adsabs/SciX_UAT_keywords huggingface dataset:
ALMA Lensing Cluster Survey: Full Spectral Energy Distribution Analysis of z ∼ 0.5–6 Lensed Galaxies Detected with millimeter Observations

Sub/millimeter galaxies are a key population for the study of galaxy evolution because the majority of star formation at high redshifts occurred in galaxies deeply embedded in dust. To search for this population, we have performed an extensive survey with Atacama Large Millimeter/submillimeter Array (ALMA), called the ALMA Lensing Cluster Survey (ALCS). This survey covers 133 arcmin2 area and securely detects 180 sources at z ∼ 0.5–6 with a flux limit of ∼0.2 mJy at 1.2 mm. Here, we report the results of multiwavelength spectral energy distribution analysis of the whole ALCS sample, utilizing the observed-frame UV to millimeter photometry. We find that the majority of the ALCS sources lie on the star-forming main sequence, with a smaller fraction showing intense starburst activities. The ALCS sample contains high infrared-excess sources ( $\mathrm{IRX}=\mathrm{log}({L}_{\mathrm{dust}}/{L}_{\mathrm{UV}})\gt 1$ ), including two extremely dust-obscured galaxies (IRX > 5). We also confirm that the ALCS sample probes a broader range in lower dust mass than conventional submillimeter galaxy samples in the same redshift range. We identify six heavily obscured active galactic nucleus (AGN) candidates that are not detected in the archival Chandra data in addition to the three X-ray AGNs reported by Uematsu et al. (2023). The inferred AGN luminosity density shows a possible excess at z = 2–3 compared with that determined from X-ray surveys below 10 keV.

Keywords: submillimeter astronomy; galaxy evolution; high-redshift galaxies; spectral energy distribution; active galactic nuclei
Current Sheet Alignment in Oblique Black Hole Magnetospheres: A Black Hole Pulsar?

We study the magnetospheric evolution of a nonaccreting spinning black hole (BH) with an initially inclined split monopole magnetic field by means of 3D general relativistic magnetohydrodynamic simulations. This serves as a model for a neutron star (NS) collapse or a BH–NS merger remnant after the inherited magnetosphere has settled into a split monopole field creating a striped wind. We show that the initially inclined split monopolar current sheet aligns over time with the BH equatorial plane. The inclination angle evolves exponentially toward alignment, with an alignment timescale that is inversely proportional to the square of the BH angular velocity, where higher spin results in faster alignment. Furthermore, magnetic reconnection in the current sheet leads to exponential decay of event-horizon-penetrating magnetic flux with nearly the same timescale for all considered BH spins. In addition, we present relations for the BH mass and spin in terms of the period and alignment timescale of the striped wind. The explored scenario of a rotating, aligning, and reconnecting current sheet can potentially lead to multimessenger electromagnetic counterparts to a gravitational-wave event due to the acceleration of particles powering high-energy radiation, plasmoid mergers resulting in coherent radio signals, and pulsating emission due to the initial misalignment of the BH magnetosphere.

Keywords: high energy astrophysics; plasma astrophysics; compact objects; magnetic fields; relativity; magnetohydrodynamics
Transition from Small-scale to Large-scale Dynamo in a Supernova-driven, Multiphase Medium

Magnetic fields are now widely recognized as critical at many scales to galactic dynamics and structure, including multiphase pressure balance, dust processing, and star formation. Using imposed magnetic fields cannot reliably model the interstellar medium's (ISM) dynamical structure nor phase interactions. Dynamos must be modeled. ISM models exist of turbulent magnetic fields using small-scale dynamo (SSD). Others model the large-scale dynamo (LSD) organizing magnetic fields at the scale of the disk or spiral arms. Separately, neither can fully describe the galactic magnetic field dynamics nor topology. We model the LSD and SSD together at a sufficient resolution to use the low explicit Lagrangian resistivity required. The galactic SSD saturates within 20 Myr. We show that the SSD is quite insensitive to the presence of an LSD and is even stronger in the presence of a large-scale shear flow. The LSD grows more slowly in the presence of SSD, saturating after 5 Gyr versus 1-2 Gyr in studies where the SSD is weak or absent. The LSD primarily grows in warm gas in the galactic midplane. Saturation of the LSD occurs due to α-quenching near the midplane as the growing mean-field produces a magnetic α that opposes the kinetic α. The magnetic energy in our models of the LSD shows a slightly sublinear response to increasing resolution, indicating that we are converging toward the physical solution at 1 pc resolution. Clustering supernovae in OB associations increases the growth rates for both the SSD and the LSD, compared to a horizontally uniform supernova distribution.

