EROs found behind lensing clusters I. Stellar populations and dust properties of optical dropout EROs and comparison with related objects

D. Schaerer, A. Hempel, E. Egami, R. Pelló, J. Richard, J. F. Le Borgne, J. P. Kneib, M. Wise, F. Boone

Resultado de la investigación: Article

3 Citas (Scopus)

Resumen

Context. On the nature, redshift, stellar populations and dust properties of optically faint or non-detected extremely red objects. Aims. Determining the nature, redshift, stellar populations and dust properties of optically faint or non-detected, extremely red objects (ERO) found from our survey of the lensing clusters A1835 and AC114 (Richard et al. 2006, A&A, 456, 861). Comparison with properties of related galaxies, such as IRAC selected EROs and a z ∼ 6.5 post-starburst galaxy candidate from the Hubble Ultra Deep Field. Methods. Using an updated version of Hyperz (Bolzonella et al. 2000, A&A, 363, 476) and a large number of spectral templates we perform broad-band SED fitting. The photometric observations, taken from Hempel et al. (2007, A&A, submitted), include deep optical, ACS/HST, ISAAC/VLT, IRAC/Spitzer data, and for some objects 24 μm MIPS/Spitzer and sub-mm data as well. Results. For most of the lensed EROs we find photometric redshifts showing a strong degeneracy between "low-z" (z ∼ 1-3) and high-z (z ∼ 6-7). Although formally best fits are often found at high-z, their resulting bright absolute magnitudes, the number density of these objects, and in some cases Spitzer photometry or longer wavelength observations, suggest strongly that all of these objects are at "low-z". The majority of these objects are best fitted with relatively young (≲0.5-0.7 Gyr) and dusty starbursts. Three of our objects show indications for strong extinction, with Av ∼ 2.4-4. The typical stellar masses of our objects are M* ∼ (0.5-5) × 1010 M after correction for lensing; for the most extreme ERO in our sample, the sub-mm galaxy SMMJ14009+0252 most likely at zfit ∼ 3, we estimate M* ∼ 6. × 1011 M . For dusty objects star formation rates (SFR) have been estimated from the bolometric luminosity determined after fitting of semi-empirical starburst, ERO, and ULIRG templates. Typically we find SFR ∼ (1-18) M yr-1. Again, SMMJ14009+0252 stands out as a LIRG with SFR ∼ 1000 M yr-1. Finally, we predict the mid-lR to sub-mm SED of the dusty objects for comparison with future observations with APEX, Herschel, and ALMA. Concerning the comparison objects, we argue that the massive post-starburst z ∼ 6.5 galaxy candidate HUDF-J2 showing observed properties very similar to our EROs, is more likely a dusty starburst at z ∼ 2.3-2.6. This interpretation also naturally explains the observed 24 μm emission from this object and we predict its IR to sub-mm SED. Both empirically and from our SED fits we find that the IRAC selectec EROs from Yan et al. (2004, ApJ, 616, 63) show very similar properties to our lensed EROs. Reasonable fits are found for most of them with relatively young and dusty stellar populations.

Idioma originalEnglish
Páginas (desde-hasta)47-60
Número de páginas14
PublicaciónAstronomy and Astrophysics
Volumen469
N.º1
DOI
EstadoPublished - jul 2007

Huella dactilar

dropouts
dust
star formation rate
galaxies
templates
extinction
starburst galaxies
wavelength
stellar mass
photometry
indication
luminosity
comparison
rate
broadband
estimates
young
wavelengths

