adsabs/SciX_UAT_keywords huggingface dataset:
From Haloes to Galaxies. II. The Fundamental Relations in Star Formation and Quenching

Star formation and quenching are two of the most important processes in galaxy formation and evolution. We explore in the local universe the interrelationships among key integrated galaxy properties, including stellar mass M*, star formation rate (SFR), specific SFR (sSFR), molecular gas mass ${M}_{{{\rm{H}}}_{2}}$ , star formation efficiency (SFE) of the molecular gas, and the molecular gas to stellar mass ratio μ. We aim to identify the most fundamental scaling relations among these key galaxy properties and their interrelationships. We show that the integrated ${M}_{{{\rm{H}}}_{2}}$ -SFR, SFR-M*, and ${M}_{{{\rm{H}}}_{2}}$ -M* relations can be simply transformed from the μ-sSFR, SFE-μ, and SFE-sSFR relations, respectively. The transformation, in principle, can increase or decrease the scatter of each relation. Interestingly, we find that the latter three relations all have significantly smaller scatter than the corresponding former three. We show that the probability to achieve the observed small scatter by accident is extremely close to zero. This suggests that the smaller scatters of the latter three relations are driven by a more universal physical connection among these quantities. We then show that the large scatters in the former relations are due to their systematic dependence on other galaxy properties, and on the star formation and quenching process. We propose the sSFR-μ-SFE relation as the fundamental formation relation (FFR), which governs the star formation and quenching process and provides a simple framework to study galaxy evolution. Other scaling relations, including the integrated Kennicutt-Schmidt law, star-forming main sequence, and molecular gas main sequence, can all be derived from the FFR.

Keywords: galaxy evolution; star formation; interstellar medium; galaxy formation
Deep Search for Molecular Oxygen in TW Hya

The dominant form of oxygen in cold molecular clouds is gas-phase carbon monoxide (CO) and ice-phase water (H2O). Yet, in planet-forming disks around young stars, gas-phase CO and H2O are less abundant relative to their interstellar medium values, and no other major oxygen-carrying molecules have been detected. Some astrochemical models predict that gas-phase molecular oxygen (O2) should be a major carrier of volatile oxygen in disks. We report a deep search for emission from the isotopologue 16O18O (N J = 21 - 01 line at 233.946 GHz) in the nearby protoplanetary disk around TW Hya. We used imaging techniques and matched filtering to search for weak emission but do not detect 16O18O. Based on our results, we calculate upper limits on the gas-phase O2 abundance in TW Hya of (6.4-70) × 10-7 relative to H, which is 2-3 orders of magnitude below solar oxygen abundance. We conclude that gas-phase O2 is not a major oxygen carrier in TW Hya. Two other potential oxygen-carrying molecules, SO and SO2, were covered in our observations, which we also do not detect. Additionally, we report a serendipitous detection of the C15N N J = 25/2 - 13/2 hyperfine transitions, F = 3 - 2 and F = 2 - 1, at 219.9 GHz, which we found via matched filtering and confirm through imaging.

Keywords: astrochemistry; protoplanetary disks
KCWI Observations of the Extended Nebulae in Mrk 273

Ultraluminous infrared galaxies (ULIRGs) represent a critical stage in the merger-driven evolution of galaxies when active galactic nucleus (AGN) activity is common and AGN feedback is expected. We present high-sensitivity and large field-of-view integral field spectroscopy of the ULIRG Mrk 273 using new data from the Keck Cosmic Web Imager (KWCI). The KCWI data capture the complex nuclear region and the two extended nebulae in the northeast (NE) and southwest (SW) to ~20 kpc scales. Kinematics in the nuclear region show a fast, extended, bipolar outflow in the direction of the previously reported nuclear superbubbles spanning ~5 kpc, two to three times greater than the previously reported size. The larger-scale extended nebulae on ~20 kpc show fairly uniform kinematics with FWHM ~ 300 km s-1 in the SW nebula and FWHM ~ 120 km s-1 in the NE nebula. We detect for the first time high-ionization [Ne V] 3426, [O III] 4363, and He II 4684 emission lines in the extended NE nebula. Emission line ratios in the nuclear region correlate with the kinematic structures, with the bipolar outflow and the less collimated "outflow regions" showing distinct line ratio trends. Line ratio diagnostics of high-ionization emission lines reveal a nontrivial contribution from shock plus precursor ionization in the NE nebula and the nuclear region mixed with AGN photoionization. These data are highly constraining for models of cool ionized gas existing 20 kpc from a galactic nucleus.

