductions. We provide combination and assessment scripts as add-on material. Our results highlight the advantage of using data combination to ensure high-quality science images of spatially resolved objects., Comment: 29 pages, 20 figures. Accepted for publication in PASP. Code repository available at: github.com/teuben/DataComb

High-spatial-resolution HI observations have led to the realisation that the nearby (within few hundreds of parsecs) Galactic atomic filamentary structures are aligned with the ambient magnetic field. Enabled by the high quality data from the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope for the Galactic ASKAP HI (GASKAP-HI) survey, we investigate the potential magnetic alignment of the $\gtrsim 10\,{\rm pc}$-scale HI filaments in the Small Magellanic Cloud (SMC). Using the Rolling Hough Transform (RHT) technique that automatically identifies filamentary structures, combined with our newly devised ray-tracing algorithm that compares the HI and starlight polarisation data, we find that the HI filaments in the northeastern end of the SMC main body ("Bar" region) and the transition area between the main body and the tidal feature ("Wing" region) appear preferentially aligned with the magnetic field traced by starlight polarisation. Meanwhile, the remaining SMC volume lacks starlight polarisation data of sufficient quality to draw any conclusions. This suggests for the first time that filamentary HI structures can be magnetically aligned across a large spatial volume ($\gtrsim\,{\rm kpc}$) outside of the Milky Way. In addition, we generate maps of the preferred orientation of HI filaments throughout the entire SMC, revealing the highly complex gaseous structures of the galaxy likely shaped by a combination of the intrinsic internal gas dynamics, tidal interactions, and star formation feedback processes. These maps can further be compared with future measurements of the magnetic structures in other regions of the SMC., Comment: 24 pages, MNRAS accepted

We present SAMI-HI, a survey of the atomic hydrogen content of 296 galaxies with integral field spectroscopy available from the SAMI Galaxy Survey. The sample spans nearly 4 dex in stellar mass ($M_\star = 10^{7.4}-10^{11.1}~ \rm M_\odot$), redshift $z<0.06$, and includes new Arecibo observations of 153 galaxies, for which we release catalogues and HI spectra. We use these data to compare the rotational velocities obtained from optical and radio observations and to show how systematic differences affect the slope and scatter of the stellar-mass and baryonic Tully-Fisher relations. Specifically, we show that H$\alpha$ rotational velocities measured in the inner parts of galaxies (1.3 effective radii in this work) systematically underestimate HI global measurements, with HI/H$\alpha$ velocity ratios that increase at low stellar masses, where rotation curves are typically still rising and H$\alpha$ measurements do not reach their plateau. As a result, the H$\alpha$ stellar mass Tully-Fisher relation is steeper (when $M_\star$ is the independent variable) and has larger scatter than its HI counterpart. Interestingly, we confirm the presence of a small fraction of low-mass outliers of the H$\alpha$ relation that are not present when HI velocity widths are used and are not explained by "aperture effects". These appear to be highly disturbed systems for which H$\alpha$ widths do not provide a reliable estimate of the rotational velocity. Our analysis reaffirms the importance of taking into account differences in velocity definitions as well as tracers used when interpreting offsets from the Tully-Fisher relation, at both low and high redshifts and when comparing with simulations., Comment: 18 pages, 12 figures. Accepted for publication in MNRAS

States collectively invest over $12 billion a year to support over 4.5 million students through financial aid programs. This interactive 50-State Comparison provides a look at the specific criteria employed in the top two largest aid programs by state. This interactive resource includes details about which state programs are linked to measuring need through the federally calculated Estimated Family Contribution (EFC) or purely family income. On the merit side, this 50-State Comparison includes details about which state programs use GPA or SAT/ACT scores to determine eligibility. It also includes information on which states require a Free Application for Federal Student Aid (FAFSA) or use their own state application process for aid. Finally, following federal action to simplify the FAFSA form, it catalogs which state aid programs specifically require Selective Service registration or restrict eligibility for students with drug convictions. Hyperlinked data tables for 50-State Comparisons on these dimensions are provided. A state-level profile of all data points can be viewed by going to the individual state profiles page.