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

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Schaerer, D. ; Hempel, A. ; Egami, E. ; Pelló, R. ; Richard, J. ; Le Borgne, J. F. ; Kneib, J. P. ; Wise, M. ; Boone, F. / EROs found behind lensing clusters I. Stellar populations and dust properties of optical dropout EROs and comparison with related objects. En: Astronomy and Astrophysics. 2007 ; Vol. 469, N.º 1. pp. 47-60.
@article{6806bdb6f80546e4acc33df7c4227cf9,
title = "EROs found behind lensing clusters I. Stellar populations and dust properties of optical dropout EROs and comparison with related objects",
abstract = "Context. On the nature, redshift, stellar populations and dust properties of optically faint or non-detected extremely red objects. Aims. Determining the nature, redshift, stellar populations and dust properties of optically faint or non-detected, extremely red objects (ERO) found from our survey of the lensing clusters A1835 and AC114 (Richard et al. 2006, A&A, 456, 861). Comparison with properties of related galaxies, such as IRAC selected EROs and a z ∼ 6.5 post-starburst galaxy candidate from the Hubble Ultra Deep Field. Methods. Using an updated version of Hyperz (Bolzonella et al. 2000, A&A, 363, 476) and a large number of spectral templates we perform broad-band SED fitting. The photometric observations, taken from Hempel et al. (2007, A&A, submitted), include deep optical, ACS/HST, ISAAC/VLT, IRAC/Spitzer data, and for some objects 24 μm MIPS/Spitzer and sub-mm data as well. Results. For most of the lensed EROs we find photometric redshifts showing a strong degeneracy between {"}low-z{"} (z ∼ 1-3) and high-z (z ∼ 6-7). Although formally best fits are often found at high-z, their resulting bright absolute magnitudes, the number density of these objects, and in some cases Spitzer photometry or longer wavelength observations, suggest strongly that all of these objects are at {"}low-z{"}. The majority of these objects are best fitted with relatively young (≲0.5-0.7 Gyr) and dusty starbursts. Three of our objects show indications for strong extinction, with Av ∼ 2.4-4. The typical stellar masses of our objects are M* ∼ (0.5-5) × 1010 M⊙ after correction for lensing; for the most extreme ERO in our sample, the sub-mm galaxy SMMJ14009+0252 most likely at zfit ∼ 3, we estimate M* ∼ 6. × 1011 M ⊙. For dusty objects star formation rates (SFR) have been estimated from the bolometric luminosity determined after fitting of semi-empirical starburst, ERO, and ULIRG templates. Typically we find SFR ∼ (1-18) M⊙ yr-1. Again, SMMJ14009+0252 stands out as a LIRG with SFR ∼ 1000 M⊙ yr-1. Finally, we predict the mid-lR to sub-mm SED of the dusty objects for comparison with future observations with APEX, Herschel, and ALMA. Concerning the comparison objects, we argue that the massive post-starburst z ∼ 6.5 galaxy candidate HUDF-J2 showing observed properties very similar to our EROs, is more likely a dusty starburst at z ∼ 2.3-2.6. This interpretation also naturally explains the observed 24 μm emission from this object and we predict its IR to sub-mm SED. Both empirically and from our SED fits we find that the IRAC selectec EROs from Yan et al. (2004, ApJ, 616, 63) show very similar properties to our lensed EROs. Reasonable fits are found for most of them with relatively young and dusty stellar populations.",
keywords = "Cosmology: early universe, Galaxies: evolution, Galaxies: high-redshift, Galaxies: starburst, Infrared: galaxies",
author = "D. Schaerer and A. Hempel and E. Egami and R. Pell{\'o} and J. Richard and {Le Borgne}, {J. F.} and Kneib, {J. P.} and M. Wise and F. Boone",
year = "2007",
month = "7",
doi = "10.1051/0004-6361:20077127",
language = "English",
volume = "469",
pages = "47--60",
journal = "Astronomy and Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",
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EROs found behind lensing clusters I. Stellar populations and dust properties of optical dropout EROs and comparison with related objects. / Schaerer, D.; Hempel, A.; Egami, E.; Pelló, R.; Richard, J.; Le Borgne, J. F.; Kneib, J. P.; Wise, M.; Boone, F.

En: Astronomy and Astrophysics, Vol. 469, N.º 1, 07.2007, p. 47-60.

Resultado de la investigación: Article

TY - JOUR

T1 - EROs found behind lensing clusters I. Stellar populations and dust properties of optical dropout EROs and comparison with related objects

AU - Schaerer, D.

AU - Hempel, A.

AU - Egami, E.

AU - Pelló, R.

AU - Richard, J.

AU - Le Borgne, J. F.

AU - Kneib, J. P.

AU - Wise, M.

AU - Boone, F.

