adsabs/SciX_UAT_keywords huggingface dataset:
Galaxy Populations in Groups and Clusters: Evidence for a Characteristic Stellar Mass Scale at M ∗ 109.5 M ⊙

We use the DR9 of the DESI legacy imaging survey and SDSS galaxy groups to measure the conditional luminosity function (CLF) for groups with halo mass M h ≥ 1012 M ⊙ and redshift 0.01 ≤ z ≤ 0.08, down to a limiting r-band magnitude of M r = -10 to -12. For given halo masses we measure the CLF for the total populations and for the red and blue populations classified using the (g - z) color. We find a clear faint-end upturn in the CLF of red satellites, with a slope α ≈ -1.8, which is almost independent of halo mass. This faint-end upturn is not seen for the blue and total populations. Our stellar population synthesis modeling shows that (g - z) provides a clean red/blue division and that red group galaxies defined by (g - z) are all dominated by old stellar populations. The fraction of old galaxies as a function of galaxy luminosity shows a minimum at M r ~ -18, corresponding to M * ~ 109.5 M ⊙. This scale is independent of halo mass and is comparable to the characteristic luminosity at which galaxies show a dichotomy in surface brightness and size, suggesting that the dichotomy in the old fraction and in galaxy structure may have a common origin. The rising of the old fraction at the faint end for Milky Way (MW)-sized halos is in good agreement with the quenched fraction measured for the MW/M31 system and from the ELVES survey. We discuss the implications of our results for the formation and evolution of low-mass galaxies and for the stellar mass functions of low-mass galaxies to be observed at high redshift.

Keywords: galaxy clusters; galaxy groups; galaxy abundances; galaxy formation
Proton- and Alpha-driven Instabilities in an Ion Cyclotron Wave Event

Ion-scale wave events or wave storms in the solar wind are characterized by enhancements in magnetic field fluctuations as well as coherent magnetic field polarization signatures at or around the local ion cyclotron frequencies. In this paper, we study in detail one such wave event from Parker Solar Probe's (PSP) fourth encounter, consisting of an initial period of left-handed (LH) polarization abruptly transitioning to a strong period of right-handed (RH) polarization, accompanied by a clear core beam structure in both the alpha and proton velocity distribution functions. A linear stability analysis shows that the LH-polarized waves are anti-sunward propagating Alfvén/ion cyclotron waves primarily driven by a proton cyclotron instability in the proton core population, and the RH polarized waves are anti-sunward propagating fast magnetosonic/whistler waves driven by a firehose-like instability in the secondary alpha beam population. The abrupt transition from LH to RH is caused by a drop in the proton core temperature anisotropy. We find very good agreement between the frequencies and polarizations of the unstable wave modes as predicted by linear theory and those observed in the magnetic field spectra. Given the ubiquity of ion-scale wave signatures observed by PSP, this work gives insight into which exact instabilities may be active and mediating energy transfer in wave-particle interactions in the inner heliosphere, as well as highlighting the role a secondary alpha population may play as a rarely considered source of free energy available for producing wave activity.

Keywords: heliosphere; fast solar wind
Coronal Microjets in Quiet-Sun Regions Observed with the Extreme Ultraviolet Imager on Board the Solar Orbiter

We report the smallest coronal jets ever observed in the quiet Sun with recent high-resolution observations from the High Resolution Telescopes (HRIEUV and HRILyα) of the Extreme Ultraviolet Imager on board the Solar Orbiter (SO). In the HRIEUV (174 Å) images, these microjets usually appear as nearly collimated structures with brightenings at their footpoints. Their average lifetime, projected speed, width, and maximum length are 4.6 minutes, 62 km s-1, 1.0 Mm, and 7.7 Mm, respectively. Inverted-Y shaped structures and moving blobs can be identified in some events. A subset of these events also reveal signatures in the HRILyα (H I Lyα at 1216 Å) images and the extreme ultraviolet images taken by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). Our differential emission-measure (EM) analysis suggests a multithermal nature and an average density of ~1.4 × 109 cm-3 for these microjets. Their thermal and kinetic energies were estimated to be ~3.9 × 1024 erg and ~2.9 × 1023 erg, respectively, which are of the same order of the released energy predicted by the nanoflare theory. Most events appear to be located at the edges of network lanes and magnetic flux concentrations, suggesting that these coronal microjets are likely generated by magnetic reconnection between small-scale magnetic loops and the adjacent network field.