Galaxies in the local Universe are thought to require ongoing replenishment of their gas reservoir in order to maintain the observed star formation rates. Cosmological simulations predict that such accretion can occur in both a dynamically hot and cold mode. However, until now observational evidence of the accretion required to match the observed star formation histories is lacking. This paper attempts to determine whether galaxies in the local Universe possess a significant reservoir of HI and what would be the accretion rates derived from such reservoirs. We search the vicinity of 22 nearby galaxies for isolated HI clouds or distinct streams in a systematic and automated manner. The HALOGAS observations represent one of the most sensitive and detailed HI surveys to date. These observations typically reach column density sensitivities of 10^19 cm^-2 over a 20 km/s width. We find 14 secure HI cloud candidates without an observed optical counterpart. These cloud candidates appear to be analogues to the most massive clouds detected around the Milky Way and M31. However, on average their numbers seem significantly reduced. We constrain upper limits for HI accretion in the local Universe. The average HI mass currently observed amounts to a rate of 0.05 Msun/yr with a stringent upper limit of 0.22 Msun/yr, confirming previous estimates. This is much lower than the average star formation rate in this sample. Our best estimate, based on GBT detection limits of several galaxies, suggests that another 0.04 Msun/yr could be accreted from undetected clouds and streams. These results show that in nearby galaxies HI is not being accreted at the same rate as stars are currently being formed. Our study can not exclude that other forms of gas accretion are at work. However, these observations also do not reveal extended neutral gas reservoirs around most nearby spiral galaxies., Comment: Accepted for publication in Astronomy & Astrophysics section 4. Extragalactic astronomy. Data available at https://www.astron.nl/halogas/data.php

We present the first unbiased survey of neutral hydrogen (HI) absorption in the Small Magellanic Cloud (SMC). The survey utilises pilot HI observations with the Australian Square Kilometre Array Pathfinder (ASKAP) telescope as part of the Galactic ASKAP HI (GASKAP-HI) project whose dataset has been processed with the GASKAP-HI absorption pipeline, also described here. This dataset provides absorption spectra towards 229 continuum sources, a 275% increase in the number of continuum sources previously published in the SMC region, as well as an improvement in the quality of absorption spectra over previous surveys of the SMC. Our unbiased view, combined with the closely matched beam size between emission and absorption, reveals a lower cold gas faction (11%) than the 2019 ATCA survey of the SMC and is more representative of the SMC as a whole. We also find that the optical depth varies greatly between the SMC's bar and wing regions. In the bar we find that the optical depth is generally low (correction factor to the optically thin column density assumption of $\mathcal{R}_{\rm HI} \sim 1.04$) but increases linearly with column density. In the wing however, there is a wide scatter in optical depth despite a tighter range of column densities., Comment: Accepted for publication in PASA, 19 pages, 17 figures, 5 tables

The COVID-19 pandemic has created and will continue to create uncertainty in all facets of everyday life, exacerbating current challenges -- and generating new ones -- for every sector of the economy, including postsecondary education. As the pandemic continues, postsecondary education faces increasing pressures as concerns about health and well-being, decreasing individual and family earnings, and questions about quality come to the fore. This Policy Brief is part of a series dedicated to various facets of the transition from secondary to postsecondary education, now complicated by the COVID-19 pandemic. This Policy Brief draws on four principles of redesigning state financial aid to better support the Classes of 2020 and 2021 as they seek to enter college or university during the pandemic. It focuses on the populations already underserved in the nation's education system. The series -- which builds upon "A State Policymaker's Guide to Equitable Transitions in the COVID-19 Era" (ED606369) -- provides actionable steps and examples for state policymakers to consider as they address the transition from high school to college and the workforce.

