adsabs/SciX_UAT_keywords huggingface dataset:
Constraints on Undetected Long-period Binaries in the Known Pulsar Population

Although neutron star-black hole binaries have been identified through mergers detected in gravitational waves, a pulsar-black hole binary has yet to be detected. While short-period binaries are detectable due to a clear signal in the pulsar's timing residuals, effects from a long-period binary could be masked by other timing effects, allowing them to go undetected. In particular, a long-period binary measured over a small subset of its orbital period could manifest via time derivatives of the spin frequency incompatible with isolated pulsar properties. We assess the possibility of pulsars having unknown companions in long-period binaries and put constraints on the range of binary properties that may remain undetected in current data, but that may be detectable with further observations. We find that for 35% of canonical pulsars with published higher-order derivatives, the precision of measurements is not enough to confidently reject binarity (period ≳2 kyr), and that a black hole binary companion could not be ruled out for a sample of pulsars without published constraints if the period is >1 kyr. While we find no convincing cases in the literature, we put more stringent limits on orbital period and longitude of periastron for the few pulsars with published higher-order frequency derivatives (n ≥ 3). We discuss the detectability of candidates and find that a sample pulsar in a 100 yr orbit could be detectable within 5-10 yr.

Keywords: binary pulsars; black holes
The RESOLVE and ECO Gas in Galaxy Groups Initiative: The Group Finder and the Group H I-Halo Mass Relation

We present a four-step group-finding algorithm for the Gas in Galaxy Groups (G3) initiative, a spin-off of the z ~ 0 REsolved Spectroscopy Of a Local VolumE (RESOLVE) and Environmental COntext (ECO) surveys. In preparation for future comparisons to intermediate redshift (e.g., the LADUMA survey), we design the group finder to adapt to incomplete, shallow, or nonuniform data. We use mock catalogs to optimize the group finder's performance. Compared to friends-of-friends (with false-pair splitting), the G3 algorithm offers improved completeness and halo-mass recovery with minimal loss of purity. Combining it with the volume-limited H I census data for RESOLVE and ECO, we examine the H I content of galaxy groups as a function of group halo mass. Group-integrated H I mass M H I,grp rises monotonically over halo masses M halo ~ 1011-1014.5 M ⊙, pivoting in slope at M halo ~ 1011.4 M ⊙, the gas-richness threshold scale. We present the first measurement of the scatter in this relation, which has a median of ~0.3 dex and is asymmetric toward lower M H I,grp. We discuss interesting tensions with theoretical predictions and prior measurements of the M H I,grp-M halo relation. In an appendix, we release RESOLVE DR4 and ECO DR3, including updates to survey redshifts, photometry, and group catalogs, as well as a major expansion of the ECO H I inventory with value-added data products.

Keywords: galaxies; galaxy evolution; galaxy groups; galaxy dark matter halos
AGN Selection and Demographics in GOODS-S/HUDF from X-Ray to Radio

We present a comprehensive census of the active galactic nuclei (AGNs) in the GOODS-S/HUDF region from the X-ray to the radio, covering both the obscured and unobscured populations. This work includes a robust analysis of the source optical to mid-IR spectral energy distributions (SEDs) featuring (semi)empirical AGN and galaxy dust emission models and Bayesian fitting techniques, ultra-deep Very Large Array 3 and 6 GHz observations, and an integrated analysis of various AGN selection techniques, including X-ray properties, UV to mid-IR SED analysis, optical spectral features, mid-IR colors, radio-loudness and spectral slope, and AGN variability. In total, we report ~900 AGNs over the ~170 arcmin2 3D-HST GOODS-S footprint, which has doubled the AGN number identified in the previous X-ray sample, with ~26% of our sample undetected in the deepest Chandra image. With a summary of AGN demographics from different selection methods, we find that no one single band or technique comes close to selecting a complete AGN sample despite the great depth of the data in GOODS-S/HUDF. We estimate the yields of various approaches and explore the reasons for incompleteness. We characterize the statistical properties, such as source number density, obscuration fraction, and luminosity function of the AGN sample in this field, and discuss their immediate implications. We also provide some qualitative predictions of the AGN sample that might be discovered by the upcoming JWST surveys.