Keywords: astroinformatics; astrophysical fluid dynamics; interstellar magnetic fields; magnetohydrodynamical simulations; supernova dynamics; disk galaxies; galaxy magnetic fields
Lyα Observations of Comet C/2013 A1 (Siding Spring) Using MAVEN IUVS Echelle

The close approach of comet C/2013 A1 (Siding Spring) to Mars in 2014 October provided a unique opportunity to observe a dynamically new Oort cloud comet with potential for interaction with a planet's atmosphere. The water-originating hydrogen coma of the comet extended to over 20 million km from the nucleus. Determining the properties of this coma contributes to characterizing the comet's water content and production rate. The present study analyzes a unique data set of high spectral resolution UV observations of comet C/2013 A1 Siding Spring measured by the Mars Atmosphere and Volatile Evolution spacecraft. The Siding Spring observations capture Lyα emissions from the Martian corona, the interplanetary medium, as well as the cometary H and D reservoirs. The isolated cometary spectra are analyzed to reveal a velocity distribution of H atoms that are consistent with model estimates of H2O photodissociated H emissions and of OH photodissociated H emissions, Doppler shifted from the main comet H emission line center by 18 km s-1 and 8 km s-1, respectively. The variations in comet H brightness with distance from the nucleus are used to constrain cometary water production to a rate of 0.5 × 1028 molecules s-1 at a time when Siding Spring was at 1.5 au, pre-perihelion.

Keywords: comets; ultraviolet sources; interplanetary medium; mars
HST/WFC3 Light Curve Supports a Terrestrial Composition for the Closest Exoplanet to Transit an M Dwarf

Previous studies of the exoplanet LTT 1445Ac concluded that the light curve from the Transiting Exoplanet Survey Satellite (TESS) was consistent with both grazing and nongrazing geometries. As a result, the radius and hence density of the planet remained unknown. To resolve this ambiguity, we observed the LTT 1445 system for six spacecraft orbits of the Hubble Space Telescope (HST) using WFC3/UVIS imaging in spatial scan mode, including one partial transit of LTT 1445Ac. This imaging produces resolved light curves of each of the three stars in the LTT 1445 system. We confirm that the planet transits LTT 1445A and that LTT 1445C is the source of the rotational modulation seen in the TESS light curve, and we refine the estimate of the dilution factor for the TESS data. We perform a joint fit to the TESS and HST observations, finding that the transit of LTT 1445Ac is not grazing with 97% confidence. We measure a planetary radius of ${1.07}_{-0.07}^{+0.10}\,{R}_{\oplus }$ . Combined with previous radial velocity observations, our analysis yields a planetary mass of 1.37 ± 0.19 M ⊕ and a planetary density of ${5.9}_{-1.5}^{+1.8}$ g cm-3. LTT 1445Ac is likely an Earth analog with respect to its mass and radius, albeit with a higher instellation, and is therefore an exciting target for future atmospheric studies.

Keywords: exoplanet astronomy; transit photometry; exoplanets; m dwarf stars; transits; hst photometry; hubble space telescope; multiple stars
The Observed Rate of Binary Black Hole Mergers can be Entirely Explained by Globular Clusters

Since the first signal in 2015, the gravitational-wave detections of merging binary black holes (BBHs) by the LIGO and Virgo collaborations (LVC) have completely transformed our understanding of the lives and deaths of compact object binaries, and have motivated an enormous amount of theoretical work on the astrophysical origin of these objects. We show that the phenomenological fit to the redshift-dependent merger rate of BBHs from Abbott et al. is consistent with a purely dynamical origin for these objects, and that the current merger rate of BBHs from the LVC could be explained entirely with globular clusters alone. While this does not prove that globular clusters are the dominant formation channel, we emphasize that many formation scenarios could contribute a significant fraction of the current LVC rate, and that any analysis that assumes a single (or dominant) mechanism for producing BBH mergers is implicitly using a specious astrophysical prior.