We present the most sensitive and detailed view of the neutral hydrogen (HI) emission associated with the Small Magellanic Cloud (SMC), through the combination of data from the Australian Square Kilometre Array Pathfinder (ASKAP) and Parkes (Murriyang), as part of the Galactic Australian Square Kilometre Array Pathfinder (GASKAP) pilot survey. These GASKAP-HI pilot observations, for the first time, reveal HI in the SMC on similar physical scales as other important tracers of the interstellar medium, such as molecular gas and dust. The resultant image cube possesses an rms noise level of 1.1 K (1.6 mJy/beam) per 0.98 km s$^{-1}$ spectral channel with an angular resolution of 30$''$ ($\sim$10 pc). We discuss the calibration scheme and the custom imaging pipeline that utilizes a joint deconvolution approach, efficiently distributed across a computing cluster, to accurately recover the emission extending across the entire $\sim$25 deg$^2$ field-of-view. We provide an overview of the data products and characterize several aspects including the noise properties as a function of angular resolution and the represented spatial scales by deriving the global transfer function over the full spectral range. A preliminary spatial power spectrum analysis on individual spectral channels reveals that the power-law nature of the density distribution extends down to scales of 10 pc. We highlight the scientific potential of these data by comparing the properties of an outflowing high velocity cloud with previous ASKAP+Parkes HI test observations., Comment: Accepted for publication in PASA, 34 pages, 18 figures, 5 tables

Using the Australian Square Kilometre Array Pathfinder to measure 21-cm absorption spectra toward continuum background sources, we study the cool phase of the neutral atomic gas in the far outer disk, and in the inner Galaxy near the end of the Galactic bar at longitude 340 degrees. In the inner Galaxy the cool atomic gas has a smaller scale height than in the solar neighborhood, similar to the molecular gas and the superthin stellar population in the bar. In the outer Galaxy the cool atomic gas is mixed with the warm, neutral medium, with the cool fraction staying roughly constant with Galactic radius. The mean spin temperature, i.e. the ratio of the emission brightness temperature to the absorption, is roughly constant for velocities corresponding to Galactic radius greater than about twice the solar circle radius. The ratio has a value of about 300 K, but this does not correspond to a physical temperature in the gas. If the gas causing the absorption has kinetic temperature of about 100 K, as in the solar neighborhood, then the value 300 K indicates that the fraction of the gas mass in this phase is one-third of the total HI mass., Comment: 29 pages, 12 figures, submitted to Astrophysical Journal

Studying the driving modes of turbulence is important for characterizing the impact of turbulence in various astrophysical environments. The driving mode of turbulence is parameterized by $b$, which relates the width of the gas density PDF to the turbulent Mach number; $b\approx 1/3$, $1$, and $0.4$ correspond to driving that is solenoidal, compressive, and a natural mixture of the two, respectively. In this work, we use high-resolution (sub-pc) ALMA $^{12}$CO ($J$ = $2-1$), $^{13}$CO ($J$ = $2-1$), and C$^{18}$O ($J$ = $2-1$) observations of filamentary molecular clouds in the star-forming region N159E (the Papillon Nebula) in the Large Magellanic Cloud (LMC) to provide the first measurement of turbulence driving parameter in an extragalactic region. We use a non-local thermodynamic equilibrium (NLTE) analysis of the CO isotopologues to construct a gas density PDF, which we find to be largely log-normal in shape with some intermittent features indicating deviations from lognormality. We find that the width of the log-normal part of the density PDF is comparable to the supersonic turbulent Mach number, resulting in $b \approx 0.9$. This implies that the driving mode of turbulence in N159E is primarily compressive. We speculate that the compressive turbulence could have been powered by gravo-turbulent fragmentation of the molecular gas, or due to compression powered by H I flows that led to the development of the molecular filaments observed by ALMA in the region. Our analysis can be easily applied to study the nature of turbulence driving in resolved star-forming regions in the local as well as the high-redshift Universe., Comment: 14 pages, 7 figures. MNRAS in press

Today's postsecondary students accumulate college credit and other validated learning experiences from more sources and in more forms than ever before. As credit accumulation options have proliferated, student mobility patterns have also shifted and are now increasingly multi-directional, crossing institutional types, system and state boundaries, and occurring over longer periods of time. The intersection of these trends has exposed systemic problems and the challenges that students face when they attempt to not only earn credits but to move those credits between postsecondary institutions. These systemic challenges disproportionately impact students from lower socioeconomic backgrounds and contribute to lower levels of credential completion. This issue brief introduces holistic credit mobility as a framework for making sense of contemporary student mobility and devising solutions that center the success of mobile students with multiple forms and sources of validated learning. Herein, the authors define holistic credit mobility and highlight strategies to support its effective deployment throughout postsecondary institutions and systems.