Keywords: active galactic nuclei; infrared galaxies; x-ray active galactic nuclei; radio active galactic nuclei; high-redshift galaxies
The Exoplanet Modeling and Analysis Center at NASA Goddard

The Exoplanet Modeling and Analysis Center (EMAC) at NASA Goddard Space Flight Center is a web-based catalog, repository, and integration platform for modeling and analysis resources focused on the study of exoplanet characteristics and environments. EMAC hosts user-submitted resources ranging in category from planetary interior models to data visualization tools. Other features of EMAC include integrated web tools developed by the EMAC team in collaboration with the tools' original author(s) and video demonstrations of a growing number of hosted tools. EMAC aims to be a comprehensive repository for researchers to access a variety of exoplanet resources that can assist them in their work, and currently hosts a growing number of code bases, models, and tools. EMAC is a key project of the NASA GSFC Sellers Exoplanet Environments Collaboration and can be accessed at https://emac.gsfc.nasa.gov.

Keywords: exoplanets; astronomy software; exoplanet dynamics; exoplanet systems; exoplanet atmospheres; open source software; software tutorials; astronomy databases; astronomy data visualization; star-planet interactions; planetary science; planetary interior
The CGM2 Survey: Circumgalactic O VI from Dwarf to Massive Star-forming Galaxies

We combine 126 new galaxy-O VI absorber pairs from the CGM2 survey with 123 pairs drawn from the literature to examine the simultaneous dependence of the column density of O VI absorbers (N O VI) on galaxy stellar mass, star-formation rate, and impact parameter. The combined sample consists of 249 galaxy-O VI absorber pairs covering z = 0-0.6, with host galaxy stellar masses M * = 107.8-1011.2 M ⊙ and galaxy-absorber impact parameters R ⊥ = 0-400 proper kiloparsecs. In this work, we focus on the variation of N O VI with galaxy mass and impact parameter among the star-forming galaxies in the sample. We find that the average N O VI within one virial radius of a star-forming galaxy is greatest for star-forming galaxies with M * = 109.2-1010 M ⊙. Star-forming galaxies with M * between 108 and 1011.2 M ⊙ can explain most O VI systems with column densities greater than 1013.5 cm-2. Sixty percent of the O VI mass associated with a star-forming galaxy is found within one virial radius, and 35% is found between one and two virial radii. In general, we find that some departure from hydrostatic equilibrium in the CGM is necessary to reproduce the observed O VI amount, galaxy mass dependence, and extent. Our measurements serve as a test set for CGM models over a broad range of host galaxy masses.

Keywords: circumgalactic medium; extragalactic astronomy
Can Emission Measure Distributions Derived from Extreme-ultraviolet Images Accurately Constrain High-temperature Plasma?

Measuring the relative amount of high-temperature, low emission measure (EM) plasma is considered to be a smoking-gun observation to constrain the frequency of plasma heating in coronal structures. Often, narrowband, extreme-ultraviolet images, such as those obtained by the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO), are used to determine the EM distribution, though the sensitivity to high-temperature plasma is limited. Conversely, the soft X-ray wavelength range offers multiple high-temperature diagnostics, including emission lines of N VII, O VII, O VIII, Fe XVII, Ne IX, and Mg XI, which can provide tight constraints to the high-temperature plasma in the log T = 6.1–6.7 (∼1–5+ MK) range. The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS), a slitless spectrograph launched on a NASA sounding rocket on 2021 July 30, resolved an X-ray-bright point in multiple emission lines in the soft X-ray wavelength range. Using coordinated observations of the same X-ray-bright point from SDO/AIA, we compare and contrast the EM distributions from the EUV image data, the X-ray spectra, and the combined EUV and X-ray data set. In this paper, we demonstrate that EM distributions from SDO/AIA data alone can overestimate the amount of high-temperature (log T > 6.4) plasma in the solar corona by a factor of 3–15. Furthermore, we present our effort to cross-calibrate Hinode/X-ray Telescope (XRT) response functions by comparing the observed XRT fluxes with the predicted ones from combined MaGIXS-1 + AIA EM analysis.

