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Stellar populations of over 1000 z ∼ 0.8 galaxies from LEGA-C : ages and star formation histories from Dn4000 and Hδ

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Abstract
Drawing from the LEGA-C data set, we present the spectroscopic view of the stellar population across a large volume-and mass-selected sample of galaxies at large look-back time. We measure the 4000 angstrom break (D(n)4000) and Balmer absorption line strengths (probed by H delta) from 1019 high-quality spectra of z = 0.6-1.0 galaxies with M-*. = 2 x 10(10)M(circle dot) to 3 x 10(11)M(circle dot). Our analysis serves as a first illustration of the power of high-resolution, high signal-to-noise ratio continuum spectroscopy at intermediate redshifts as a qualitatively new tool to constrain galaxy formation models. The observed D(n)4000-EW(H delta) distribution of our sample overlaps with the distribution traced by present-day galaxies, but z similar to 0.8 galaxies populate that locus in a fundamentally different manner. While old galaxies dominate the present-day population at all stellar masses >2 x 10(10)M(circle dot), we see a bimodal D(n)4000-EW(H delta) distribution at z similar to 0.8, implying a bimodal light-weighted age distribution. The light-weighted age depends strongly on stellar mass, with the most massive galaxies > 1 x 10(11)M(circle dot) being almost all older than 2 Gyr. At the same time, we estimate that galaxies in this high-mass range are only similar to 3. Gyr younger than their z. similar to 0.1 counterparts, at odds with purely passive evolution given a difference in look-back time of > 5 Gyr; younger galaxies must grow to > 10(11)M(circle dot) in the meantime, or small amounts of young stars must keep the lightweighted ages young. Star-forming galaxies at z similar to 0.8 have stronger Hd absorption than present-day galaxies with the same D(n)4000, implying larger short-term variations in star formation activity.
Keywords
galaxies: evolution, galaxies: high-redshift, galaxies: stellar content, DIGITAL SKY SURVEY, MASS ASSEMBLY HISTORY, LESS-THAN 2, FORMING GALAXIES, QUIESCENT GALAXY, TARGET SELECTION, DUST EXTINCTION, LOCAL UNIVERSE, FIELD GALAXIES, LIGHT RATIOS

