skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: A CONSISTENT STUDY OF METALLICITY EVOLUTION AT 0.8 < z < 2.6

Abstract

We present the correlations between stellar mass, star formation rate (SFR), and the [N II]/Hα flux ratio as an indicator of gas-phase metallicity for a sample of 222 galaxies at 0.8 < z < 2.6 and log (M {sub *}/M {sub ☉}) = 9.0-11.5 from the LUCI, SINS/zC-SINF, and KMOS{sup 3D} surveys. This sample provides a unique analysis of the mass-metallicity relation (MZR) over an extended redshift range using consistent data analysis techniques and a uniform strong-line metallicity indicator. We find a constant slope at the low-mass end of the relation and can fully describe its redshift evolution through the evolution of the characteristic turnover mass where the relation begins to flatten at the asymptotic metallicity. At a fixed mass and redshift, our data do not show a correlation between the [N II]/Hα ratio and SFR, which disagrees with the 0.2-0.3 dex offset in [N II]/Hα predicted by the ''fundamental relation'' between stellar mass, SFR, and metallicity discussed in recent literature. However, the overall evolution toward lower [N II]/Hα at earlier times does broadly agree with these predictions.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;  [1];  [2];  [3]; ;  [4] more »; « less
  1. Max-Planck-Institut für extraterrestrische Physik, Giessenbachstr. 1, D-85741 Garching (Germany)
  2. Space Telescope Science Institute, Baltimore, MD 21218 (United States)
  3. Universitäts-Sternwarte München, Scheinerstr. 1, D-81679 München (Germany)
  4. Institute of Astronomy, Department of Physics, Eidgensösische Technische Hochschule, ETH Zürich, CH-8093 (Switzerland)
Publication Date:
OSTI Identifier:
22365642
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 789; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMPTOTIC SOLUTIONS; CORRELATIONS; DATA ANALYSIS; GALAXIES; INDICATORS; MASS; METALLICITY; RED SHIFT; STAR EVOLUTION; STARS

Citation Formats

Wuyts, Eva, Kurk, Jaron, Förster Schreiber, Natascha M., Genzel, Reinhard, Wisnioski, Emily, Bandara, Kaushala, Wuyts, Stijn, Beifiori, Alessandra, Bender, Ralf, Buschkamp, Peter, Chan, Jeffrey, Davies, Ric, Eisenhauer, Frank, Fossati, Matteo, Kulkarni, Sandesh K., Lang, Philipp, Brammer, Gabriel B., Burkert, Andreas, Carollo, C. Marcella, Lilly, Simon J., E-mail: evawuyts@mpe.mpg.de, and and others. A CONSISTENT STUDY OF METALLICITY EVOLUTION AT 0.8 < z < 2.6. United States: N. p., 2014. Web. doi:10.1088/2041-8205/789/2/L40.
Wuyts, Eva, Kurk, Jaron, Förster Schreiber, Natascha M., Genzel, Reinhard, Wisnioski, Emily, Bandara, Kaushala, Wuyts, Stijn, Beifiori, Alessandra, Bender, Ralf, Buschkamp, Peter, Chan, Jeffrey, Davies, Ric, Eisenhauer, Frank, Fossati, Matteo, Kulkarni, Sandesh K., Lang, Philipp, Brammer, Gabriel B., Burkert, Andreas, Carollo, C. Marcella, Lilly, Simon J., E-mail: evawuyts@mpe.mpg.de, & and others. A CONSISTENT STUDY OF METALLICITY EVOLUTION AT 0.8 < z < 2.6. United States. doi:10.1088/2041-8205/789/2/L40.
Wuyts, Eva, Kurk, Jaron, Förster Schreiber, Natascha M., Genzel, Reinhard, Wisnioski, Emily, Bandara, Kaushala, Wuyts, Stijn, Beifiori, Alessandra, Bender, Ralf, Buschkamp, Peter, Chan, Jeffrey, Davies, Ric, Eisenhauer, Frank, Fossati, Matteo, Kulkarni, Sandesh K., Lang, Philipp, Brammer, Gabriel B., Burkert, Andreas, Carollo, C. Marcella, Lilly, Simon J., E-mail: evawuyts@mpe.mpg.de, and and others. Thu . "A CONSISTENT STUDY OF METALLICITY EVOLUTION AT 0.8 < z < 2.6". United States. doi:10.1088/2041-8205/789/2/L40.