Keywords: quiet sun; solar ultraviolet emission; solar corona
Probing UV-sensitive Pathways for CN and HCN Formation in Protoplanetary Disks with the Hubble Space Telescope

The UV radiation field is a critical regulator of gas-phase chemistry in surface layers of disks around young stars. In an effort to understand the relationship between photocatalyzing UV radiation fields and gas emission observed at infrared and submillimeter wavelengths, we present an analysis of new and archival Hubble Space Telescope (HST), Spitzer, ALMA, IRAM, and SMA data for five targets in the Lupus cloud complex and 14 systems in Taurus-Auriga. The HST spectra were used to measure Lyα and far-UV (FUV) continuum fluxes reaching the disk surface, which are responsible for dissociating relevant molecular species (e.g., HCN, N2). Semi-forbidden C II] λ2325 and UV-fluorescent H2 emission were also measured to constrain inner disk populations of C+ and vibrationally excited H2. We find a significant positive correlation between 14 μm HCN emission and fluxes from the FUV continuum and C II] λ2325, consistent with model predictions requiring N2 photodissociation and carbon ionization to trigger the main CN/HCN formation pathways. We also report significant negative correlations between submillimeter CN emission and both C II] and FUV continuum fluxes, implying that CN is also more readily dissociated in disks with stronger FUV irradiation. No clear relationships are detected between either CN or HCN and Lyα or UV-H2 emission. This is attributed to the spatial stratification of the various molecular species, which span several vertical layers and radii across the inner and outer disk. We expect that future observations with the James Webb Space Telescope will build on this work by enabling more sensitive IR surveys than were possible with Spitzer.

Keywords: protoplanetary disks; ultraviolet astronomy; young stellar objects; molecular spectroscopy; astrochemistry
Do the Outburst Properties of M31N 2008-12a Depend on the Time Since the Previous Eruption?

Photometric observations spanning the UV to the near-IR during the nine most recent eruptions (2014-2022) of the extragalactic nova M31N 2008-12a are presented and analyzed in order to explore whether the lightcurve properties for a given eruption, specifically the peak magnitudes and fade rates, are correlated with the time interval since the previous eruption. No significant correlation between the pre-eruption interval and the rate of decline was found, however it appears that the brightness at the peak of an outburst may be positively correlated with the time interval since the previous eruption.

Keywords: andromeda galaxy; novae; recurrent novae
Consistent Eccentricities for Gravitational-wave Astronomy: Resolving Discrepancies between Astrophysical Simulations and Waveform Models

Detecting imprints of orbital eccentricity in gravitational-wave (GW) signals promises to shed light on the formation mechanisms of binary black holes. To constrain the formation mechanisms, distributions of eccentricity derived from numerical simulations of astrophysical formation channels are compared to the estimates of eccentricity inferred from GW signals. We report that the definition of eccentricity typically used in astrophysical simulations is inconsistent with the one used while modeling GW signals, with the differences mainly arising due to the choice of reference frequency used in both cases. We also posit a prescription for calculating eccentricity from astrophysical simulations, by evolving ordinary differential equations obtained from post-Newtonian theory and using the dominant (ℓ = m = 2) mode's frequency as the reference frequency; this ensures consistency in the definitions. On comparing the existing eccentricities of the binaries present in the Cluster Monte Carlo catalog of globular cluster simulations with the eccentricities calculated using the prescription presented here, we find a significant discrepancy at e ≳ 0.2; this discrepancy becomes worse with increasing eccentricity. We note the implications this discrepancy has for existing studies and recommend that care be taken when comparing data-driven constraints on eccentricity to expectations from astrophysical formation channels.