Keywords: solar coronal heating; solar corona; solar extreme ultraviolet emission; solar x-ray emission; solar active regions
An Improved Wiener Filtration Method for Constructing the Ensemble Pulsar Timescale

An improved Wiener filtration (WF) method for constructing the ensemble pulsar timescale (EPT) is proposed to solve the existing problems in the WF algorithm. The improvements consist of three parts: (i) adjusting the cross-power spectral density (PSD) and PSD estimated by the weighted average (WA) algorithm by the concept of the energy upper limit; (ii) combining the cross-PSD and WA PSD to form a different signal modulus for the filtration of residuals of different noise levels; and (iii) setting a weight for each residual by a more general algorithm based on the concept of effective power. We use this improved WF method to construct the EPT by both simulated data and observational data from the second data release of the International Pulsar Timing Array. The results from the simulated data indicate this improved WF can successfully suppress the noise level and reform the common signal. For observational data, this method also successfully detects the fluctuations of International Atomic Time (TAI) and local atomic time TA(NTSC). A stability analysis shows that an EPT will have the potential to reveal the instability of TAI on a scale longer than 7 yr. This improved WF method can also be used to detect and monitor the noise in pulsar timing residuals inversely, by using multiple atomic time standards, which can in turn improve the EPT.

Keywords: pulsars; time series analysis; astronomy data analysis
The Pan-STARRS1 z > 5.6 Quasar Survey. III. The z ≈ 6 Quasar Luminosity Function

We present the z ≈ 6 type-1 quasar luminosity function (QLF), based on the Pan-STARRS1 (PS1) quasar survey. The PS1 sample includes 125 quasars at z ≈ 5.7-6.2, with -28 ≲ M 1450 ≲ -25. With the addition of 48 fainter quasars from the SHELLQs survey, we evaluate the z ≈ 6 QLF over -28 ≲ M 1450 ≲ -22. Adopting a double power law with an exponential evolution of the quasar density (Φ(z) ∝ 10 k(z-6); k = -0.7), we use a maximum likelihood method to model our data. We find a break magnitude of ${M}^{* }=-{26.38}_{-0.60}^{+0.79}\,\mathrm{mag}$ , a faint-end slope of $\alpha =-{1.70}_{-0.19}^{+0.29}$ , and a steep bright-end slope of $\beta =-{3.84}_{-1.21}^{+0.63}$ . Based on our new QLF model, we determine the quasar comoving spatial density at z ≈ 6 to be $n({M}_{1450}\lt -26)={1.16}_{-0.12}^{+0.13}\,{\mathrm{cGpc}}^{-3}$ . In comparison with the literature, we find the quasar density to evolve with a constant value of k ≈ -0.7, from z ≈ 7 to z ≈ 4. Additionally, we derive an ionizing emissivity of ${\epsilon }_{912}(z=6)={7.23}_{-1.02}^{+1.65}\times {10}^{22}\,\mathrm{erg}\,{{\rm{s}}}^{-1}\,{\mathrm{Hz}}^{-1}\,{\mathrm{cMpc}}^{-3}$ , based on the QLF measurement. Given standard assumptions, and the recent measurement of the mean free path by Becker et al. at z ≈ 6, we calculate an H I photoionizing rate of ΓH I(z = 6) ≈ 6 × 10-16 s-1, strongly disfavoring a dominant role of quasars in hydrogen reionization.

