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3281. SFR & gas-phase metallicity in MaNGA gal.
ID:
ivo://CDS.VizieR/J/ApJ/882/9
Title:
SFR & gas-phase metallicity in MaNGA gal.
Short Name:
J/ApJ/882/9
Date:
21 Oct 2021
Publisher:
CDS
Description:
The role of gas accretion in galaxy evolution is still a matter of debate. The presence of inflows of metal-poor gas that trigger star formation bursts of low metallicity has been proposed as an explanation for the local anticorrelation between star formation rate (SFR) and gas-phase metallicity (Z_g_) found in the literature. In the present study, we show how the anticorrelation is also present as part of a diversified range of behaviors for a sample of more than 700 nearby spiral galaxies from the SDSS-IV MaNGA survey. We have characterized the local relation between SFR and Z_g_ after subtracting the azimuthally averaged radial profiles of both quantities. Of the analyzed galaxies, 60% display an SFR-Z_g_ anticorrelation, with the remaining 40% showing no correlation (19%) or positive correlation (21%). Applying a random forest machine-learning algorithm, we find that the slope of the correlation is mainly determined by the average gas-phase metallicity of the galaxy. Galaxy mass, g-r colors, stellar age, and mass density seem to play a less significant role. This result is supported by the performed second-order polynomial regression analysis. Thus, the local SFR-Z_g_ slope varies with the average metallicity, with the more metal-poor galaxies presenting the lowest slopes (i.e., the strongest SFR-Z_g_ anticorrelations), and reversing the relation for more metal-rich systems. Our results suggest that external gas accretion fuels star formation in metal-poor galaxies, whereas in metal-rich systems, the gas comes from previous star formation episodes.
3282. SFR in galaxies at redshift z~0.8
ID:
ivo://CDS.VizieR/J/MNRAS/454/1332
Title:
SFR in galaxies at redshift z~0.8
Short Name:
J/MNRAS/454/1332
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the star formation history for a sample of 154 galaxies with stellar mass 10^10^<~M*<~10^12^M_{sun}_ in the redshift range 0.7<z<0.9. We do this using stellar population models combined with full-spectrum fitting of good quality spectra and high-resolution photometry. For a subset of 68 galaxies (M*>~10^11^M_{sun}_) we additionally construct dynamical models. These use an axisymmetric solution to the Jeans equations, which allows for velocity anisotropy, and adopts results from abundance matching techniques to account for the dark matter content. We find that (i) the trends in star formation history observed in the local Universe are already in place by z~1: the most massive galaxies are already passive, while lower mass ones have a more extended star formation histories, and the lowest mass galaxies are actively forming stars; (ii) we place an upper limit of a factor 1.5 to the size growth of the massive galaxy population; (iii) we present strong evidence for low dark matter fractions within 1Re (median of 9 per cent and 90th percentile of 21 per cent) for galaxies with M*>~10^11^M_{sun}_ at these redshifts; and (iv) we confirm that these galaxies have, on average, a Salpeter normalization of the stellar initial mass function.
3283. SFR-M_*_ relation from ZFOURGE
ID:
ivo://CDS.VizieR/J/ApJ/817/118
Title:
SFR-M_*_ relation from ZFOURGE
Short Name:
J/ApJ/817/118
Date:
21 Oct 2021
Publisher:
CDS
Description:
We explore star formation histories (SFHs) of galaxies based on the evolution of the star formation rate stellar mass relation (SFR-M_*_). Using data from the FourStar Galaxy Evolution Survey (ZFOURGE) in combination with far-IR imaging from the Spitzer and Herschel observatories we measure the SFR-M_*_ relation at 0.5<z<4. Similar to recent works we find that the average infrared spectral energy distributions of galaxies are roughly consistent with a single infrared template across a broad range of redshifts and stellar masses, with evidence for only weak deviations. We find that the SFR-M_*_ relation is not consistent with a single power law of the form SFR{propto}M_{star}_^{alpha}^ at any redshift; it has a power law slope of {alpha}~1 at low masses, and becomes shallower above a turnover mass (M_0_) that ranges from 10^9.5^ to 10^10.8^M_{sun}_, with evidence that M_0_ increases with redshift. We compare our measurements to results from state-of-the-art cosmological simulations, and find general agreement in the slope of the SFR-M_*_ relation albeit with systematic offsets. We use the evolving SFR-M_*_ sequence to generate SFHs, finding that typical SFRs of individual galaxies rise at early times and decline after reaching a peak. This peak occurs earlier for more massive galaxies. We integrate these SFHs to generate mass growth histories and compare to the implied mass growth from the evolution of the stellar mass function (SMF). We find that these two estimates are in broad qualitative agreement, but that there is room for improvement at a more detailed level. At early times the SFHs suggest mass growth rates that are as much as 10x higher than inferred from the SMF. However, at later times the SFHs under-predict the inferred evolution, as is expected in the case of additional growth due to mergers.
