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1281. Gas infall in disc galaxy models
ID:
ivo://CDS.VizieR/J/MNRAS/462/1329
Title:
Gas infall in disc galaxy models
Short Name:
J/MNRAS/462/1329
Date:
21 Oct 2021
Publisher:
CDS
Description:
Spiral galaxies are thought to acquire their gas through a protracted infall phase resulting in the inside-out growth of their associated discs. For field spirals, this infall occurs in the lower density environments of the cosmic web. The overall infall rate, as well as the galactocentric radius at which this infall is incorporated into the star-forming disc, plays a pivotal role in shaping the characteristics observed today. Indeed, characterizing the functional form of this spatio-temporal infall in situ is exceedingly difficult, and one is forced to constrain these forms using the present day state of galaxies with model or simulation predictions. We present the infall rates used as input to a grid of chemical evolution models spanning the mass spectrum of discs observed today. We provide a systematic comparison with alternate analytical infall schemes in the literature, including a first comparison with cosmological simulations. Identifying the degeneracies associated with the adopted infall rate prescriptions in galaxy models is an important step in the development of a consistent picture of disc galaxy formation and evolution.
1282. GAS I. Stellar mass functions
ID:
ivo://CDS.VizieR/J/A+A/627/A131
Title:
GAS I. Stellar mass functions
Short Name:
J/A+A/627/A131
Date:
21 Oct 2021
Publisher:
CDS
Description:
Star formation in galaxies is inefficient, and understanding how star formation is regulated in galaxies is one of the most fundamental challenges of contemporary astrophysics. Radiative cooling, feedback from supernovae and active galactic nuclei, largescale dynamics and dissipation of turbulent energy act over various time and spatial scales, and all regulate star formation in a complex gas cycle. This paper presents the physics implemented in a new semi-analytical model of galaxy formation and evolution: G.A.S. . The fundamental underpinning of our new model is the development of a multi-phase interstellar medium (ISM) in which energy produced by supernovae and active galaxy nuclei maintains an equilibrium between the diffuse, hot, stable gas and a cooler, clumpy, low-volume filling factor gas. The hot gas is susceptible to thermal and dynamical instabilities. We include a description of how turbulence leads to the formation of giant molecular clouds through an inertial turbulent energy cascade, assuming a constant kinetic energy transfer per unit volume. We explicitly model the evolution of the velocity dispersion at different scales of the cascade and account for thermal instabilities in the hot halo gas. Thermal instabilities effectively reduces the impact of radiative cooling and moderates accretion rates onto galaxies, and in particular, for those residing in massive halos. We show that rapid and multiple exchanges between diffuse and unstable gas phases strongly regulates star-formation rates in galaxies because only a small fraction of the unstable gas is forming stars. We checked that the characteristic timescales describing the gas cycle, the gas depletion timescale and the star-forming laws at different scales are in good agreement with observations. For high mass halos and galaxies, cooling is naturally regulated by the growth of thermal instabilities, so we do not need to implement strong AGN feedback in this model. Our results are also in good agreement with the observed stellar mass function from z~=6.0 to z~=0.5. Our model offers the flexibility to test the impact of various physical processes on the regulation of star formation on a representative population of galaxies across cosmic times. Thermal instabilities and the cascade of turbulent energy in the dense gas phase introduce a delay between gas accretion and star formation, which keeps galaxy growth inefficient in the early Universe. The main results presented in this paper, such as stellar mass functions, are available in the GALAKSIENN library.
1283. Gas kinematics in CALIFA survey
ID:
ivo://CDS.VizieR/J/A+A/573/A59
Title:
Gas kinematics in CALIFA survey
Short Name:
J/A+A/573/A59
Date:
21 Oct 2021
Publisher:
CDS
Description:
Ionized gas kinematics provide important clues to the dynamical structure of galaxies and hold constraints to the processes driving their evolution. The motivation of this work is to provide an overall characterization of the kinematic behavior of the ionized gas of the galaxies included in the Calar Alto Legacy Integral field Area (CALIFA), offering kinematic clues to potential users of the CALIFA survey for including kinematical criteria in their selection of targets for specific studies. From the first 200 galaxies observed by CALIFA survey in its two configurations, we present the two-dimensional kinematic view of the 177 galaxies satisfaying a gas content/detection threshold. After removing the stellar contribution, we used the cross-correlation technique to obtain the radial velocity of the dominant gaseous component for each spectrum in the CALIFA data cubes for different emission lines (namely, [OII] {lambda}{lambda}3726,3729, [OIII] {lambda}{lambda}4959,5007, H{alpha}+[NII] {lambda}{lambda}6548,6584, and [SII]{lambda}{lambda}6716,6730). The main kinematic parameters measured on the plane of the sky were directly derived from the radial velocities with no assumptions on the internal prevailing motions. Evidence of the presence of several gaseous components with different kinematics were detected by using [OIII] {lambda}{lambda}4959,5007 emission line profiles.