The turbulent dynamics of nearby and extragalactic gas structures can be studied with the column density power spectrum, which is often described by a broken power-law.In an extragalactic context, the breaks in the power spectra have been interpreted to constrain the disc scale height, which marks a transition from 2D disc-like to 3D motion. However, this interpretation has recently been questioned when accounting for instrumental effects. We use numerical simulations to study the spatial power spectra of isolated galaxies and investigate the origins of the break scale. We split the gas into various phases and analyze the time evolution of the power spectrum characteristics, such as the slope(s) and the break scale. We find that the break scale is phase dependent. The physics traced by the break scale also differ: in the warm gas it marks the transition from 2D (disk-like) to 3D (isotropic) turbulence. In the cold gas, the break scale traces the typical size of molecular clouds. We further show that the break scale almost never traces the disc scale height. We study turbulent properties of the ISM to show that, in the case where the break scale traces a transition to isotropic turbulence, the fraction of required accretion energy to sustain turbulent motions in the ISM increases significantly. Lastly, we demonstrate through simulated observations that it is crucial to account for observational effects, such as the beam and instrumental noise, in order to accurately recover the break scale in real observations., Comment: 16 pages. 12 figures. Accepted for publication by MNRAS. Comments welcome

We present the results of commissioning observations for a new digital beamforming back end for the Focal plane L-band Array for the Robert C. Byrd Green Bank Telescope (FLAG), a cryogenically cooled Phased Array Feed (PAF) with the lowest measured T_sys/eta of any PAF outfitted on a radio telescope to date. We describe the custom software used to apply beamforming weights to the raw element covariances to create research quality spectral line images for the new fine-channel mode, study the stability of the beam weights over time, characterize FLAG's sensitivity over a frequency range of 150 MHz, and compare the measured noise properties and observed distribution of neutral hydrogen emission from several extragalactic and Galactic sources with data obtained with the current single-pixel L-band receiver. These commissioning runs establish FLAG as the preeminent PAF receiver currently available for spectral line observations on the world's major radio telescopes., Comment: 28 ages, 18 figures. Accepted for publication in the Astronomical Journal

We present the analysis of the diffuse, low column density HI environment of 18 MHONGOOSE galaxies. We obtained deep observations with the Robert C. Byrd Green Bank Telescope, and reached down to a 3sigma column density detection limit of NHI=6.3x10^{17} cm^{-2} over a 20 km/s linewidth. We analyze the environment around these galaxies, with a focus on HI gas that reaches column densities below NHI=10^{19} cm^{-2}. We calculate the total amount of HI gas in and around the galaxies revealing that nearly all of these galaxies contained excess HI outside of their disks. We quantify the amount of diffuse gas in the maps of each galaxy, defined by HI gas with column densities below 10^{19} cm^{-2}, and find a large spread in percentages of diffuse gas. However, by binning the percentage of diffuse HI into quarters, we find that the bin with the largest number of galaxies is the lowest quartile (0-25\% diffuse HI). We identified several galaxies which may be undergoing gas accretion onto the galaxy disk using multiple methods of analysis, including azimuthally averaging column densities beyond the disk, and identifying structure within our integrated intensity (Moment 0) maps. We measured HI mass outside the disks of most of our galaxies, with rising cumulative flux even at large radii. We also find a strong correlation between the fraction of diffuse gas in a galaxy and its baryonic mass, and test this correlation using both Spearman and Pearson correlation coefficients. We see evidence of a dark matter halo mass threshold of M_{halo}~10^{11.1} \msun{} in which galaxies with high fractions of diffuse HI all reside below. It is in this regime in which cold-mode accretion should dominate. Finally, we suggest a rotation velocity of v_{rot}~80 km\s as an upper threshold to find diffuse gas-dominated galaxies., Comment: Accepted, ApJ, Jan. 1, 2021

