IMAGES IV: strong evolution of the oxygen abundance in gaseous phases of intermediate mass galaxies from z ~ 0.8

Astronomy and Astrophysics (Impact Factor: 5.08). 01/2008; DOI:10.1051/0004-6361:200810435
Source: arXiv

ABSTRACT Context. Intermediate mass galaxies (> 10$^{10}$ $M_\odot$) at $z$ ~ 0.6 are the likeliest progenitors of the present-day, numerous population of spirals. There is growing evidence that they have evolved rapidly in the last 6 to 8 Gyr, and likely already have formed a significant fraction of their stellar mass, often showing perturbed morphologies and kinematics.Aims. We have gathered a representative sample of 88 such galaxies and have provided robust estimates of their gas phase metallicity.Methods. We used moderate spectral resolution spectroscopy at VLT/FORS2 with an unprecedentedly high $S/N$ allowing us to remove biases coming from interstellar absorption lines and extinction, to establish robust values of $R_{23}$ = ([OII]$\lambda$3727 + [OIII]$\lambda\lambda$4959, 5007)/H$\beta$.Results. We definitively confirm that the predominant population of $z$ ~ 0.6 starbursts and luminous IR galaxies (LIRGs) are on average two times less metal rich than the local galaxies at a given stellar mass. We do find that the metal abundance of the gaseous phase of galaxies evolves linearly with time, from $z = 1$ to $z = 0$ and after comparing with other studies, from $z = 3$ to $z = 0$. Combining our results with the reported evolution of the Tully Fisher relation, we find that such an evolution requires that ~30% of the stellar mass of local galaxies have been formed through an external supply of gas, thus excluding the closed box model. Distant starbursts & LIRGs have properties (metal abundance, star formation efficiency & morphologies) similar to those of local LIRGs. Their underlying physics is likely dominated by gas infall, probably through merging or interactions.Conclusions. Our study further supports the rapid evolution of $z$ ~ 0.4–1 galaxies. Gas exchange between galaxies is likely the main cause of this evolution.

0 0
  • Source
    The Astrophysical Journal 12/1954; 121:161. · 6.73 Impact Factor
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: Observations of star formation rates (SFRs) in galaxies provide vital clues to the physical nature of the Hubble sequence, and are key probes of the evolutionary properties of galaxies. The focus of this review is on the broad patterns in the star formation properties of galaxies along the Hubble sequence, and their implications for understanding galaxy evolution and the physical processes that drive the evolution. Star formation in the disks and nuclear regions of galaxies are reviewed separately, then discussed within a common interpretive framework. The diagnostic methods used to measure SFRs are also reviewed, and a self-consistent set of SFR calibrations is presented as an aid to workers in the field.
    Annual Review of Astronomy and Astrophysics 08/1998; · 23.33 Impact Factor
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: We use a large sample of galaxies from the Two Micron All Sky Survey (2MASS) and the Sloan Digital Sky Survey (SDSS) to calculate galaxy luminosity and stellar mass functions in the local Universe. We estimate k-corrections, evolution corrections, and stellar mass-to-light ratios (M/Ls) by fitting the galaxy colors with simple models. Our optical and near-infrared luminosity functions agree with most recent literature optical and near-infrared determinations within the uncertainties. We argue that 2MASS is biased against low surface brightness galaxies, and use SDSS plus our knowledge of stellar populations to estimate that the true K-band luminosity function has a steeper faint end slope than the direct estimate. Assuming a universally-applicable stellar initial mass function (IMF), we derive the stellar mass function of galaxies. The faint end slope slope for the stellar mass function is steeper than -1.1, reflecting the low stellar M/Ls characteristic of low-mass galaxies. We estimate an upper limit to the stellar mass density in the local Universe Omega* h = 0.0020+/-0.0006 by assuming an IMF as rich in low-mass stars as allowed by observations of galaxy dynamics. Finally, we find that the characteristic luminosity or mass of early-type galaxies is larger than for later types, and the faint end slope is steeper for later types than for earlier types. Accounting for typing uncertainties, we estimate that at least half, and perhaps as much as 3/4, of the stellar mass in the Universe is in early-type galaxies. We present also SDSS/2MASS color-M/L correlations, an updated discussion of near-infrared stellar M/L estimates, and the volume-corrected distribution of g and K-band stellar M/Ls as a function of stellar mass. [Abridged]
    The Astrophysical Journal Supplement Series 02/2003; 149. · 16.24 Impact Factor

Full-text (4 Sources)

Available from
May 2, 2013