1284. Gas phase oxygen abundances for HII regions
ID:
ivo://CDS.VizieR/J/ApJ/887/80
Title:
Gas phase oxygen abundances for HII regions
Short Name:
J/ApJ/887/80
Date:
21 Oct 2021
Publisher:
CDS
Description:
The distribution of metals within a galaxy traces the baryon cycle and the buildup of galactic disks, but the detailed gas phase metallicity distribution remains poorly sampled. We have determined the gas phase oxygen abundances for 7138 HII regions across the disks of eight nearby galaxies using Very Large Telescope/Multi Unit Spectroscopic Explorer (MUSE) optical integral field spectroscopy as part of the PHANGS-MUSE survey. After removing the first-order radial gradients present in each galaxy, we look at the statistics of the metallicity offset ({Delta}O/H) and explore azimuthal variations. Across each galaxy, we find low ({sigma}=0.03-0.05dex) scatter at any given radius, indicative of efficient mixing. We compare physical parameters for those HII regions that are 1{sigma} outliers toward both enhanced and reduced abundances. Regions with enhanced abundances have high ionization parameter, higher H{alpha} luminosity, lower H{alpha} velocity dispersion, younger star clusters, and associated molecular gas clouds showing higher molecular gas densities. This indicates recent star formation has locally enriched the material. Regions with reduced abundances show increased H{alpha} velocity dispersions, suggestive of mixing introducing more pristine material. We observe subtle azimuthal variations in half of the sample, but cannot always cleanly associate this with the spiral pattern. Regions with enhanced and reduced abundances are found distributed throughout the disk, and in half of our galaxies we can identify subsections of spiral arms with clearly associated metallicity gradients. This suggests spiral arms play a role in organizing and mixing the interstellar medium.
1285. GASP. XXI. Star forming rate in 54 galaxies
ID:
ivo://CDS.VizieR/J/ApJ/899/13
Title:
GASP. XXI. Star forming rate in 54 galaxies
Short Name:
J/ApJ/899/13
Date:
15 Mar 2022 08:27:30
Publisher:
CDS
Description:
Using MUSE observations from the GASP survey, we study 54 galaxies undergoing ram pressure stripping (RPS) and spanning a wide range in galaxy mass and host cluster mass. We use this rich sample to study how the star formation rate (SFR) in the tails of stripped gas depends on the properties of the galaxy and its host cluster. We show that the interplay between all the parameters involved is complex and that there is not a single, dominant one in shaping the observed amount of SFR. Hence, we develop a simple analytical approach to describe the mass fraction of stripped gas and the SFR in the tail, as a function of the cluster velocity dispersion, galaxy stellar mass, clustercentric distance, and speed in the intracluster medium. Our model provides a good description of the observed gas truncation radius and of the fraction of SFR observed in the stripped tails, once we take into account the fact that the star formation efficiency in the tails is a factor of ~5 lower than in the galaxy disk, in agreement with GASP ongoing HI and CO observations. Finally, we estimate the contribution of RPS to the intracluster light (ICL) and find that the average SFR in the tails of ram pressure stripped gas is ~0.22M{odot}/yr per cluster. By extrapolating this result to evaluate the contribution to the ICL at different epochs, we compute an integrated average value per cluster of ~4x109M{sun} of stars formed in the tails of RPS galaxies since z~1.
1286. Gas-rich dwarfs from the POSS-II. III.
ID:
ivo://CDS.VizieR/J/ApJS/131/47
Title:
Gas-rich dwarfs from the POSS-II. III.
Short Name:
J/ApJS/131/47
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present Arecibo neutral hydrogen data on a sample of optically selected dwarf galaxies. The sample ranges in H I mass from 10^6^ to 5x10^9^M_{sun}_, with a mean of 7.9x10^8^M_{sun}_. Using estimated H I radii, the H I surface densities range from 0.6 to 20M_{sun}_/pc^2^, all well below the critical threshold for star formation (Kennicutt, 1998ApJ...498..541K). M_HI_/L values of the LSB dwarfs range from 0.3 to 12 with a mean value of 2.0. Dynamical masses, calculated from the H I profile widths, range from 10^8^ to 10^11^M_{sun}_. There is a strong correlation between optical luminosity and dynamical mass for LSB dwarfs implying that the dark matter (whether baryonic or nonbaryonic) follows the detectable baryonic matter.
1287. GAs Stripping Phenomena in galaxies with MUSE
ID:
ivo://CDS.VizieR/J/ApJ/895/106
Title:
GAs Stripping Phenomena in galaxies with MUSE
Short Name:
J/ApJ/895/106
Date:
15 Mar 2022 07:48:07
Publisher:
CDS
Description:
Exploiting the data from the GAs Stripping Phenomena in galaxies with MUSE (GASP) survey, we study the gas-phase metallicity scaling relations of a sample of 29 cluster galaxies undergoing ram pressure stripping and of a reference sample of (16 cluster and 16 field) galaxies with no significant signs of gas disturbance. We adopt the pyqz code to infer the mean gas metallicity at the effective radius and achieve a well-defined mass-metallicity relation (MZR) in the stellar mass range 10^9.25^<=M_*_<=10^11.5^M{odot} with a scatter of 0.12dex. At any given mass, reference cluster and stripping galaxies have similar metallicities, while the field galaxies with M_*_<1010.25M{sun} show on average lower gas metallicity than galaxies in clusters. Our results indicate that at the effective radius, the chemical properties of the stripping galaxies are independent of the ram pressure stripping mechanism. Nonetheless, at the lowest masses, we detect four stripping galaxies well above the common MZR that suggest a more complex scenario. Overall, we find signs of an anticorrelation between the metallicity and both the star formation rate and the galaxy size, in agreement with previous studies. No significant trends are instead found with the halo mass, clustercentric distance, and local galaxy density in clusters. In conclusion, we advise a more detailed analysis of the spatially resolved gas metallicity maps of the galaxies, able to highlight effects of gas redistribution inside the disk due to ram pressure stripping.