Keywords: astrophysical black holes; gravitational wave sources
From Halos to Galaxies. VII. The Connections between Stellar Mass Growth History, Quenching History, and Halo Assembly History for Central Galaxies

The assembly of galaxies over cosmic time is tightly connected to the assembly of their host dark matter halos. We investigate the stellar mass growth history and the chemical enrichment history of central galaxies in the Sloan Digital Sky Survey Mapping Nearby Galaxies at Apache Point Observatory. We find that the derived stellar metallicity of passive central galaxies is always higher than that of the star-forming ones. This stellar metallicity enhancement becomes progressively larger toward low-mass galaxies (at a given epoch) and earlier epochs (at a given stellar mass), which suggests strangulation as the primary mechanism for star formation quenching in central galaxies not only in the local Universe but also very likely at higher redshifts up to z ~ 3. We show that at the same present-day stellar mass, passive central galaxies assembled half of their final stellar mass ~2 Gyr earlier than star-forming central galaxies, which agrees well with the semi-analytic model. Exploring the semi-analytic model, we find that this is because passive central galaxies reside in, on average, more massive halos with a higher halo mass increase rate across cosmic time. As a consequence, passive central galaxies are assembled faster and also quenched earlier than their star-forming counterparts. While at the same present-day halo mass, different halo assembly history also produces a very different final stellar mass of the central galaxy within, and halos assembled earlier host more massive centrals with a higher quenched fraction, in particular around the "golden halo mass" at 1012 M ⊙. Our results call attention back to the dark matter halo as a key driver of galaxy evolution.

Keywords: galaxy evolution; galaxy dark matter halos; star formation
Correlations in Chromospheric and Coronal Activity Indicators of Giant Stars

The main goal of this paper is to use ultraviolet photometry from the Galaxy Evolution Explorer (GALEX) satellite to study chromospheric activity among red giant and core-helium-burning (CHeB) stars. Correlations are sought between several chromospheric and coronal activity indicators for giants that were detected in soft X-rays by the ROentgen SATellite. There is an evident correlation between $\mathrm{log}({L}_{{\rm{X}}}/{L}_{\mathrm{bol}})$ and $\mathrm{log}({F}_{\mathrm{Mg}\,{\rm\small{II}}}/{F}_{\mathrm{bol}})$ , where L X is the X-ray luminosity and F Mg II is the flux from Mg II h and k emission lines, although there is substantial scatter. Using GALEX far-ultraviolet (FUV) magnitudes, the relationship between an FUV-excess parameter (a proxy for chromospheric and transition-region emission lines) and X-ray luminosity is documented. Correlations found herein are not strong, and may be linked to binarity. There is a varied range of FUV emission among CHeB stars, indicating that giants in this phase may be exhibiting differences or cycles in outer atmospheric activity. Additionally, efforts were made to constrain a relationship between excess FUV and near-ultraviolet emission and the projected surface rotation velocity, $v\sin i$ , of giants. No clear relationship was found. Obscurities in this relationship may result from a spread in $\sin i$ inclinations, and/or too few stars with $v\sin i\gt 7$ km s-1.

Keywords: late stellar evolution; giant stars; x-ray stars; ultraviolet astronomy
Renormalization Group Analysis of the Turbulent Hydromagnetic Dynamo: The Effect of Nonstationarity