Keywords: gravitational wave sources; gravitational wave astronomy
From Haloes to Galaxies. III. The Gas Cycle of Local Galaxy Populations

In Dou et al., we introduced the fundamental formation relation (FFR), a tight relation between specific star formation rate (sSFR), H2 star formation efficiency (SFE ${}_{{{\rm{H}}}_{2}}$ ), and the ratio of H2 to stellar mass. Here, we show that atomic gas H ɪ does not follow a similar FFR as H2. The relation between SFEHɪ and sSFR shows significant scatter and strong systematic dependence on all of the key galaxy properties that we have explored. The dramatic difference between H ɪ and H2 indicates that different processes (e.g., quenching by different mechanisms) may have very different effects on H ɪ in different galaxies and hence produce different SFEHɪ-sSFR relations, while the SFE ${}_{{{\rm{H}}}_{2}}$ -sSFR relation remains unaffected. The fact that the SFE ${}_{{{\rm{H}}}_{2}}$ -sSFR relation is independent of other key galaxy properties, and that sSFR is directly related to the cosmic time and acts as the cosmic clock, make it natural and very simple to study how different galaxy populations (with different properties and undergoing different processes) evolve on the same SFE ${}_{{{\rm{H}}}_{2}}$ -sSFR ~ t relation. In the gas regulator model (GRM), the evolution of a galaxy on the SFE ${}_{{{\rm{H}}}_{2}}$ -sSFR(t) relation is uniquely set by a single mass-loading parameter ${\lambda }_{\mathrm{net},{{\rm{H}}}_{2}}$ . This simplicity allows us to accurately derive the H2 supply and removal rates of the local galaxy populations with different stellar masses, from star-forming galaxies to the galaxies in the process of being quenched. This combination of FFR and GRM, together with the stellar metallicity requirement, provide a new powerful tool to study galaxy formation and evolution.

Keywords: galaxy evolution; interstellar medium; star formation; galaxy formation; galaxy quenching
Molecular Gas Reservoirs in Massive Quiescent Galaxies at z 0.7 Linked to Late-time Star Formation

We explore how the presence of detectable molecular gas depends on the inferred star formation histories (SFHs) in eight massive, quiescent galaxies at z ~ 0.7. Half of the sample have clear detections of molecular gas, traced by CO(2-1). We find that the molecular gas content is unrelated to the rate of star formation decline prior to the most recent 1 Gyr, suggesting that the gas reservoirs are not left over from their primary star formation epoch. However, the recent SFHs of CO-detected galaxies demonstrate evidence for secondary bursts of star formation in their last Gyr. The fraction of stellar mass formed in these secondary bursts ranges from f burst ≈ 0.3%-6% and ended between t end-burst ≈ 0-330 Myr ago. The CO-detected galaxies form a higher fraction of mass in the last Gyr ( ${f}_{{M}_{1\,\mathrm{Gyr}}}=2.6 \% \pm 1.8 \% $ ) compared to the CO-undetected galaxies ( ${f}_{{M}_{1\,\mathrm{Gyr}}}=0.2 \% \pm 0.1 \% $ ). The galaxies with gas reservoirs have enhanced late-time star formation, highlighting this as a contributing factor to the observed heterogeneity in the gas reservoirs in high-redshift quiescent galaxies. We find that the amount of gas and star formation driven by these secondary bursts are inconsistent with that expected from dry minor mergers, and instead are likely driven by recently accreted gas, i.e., gas-rich minor mergers. This conclusion would not have been made based on SFRUV+IR measurements alone, highlighting the power of detailed SFH modeling in the interpretation of gas reservoirs. Larger samples are needed to understand the frequency of low-level rejuvenation among quiescent galaxies at intermediate redshifts, and to what extent this drives the diversity of molecular gas reservoirs.

Keywords: galaxy evolution; galaxy quenching; galaxy formation; galaxy stellar content; quenched galaxies; molecular gas; early-type galaxies; high-redshift galaxies
Robo-AO M-dwarf Multiplicity Survey: Catalog

We analyze observations from Robo-AO's field M dwarf survey taken on the 2.1 m Kitt Peak telescope and perform a multiplicity comparison with Gaia DR2. Through its laser-guided, automated system, the Robo-AO instrument has yielded the largest adaptive optics M dwarf multiplicity survey to date. After developing an interface to visually identify and locate stellar companions, we selected 11 low-significance Robo-AO detections for follow-up on the Keck II telescope using NIRC2. In the Robo-AO survey we find 553 candidate companions within 4″ around 534 stars out of 5566 unique targets, most of which are new discoveries. Using a position cross-match with DR2 on all targets, we assess the binary recoverability of Gaia DR2 and compare the properties of multiples resolved by both Robo-AO and Gaia. The catalog of nearby M dwarf systems and their basic properties presented here can assist other surveys which observe these stars, such as the NASA TESS mission.