Keywords: active galaxies; markarian galaxies; ultraluminous infrared galaxies; galactic winds; galaxy evolution
Measuring the Milky Way Vertical Potential with the Phase Snail in a Model-independent Way

The vertical phase-space spiral (snail) is a direct sign of disequilibrium of the Milky Way's disk. Nevertheless, the wrapping of the phase snail contains information on the vertical potential. We propose a novel method to measure the vertical potential utilizing the intersections between the snail and z/V z axes, for which we know the maximum vertical heights (Z max) or velocities ( ${V}_{z,\max }$ ). Using a refined linear interpolation method, we directly obtain $({Z}_{\max },\tfrac{1}{2}{V}_{z,\max }^{2})$ for these snail intersections to constrain the vertical potential profile empirically. Our method is model-independent, since no assumptions about the snail shape or the vertical potential have been made. Although the snail binned by the guiding center radius (R g ) is more prominent, it traces a vertical potential shallower than that of the snail binned by the same galactocentric radius (R). We apply an empirical method to correct this difference. We measure the snail intersections in several R g bins within 7.5 < R g < 11.0 kpc for Gaia DR3 and apply the interpolation method to deduce the potential values at several vertical heights. The potential at the snail intersections, as well as the following mass modeling, is consistent with the popular Milky Way potentials in the literature. For the R g -binned phase snail in the solar neighborhood, the mass modeling indicates a local dark matter density of ρ dm = 0.0150 ± 0.0031 M ⊙ pc-3, consistent with previous works. Our method could be applied to larger radial ranges in future works to provide independent and stronger constraints on the Milky Way's potential.

Keywords: milky way disk; milky way dynamics; galaxy structure; stellar kinematics; stellar dynamics
Birds of a Feather? Magellan/IMACS Spectroscopy of the Ultra-faint Satellites Grus II, Tucana IV, and Tucana V

We present Magellan/IMACS spectroscopy of three recently discovered ultra-faint Milky Way satellites, Grus II, Tucana IV, and Tucana V. We measure systemic velocities of Vhel = 110.0 ± 0.5 km s-1, Vhel = 15.9-1.7+1.8 km s-1, and Vhel=-36.2-2.2+2.5 km s-1 for the three objects, respectively. Their large relative velocities demonstrate that the satellites are unrelated despite their close physical proximity. We determine a velocity dispersion for Tuc IV of σ = 4.3-1.0+1.7 km s-1, but we cannot resolve the velocity dispersions of the other two systems. For Gru II, we place an upper limit (90% confidence) on the dispersion of σ < 1.9 km s-1, and for Tuc V, we do not obtain any useful limits. All three satellites have metallicities below [Fe/H]=-2.1, but none has a detectable metallicity spread. We determine proper motions for each satellite based on Gaia astrometry and compute their orbits around the Milky Way. Gru II is on a tightly bound orbit with a pericenter of 25-7+6 kpc and orbital eccentricity of 0.45-0.05+0.08. Tuc V likely has an apocenter beyond 100 kpc and could be approaching the Milky Way for the first time. The current orbit of Tuc IV is similar to that of Gru II, with a pericenter of 25-8+11 kpc and an eccentricity of 0.36-0.06+0.13. However, a backward integration of the position of Tuc IV demonstrates that it collided with the Large Magellanic Cloud at an impact parameter of 4 kpc ∼120 Myr ago, deflecting its trajectory and possibly altering its internal kinematics. Based on their sizes, masses, and metallicities, we classify Gru II and Tuc IV as likely dwarf galaxies, but the nature of Tuc V remains uncertain.