1288. Gas structure comparison; NGC 253 and Milky Way
ID:
ivo://CDS.VizieR/J/ApJ/899/158
Title:
Gas structure comparison; NGC 253 and Milky Way
Short Name:
J/ApJ/899/158
Date:
14 Mar 2022 07:10:20
Publisher:
CDS
Description:
We compare molecular gas properties in the starbursting center of NGC253 and the Milky Way Galactic center (GC) on scales of ~1-100pc using dendrograms and resolution-, area-, and noise-matched data sets in CO(1-0) and CO(3-2). We find that the size-line width relations in NGC253 and the GC have similar slope, but NGC253 has larger line widths by factors of ~2-3. The {sigma}2/R dependency on column density shows that, in the GC, on scales of 10-100pc the kinematics of gas over N>3x1021/cm^2^ are compatible with gravitationally bound structures. In NGC253 this is only the case for column densities N>3x1022/cm^2^. The increased line widths in NGC253 originate in the lower column density gas. This high velocity dispersion, not gravitationally self-bound gas, is likely in transient structures created by the combination of high average densities and feedback in the starburst. The high densities turn the gas molecular throughout the volume of the starburst, and the injection of energy and momentum by feedback significantly increases the velocity dispersion at a given spatial scale over what is observed in the GC.
1289. GASS VII. Bivariate HI-stellar mass function
ID:
ivo://CDS.VizieR/J/ApJ/776/74
Title:
GASS VII. Bivariate HI-stellar mass function
Short Name:
J/ApJ/776/74
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the bivariate neutral atomic hydrogen (HI)-stellar mass function (HISMF) {phi}(M_HI_, M_{star}_) for massive (logM_*_/M_{sun}_>10) galaxies derived from a sample of 480 local (0.025<z<0.050) galaxies observed in H I at Arecibo as part of the GALEX Arecibo SDSS Survey. We fit six different models to the HISMF and find that a Schechter function that extends down to a 1% HI gas fraction, with an additional fractional contribution below that limit, is the best parameterization of the HISMF. We calculate {Omega}_HI,M_{star}__>10^10^ and find that massive galaxies contribute 41% of the H I density in the local universe. In addition to the binned HISMF, we derive a continuous bivariate fit, which reveals that the Schechter parameters only vary weakly with stellar mass: M_HI_^*^, the characteristic H I mass, scales as M_{star}_^0.39^; {alpha}, the slope of the HISMF at moderate H I masses, scales as M_{star}_^0.07^; and f, the fraction of galaxies with HI gas fraction greater than 1%, scales as M_{star}_^-0.24^. The variation of f with stellar mass should be a strong constraint for numerical simulations. To understand the physical mechanisms that produce the shape of the HISMF, we redefine the parameters of the Schechter function as explicit functions of stellar mass and star formation rate (SFR) to produce a trivariate fit. This analysis reveals strong trends with SFR. While M_HI_^*^ varies weakly with stellar mass and SFR (M_HI_^*^{prop.to}M_{star}_^0.22^, M_HI_^*^{prop.to}SFR^-0.03^), {alpha} is a stronger function of both stellar mass and especially SFR ({alpha}{prop.to}M_{star}_^0.47^, {alpha}{prop.to}SFR^0.95^). The HISMF is a crucial tool that can be used to constrain cosmological galaxy simulations, test observational predictions of the H I content of populations of galaxies, and identify galaxies whose properties deviate from average trends.
1290. Gas velocity curve along five spiral galaxies
ID:
ivo://CDS.VizieR/J/A+A/440/107
Title:
Gas velocity curve along five spiral galaxies
Short Name:
J/A+A/440/107
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the minor-axis kinematics of ionized gas and stars for a sample of 5 spiral galaxies, which are characterized by either a zero or a shallow gas velocity gradient along their major axis. The asymmetric velocity profiles observed along the minor axis of NGC 4064 and NGC 4189 can be explained as due to the presence of a bar. This is also the case of NGC 4178 where the innermost portion of the gaseous disk is nearly face on. In NGC 4424 and NGC 4941, we measured non-zero gas velocities only in the central regions along the minor axis and gas velocities drop to zero at larger radii. This kinematic feature is suggestive of the presence of an orthogonally-rotating gaseous component which is confined in the innermost regions (i.e. an inner polar disk) to be confirmed with integral-field spectroscopy.

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