PY - 2007/7

Y1 - 2007/7

N2 - Context. On the nature, redshift, stellar populations and dust properties of optically faint or non-detected extremely red objects. Aims. Determining the nature, redshift, stellar populations and dust properties of optically faint or non-detected, extremely red objects (ERO) found from our survey of the lensing clusters A1835 and AC114 (Richard et al. 2006, A&A, 456, 861). Comparison with properties of related galaxies, such as IRAC selected EROs and a z ∼ 6.5 post-starburst galaxy candidate from the Hubble Ultra Deep Field. Methods. Using an updated version of Hyperz (Bolzonella et al. 2000, A&A, 363, 476) and a large number of spectral templates we perform broad-band SED fitting. The photometric observations, taken from Hempel et al. (2007, A&A, submitted), include deep optical, ACS/HST, ISAAC/VLT, IRAC/Spitzer data, and for some objects 24 μm MIPS/Spitzer and sub-mm data as well. Results. For most of the lensed EROs we find photometric redshifts showing a strong degeneracy between "low-z" (z ∼ 1-3) and high-z (z ∼ 6-7). Although formally best fits are often found at high-z, their resulting bright absolute magnitudes, the number density of these objects, and in some cases Spitzer photometry or longer wavelength observations, suggest strongly that all of these objects are at "low-z". The majority of these objects are best fitted with relatively young (≲0.5-0.7 Gyr) and dusty starbursts. Three of our objects show indications for strong extinction, with Av ∼ 2.4-4. The typical stellar masses of our objects are M* ∼ (0.5-5) × 1010 M⊙ after correction for lensing; for the most extreme ERO in our sample, the sub-mm galaxy SMMJ14009+0252 most likely at zfit ∼ 3, we estimate M* ∼ 6. × 1011 M ⊙. For dusty objects star formation rates (SFR) have been estimated from the bolometric luminosity determined after fitting of semi-empirical starburst, ERO, and ULIRG templates. Typically we find SFR ∼ (1-18) M⊙ yr-1. Again, SMMJ14009+0252 stands out as a LIRG with SFR ∼ 1000 M⊙ yr-1. Finally, we predict the mid-lR to sub-mm SED of the dusty objects for comparison with future observations with APEX, Herschel, and ALMA. Concerning the comparison objects, we argue that the massive post-starburst z ∼ 6.5 galaxy candidate HUDF-J2 showing observed properties very similar to our EROs, is more likely a dusty starburst at z ∼ 2.3-2.6. This interpretation also naturally explains the observed 24 μm emission from this object and we predict its IR to sub-mm SED. Both empirically and from our SED fits we find that the IRAC selectec EROs from Yan et al. (2004, ApJ, 616, 63) show very similar properties to our lensed EROs. Reasonable fits are found for most of them with relatively young and dusty stellar populations.

AB - Context. On the nature, redshift, stellar populations and dust properties of optically faint or non-detected extremely red objects. Aims. Determining the nature, redshift, stellar populations and dust properties of optically faint or non-detected, extremely red objects (ERO) found from our survey of the lensing clusters A1835 and AC114 (Richard et al. 2006, A&A, 456, 861). Comparison with properties of related galaxies, such as IRAC selected EROs and a z ∼ 6.5 post-starburst galaxy candidate from the Hubble Ultra Deep Field. Methods. Using an updated version of Hyperz (Bolzonella et al. 2000, A&A, 363, 476) and a large number of spectral templates we perform broad-band SED fitting. The photometric observations, taken from Hempel et al. (2007, A&A, submitted), include deep optical, ACS/HST, ISAAC/VLT, IRAC/Spitzer data, and for some objects 24 μm MIPS/Spitzer and sub-mm data as well. Results. For most of the lensed EROs we find photometric redshifts showing a strong degeneracy between "low-z" (z ∼ 1-3) and high-z (z ∼ 6-7). Although formally best fits are often found at high-z, their resulting bright absolute magnitudes, the number density of these objects, and in some cases Spitzer photometry or longer wavelength observations, suggest strongly that all of these objects are at "low-z". The majority of these objects are best fitted with relatively young (≲0.5-0.7 Gyr) and dusty starbursts. Three of our objects show indications for strong extinction, with Av ∼ 2.4-4. The typical stellar masses of our objects are M* ∼ (0.5-5) × 1010 M⊙ after correction for lensing; for the most extreme ERO in our sample, the sub-mm galaxy SMMJ14009+0252 most likely at zfit ∼ 3, we estimate M* ∼ 6. × 1011 M ⊙. For dusty objects star formation rates (SFR) have been estimated from the bolometric luminosity determined after fitting of semi-empirical starburst, ERO, and ULIRG templates. Typically we find SFR ∼ (1-18) M⊙ yr-1. Again, SMMJ14009+0252 stands out as a LIRG with SFR ∼ 1000 M⊙ yr-1. Finally, we predict the mid-lR to sub-mm SED of the dusty objects for comparison with future observations with APEX, Herschel, and ALMA. Concerning the comparison objects, we argue that the massive post-starburst z ∼ 6.5 galaxy candidate HUDF-J2 showing observed properties very similar to our EROs, is more likely a dusty starburst at z ∼ 2.3-2.6. This interpretation also naturally explains the observed 24 μm emission from this object and we predict its IR to sub-mm SED. Both empirically and from our SED fits we find that the IRAC selectec EROs from Yan et al. (2004, ApJ, 616, 63) show very similar properties to our lensed EROs. Reasonable fits are found for most of them with relatively young and dusty stellar populations.

KW - Cosmology: early universe

KW - Galaxies: evolution

KW - Galaxies: high-redshift

KW - Galaxies: starburst

KW - Infrared: galaxies

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