Total Stellar Mass Of Galaxies Research Articles

Revisiting the Mass-excitation (MEx) Diagram using the MaNGA Data Set

The diagram comparing the flux ratio of the [O iii] and Hβ emission lines with the total stellar mass of galaxies (also known as the mass-excitation diagram, MEx) has been widely used to classify the ionization mechanism in high redshift galaxies, dividing star-forming galaxies from those where active galactic nuclei are important. This diagram was mainly derived using single-fiber spectroscopy from the SDSS-DR7 survey. In this study, we revise this diagram using the central and integrated spectral measurement from the entire Integral Field Spectroscopic MaNGA sample. Our results suggest that along with these physical parameters, the equivalent width of the Hα emission line is also required to constrain the ionization mechanism of a high-redshifted galaxy. Furthermore, the location of a galaxy in the excitation-mass diagram varies depending on the use of central or integrated properties.

Clusters of galaxies up to z = 1.5 identified from photometric data of the Dark Energy Survey and unWISE

ABSTRACT Using photometric data from the Dark Energy Survey and the Wide-field Infrared Survey Explorer, we estimate photometric redshifts for 105 million galaxies using the nearest-neighbour algorithm. From such a large data base, 151 244 clusters of galaxies are identified in the redshift range of 0.1 < z ≲ 1.5 based on the overdensity of the total stellar mass of galaxies within a given photometric redshift slice, among which 76 826 clusters are newly identified and 30 477 clusters have a redshift z > 1. We cross-match these clusters with those in the catalogues identified from the X-ray surveys and the Sunyaev–Zel’dovich (SZ) effect by the Planck, South Pole Telescope and Atacama Cosmology Telescope surveys, and get the redshifts for 45 X-ray clusters and 56 SZ clusters. More than 95 per cent SZ clusters in the sky region have counterparts in our catalogue. We find multiple optical clusters in the line of sight towards about 15 per cent of SZ clusters.

On the Correlation between Atomic Gas and Bars in Galaxies

Abstract We analyze the correlation between properties of large-scale bars and atomic gas content of galaxies to explore the role of H i gas on bar evolution in galaxies. We show that the absolute bar size depends strongly on total stellar mass of galaxies and does not change significantly with H i gas fraction at fixed stellar mass. Furthermore, the physical size of the bar is small and nearly constant in high H i gas fraction and low-mass galaxies and becomes larger with increasing galactic stellar mass in low gas fraction galaxies. When the stellar masses are fixed, the relative bar length normalized to the disk shows a decrease with increasing H i gas fraction due to the larger disks in gas-richer galaxies. We measure the gas deficiency of the samples and find that the gas-rich galaxies have longer and stronger bars compared with the H i gas-deficient galaxies at fixed stellar mass, especially for the massive ones. When splitting the samples into star-forming and quiescent subgroups, the star-forming galaxies tend to have longer bars than the quiescent ones at fixed stellar mass and gas deficiency. In addition, our results suggest two different types of bar properties, in which the bars in gas-rich galaxies grow longer but retain similar axial ratio over time, while they grow longer and fatter over time in gas-poor galaxies.

Stellar Mass—Halo Mass Relation and Star Formation Efficiency in High-Mass Halos

We study relation between stellar mass and halo mass for high-mass halos using a sample of galaxy clusters with accurate measurements of stellar masses from optical and IR data and total masses from X-ray observations. We find that stellar mass of the brightest cluster galaxies (BCGs) scales as M*BCG\propto M500^a_BCG with the best fit slope of a_BCG~0.35+-0.1 and scatter of M*BCG at a fixed M500 of ~0.2 dex. We show that M*-M relations from abundance matching or halo modelling reported in recent studies underestimate stellar masses of BCGs by a factor of ~2-4, because these studies used stellar mass functions (SMF) based on photometry that severely underestimates the outer surface brightness profiles of massive galaxies. We show that M*-M relation derived using abundance matching with the recent SMF calibration by Bernardi et al. (2013) based on improved photometry is in a much better agreement with the relation we derive. The total stellar mass of galaxies correlates with total mass M500 with the slope of \approx 0.6+-0.1 and scatter of 0.1 dex. This indicates that efficiency with which baryons are converted into stars decreases with increasing cluster mass. We show that for a fixed choice of the initial mass function (IMF) total stellar fraction in clusters is only a factor of ~3-5 lower than the peak stellar fraction reached in M\approx 10^12 Msun halos, and only a factor of ~1.5-3 if the IMF becomes progressively more bottom heavy with increasing mass in early type galaxies, as indicated by recent observations. The larger normalization and slope of the M*-M relation derived in this study shows that the overall efficiency of star formation in massive halos is suppressed much less than was thought before and that feedback and associated suppression of star formation in massive halos should be weaker than assumed in most of the current semi-analytic models and simulations.

