The ages, masses and star formation rates of spectroscopically confirmed z ˜ 6 galaxies in CANDELS

E. Curtis-Lake; R. J. McLure; J. S. Dunlop; M. Schenker; A. B. Rogers; T. Targett; M. Cirasuolo; O. Almaini; M. L. N. Ashby; E. J. Bradshaw; S. L. Finkelstein; M. Dickinson; R. S. Ellis; S. M. Faber; G. G. Fazio; H. C. Ferguson; A. Fontana; N. A. Grogin; W. G. Hartley; D. D. Kocevski; A. M. Koekemoer; K. Lai; B. E. Robertson; E. Vanzella; S. P. Willner

The ages, masses and star formation rates of spectroscopically confirmed z ˜ 6 galaxies in CANDELS

E. Curtis-Lake, R. J. McLure, J. S. Dunlop, M. Schenker, A. B. Rogers, T. Targett, M. Cirasuolo, O. Almaini, M. L. N. Ashby, E. J. Bradshaw, S. L. Finkelstein, M. Dickinson, R. S. Ellis, S. M. Faber, G. G. Fazio, H. C. Ferguson, A. Fontana, N. A. Grogin, W. G. Hartley, D. D. KocevskiA. M. Koekemoer, K. Lai, B. E. Robertson, E. Vanzella, S. P. Willner

School of Physics and Astronomy

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Abstract

We report the results of a study exploring the stellar populations of 13 luminous (L > 1.2L*), spectroscopically confirmed, galaxies in the redshift interval 5.5 <z <6.5, all with Hubble Space Telescope (HST) Wide Field Camera 3/infrared and Spitzer Infrared Array Camera imaging from the HST/Cosmic Assembly Near-infrared Deep Survey and Spitzer Extended Deep Survey. Based on fitting the observed photometry with galaxy spectral energy distribution (SED) templates covering a wide range of different star formation histories, including exponentially increasing star formation rates and a self-consistent treatment of Lyα emission, we find that the derived stellar masses lie within the range of 109<M* <1010 M⊙ and are robust to within a factor of 2. In contrast, we confirm previous reports that the ages of the stellar populations are poorly constrained. Although the best-fitting models for 3/13 of the sample have ages of ≳300 Myr, the degeneracies introduced by dust extinction mean that only two of these objects actually require a ≳300 Myr old stellar population to reproduce the observed photometry. We also explore SED fitting with more general, two-component models (burst plus ongoing star formation), thereby relaxing the requirement that the current star formation rate and assembled stellar mass must be coupled, and allow for nebular line+continuum emission. On average, the inclusion of nebular emission leads to lower stellar mass estimates (median offset 0.18 dex), moderately higher specific star formation rates, and allows for a wider range of plausible stellar ages. However, based on our SED modelling, we find no strong evidence for extremely young ages in our sample (i.e.

Original language	English
Pages (from-to)	302-322
Journal	Monthly Notices of the Royal Astronomical Society
Volume	429
Publication status	Published - 1 Feb 2013

Keywords

galaxies: evolution
galaxies: formation
galaxies: high-redshift

Access to Document

http://adsabs.harvard.edu/abs/2013MNRAS.429..302C

Cite this

Curtis-Lake, E., McLure, R. J., Dunlop, J. S., Schenker, M., Rogers, A. B., Targett, T., Cirasuolo, M., Almaini, O., Ashby, M. L. N., Bradshaw, E. J., Finkelstein, S. L., Dickinson, M., Ellis, R. S., Faber, S. M., Fazio, G. G., Ferguson, H. C., Fontana, A., Grogin, N. A., Hartley, W. G., ... Willner, S. P. (2013). The ages, masses and star formation rates of spectroscopically confirmed z ˜ 6 galaxies in CANDELS. Monthly Notices of the Royal Astronomical Society, 429, 302-322. http://adsabs.harvard.edu/abs/2013MNRAS.429..302C