The turbulent hydromagnetic dynamo is a process of magnetic field generation by chaotic flow of an electrically conducting fluid (plasma, liquid iron, etc.). It is responsible for generation of large-scale magnetic fields of astrophysical objects such as planets, stars, accretion disks, galaxies, galaxy clusters, etc. In particular, the dynamical process of induction of large-scale fields by highly conducting plasma has been very difficult to understand, as very low resistivity is not capable of creating a phase shift between magnetic and kinetic components of waves, making their interaction ineffective for generation of a large-scale electromotive force (EMF). The aim of the analysis presented here is to demonstrate that when the typically invoked statistical stationarity of turbulence is relaxed, large-scale magnetic fields can be very effectively generated by low-resistivity plasma. The renormalization group technique is applied to extract the final expression for the mean EMF from the fully nonlinear dynamical equations (Navier-Stokes, induction equation), and the mean field equations are solved for a force-free mode. Nonstationarity is shown to strongly enhance the process of large-scale EMF generation via wave interactions, and the dynamo effect induced by nonstationarity is proved to be effective. The results are also used to demonstrate the influence of magnetic fields and nonstationarity on energy and helicity spectra of turbulent flows.

Keywords: astrophysical fluid dynamics; magnetohydrodynamics; astrophysical magnetism; cosmic magnetic fields theory; galaxy magnetic fields
Searching for Short-period Variables in M31: Method and Catalogs

Utilizing high-cadence and continuous g- and r-band data over three nights acquired from the 3.6 m Canada–France–Hawaii Telescope, aiming to find short-duration microlensing events, we conduct a systematic search for variables, transients, and asteroids across a ∼1° field of view of the Andromeda galaxy (M31). We present a catalog of 5859 variable stars, yielding the most extensive compilation of short-period variable sources of M31. We also detected 19 flares, predominantly associated with foreground M dwarfs in the Milky Way. In addition, we discovered 17 previously unknown asteroid candidates, and we subsequently reported them to the Minor Planet Center. Lastly, we report a microlensing event candidate C-ML-1 and present a preliminary analysis.

Keywords: andromeda galaxy; time domain astronomy; asteroids; variable stars; gravitational microlensing; astronomy data reduction
Forecasting Rates of Volcanic Activity on Terrestrial Exoplanets and Implications for Cryovolcanic Activity on Extrasolar Ocean Worlds

Like the planets and moons in our solar system, the surfaces of terrestrial exoplanets may be shaped by volcanic activity. The magnitudes and rates of volcanic activity on terrestrial exoplanets will be intimately linked to their sizes and internal heating rates and can either facilitate or preclude the existence of habitable environments. In order to place bounds on the potential for such activity, we estimate total internal heating rates for 53 exoplanets with masses and radii up to ∼8M⊕ and 2R⊕, respectively, assuming that internal heating is drawn from both radiogenic and tidal sources. We then compare these internal heating rates to those of the planets and moons in our solar system in an attempt to constrain the expected rates of volcanic activity on these extrasolar worlds. We find that all 53 of the exoplanets surveyed are likely to have volcanic activity at their surfaces, and that at least 26% of these planets may be extrasolar ocean worlds. The majority of these ocean worlds may be similar in structure to the icy moons of the giant planets, having internal oceans beneath layers of surface ice. If so, these planets may exhibit cryovolcanism (i.e., icy volcanism) at their surfaces. Recent studies have shown that extrasolar volcanism could be detected by high-resolution spectrographs on existing ground-based telescopes. In the case of planets with densities and/or effective temperatures that are consistent with H2O-rich compositions, spectral identification of excess water vapor and other molecules that are explosively vented into space during cryovolcanic eruptions could serve as a way to infer the presence of subsurface oceans, and therefore indirectly assess their habitability. Considering the implications for habitability, our results suggest that continued characterization of terrestrial exoplanets in terms of their potential for volcanic activity should be a priority in the coming years.