Keywords: quasars; supermassive black holes; reionization; early universe; luminosity function
The R2D2 Deep Neural Network Series Paradigm for Fast Precision Imaging in Radio Astronomy

Radio-interferometric imaging entails solving high-resolution high-dynamic-range inverse problems from large data volumes. Recent image reconstruction techniques grounded in optimization theory have demonstrated remarkable capability for imaging precision, well beyond CLEAN's capability. These range from advanced proximal algorithms propelled by handcrafted regularization operators, such as the SARA family, to hybrid plug-and-play (PnP) algorithms propelled by learned regularization denoisers, such as AIRI. Optimization and PnP structures are however highly iterative, which hinders their ability to handle the extreme data sizes expected from future instruments. To address this scalability challenge, we introduce a novel deep-learning approach, dubbed "Residual-to-Residual DNN series for high-Dynamic-range imaging" or in short R2D2. R2D2's reconstruction is formed as a series of residual images, iteratively estimated as outputs of deep neural networks (DNNs) taking the previous iteration's image estimate and associated data residual as inputs. It thus takes a hybrid structure between a PnP algorithm and a learned version of the matching pursuit algorithm that underpins CLEAN. We present a comprehensive study of our approach, featuring its multiple incarnations distinguished by their DNN architectures. We provide a detailed description of its training process, targeting a telescope-specific approach. R2D2's capability to deliver high precision is demonstrated in simulation, across a variety of image and observation settings using the Very Large Array. Its reconstruction speed is also demonstrated: with only a few iterations required to clean data residuals at dynamic ranges up to 105, R2D2 opens the door to fast precision imaging. R2D2 codes are available in the BASPLib (https://basp-group.github.io/BASPLib/) library on GitHub.

Keywords: computational methods; neural networks; astronomy image processing; aperture synthesis
Radiative Supernova Remnants and Supernova Feedback

Supernova (SN) explosions are a major feedback mechanism, regulating star formation in galaxies through their momentum input. We review the observations of SNRs in radiative stages in the Milky Way, to validate theoretical results regarding the momentum/energy injection from a single SN explosion. For seven supernova remnants (SNRs) where we can observe fast-expanding, atomic radiative shells, we show that the shell momentum inferred from H I 21 cm line observations is in the range of (0.5-4.5) × 105M⊙ km s-1. In two SNRs (W44 and IC 443), shocked molecular gas with momentum comparable to that of the atomic SNR shells has also been observed. We compare the momentum and kinetic/thermal energy of these seven SNRs with the results from 1D and 3D numerical simulations. The observation-based momentum and kinetic energy agree well with the expected momentum/energy input from an SN explosion of ∼1051 erg. It is much more difficult to use data/model comparisons of thermal energy to constrain the initial explosion energy, however, due to rapid cooling and complex physics at the hot/cool interface in radiative SNRs. We discuss the observational and theoretical uncertainties of these global parameters and explosion energy estimates for SNRs in complex environments.

Keywords: supernova remnants; interstellar medium
Diagnostics from Polarization of Scattered Optical Light from Galactic Infrared Cirrus

We propose polarization of scattered optical light from intermediate Galactic latitude infrared cirrus as a new diagnostic to constrain models of interstellar dust and the anisotropic interstellar radiation field (aISRF). For single scattering by a sphere, with Mie scattering phase functions for intensity and polarized intensity for a dust model at a given wavelength (Sloan r and g bands), and with models of anisotropic illumination from the entire sky (represented in HEALPix), we develop the formalism for calculating useful summary parameters for an integrated flux nebula (IFN): the average of the phase function weighted by the illumination, polarization angle (ψ), and polarization fraction (p). To demonstrate the diagnostic discrimination of polarization from scattered light, we report on the effects of different anisotropic illumination models and different dust models on the summary parameters for the Spider IFN. The summary parameters are also sensitive to the IFN location, as we illustrate using FRaNKIE illumination models. For assessing the viability of dust and aISRF models, we find that observations of ψ and p of scattered light are indeed powerful new diagnostics to complement joint modeling of the intensity of scattered light (related to the average phase function) and the intensity of thermal dust emission. However, optically thin IFNs that can be modeled using single scattering are faint and p is not large, as it could be with Rayleigh scattering, and so these observations need to be carried out with care and precision. Results for the Draco nebula compared to the Spider illustrate the challenge.