@article{4ea448a913a8401394cbcb377c8ee910,

title = "The ages, masses and star formation rates of spectroscopically confirmed z ˜ 6 galaxies in CANDELS",

abstract = "We report the results of a study exploring the stellar populations of 13 luminous (L > 1.2L*), spectroscopically confirmed, galaxies in the redshift interval 5.5 <z <6.5, all with Hubble Space Telescope (HST) Wide Field Camera 3/infrared and Spitzer Infrared Array Camera imaging from the HST/Cosmic Assembly Near-infrared Deep Survey and Spitzer Extended Deep Survey. Based on fitting the observed photometry with galaxy spectral energy distribution (SED) templates covering a wide range of different star formation histories, including exponentially increasing star formation rates and a self-consistent treatment of Lyα emission, we find that the derived stellar masses lie within the range of 109<M* <1010 M⊙ and are robust to within a factor of 2. In contrast, we confirm previous reports that the ages of the stellar populations are poorly constrained. Although the best-fitting models for 3/13 of the sample have ages of ≳300 Myr, the degeneracies introduced by dust extinction mean that only two of these objects actually require a ≳300 Myr old stellar population to reproduce the observed photometry. We also explore SED fitting with more general, two-component models (burst plus ongoing star formation), thereby relaxing the requirement that the current star formation rate and assembled stellar mass must be coupled, and allow for nebular line+continuum emission. On average, the inclusion of nebular emission leads to lower stellar mass estimates (median offset 0.18 dex), moderately higher specific star formation rates, and allows for a wider range of plausible stellar ages. However, based on our SED modelling, we find no strong evidence for extremely young ages in our sample (i.e. ",

keywords = "galaxies: evolution, galaxies: formation, galaxies: high-redshift",

author = "E. Curtis-Lake and McLure, {R. J.} and Dunlop, {J. S.} and M. Schenker and Rogers, {A. B.} and T. Targett and M. Cirasuolo and O. Almaini and Ashby, {M. L. N.} and Bradshaw, {E. J.} and Finkelstein, {S. L.} and M. Dickinson and Ellis, {R. S.} and Faber, {S. M.} and Fazio, {G. G.} and Ferguson, {H. C.} and A. Fontana and Grogin, {N. A.} and Hartley, {W. G.} and Kocevski, {D. D.} and Koekemoer, {A. M.} and K. Lai and Robertson, {B. E.} and E. Vanzella and Willner, {S. P.}",

year = "2013",

month = feb,

day = "1",

language = "English",

volume = "429",

pages = "302--322",

journal = "Monthly Notices of the Royal Astronomical Society ",

issn = "0035-8711",

publisher = "Oxford University Press",

}

Curtis-Lake, E, McLure, RJ , Dunlop, JS, Schenker, M, Rogers, AB, Targett, T, Cirasuolo, M, Almaini, O, Ashby, MLN, Bradshaw, EJ, Finkelstein, SL, Dickinson, M, Ellis, RS, Faber, SM, Fazio, GG, Ferguson, HC, Fontana, A, Grogin, NA, Hartley, WG, Kocevski, DD, Koekemoer, AM, Lai, K, Robertson, BE, Vanzella, E & Willner, SP 2013, 'The ages, masses and star formation rates of spectroscopically confirmed z ˜ 6 galaxies in CANDELS', Monthly Notices of the Royal Astronomical Society, vol. 429, pp. 302-322. <http://adsabs.harvard.edu/abs/2013MNRAS.429..302C>

TY - JOUR

T1 - The ages, masses and star formation rates of spectroscopically confirmed z ˜ 6 galaxies in CANDELS

AU - Curtis-Lake, E.

AU - McLure, R. J.

AU - Dunlop, J. S.

AU - Schenker, M.

AU - Rogers, A. B.

AU - Targett, T.

AU - Cirasuolo, M.