Keywords: exoplanet structure; exoplanets; volcanoes; ocean planets; exosphere; exoplanet atmospheres; tidal friction; exoplanet surface characteristics; extrasolar rocky planets
The Feasibility of Detecting Biosignatures in the TRAPPIST-1 Planetary System with JWST

The James Webb Space Telescope (JWST) provides the first opportunity to detect gases in the atmospheres of M-dwarf terrestrial planets and search for signs of life. Here we determine the detectability of a comprehensive suite of biosignature gases that may have been episodically prevalent across Earth's history. We used coupled 1D climate-photochemical models to generate synthetic inhabited terrestrial planetary environments for TRAPPIST-1 d and e. These encompass cloudy and/or hazy Archean-Earth-like environments with either a dominant sulfur- or methane-producing biosphere, as well as clear and cloudy modern-Earth-like environments with photosynthetic oxygen-producing biospheres. We generate transmission spectra and assess the likely detectability of different biosignatures with JWST. Our simulations suggest that biogenically generated O2 and its photosynthetic by-product O3 will likely be extremely difficult to detect. We explored the detectability of methyl chloride (CH3Cl) as an alternative indicator for a photosynthetic biosphere but find that it will likely require significantly higher global surface fluxes than Earth's. We find that the CH4 and CO2 disequilibrium pair is potentially detectable in ~10 transits for both the methanogen-dominated Archean-like environment and the modern photosynthetic-dominated biosphere-even in cloudy atmospheres. Organic haze and methyl mercaptan are other potential biosignatures for the Archean. Given the likely difficulties in observing an oxygenic-photosynthetic biosphere with JWST, we conclude that the methanogenic biosphere revealed by the combination of outgassed CO2 in the presence of methanogenically generated CH4 may be the most persistent detectable biosignature for an Earth-like planet.

Keywords: astrobiology; biosignatures; transmission spectroscopy; exoplanet atmospheres
Stratification Dynamics of Titan's Lakes via Methane Evaporation

Saturn's moon Titan is the only extraterrestrial body known to host stable lakes and a hydrological cycle. Titan's lakes predominantly contain liquid methane, ethane, and nitrogen, with methane evaporation driving its hydrological cycle. Molecular interactions between these three species lead to nonideal behavior that causes Titan's lakes to behave differently than Earth's lakes. Here, we numerically investigate how methane evaporation and nonideal interactions affect the physical properties, structure, dynamics, and evolution of shallow lakes on Titan. We find that, under certain temperature regimes, methane-rich mixtures are denser than relatively ethane-rich mixtures. This allows methane evaporation to stratify Titan's lakes into ethane-rich upper layers and methane-rich lower layers, separated by a strong compositional gradient. At temperatures above 86 K, lakes remain well mixed and unstratified. Between 84 and 86 K, lakes can stratify episodically. Below 84 K, lakes permanently stratify and develop very methane-depleted epilimnia. Despite small seasonal and diurnal deviations (<5 K) from typical surface temperatures, Titan's rain-filled ephemeral lakes and "phantom lakes" may nevertheless experience significantly larger temperature fluctuations, resulting in polymictic or even meromictic stratification, which may trigger ethane ice precipitation.

Keywords: saturnian satellites
Supernova Dust Evolution Probed by Deep-sea 60Fe Time History

There is a wealth of data on live, undecayed 60Fe (t 1/2 = 2.6 Myr) in deep-sea deposits, the lunar regolith, cosmic rays, and Antarctic snow, which is interpreted as originating from the recent explosions of at least two near-Earth supernovae. We use the 60Fe profiles in deep-sea sediments to estimate the timescale of supernova debris deposition beginning ~3 Myr ago. The available data admits a variety of different profile functions, but in all cases the best-fit 60Fe pulse durations are >1.6 Myr when all the data is combined. This timescale far exceeds the ≲0.1 Myr pulse that would be expected if 60Fe was entrained in the supernova blast wave plasma. We interpret the long signal duration as evidence that 60Fe arrives in the form of supernova dust, whose dynamics are separate from but coupled to the evolution of the blast plasma. In this framework, the >1.6 Myr is that for dust stopping due to drag forces. This scenario is consistent with the simulations in Fry et al. (2020), where the dust is magnetically trapped in supernova remnants and thereby confined around regions of the remnant dominated by supernova ejects, where magnetic fields are low. This picture fits naturally with models of cosmic-ray injection of refractory elements as sputtered supernova dust grains and implies that the recent 60Fe detections in cosmic rays complement the fragments of grains that survived to arrive on the Earth and Moon. Finally, we present possible tests for this scenario.

Keywords: supernovae; nucleosynthesis; mass spectrometry; astrophysical dust processes