@article{osti_22365642,
title = {A CONSISTENT STUDY OF METALLICITY EVOLUTION AT 0.8 < z < 2.6},
author = {Wuyts, Eva and Kurk, Jaron and Förster Schreiber, Natascha M. and Genzel, Reinhard and Wisnioski, Emily and Bandara, Kaushala and Wuyts, Stijn and Beifiori, Alessandra and Bender, Ralf and Buschkamp, Peter and Chan, Jeffrey and Davies, Ric and Eisenhauer, Frank and Fossati, Matteo and Kulkarni, Sandesh K. and Lang, Philipp and Brammer, Gabriel B. and Burkert, Andreas and Carollo, C. Marcella and Lilly, Simon J., E-mail: evawuyts@mpe.mpg.de and and others},
abstractNote = {We present the correlations between stellar mass, star formation rate (SFR), and the [N II]/Hα flux ratio as an indicator of gas-phase metallicity for a sample of 222 galaxies at 0.8 < z < 2.6 and log (M {sub *}/M {sub ☉}) = 9.0-11.5 from the LUCI, SINS/zC-SINF, and KMOS{sup 3D} surveys. This sample provides a unique analysis of the mass-metallicity relation (MZR) over an extended redshift range using consistent data analysis techniques and a uniform strong-line metallicity indicator. We find a constant slope at the low-mass end of the relation and can fully describe its redshift evolution through the evolution of the characteristic turnover mass where the relation begins to flatten at the asymptotic metallicity. At a fixed mass and redshift, our data do not show a correlation between the [N II]/Hα ratio and SFR, which disagrees with the 0.2-0.3 dex offset in [N II]/Hα predicted by the ''fundamental relation'' between stellar mass, SFR, and metallicity discussed in recent literature. However, the overall evolution toward lower [N II]/Hα at earlier times does broadly agree with these predictions.},
doi = {10.1088/2041-8205/789/2/L40},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 789,
place = {United States},
year = {Thu Jul 10 00:00:00 EDT 2014},
month = {Thu Jul 10 00:00:00 EDT 2014}
}
  • We present the mass-metallicity (MZ) and luminosity-metallicity (LZ) relations at z {approx} 0.8 from {approx}1350 galaxies in the Deep Extragalactic Evolutionary Probe 2 survey. We determine stellar masses by fitting the spectral energy distribution inferred from photometry with current stellar population synthesis models. This work raises the number of galaxies with metallicities at z {approx}0.8 by more than an order of magnitude. We investigate the evolution in the MZ and LZ relations in comparison with local MZ and LZ relations determined in a consistent manner using {approx}21, 000 galaxies in the Sloan Digital Sky Survey. We show that high stellarmore » mass galaxies (M {approx} 10{sup 10.6} M{sub sun}) at z {approx}0.8 have attained the chemical enrichment seen in the local universe, while lower stellar mass galaxies (M {approx} 10{sup 9.2} M{sub sun}) at z {approx}0.8 have lower metallicities ({Delta}log(O/H) {approx} 0.15 dex) than galaxies at the same stellar mass in the local universe. We find that the LZ relation evolves in both metallicity and B-band luminosity between z {approx}0.8 and z {approx} 0, with the B-band luminosity evolving as a function of stellar mass. We emphasize that the B-band luminosity should not be used as a proxy for stellar mass in chemical evolution studies of star-forming galaxies. Our study shows that both the metallicity evolution and the B-band luminosity evolution for emission-line galaxies between the epochs are a function of stellar mass, consistent with the cosmic downsizing scenario of galaxy evolution.« less
  • Using a sample of 299 Hα-selected galaxies at z≈0.8, we study the relationship between galaxy stellar mass, gas-phase metallicity, and star formation rate (SFR), and compare to previous results. We use deep optical spectra obtained with the IMACS spectrograph at the Magellan telescope to measure strong oxygen lines. We combine these spectra and metallicities with (1) rest-frame UV-to-optical imaging, which allows us to determine stellar masses and dust attenuation corrections, and (2) Hα narrowband imaging, which provides a robust measurement of the instantaneous SFR. Our sample spans stellar masses of ∼10{sup 9}–6 × 10{sup 11} M{sub ⊙}, SFRs of 0.4–270more » M{sub ⊙} yr{sup −1}, and metal abundances of 12+log(O/H)≈8.3–9.1 (≈0.4–2.6 Z{sub ⊙}). The correlations that we find between the Hα-based SFR and stellar mass (i.e., the star-forming “main sequence”) and between the stellar mass and metallicity are both consistent with previous z∼1 studies of star-forming galaxies. We then study the relationship between the three properties using various plane-fitting techniques and a curve-fitting projection. In all cases, we exclude strong dependence of the M{sub ⋆}–Z relation on SFR, but are unable to distinguish between moderate and no dependence. Our results are consistent with previous mass–metallicity–SFR studies. We check whether data set limitations may obscure a strong dependence on the SFR by using mock samples drawn from the Sloan Digital Sky Survey. These experiments reveal that the adopted signal-to-noise ratio cuts may have a significant effect on the measured dependence. Further work is needed to investigate these results, and to test whether a “fundamental metallicity relation” or a “fundamental plane” describes star-forming galaxies across cosmic time.« less