Keywords: m dwarf stars; binary stars; catalogs; multiple stars; close binary stars; trinary stars; visual binary stars
ALMA 1.1 mm Observations of a Conservative Sample of High-redshift Massive Quiescent Galaxies in SHELA

We present a sample of 30 massive (log(M */M ⊙) > 11) z = 3-5 quiescent galaxies selected from the Spitzer-HETDEX Exploratory Large Area (SHELA) Survey and observed at 1.1 mm with Atacama Large Millimeter/submillimeter Array (ALMA) Band 6 observations. These ALMA observations would detect even modest levels of dust-obscured star formation, on the order of ~20 M ⊙ yr-1 at z ~ 4 at the 1σ level, allowing us to quantify the amount of contamination from dusty star-forming sources in our quiescent sample. Starting with a parent sample of candidate massive quiescent galaxies from the Stevans et al. v1 SHELA catalog, we use the Bayesian BAGPIPES spectral energy distribution fitting code to derive robust stellar masses (M *) and star formation rates (SFRs) for these sources, and select a conservative sample of 36 candidate massive (M * > 1011 M ⊙) quiescent galaxies, with specific SFRs >2σ below the Salmon et al. star-forming main sequence at z ~ 4. Based on the ALMA imaging, six of these candidate quiescent galaxies show the presence of significant dust-obscured star formation, and thus were removed from our final sample. This implies a ~17% contamination rate from dusty star-forming galaxies with our selection criteria using the v1 SHELA catalog. This conservatively selected quiescent galaxy sample at z = 3-5 will provide excellent targets for future observations to constrain better how massive galaxies can both grow and shut down their star formation in a relatively short period.

Keywords: galaxy evolution; submillimeter astronomy; quenched galaxies; galaxies
Using the Gaia Excess Uncertainty as a Proxy for Stellar Variability and Age

Stars are known to be more active when they are young, resulting in a strong correlation between age and photometric variability. The amplitude variation between stars of a given age is large, but the age-variability relation becomes strong over large groups of stars. We explore this relation using the excess photometric uncertainty in Gaia photometry (VarG, VarBP, and VarRP) as a proxy for variability. The metrics follow a Skumanich-like relation, scaling as ≃t -0.4. By calibrating against a set of associations with known ages, we show how the Var of population members can predict group ages within 10%-20% for associations younger than ≃2.5 Gyr. In practice, age uncertainties are larger, primarily due to the finite group size. The index is most useful at the youngest ages (<100 Myr), where the uncertainties are comparable to or better than those derived from a color-magnitude diagram (CMD). The index is also widely available, easy to calculate, and can be used at intermediate ages where there are few or no pre- or post-main-sequence stars. We further show how Var can be used to find new associations and test if a group of comoving stars is a real coeval population. We apply our methods to Theia groups within 350 pc and find ≳90% are inconsistent with drawing stars from the field and ≃80% have variability ages consistent with those derived from the CMD. Our findings suggest the great majority of these groups contain real populations.

Keywords: stellar ages; young star clusters; stellar rotation; stellar evolution
Investigation on Doppler Imaging and Chromospheric Activity of the Young Dwarf LQ Hya Based on High-resolution Spectroscopy

We have obtained four Doppler images of LQ Hya in 2005 November-December, 2006 November-December, 2008 November, and 2014 January-February using high-resolution spectra obtained at three different observing sites. All of the surface maps show that the spots of LQ Hya are in bimodal distribution, i.e., in polar/high-latitude and low-latitude regions. Its chromospheric activity indicators exhibit obvious rotational modulations that are correlated with the simultaneous light curves, except in 2008. The correspondence between the maximum value of chromospheric emission and the low-latitude spot of new reconstructed image is clear, which indicates that both of them are driven by homologous magnetic field. The variation of H α emission over a long time span suggests that the chromospheric plages may implicate a similar active cycle as photospheric spots.