With the further development of highly automated vehicles, drivers will engage in non-related tasks while being driven. Still, drivers have to take over control when requested by the car. Here the question arises, how potentially distracted drivers get back into the control-loop quickly and safely when the car requests a takeover. To investigate effective human-machine interactions in mobile, versatile, and cost-efficient setup is needed. We developed a virtual reality toolkit for the Unity 3D game engine containing all necessary code and assets to enable fast adaptations to various human-machine interaction experiments, including close monitoring of the subject. The presented project contains all needed functionalities for realistic traffic behavior, cars, and pedestrians, as well as a large, open-source, scriptable, and modular VR environment. It covers roughly 25 square km, a package of 125 animated pedestrians and numerous vehicles, including motorbikes, trucks, and cars. It also contains all needed nature assets to make it both highly dynamic and realistic. The presented repository contains a C++ library made for LoopAR that enables force feedback for gaming steering wheels as a fully supported component. It also includes All necessary scripts for eye-tracking in the used devices. All main functions are integrated into the graphical user interface of the Unity Editor or are available as prefab variants to ease the use of the embedded functionalities. The primary purpose of this project is to serve as open access, cost-efficient toolkit that enables interested researchers to conduct realistic virtual reality research studies without costly and immobile simulators.

Nationally, Ithaka S+R estimates that over six million students have completed credits at postsecondary institutions that they cannot document due to a past due balance. These overdue balances contribute to a national problem of stranded credits--credits that students have completed but cannot document because they were unable to fulfill their financial obligations to their institution. This brief provides a roadmap for stakeholders interested in the underlying practices that create stranded credits and what can be done to improve them. To begin, the author provides specific definitions of the terms and practices implicated in the creation of stranded credits. While researchers and policy leaders have increased their attention on the problem of stranded credits, this brief lays out in detail how they are created, why they matter, and what can be done to better balance the interests of institutions, students, and a modern economy that relies on postsecondary education for the development of a competitive workforce.

In today's evolving economy, state policymakers, education leaders, workforce system leaders and employers are all looking for opportunities to meet rapidly changing workforce needs. Economists project that shortages of workers with postsecondary education -- some college, an associate degree, bachelor's degree or higher -- could lead to nearly $1.2 trillion in lost revenue over the next decade. To mitigate the shortage and avoid economic losses, both existing and future workers will need more education and training. The World Economic Forum projects that at least 54% of workers will need significant work-relevant education in the next five years -- with over half of these individuals requiring six months or more of education and training. State policymakers recognize the economic imperative to ensure that education and training are connected to jobs. In response, they are forging stronger connections between education, workforce and employers at state, regional and local levels. Policymakers are also acting to expand secondary and postsecondary career and technical education, promote access to postsecondary programs and engage employers through work-based learning and apprenticeships. Yet systems and initiatives are not always fully connected; and access to postsecondary education continues to be out of reach for many people, especially individuals from a lower socioeconomic status. This Policy Brief, informed by a group of education and workforce leaders, explores three principles to guide policy considerations for state leaders working to develop intentional, outcomes-focused connections between postsecondary education and work.

We present detections of 21-cm emission from neutral hydrogen (HI) in the circumgalactic medium (CGM) of the local edge-on galaxies NGC 891 and NGC 4565 using the Robert C. Byrd Green Bank Telescope (GBT). With our 5$\sigma$ sensitivity of $8.2 \times 10^{16}$ cm$^{-2}$ calculated over a 20 km s$^{-1}$ channel, we achieve $>5\sigma$ detections out to $90-120$ kpc along the minor axes. The velocity width of the CGM emission is as large as that of the disk $\approx 500$ km s$^{-1}$, indicating the existence of a diffuse component permeating the halo. We compare our GBT measurements with interferometric data from the Westerbork Synthesis Radio Telescope (WSRT). The WSRT maps the HI emission from the disk at high S/N but has limited surface brightness sensitivity at the angular scales probed with the GBT. After convolving the WSRT data to the spatial resolution of the GBT (FWHM = 9.1$'$), we find that the emission detected by the WSRT accounts for $48^{+15}_{-25}$% ($58^{+4}_{-18}$%) of the total flux recovered by the GBT from the CGM of NGC 891(NGC 4565). The existence of significant GBT-only flux suggests the presence of a large amount of diffuse, low column density HI emission in the CGM. For reasonable assumptions, the extended diffuse HI could account for $5.2\pm0.9$% and $2.0\pm0.8$% of the total HI emission of NGC 891 and NGC 4565., Comment: 14 pages, 5 figures, published in ApJ

This Special Report examines four principles for state leaders to consider as they develop or evaluate financial aid redesign reform efforts. The financial aid redesign principles, identified through a Thinkers Meeting that included experts from across the country, fall into four areas: Financial aid programs should be student-centered, goal-driven and data-informed, timely and flexible, and broadly inclusive. [Support for this paper and this initiative was provided by Strada Education Network. For the first iteration of "Redesigning State Financial Aid: Principles to Guide State Aid Policymaking," see ED556236.]