  • We present chemical abundance measurements for 47 damped Ly{alpha} (DLA) systems, 30 at z > 4, observed with the Echellette Spectrograph and Imager and the High Resolution Echelle Spectrometer on the Keck telescopes. H I column densities of the DLAs are measured with Voigt profile fits to the Ly{alpha} profiles, and we find an increased number of false DLA identifications with Sloan Digital Sky Survey at z > 4 due to the increased density of the Ly{alpha} forest. Ionic column densities are determined using the apparent optical depth method, and we combine our new metallicity measurements with 195 from previousmore » surveys to determine the evolution of the cosmic metallicity of neutral gas. We find the metallicity of DLAs decreases with increasing redshift, improving the significance of the trend and extending it to higher redshifts, with a linear fit of -0.22 {+-} 0.03 dex per unit redshift from z = 0.09-5.06. The metallicity 'floor' of Almost-Equal-To 1/600 solar continues out to z {approx} 5, despite our sensitivity for finding DLAs with much lower metallicities. However, this floor is not statistically different from a steep tail to the distribution. We also find that the intrinsic scatter of metallicity among DLAs of {approx}0.5 dex continues out to z {approx} 5. In addition, the metallicity distribution and the {alpha}/Fe ratios of z > 2 DLAs are consistent with being drawn from the same parent population with those of halo stars. It is therefore possible that the halo stars in the Milky Way formed out of gas that commonly exhibits DLA absorption at z > 2.« less
  • We present and discuss measurements of the gas-phase metallicity gradient in four gravitationally lensed galaxies at z = 2.0-2.4 based on adaptive optics-assisted imaging spectroscopy with the Keck II telescope. Three galaxies with well-ordered rotation reveal metallicity gradients with lower gas-phase metallicities at larger galactocentric radii. Two of these display gradients much steeper than found locally, while a third has one similar to that seen in local disk galaxies. The fourth galaxy exhibits complex kinematics indicative of an ongoing merger and reveals an 'inverted' gradient with lower metallicity in the central regions. By comparing our sample to similar data inmore » the literature for lower redshift galaxies, we determine that, on average, metallicity gradients must flatten by a factor of 2.6 {+-} 0.9 between z = 2.2 and the present epoch. This factor is in rough agreement with the size growth of massive galaxies, suggesting that inside-out growth can account for the evolution of metallicity gradients. Since the addition of our new data provides the first indication of a coherent picture of this evolution, we develop a simple model of chemical evolution to explain the collective data. We find that metallicity gradients and their evolution can be explained by the inward radial migration of gas together with a radial variation in the mass loading factor governing the ratio of outflowing gas to the local star formation rate. Average mass loading factors of {approx}< 2 are inferred from our model in good agreement with direct measurements of outflowing gas in z {approx_equal} 2 galaxies.« less
  • Emission line diagnostic diagrams probing the ionization sources in galaxies, such as the Baldwin-Phillips-Terlevich (BPT) diagram, have been used extensively to distinguish active galactic nuclei (AGN) from purely star-forming galaxies. However, they remain poorly understood at higher redshifts. We shed light on this issue with an empirical approach based on a z ∼ 0 reference sample built from ∼300,000 Sloan Digital Sky Survey galaxies, from which we mimic selection effects due to typical emission line detection limits at higher redshift. We combine this low-redshift reference sample with a simple prescription for luminosity evolution of the global galaxy population to predictmore » the loci of high-redshift galaxies on the BPT and Mass-Excitation (MEx) diagnostic diagrams. The predicted bivariate distributions agree remarkably well with direct observations of galaxies out to z ∼ 1.5, including the observed stellar mass-metallicity (MZ) relation evolution. As a result, we infer that high-redshift star-forming galaxies are consistent with having normal interstellar medium (ISM) properties out to z ∼ 1.5, after accounting for selection effects and line luminosity evolution. Namely, their optical line ratios and gas-phase metallicities are comparable to that of low-redshift galaxies with equivalent emission-line luminosities. In contrast, AGN narrow-line regions may show a shift toward lower metallicities at higher redshift. While a physical evolution of the ISM conditions is not ruled out for purely star-forming galaxies and may be more important starting at z ≳ 2, we find that reliably quantifying this evolution is hindered by selections effects. The recipes provided here may serve as a basis for future studies toward this goal. Code to predict the loci of galaxies on the BPT and MEx diagnostic diagrams and the MZ relation as a function of emission line luminosity limits is made publicly available.« less