Keywords: starspots; doppler imaging; stellar activity; optical flares
Evidence for Very Early Planetesimal Formation and 26Al/27Al Heterogeneity in the Protoplanetary Disk

We present a U-corrected Pb-Pb age of 4566.19 ± 0.20 Ma (1.11 ± 0.26 Myr after t 0) for the moderately volatile element rich, andesitic meteorite Erg Chech 002 (EC002). Our Al-Mg isochron defines a 26Al/27Al initial ratio of (8.65 ± 0.09) × 10-6 that corresponds to a 26Al/27Al ratio of ${2.48}_{-0.56}^{+0.67}$ × 10-5 for the parent body precursor at the time of solar system formation. Whereas the published bulk chemistry and our high-precision Ca isotope measurement correspond to those for inner solar system materials, the 26Al/27Al ratio overlaps that for outer solar system CI chondrites. This indicates that the carriers and/or processes responsible for the nucleosynthetic isotope compositions for inner and outer disk materials are different than those controlling the heterogeneous distribution of 26Al. A low μ 26Mg* initial value of -6.1 ± 1.7 ppm infers a source region with a subchondritic Al/Mg ratio until 1.1 Myr after t 0 such that melt generation must have immediately preceded its crystallization. With 26Al as the main heating source, a modeled temperature-time path for a 100 km radius parent body with our inferred 26Al abundance suggests that accretion must have occurred before 0.5 Myr after t 0 to reach melting temperatures at appropriate depths within 1.1 Myr. This requires that the parent body formed very early within the protoplanetary disk, consistent with predictions of rapid formation of planetesimals by streaming instabilities within high-density dust filaments during the earliest phase of the protoplanetary disk. Finally, an absence of initial Pb in this otherwise moderately volatile-rich achondrite implies Pb was effectively sequestered to the Fe-Ni core.

Keywords: planet formation; cosmochronology; cosmochemistry
New Compound and Hybrid Binding Energy Sputter Model for Modeling Purposes in Agreement with Experimental Data

Rocky planets and moons experiencing solar wind sputtering are continuously supplying their enveloping exosphere with ejected neutral atoms. To understand the quantity and properties of the ejecta, well-established binary collision approximation Monte Carlo codes like TRIM with default settings are used predominantly. Improved models such as SDTrimSP have come forward, and together with new experimental data, the underlying assumptions have been challenged. We introduce a hybrid model, combining the previous surface binding approach with a new bulk binding model akin to Hofsäss & Stegmaier. In addition, we expand the model implementation by distinguishing between free and bound components sourced from mineral compounds such as oxides or sulfides. The use of oxides and sulfides also enables the correct setting of the mass densities of minerals, which was previously limited to the manual setting of individual atomic densities of elements. All of the energies and densities used are thereby based on tabulated data, so that only minimal user input and no fitting of parameters are required. We found unprecedented agreement between the newly implemented hybrid model and previously published sputter yields for incidence angles up to 45° from surface normal. Good agreement is found for the angular distribution of mass sputtered from enstatite MgSiO3 compared to the latest experimental data. Energy distributions recreate trends of experimental data of oxidized metals. Similar trends are to be expected from future mineral experimental data. The model thus serves its purpose of widespread applicability and ease of use for modelers of rocky body exospheres.

Keywords: solar wind; exosphere; mercury (planet); the moon
Survey of Near-infrared Diffuse Interstellar Bands in Y and J Bands. I. Newly Identified Bands

We searched for diffuse interstellar bands (DIBs) in the 0.91 < λ < 1.33 μm region by analyzing the near-infrared (NIR) high-resolution (R = 20,000 and 28,000) spectra of 31 reddened early-type stars (0.04 < E(B - V) < 4.58) and an unreddened reference star. The spectra were collected using the WINERED spectrograph, which was mounted on the 1.3 m Araki telescope at Koyama Astronomical Observatory, Japan, in 2012-2016, and on the 3.58 m New Technology Telescope at La Silla Observatory, Chile, in 2017-2018. We detected 54 DIBs-25 of which are newly detected by this study-and eight DIB candidates. Using this updated list, the DIB distributions over a wide wavelength range, from optical to NIR, are investigated. The FWHM values of the NIR DIBs are found to be narrower than those of the optical DIBs, on average, which suggests that the DIBs at longer wavelengths tend to be caused by larger molecules. Assuming that the larger carriers are responsible for the DIBs at longer wavelengths, and have larger oscillator strengths, we found that the total column densities of the DIB carriers tend to decrease with increasing DIB wavelength. The candidate molecules and ions for the NIR DIBs are also discussed.

Keywords: diffuse interstellar bands; interstellar medium; interstellar molecules; interstellar dust extinction