Keywords: interstellar scattering; diffuse nebulae; reflection nebulae; dust continuum emission; dust composition; interstellar dust; interstellar radiation field; interstellar clouds; interstellar medium
CO Outflow Candidates toward the W3/4/5 Complex. II. Feedback from Candidate Outflows

To date, few studies have focused on protostellar outflow feedback at scales larger than several parsecs. To address this paucity of research, we investigate the effects of feedback from CO outflow candidates on their parent clouds over ∼110 deg2 toward the W3/4/5 complex and its surroundings. Our search identified 265 13CO clouds with radii being ∼0.04-17.12 pc. We estimate the turbulent support and potential disruptive effect of the outflow activities through analyzing physical properties of outflow candidates and their host clouds in terms of turbulence and gravitational binding energy. We find that (1) clouds of larger size might be less affected by feedback; (2) the possible scale break is ≳4.7 pc for both turbulent support and potential disruptive effect; (3) if outflows couple to dense gas where stars are forming, for clouds in the Perseus arm, a scale ≲0.2-0.4 pc is sufficient for the energy and momentum injected by outflow activity to maintain turbulence, while for clouds in the Local arm, the scale is ≲0.1-0.2 pc; and (4) for clouds in the Perseus arm, a scale ≲0.3-1.0 pc is needed for outflow activity to potentially disperse material away from the natal clouds, while for clouds in the Local arm, the scale is ≲0.2-0.6 pc. The strength of outflow activity may affect the values in points 3 and 4. Finally, we find that outflow feedback probably possesses the power to alter the line width-size relation.

Keywords: interstellar clouds; jets; interstellar dynamics; star formation
Evidence for Population-dependent Vertical Motions and the Long-lived Nonsteady Lopsided Milky Way Warp

We present a Galactic disk vertical velocity analysis using OB type stars (OB stars), red clump (RC) stars, and main-sequence turnoff (MSTO) stars with different average age populations crossmatched with LAMOST DR5 and Gaia DR3. We show that the vertical velocities of the three populations clearly vary with the Galactocentric distance (R) and the younger stellar population has a stronger increasing trend in general. The bending and breathing modes indicated by the vertical motions are dependent on the populations and vary with spatial locations. These vertical motions may be due to the Galactic warp, or minor mergers, or nonequilibrium of the disk. Assuming the warp is the dominant component, we find that the amplitude of the warp (γ, Z ω ) of OB stars (younger population) is larger than that of RC stars (medium population) and the latter is also larger than that for MSTO stars (older population), which is in agreement with other independent analyses of stellar density distribution, and supports that the warp is a long-lived, nonsteady structure and is time evolving. This conclusion is robust whether the line of nodes ϕ w is fixed or is a free parameter (with ϕ w being around 3°-8.°5 as the best fit). Furthermore, we find that the warp is lopsided with asymmetries along the azimuthal angle (ϕ).

Keywords: milky way disk
Reflection Modeling of the Black Hole Binary 4U 1630-47: The Disk Density and Returning Radiation

We present the analysis of X-ray observations of the black hole binary 4U 1630-47 using relativistic reflection spectroscopy. We use archival data from the Rossi X-ray Timing Explorer, Neil Gehrels Swift Observatory, and Nuclear Spectroscopic Telescope Array observatories, taken during different outbursts of the source between 1998 and 2015. Our modeling includes two relatively new advances in modern reflection codes: high-density disks, and returning thermal disk radiation. Accretion disks around stellar-mass black holes are expected to have densities well above the standard value assumed in traditional reflection models (i.e., ne ∼ 1015 cm-3). New high-density reflection models have important implications in the determination of disk truncation (i.e., the disk inner radius). This is because one must retain self-consistency in the irradiating flux and corresponding disk ionization state, which is a function of disk density and system geometry. We find that the disk density is ne ≥ 1020 cm-3 across all spectral states. This density, combined with our constraints on the ionization state of the material, implies an irradiating flux impinging on the disk that is consistent with the expected theoretical estimates. Returning thermal disk radiation—the fraction of disk photons that bend back to the disk producing additional reflection components—is expected predominantly in the soft state. We show that returning radiation models indeed provide a better fit to the soft-state data, reinforcing previous results that show that in the soft state, the irradiating continuum may be blackbody emission from the disk itself.

Keywords: accretion; stellar accretion disks; black hole physics; atomic physics; low-mass x-ray binary stars