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Citation

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MLA
Wu, Po-Feng, Arjen van der Wel, Anna Gallazzi, et al. “Stellar Populations of over 1000 z ∼ 0.8 Galaxies from LEGA-C : Ages and Star Formation Histories from Dn4000 and Hδ.” ASTROPHYSICAL JOURNAL 855.2 (2018): n. pag. Print.
APA
Wu, P.-F., van der Wel, A., Gallazzi, A., Bezanson, R., Pacifici, C., Straatman, C., Franx, M., et al. (2018). Stellar populations of over 1000 z ∼ 0.8 galaxies from LEGA-C : ages and star formation histories from Dn4000 and Hδ. ASTROPHYSICAL JOURNAL, 855(2).
Chicago author-date
Wu, Po-Feng, Arjen van der Wel, Anna Gallazzi, Rachel Bezanson, Camilla Pacifici, Caroline Straatman, Marijn Franx, et al. 2018. “Stellar Populations of over 1000 z ∼ 0.8 Galaxies from LEGA-C : Ages and Star Formation Histories from Dn4000 and Hδ.” Astrophysical Journal 855 (2).
Chicago author-date (all authors)
Wu, Po-Feng, Arjen van der Wel, Anna Gallazzi, Rachel Bezanson, Camilla Pacifici, Caroline Straatman, Marijn Franx, Ivana Barišić, Eric F Bell, Gabriel B Brammer, Joao Calhau, Priscilla Chauke, Josha van Houdt, Michael V Maseda, Adam Muzzin, Hans-Walter Rix, David Sobral, Justin Spilker, Jesse van de Sande, Pieter van Dokkum, and Vivienne Wild. 2018. “Stellar Populations of over 1000 z ∼ 0.8 Galaxies from LEGA-C : Ages and Star Formation Histories from Dn4000 and Hδ.” Astrophysical Journal 855 (2).
Vancouver
1.
Wu P-F, van der Wel A, Gallazzi A, Bezanson R, Pacifici C, Straatman C, et al. Stellar populations of over 1000 z ∼ 0.8 galaxies from LEGA-C : ages and star formation histories from Dn4000 and Hδ. ASTROPHYSICAL JOURNAL. 2018;855(2).
IEEE
[1]
P.-F. Wu et al., “Stellar populations of over 1000 z ∼ 0.8 galaxies from LEGA-C : ages and star formation histories from Dn4000 and Hδ,” ASTROPHYSICAL JOURNAL, vol. 855, no. 2, 2018.
@article{8562429,
  abstract     = {Drawing from the LEGA-C data set, we present the spectroscopic view of the stellar population across a large volume-and mass-selected sample of galaxies at large look-back time. We measure the 4000 angstrom break (D(n)4000) and Balmer absorption line strengths (probed by H delta) from 1019 high-quality spectra of z = 0.6-1.0 galaxies with M-*. = 2 x 10(10)M(circle dot) to 3 x 10(11)M(circle dot). Our analysis serves as a first illustration of the power of high-resolution, high signal-to-noise ratio continuum spectroscopy at intermediate redshifts as a qualitatively new tool to constrain galaxy formation models. The observed D(n)4000-EW(H delta) distribution of our sample overlaps with the distribution traced by present-day galaxies, but z similar to 0.8 galaxies populate that locus in a fundamentally different manner. While old galaxies dominate the present-day population at all stellar masses >2 x 10(10)M(circle dot), we see a bimodal D(n)4000-EW(H delta) distribution at z similar to 0.8, implying a bimodal light-weighted age distribution. The light-weighted age depends strongly on stellar mass, with the most massive galaxies > 1 x 10(11)M(circle dot) being almost all older than 2 Gyr. At the same time, we estimate that galaxies in this high-mass range are only similar to 3. Gyr younger than their z. similar to 0.1 counterparts, at odds with purely passive evolution given a difference in look-back time of > 5 Gyr; younger galaxies must grow to > 10(11)M(circle dot) in the meantime, or small amounts of young stars must keep the lightweighted ages young. Star-forming galaxies at z similar to 0.8 have stronger Hd absorption than present-day galaxies with the same D(n)4000, implying larger short-term variations in star formation activity.},
  articleno    = {85},
  author       = {Wu, Po-Feng and van der Wel, Arjen and Gallazzi, Anna and Bezanson, Rachel and Pacifici, Camilla and Straatman, Caroline and Franx, Marijn and Barišić, Ivana and Bell, Eric F and Brammer, Gabriel B and Calhau, Joao and Chauke, Priscilla and van Houdt, Josha and Maseda, Michael V and Muzzin, Adam and Rix, Hans-Walter and Sobral, David and Spilker, Justin and van de Sande, Jesse and van Dokkum, Pieter and Wild, Vivienne},
  issn         = {0004-637X},
  journal      = {ASTROPHYSICAL JOURNAL},
  keywords     = {galaxies: evolution,galaxies: high-redshift,galaxies: stellar content,DIGITAL SKY SURVEY,MASS ASSEMBLY HISTORY,LESS-THAN 2,FORMING GALAXIES,QUIESCENT GALAXY,TARGET SELECTION,DUST EXTINCTION,LOCAL UNIVERSE,FIELD GALAXIES,LIGHT RATIOS},
  language     = {eng},
  number       = {2},
  pages        = {13},
  title        = {Stellar populations of over 1000 z ∼ 0.8 galaxies from LEGA-C : ages and star formation histories from Dn4000 and Hδ},
  url          = {http://dx.doi.org/10.3847/1538-4357/aab0a6},
  volume       = {855},
  year         = {2018},
}

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