Keywords: local group; dwarf galaxies; magellanic clouds; milky way galaxy; dark matter
Determining Star Formation Rates of Active Galactic Nucleus Host Galaxies Based on SED Fitting with Submillimeter Data

We present the star formation rate (SFR) measurements based on the spectral energy distribution (SED) analysis with new submillimeter fluxes combined with archival multiwavelength data for a sample of 52 active galactic nucleus (AGN) host galaxies at z < 0.2. We carried out submillimeter observations using the SCUBA-2 camera at the James Clerk Maxwell Telescope and obtained flux or an upper limit at 450 and 850 μm for each target. By experimenting with the effect of the AGN dust component in the SED fit, we find that the dust luminosity can be overestimated if the AGN contribution is ignored. While the SFR based on the 4000 Å break shows a significant offset compared to the dust-luminosity-based SFR, the SFR obtained by the artificial neural network generally shows consistency, albeit with a large scatter. We find that SFR correlates with the AGN outflow strength manifested by the [O III] λ5007 emission line, and that AGNs with higher Eddington ratios and stronger outflows are generally hosted by galaxies with a higher SFR, which is consistent with the correlation reported by Woo et al. This suggests no instantaneous quenching of star formation due to AGN feedback.

Keywords: active galactic nuclei; star formation
From the External to the Internal Dynamics of the Neutron Star: The Exotic Braking Indices of PSR B0540-69

The braking index is of great importance for interpreting the spin-down mechanism of pulsar rotation. The sudden spin-down rate transition of PSR B0540-69, the lowest braking index n = 0.031, and its variations up to 1.2 in its later phases, without glitches or changes in X-ray pulsed flux or shape, are the most enigmatic problem that challenges our understanding of the correlation between pulsar spin-down and magnetospheric emission. Here we discuss the above issue on the external and internal grounds of pulsar dynamics. It is found that the increase of the open field line region of the pulsar magnetosphere would give a plausible explanation for the state transition and the braking index of 0.031 of PSR B0540-69, and changes in the moment of inertia of PSR B0540-69 after the state transition may account for the variable braking indices in its subsequent phases. Results indicate that, on the one hand, a change in the magnetosphere size of a pulsar would influence the external braking torque and have a substantial impact on the observed braking index; and, on the other hand, a sudden change in external torque may trigger the mechanism that could slowly increase the moment of inertia of the pulsar and cause an observable effect on the spin frequency second derivatives. This is hardly explained under the regular glitch hypothesis. In this respect, PSR B0540-69 would be the ideal candidate to study the inside and outside dynamics of a pulsar.

Keywords: pulsars; neutron stars
The Next Generation Virgo Cluster Survey. XXXVII. Distant RR Lyrae Stars and the Milky Way Stellar Halo Out to 300 kpc

RR Lyrae stars are standard candles with characteristic photometric variability and serve as powerful tracers of Galactic structure, substructure, accretion history, and dark matter content. Here we report the discovery of distant RR Lyrae stars, including some of the most distant stars known in the Milky Way halo, with Galactocentric distances of ∼300 kpc. We use time-series ${u}^{* }g^{\prime} i^{\prime} z^{\prime} $ Canada–France–Hawaii Telescope/MegaCam photometry from the Next Generation Virgo Cluster Survey (NGVS). We use a template light-curve fitting method based on empirical Sloan Digital Sky Survey Stripe 82 RR Lyrae data to identify RR Lyrae candidates in the NGVS data set. We eliminate several hundred suspected quasars and identify 180 RR Lyrae candidates with heliocentric distances of ∼20–300 kpc. The halo stellar density distribution is consistent with an r ‑4.09±0.10 power-law radial profile over most of this distance range with no signs of a break. The distribution of ab-type RR Lyrae in a period–amplitude plot (Bailey diagram) suggests that the mean metallicity of the halo decreases outward. Compared to other recent RR Lyrae surveys, like Pan-STARRS1, the High Cadence Transient Survey, and the Dark Energy Survey, our NGVS study has better single-epoch photometric precision and a comparable number of epochs but smaller sky coverage. At large distances, our RR Lyrae sample appears to be relatively pure and complete, with well-measured periods and amplitudes. These newly discovered distant RR Lyrae stars are important additions to the few secure stellar tracers beyond 150 kpc in the Milky Way halo.

Keywords: milky way stellar halo; rr lyrae variable stars
The DR21(OH) Trident-Resolving the Massive Ridge into Three Entangled Fibers as the Initial Condition of Cluster Formation