The stellar mass assembly of galaxies in the Illustris simulation: growth by mergers and the spatial distribution of accreted stars

We use the Illustris simulation to study the relative contributions of in situ star formation and stellar accretion to the build-up of galaxies over an unprecedentedly wide range of masses ($M_{\ast} = 10^9-10^{12} \, {\rm M_{\odot}}$), galaxy types, environments, and assembly histories. We find that the `two-phase' picture of galaxy formation predicted by some models is a good approximation only for the most massive galaxies in our simulation -- namely, the stellar mass growth of galaxies below a few times $10^{11} \, {\rm M_{\odot}}$ is dominated by in situ star formation at all redshifts. The fraction of the total stellar mass of galaxies at $z=0$ contributed by accreted stars shows a strong dependence on galaxy stellar mass, ranging from about 10 per cent for Milky Way-sized galaxies to over 80 per cent for $M_{\ast} \approx 10^{12} \, {\rm M_{\odot}}$ objects, yet with a large galaxy-to-galaxy variation. At a fixed stellar mass, elliptical galaxies and those formed at the centres of younger haloes exhibit larger fractions of ex situ stars than disc-like galaxies and those formed in older haloes. On average, $\sim$50 per cent of the ex situ stellar mass comes from major mergers (stellar mass ratio $\mu > 1/4$), $\sim$20 per cent from minor mergers ($1/10 < \mu < 1/4$), $\sim$20 per cent from very minor mergers ($\mu < 1/10$), and $\sim$10 per cent from stars that were stripped from surviving galaxies (e.g. flybys or ongoing mergers). These components are spatially segregated, with in situ stars dominating the innermost regions of galaxies, and ex situ stars being deposited at larger galactocentric distances in order of decreasing merger mass ratio.

Effect of the Remnant Mass in Estimating the Stellar Mass of Galaxies

Abstract The definition of the galactic stellar mass estimated from the spectral energy distribution is ambiguous in the literature; whether the stellar mass includes the mass of the stellar remnants, i.e., white dwarfs, neutron stars, and black holes, is not well described. The remnant mass fraction in the total (living + remnant) stellar mass of a simple stellar population monotonically increases with the age of the population, and the initial mass function and metallicity affect the increasing rate. Since galaxies are composed of a number of stellar populations, the remnant mass fraction may depend on the total stellar mass of galaxies in a complex way. As a result, the shape of the stellar mass function of galaxies may change, depending on the definition of the stellar mass. In order to explore this issue, we ran a cosmological hydrodynamical simulation, and subsequently found that the remnant mass fraction indeed correlates with the total stellar mass of galaxies. However, this correlation is weak, and the remnant fraction can be regarded as a constant that depends only on the redshift. Therefore, the shape of the stellar mass function is almost unchanged, but it simply shifts horizontally if the remnant mass is included or not. The shift is larger at lower redshift, and it reaches 0.2-dex at z = 0 for a Chabrier IMF. Since this causes a systematic difference, we should take care of the definition of the ‘stellar’ mass, when comparing one's result with others.

Connecting stellar mass and star-formation rate to dark matter halo mass out to z ∼ 2

We have constructed an extended halo model (EHM) which relates the total stellar mass and star-formation rate (SFR) to halo mass (M_h). An empirical relation between the distribution functions of total stellar mass of galaxies and host halo mass, tuned to match the spatial density of galaxies over 0<z<2 and the clustering properties at z~0, is extended to include two different scenarios describing the variation of SFR on M_h. We also present new measurements of the redshift evolution of the average SFR for star-forming galaxies of different stellar mass up to z=2, using data from the Herschel Multi-tiered Extragalactic Survey (HerMES) for infrared-bright galaxies. Combining the EHM with the halo accretion histories from numerical simulations, we trace the stellar mass growth and star-formation history in halos spanning a range of masses. We find that: (1) The intensity of the star-forming activity in halos in the probed mass range has steadily decreased from z~2 to 0; (2) At a given epoch, halos in the mass range between a few times 10^{11} M_Sun and a few times 10^{12} M_Sun are the most efficient at hosting star formation; (3) The peak of SFR density shifts to lower mass halos over time; (4) Galaxies that are forming stars most actively at z~2 evolve into quiescent galaxies in today's group environments, strongly supporting previous claims that the most powerful starbursts at z~2 are progenitors of today's elliptical galaxies.