Postsecondary education is one of the largest investments that students and their families make, with average yearly cost of attendance--including tuition, fees, room and board--of just under $17,000 to attend a public institution in the 2015-16 academic year. In the context of increasing college costs, aid dollars have failed to keep pace with the rising number of students requiring financial assistance. This leaves many students to rely on multiple sources of support to pay for their postsecondary experience. This primer explores the main sources of support--including federal grants, state assistance programs, loans and institutional aid--that are available to students today. Each type of program is explained in detail, with particular attention to the salient characteristics for state policymakers and the potential limitations of each stream of support.

We report the first evidence of molecular gas in two atomic hydrogen (HI) clouds associated with gas outflowing from the Small Magellanic Cloud (SMC). We used the Atacama Pathfinder Experiment (APEX) to detect and spatially resolve individual clumps of CO(2-1) emission in both clouds. CO clumps are compact (~ 10 pc) and dynamically cold (linewidths < 1 km/s). Most CO emission appears to be offset from the peaks of the HI emission, some molecular gas lies in regions without a clear HI counterpart. We estimate a total molecular gas mass of 10^3-10^4 Msun in each cloud and molecular gas fractions up to 30% of the total cold gas mass (molecular + neutral). Under the assumption that this gas is escaping the galaxy, we calculated a cold gas outflow rate of 0.3-1.8 Msun/yr and mass loading factors of 3 -12 at a distance larger than 1 kpc. These results show that relatively weak star-formation-driven winds in dwarf galaxies like the SMC are able to accelerate significant amounts of cold and dense matter and inject it into the surrounding environment., Comment: Accepted for publication in ApJ Letters

Phased Array Feed (PAF) receivers are at the forefront of modern day radio astronomy. PAFs are currently being developed for spectral line and radio continuum surveys and to search for pulsars and fast radio bursts. Here, we present results of the pilot survey for pulsars and fast radio bursts using the Focal plane L-band Array for the Green Bank Telescope (FLAG) receiver operating in the frequency range of 1.3--1.5 GHz. With a system temperature of $\sim$18 K, the receiver provided unprecedented sensitivity to the survey over an instantaneous field of view (FoV) of 0.1 deg$^{2}$. For the survey, we implemented both time and frequency domain search pipelines designed to find pulsars and fast radio bursts that were validated by test pulsar observations. Although no new sources were found, we were able to demonstrate the capability of this instrument from observations of known pulsars. We report an upper limit on the rate of fast radio bursts above a fluence of 0.36~Jy ms to be 1.3 $\times$ 10$^6$ events per day per sky. Using population simulations, we show that the FLAG will find a factor of 2--3 more pulsars in same survey duration compared to its single pixel counterpart at the Green Bank Telescope. We also demonstrate that the new phased array receiver, ALPACA for the Arecibo telescope, will be a superior survey instrument and will find pulsars at a higher rate than most contemporary receivers by a factor of 2--10., Comment: 10 pages, 10 figures, 2 tables, accepted for publication in MNRAS

This 50-State Comparison shows how states approach adult inclusion in state financial aid policies. Education Commission of the States researched state financial aid policies in all states to provide this comprehensive resource, with information provided for the two largest financial aid programs (by expenditure) in each state, according to 2015 data. The following hyperlinks to data tables are included: (1) Are awards based on academic merit, financial need, or other criteria?; (2) Do students need to enroll full-time to receive aid?; (3) Is eligibility linked to the date that the student graduated high school?; (4) Does the state define a statewide application deadline, and if so, what is the deadline?; (5) Which postsecondary sectors are eligible to participate?; and (6) All data points for all states.