AU - Almaini, O.

AU - Ashby, M. L. N.

AU - Bradshaw, E. J.

AU - Finkelstein, S. L.

AU - Dickinson, M.

AU - Ellis, R. S.

AU - Faber, S. M.

AU - Fazio, G. G.

AU - Ferguson, H. C.

AU - Fontana, A.

AU - Grogin, N. A.

AU - Hartley, W. G.

AU - Kocevski, D. D.

AU - Koekemoer, A. M.

AU - Lai, K.

AU - Robertson, B. E.

AU - Vanzella, E.

AU - Willner, S. P.

PY - 2013/2/1

Y1 - 2013/2/1

N2 - We report the results of a study exploring the stellar populations of 13 luminous (L > 1.2L*), spectroscopically confirmed, galaxies in the redshift interval 5.5 <z <6.5, all with Hubble Space Telescope (HST) Wide Field Camera 3/infrared and Spitzer Infrared Array Camera imaging from the HST/Cosmic Assembly Near-infrared Deep Survey and Spitzer Extended Deep Survey. Based on fitting the observed photometry with galaxy spectral energy distribution (SED) templates covering a wide range of different star formation histories, including exponentially increasing star formation rates and a self-consistent treatment of Lyα emission, we find that the derived stellar masses lie within the range of 109<M* <1010 M⊙ and are robust to within a factor of 2. In contrast, we confirm previous reports that the ages of the stellar populations are poorly constrained. Although the best-fitting models for 3/13 of the sample have ages of ≳300 Myr, the degeneracies introduced by dust extinction mean that only two of these objects actually require a ≳300 Myr old stellar population to reproduce the observed photometry. We also explore SED fitting with more general, two-component models (burst plus ongoing star formation), thereby relaxing the requirement that the current star formation rate and assembled stellar mass must be coupled, and allow for nebular line+continuum emission. On average, the inclusion of nebular emission leads to lower stellar mass estimates (median offset 0.18 dex), moderately higher specific star formation rates, and allows for a wider range of plausible stellar ages. However, based on our SED modelling, we find no strong evidence for extremely young ages in our sample (i.e.

AB - We report the results of a study exploring the stellar populations of 13 luminous (L > 1.2L*), spectroscopically confirmed, galaxies in the redshift interval 5.5 <z <6.5, all with Hubble Space Telescope (HST) Wide Field Camera 3/infrared and Spitzer Infrared Array Camera imaging from the HST/Cosmic Assembly Near-infrared Deep Survey and Spitzer Extended Deep Survey. Based on fitting the observed photometry with galaxy spectral energy distribution (SED) templates covering a wide range of different star formation histories, including exponentially increasing star formation rates and a self-consistent treatment of Lyα emission, we find that the derived stellar masses lie within the range of 109<M* <1010 M⊙ and are robust to within a factor of 2. In contrast, we confirm previous reports that the ages of the stellar populations are poorly constrained. Although the best-fitting models for 3/13 of the sample have ages of ≳300 Myr, the degeneracies introduced by dust extinction mean that only two of these objects actually require a ≳300 Myr old stellar population to reproduce the observed photometry. We also explore SED fitting with more general, two-component models (burst plus ongoing star formation), thereby relaxing the requirement that the current star formation rate and assembled stellar mass must be coupled, and allow for nebular line+continuum emission. On average, the inclusion of nebular emission leads to lower stellar mass estimates (median offset 0.18 dex), moderately higher specific star formation rates, and allows for a wider range of plausible stellar ages. However, based on our SED modelling, we find no strong evidence for extremely young ages in our sample (i.e.

KW - galaxies: evolution

KW - galaxies: formation

KW - galaxies: high-redshift

M3 - Article

VL - 429

SP - 302

EP - 322

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

ER -

The ages, masses and star formation rates of spectroscopically confirmed z ˜ 6 galaxies in CANDELS

Abstract

Keywords

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