3284. SFR of distant galaxies
ID:
ivo://CDS.VizieR/J/A+A/430/115
Title:
SFR of distant galaxies
Short Name:
J/A+A/430/115
Date:
21 Oct 2021
Publisher:
CDS
Description:
Studies of distant galaxies have shown that ellipticals and large spirals (Schade et al., 1999ApJ...525...31S; Lilly et al., 1998ApJ...500...75L) were already in place 8Gyr ago, leading to a very modest recent star formation (Brinchmann & Ellis, 2000ApJ...536L..77B) in intermediate mass galaxies (3-30*10^10^M_{sun}_). This is challenged by a recent analysis (Heavens et al., 2004Natur.428..625H) of the fossil record of the stellar populations of ~105 nearby galaxies, which shows that intermediate mass galaxies formed or assembled the bulk of their stars 4 to 8Gyr ago. Here we present direct observational evidence supporting this findings from a long term, multi-wavelength study of 195 z>0.4 intermediate mass galaxies, mostly selected from the Canada France Redshift Survey (CFRS, Cat. <VII/225>).
3285. SFR of M31 from resolved stars in near-IR
ID:
ivo://CDS.VizieR/J/AJ/132/271
Title:
SFR of M31 from resolved stars in near-IR
Short Name:
J/AJ/132/271
Date:
21 Oct 2021
Publisher:
CDS
Description:
We discuss H and K observations of three fields in the bulge and disk of M31 obtained with the ALTAIR adaptive optics system and NIRI instrument on Gemini North. These are the highest resolution and deepest near-infrared observations obtained to date of the inner regions of M31 and demonstrate the promise of ground-based adaptive optics for studying the crowded regions of nearby galaxies. We have combined our observations with previously published Hubble Space Telescope Near-Infrared Camera and Multi-Object Spectrometer observations of nine M31 fields and have derived the coarse star formation histories of M31's bulge and inner disk. From fits to the MK luminosity functions, we find the stellar population mix to be dominated by old, nearly solar-metallicity stars. The old populations, which we define as having age >=6Gyr, indeed dominate the star formation histories at all radii independent of the relative contributions of bulge and disk stars. Although all of our fields contain some bulge contribution, our results suggest that there is no age difference between the bulge and disk to the limit of our precision.
3286. S0 galaxies morpho-kinematic properties
ID:
ivo://CDS.VizieR/J/MNRAS/474/1307
Title:
S0 galaxies morpho-kinematic properties
Short Name:
J/MNRAS/474/1307
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study a sample of 28 S0 galaxies extracted from the integral field spectroscopic (IFS) survey Calar Alto Legacy Integral Field Area. We combine an accurate two-dimensional (2D) multicomponent photometric decomposition with the IFS kinematic properties of their bulges to understand their formation scenario. Our final sample is representative of S0s with high stellar masses (M*/M_{sun}_>10^10^). They lay mainly on the red sequence and live in relatively isolated environments similar to that of the field and loose groups. We use our 2D photometric decomposition to define the size and photometric properties of the bulges, as well as their location within the galaxies. We perform mock spectroscopic simulations mimicking our observed galaxies to quantify the impact of the underlying disc on our bulge kinematic measurements ({nu} and v/{lambda}). We compare our bulge corrected kinematic measurements with the results from Schwarzschild dynamical modelling. The good agreement confirms the robustness of our results and allows us to use bulge deprojected values of {lambda} and v/{sigma}. We find that the photometric (n and B/T) and kinematic (v/{sigma} and {lambda}) properties of our field S0 bulges are not correlated. We demonstrate that this morpho-kinematic decoupling is intrinsic to the bulges and it is not due to projection effects. We conclude that photometric diagnostics to separate different types of bulges (disc-like versus classical) might not be useful for S0 galaxies. The morpho-kinematics properties of S0 bulges derived in this paper suggest that they are mainly formed by dissipational processes happening at high redshift, but dedicated high-resolution simulations are necessary to better identify their origin.