DR21(OH) ridge, the central part of a high-mass star- and cluster-forming hub-filament system, is resolved spatially and kinematically into three nearly parallel fibers (f1, f2, and f3) with a roughly north-south orientation, using the observations of molecular transitions of H13CO+ (1 - 0), N2H+ (1 - 0), and NH2D (11,1 - 10,1) with the Combined Array for Research in Millimeter Astronomy. These fibers are all mildly supersonic (σ velocity dispersions about 2 times the sound speed), having lengths around 2 pc and widths about 0.1 pc, and they entangle and conjoin in the south where the most active high-mass star formation takes place. They all have line masses 1-2 orders of magnitude higher than their low-mass counterparts and are gravitationally unstable both radially and axially. However, only f1 exhibits high-mass star formation all the way along the fiber, yet f2 and f3 show no signs of significant star formation in their northern parts. A large velocity gradient increasing from north to south is seen in f3, and can be well reproduced with a model of freefall motion toward the most massive and active dense core in the region, which corroborates the global collapse of the ridge and suggests that the disruptive effects of the tidal forces may explain the inefficiency of star formation in f2 and f3. On larger scales, some of the lower-density, peripheral filaments are likely to be the outer extensions of the fibers, and provide hints on the origin of the ridge.

Keywords: interstellar filaments; dense interstellar clouds; star formation; star forming regions; young massive clusters; dust continuum emission; interstellar line emission
The Advective Flux Transport Model: Improving the Far Side with Active Regions Observed by STEREO 304 Å

Observations of the Sun's photospheric magnetic field are often confined to the Sun–Earth line. Surface flux transport (SFT) models, such as the Advective Flux Transport (AFT) model, simulate the evolution of the photospheric magnetic field to produce magnetic maps over the entire surface of the Sun. While these models are able to evolve active regions that transit the near side of the Sun, new far-side side flux emergence is typically neglected. We demonstrate a new method for creating improved maps of the magnetic field over the Sun's entire photosphere using data obtained by the Solar TErrestrial RElations Observatory (STEREO) mission. STEREO He II 304 Å intensity images are used to infer the time, location, and total unsigned magnetic flux of far-side active regions. We have developed an automatic detection algorithm for finding and ingesting new far-side active region emergence into the AFT model. We conduct a series of simulations to investigate the impact of including active region emergence in AFT, both with and without data assimilation of magnetograms. We find that while He II 304 Å can be used to improve surface flux models, care must taken to mitigate intensity surges from flaring events. We estimate that during Solar Cycle 24's maximum (2011–2015), 4–6 × 1022 Mx of flux is missing from SFT models that do not include far-side data. We find that while He II 304 Å data alone can be used to create synchronic maps of photospheric magnetic field that resemble the observations, it is insufficient to produce a complete picture without direct magnetic observations from magnetographs.

Keywords: solar physics; bipolar sunspot groups; solar cycle; solar evolution; active sun; sunspots; the sun; solar active region magnetic fields; magnetic fields; space weather
Comparison of Polarized Radiative Transfer Codes Used by the EHT Collaboration

Interpretation of resolved polarized images of black holes by the Event Horizon Telescope (EHT) requires predictions of the polarized emission observable by an Earth-based instrument for a particular model of the black hole accretion system. Such predictions are generated by general relativistic radiative transfer (GRRT) codes, which integrate the equations of polarized radiative transfer in curved spacetime. A selection of ray-tracing GRRT codes used within the EHT Collaboration is evaluated for accuracy and consistency in producing a selection of test images, demonstrating that the various methods and implementations of radiative transfer calculations are highly consistent. When imaging an analytic accretion model, we find that all codes produce images similar within a pixel-wise normalized mean squared error (NMSE) of 0.012 in the worst case. When imaging a snapshot from a cell-based magnetohydrodynamic simulation, we find all test images to be similar within NMSEs of 0.02, 0.04, 0.04, and 0.12 in Stokes I, Q, U, and V, respectively. We additionally find the values of several image metrics relevant to published EHT results to be in agreement to much better precision than measurement uncertainties.

Keywords: supermassive black holes; radiative transfer simulations; astronomy software
Extended Calculations of Energy Levels and Transition Rates for Singly Ionized Lanthanide Elements. I. Pr-Gd

Lanthanide elements play important roles as an opacity source in the ejected material from neutron star mergers. Accurate and complete atomic data are necessary to evaluate the opacities and to analyze the observed data. In this paper, we perform extended, ab initio atomic calculations from Pr II (Z = 59) to Gd II (Z = 64). By using multiconfiguration Dirac-Hartree-Fock and relativistic configuration-interaction methods, implemented in the general-purpose relativistic atomic structure package (GRASP2K), we calculate the energy levels and transition data of electric dipole transitions. These computations are based on strategies (with small variations) of Nd II published by Gaigalas et al. Accuracy of data is evaluated by comparing computed energy levels with the National Institute of Standards and Technology (NIST) database or other works. For the energy levels, we obtain the average relative accuracy of 8%, 12%, 6%, 8%, and 7% for Pr II, Pm II, Sm II, Eu II, and Gd II ions, respectively, as compared with the NIST data. Accuracy of energy transfer to the wavelength is 3%, 14%, and 11% for Pr II, Eu II, and Gd II. Our computed E1 type transition probabilities are in good agreement with experimental values presented by other authors especially for strong transitions.