3287. S4G disk galaxies stellar mass distribution
ID:
ivo://CDS.VizieR/J/A+A/596/A84
Title:
S4G disk galaxies stellar mass distribution
Short Name:
J/A+A/596/A84
Date:
21 Oct 2021
Publisher:
CDS
Description:
Models of galaxy formation in a cosmological framework require observational constraints to be tested against, such as the average stellar density profiles (and their dispersion) as a function of fundamental galaxy properties (e.g. the total stellar mass). Simulation models predict that the torques produced by stellar bars efficiently redistribute the stellar and gaseous material inside the disk, pushing it outwards or inwards depending on whether it is beyond or inside the bar corotation resonance radius, respectively. Bars themselves are expected to evolve, getting longer and narrower as they trap particles from the disk and slow down their rotation speed. We use 3.6um photometry from the Spitzer Survey of Stellar Structure in Galaxies (S4G) to trace the stellar distribution in nearby disk galaxies (z~~0) with total stellar masses 10^8.5^<=M*/M_{sun}_<=10^11^ and mid IR Hubble types -3<=T<=10. We characterize the stellar density profiles ({SIGMA}*), the stellar contribution to the rotation curves (V3.6um) and the m=2 Fourier amplitudes (A2) as a function of M* and T. We also describe the typical shapes and strengths of stellar bars in the S4G sample and link their properties to the total stellar mass and morphology of their host galaxy. For 1154 S4G galaxies with disk inclinations lower than 65{deg}, we perform a Fourier decomposition and rescale their images to a common frame determined by the size in physical units, by their disk scalelength, and for 748 barred galaxies by both the length and orientation of their bars. We stack the resized density profiles and images to obtain statistically representative average stellar disks and bars in bins of M* and T. Based on the radial force profiles of individual galaxies we calculate the mean stellar contribution to the circular velocity. We also calculate average A2 profiles, where the radius is normalized to R25.5. Furthermore, we infer the gravitational potentials from the synthetic bars to obtain the tangential-to-radial force ratio (QT) and A2 profiles in the different bins. We also apply ellipse fitting to quantitatively characterize the shape of the bar stacks. For M*>=10^9^M_{sun}_, we find a significant difference in the stellar density profiles of barred and non-barred systems: (i) disks in barred galaxies show larger scalelengths (hR) and fainter extrapolated central surface brightnesses ({SIGMA}0), (ii) the mean surface brightness profiles ({SIGMA}*) of barred and non-barred galaxies intersect each other slightly beyond the mean bar length, most likely at the bar corotation, and (iii) the central mass concentration of barred galaxies is larger (by almost a factor 2 when T<=5) than in their non-barred counterparts. The averaged {SIGMA}* profiles follow an exponential slope down to at least ~10M_{sun}_/pc^2^, which is the typical depth beyond which the sample coverage in the radial direction starts to drop. Central mass concentrations in massive systems (>=10^10^M_{sun}_) are substantially larger than in fainter galaxies, and their prominence scales with T. This segregation also manifests in the inner slope of the mean stellar component of the circular velocity: lenticular (S0) galaxies present the most sharply rising V3.6um . Based on the analysis of bar stacks, we show that early- and intermediate-type spirals (0<=T<5) have intrinsically narrower bars compared to later types and S0s, whose bars are oval-shaped. We show a clear agreement between galaxy family and quantitative estimates of bar strength. In early- and intermediate-type spirals, A2 is larger within and beyond the typical bar region among barred galaxies, compared to the non-barred subsample. Strongly barred systems also tend to have larger A2 amplitudes at all radii than their weakly barred counterparts. Using near-IR wavelengths (S4G 3.6um), we provide observational constraints for galaxy formation models to be checked against. In particular, we calculate the mean stellar density profiles, and the disk(+bulge) component of the rotation curve (and their dispersion) in bins of M* and T. We find evidence for bar-induced secular evolution of disk galaxies, in terms of disk spreading and enhanced central mass concentration. We also obtain average bars (2-D), and we show that bars hosted by early-type galaxies are more centrally concentrated and have larger density amplitudes than their late-type counterparts.
3288. S4G galaxies disk/bar decomposition
ID:
ivo://CDS.VizieR/J/MNRAS/478/5689
Title:
S4G galaxies disk/bar decomposition
Short Name:
J/MNRAS/478/5689
Date:
08 Feb 2022 00:30:06
Publisher:
CDS
Description:
We present photometric models of 532 disc galaxies in 3.6um images from the Spitzer Survey of Stellar Structure in Galaxies (S^4^G) using the non-parametric DISKFIT algorithm. We first test DISKFIT's performance on 400 synthetic S^4^G-like galaxy images. DISKFIT is unreliable in the bulge region, but accurately disentangles exponential discs from Ferrers bars farther out as long as their position angles differ by more than 5{deg}. We then proceed to model the S^4^G galaxies, successfully fitting 489 of them using an automated approach for initializing DISKFIT, optimizing the model and deriving uncertainties using a bootstrap-resampling technique. The resulting component geometries and surface brightness profiles are compared to those derived by Salo et al. using the parametric model GALFIT. We find generally good agreement between the models, but discrepancies between best-fitting values for individual systems are often significant: the choice of algorithm clearly impacts the inferred disc and bar structure. In particular, we find that DISKFIT typically assigns more light to the bar and less light to the disc relative to the Ferrers and exponential profiles derived using GALFIT in the bar region. Given DISKFIT's reliability at disentangling these components in our synthetic images, we conclude that the surface brightness distributions of barred S^4^G galaxies are not well-represented by these functional forms. The results presented here underscore the importance of validating photometric decomposition algorithms before applying them to real data and the utility of DISKFIT's non-parametric approach at measuring the structure of discs and bars in nearby galaxies.
3289. S4G galaxy morphologies in the CVRHS system
ID:
ivo://CDS.VizieR/J/ApJS/217/32
Title:
S4G galaxy morphologies in the CVRHS system
Short Name:
J/ApJS/217/32
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Spitzer Survey of Stellar Structure in Galaxies (S^4^G) is the largest available database of deep, homogeneous middle-infrared (mid-IR) images of galaxies of all types. The survey, which includes 2352 nearby galaxies, reveals galaxy morphology only minimally affected by interstellar extinction. This paper presents an atlas and classifications of S^4^G galaxies in the Comprehensive de Vaucouleurs revised Hubble-Sandage (CVRHS) system. The CVRHS system follows the precepts of classical de Vaucouleurs morphology, modified to include recognition of other features such as inner, outer, and nuclear lenses, nuclear rings, bars, and disks, spheroidal galaxies, X patterns and box/peanut structures, OLR subclass outer rings and pseudorings, bar ansae and barlenses, parallel sequence late-types, thick disks, and embedded disks in 3D early-type systems. We show that our CVRHS classifications are internally consistent, and that nearly half of the S^4^G sample consists of extreme late-type systems (mostly bulgeless, pure disk galaxies) in the range Scd-Im. The most common family classification for mid-IR types S0/a to Sc is SA while that for types Scd to Sm is SB. The bars in these two type domains are very different in mid-IR structure and morphology. This paper examines the bar, ring, and type classification fractions in the sample, and also includes several montages of images highlighting the various kinds of "stellar structures" seen in mid-IR galaxy morphology.
3290. SG1120-1202 members HST imaging & 24um fluxes
ID:
ivo://CDS.VizieR/J/ApJ/836/7
Title:
SG1120-1202 members HST imaging & 24um fluxes
Short Name:
J/ApJ/836/7
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use the Hubble Space Telescope to obtain WFC3/F390W imaging of the supergroup SG1120-1202 at z=0.37, mapping the UV emission of 138 spectroscopically confirmed members. We measure total (F390W-F814W) colors and visually classify the UV morphology of individual galaxies as "clumpy" or "smooth." Approximately 30% of the members have pockets of UV emission (clumpy) and we identify for the first time in the group environment galaxies with UV morphologies similar to the "jellyfish" galaxies observed in massive clusters. We stack the clumpy UV members and measure a shallow internal color gradient, which indicates that unobscured star formation is occurring throughout these galaxies. We also stack the four galaxy groups and measure a strong trend of decreasing UV emission with decreasing projected group distance (R_proj_). We find that the strong correlation between decreasing UV emission and increasing stellar mass can fully account for the observed trend in (F390W-F814W)-R_proj_, i.e., mass-quenching is the dominant mechanism for extinguishing UV emission in group galaxies. Our extensive multi-wavelength analysis of SG1120-1202 indicates that stellar mass is the primary predictor of UV emission, but that the increasing fraction of massive (red/smooth) galaxies at R_proj_<~2R_200_ and existence of jellyfish candidates is due to the group environment.

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