Keywords: neutron stars; r-process; gravitational wave sources; atomic spectroscopy; transition probabilities
Multispacecraft Observations of Coronal Loops to Verify a Force-free Field Reconstruction and Infer Loop Cross Sections

Active region EUV loops are believed to trace a subset of magnetic field lines through the corona. Malanushenko et al. proposed a method, using loop images and line-of-sight photospheric magnetograms, to infer the 3D shape and field strength along each loop. McCarthy et al. used this novel method to compute the total magnetic flux interconnecting a pair of active regions observed by SDO/AIA. They adopted the common assumption that each loop had a circular cross section. The accuracy of inferred shape and circularity of cross sections can both be tested using observations of the same loops from additional vantage points as provided by STEREO/EUVI. Here we use multiple viewing angles to confirm the 3D structure of loops. Of 151 viable cases, 105 (69.5%) matched some form of visible coronal structure when viewed approximately in quadrature. A loop with a circular cross section should appear of a similar width in different perspectives. In contradiction to this, we find a puzzling lack of correlation between loop diameters seen from different perspectives, even an anticorrelation in some cases. Features identified as monolithic loops in AIA may, in fact, be more complex density enhancements. The 30.5% of reconstructions from AIA that did not match any feature in EUVI might be such enhancements. Others may be genuine loop structures, but with elliptical cross sections. We observe an anticorrelation between diameter and brightness, lending support to the latter hypothesis. Of 13 loops suitable for width analysis, 4 are consistent with noncircular cross sections, where we find anticorrelation in both comparisons.

Keywords: solar coronal loops; solar active region magnetic fields
JWST Reveals a Luminous Infrared Source at the Position of the Failed Supernova Candidate N6946-BH1

N6946-BH1 (BH1) is the first plausible candidate for a failed supernova (SN), a peculiar event in which a massive star disappears without the expected bright SN, accompanied by collapse into a black hole (BH). Following a luminous outburst in 2009, the source experienced a significant decline in optical brightness, while maintaining a persistent IR presence. While it was proposed to be a potential failed SN, such behavior has been observed in SN impostor events in nearby galaxies. Here, we present late-time observations of BH1, taken 14 yr after disappearance, using JWST's NIRCam and MIRI instruments to probe a never before observed region of the object's spectral energy distribution (SED). We show for the first time that all previous observations of BH1 (pre- and postdisappearance) are actually a blend of at least three sources. In the near-infrared, BH1 is notably fainter than the progenitor but retains similar brightness to its state in 2017. In the mid-infrared the flux appears to have brightened compared to the inferred fluxes from the best-fitting progenitor model. The total luminosity of the source is between 13% and 25% that of the progenitor. We also show that the IR SED appears consistent with polycyclic aromatic hydrocarbon features that arise when dust is illuminated by near-ultraviolet radiation. At present, the interpretation of BH1 remains uncertain. The observations match expectations for a stellar merger, but theoretical ambiguity in the failed SN hypothesis makes it hard to dismiss.

Keywords: massive stars; core-collapse supernovae; black holes; stellar evolution
Fifteen Years of Millimeter Accuracy Lunar Laser Ranging with APOLLO: Data Set Characterization

We present data from the Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) covering the 15 yr span from 2006 April through the end of 2020. APOLLO measures the Earth-Moon separation by recording the round-trip travel time of photons from the Apache Point Observatory to five retro-reflector arrays on the Moon. The APOLLO data set, combined with the 50 yr archive of measurements from other lunar laser ranging (LLR) stations, can be used to probe fundamental physics such as gravity and Lorentz symmetry, as well as properties of the Moon itself. We show that range measurements performed by APOLLO since 2006 have a median nightly accuracy of 1.7 mm, which is significantly better than other LLR stations.

Keywords: general relativity; gravitation; lunar geodesy