TY - JOUR
T1 - An Imperfectly Passive Nature: Bright Submillimeter Emission from Dust-obscured Star Formation in the z = 3.717 ldquoPassiverdquo System, ZF 20115
AU - Simpson, J.~M.
AU - Smail, I.
AU - Wang, W.-H.
AU - Riechers, D.
AU - Dunlop, J.~S.
AU - Ao, Y.
AU - Bourne, N.
AU - Bunker, A.
AU - Chapman, S.~C.
AU - Chen, C.-C.
AU - Dannerbauer, H.
AU - Geach, J.~E.
AU - Goto, T.
AU - Harrison, C.~M.
AU - Hwang, H.~S.
AU - Ivison, R.~J.
AU - Kodama, T.
AU - Lee, C.-H.
AU - Lee, H.-M.
AU - Lee, M.
AU - Lim, C.-F.
AU - Michalowski, M.~J.
AU - Rosario, D.~J.
AU - Shim, H.
AU - Shu, X.~W.
AU - Swinbank, A.~M.
AU - Tee, W.-L.
AU - Toba, Y.
AU - Valiante, E.
AU - Wang, J.
AU - Zheng, X.~Z.
N1 - © 2017. The American Astronomical Society. All rights reserved.
PY - 2017/7/19
Y1 - 2017/7/19
N2 - The identification of high-redshift, massive galaxies with old stellar populations may pose challenges to some models of galaxy formation. However, to securely classify a galaxy as quiescent, it is necessary to exclude significant ongoing star formation, something that can be challenging to achieve at high redshifts. In this Letter, we analyze deep ALMA/870 μm and SCUBA-2/450 μm imaging of the claimed "post-starburst" galaxy ZF 20115 at z = 3.717 that exhibits a strong Balmer break and absorption lines. The rest-frame far-infrared imaging identifies a luminous starburst 0farcs4 ± 0farcs1 (~3 kpc in projection) from the position of the ultraviolet/optical emission and is consistent with lying at the redshift of ZF 20115. The star-forming component, with an obscured star formation rate of ${100}_{-70}^{+15}\,{M}_{\odot }\,{\mathrm{yr}}^{-1}$, is undetected in the rest-frame ultraviolet but contributes significantly to the lower angular resolution photometry at rest-frame wavelengths gsim3500 Å. This contribution from the obscured starburst, especially in the Spitzer/IRAC wavebands, significantly complicates the determination of a reliable stellar mass for the ZF 20015 system, and we conclude that this source does not pose a challenge to current models of galaxy formation. The multi-wavelength observations of ZF 20115 unveil a complex system with an intricate and spatially varying star formation history. ZF 20115 demonstrates that understanding high-redshift obscured starbursts will only be possible with multi-wavelength studies that include high-resolution observations, available with the James Webb Space Telescope, at mid-infrared wavelengths.
AB - The identification of high-redshift, massive galaxies with old stellar populations may pose challenges to some models of galaxy formation. However, to securely classify a galaxy as quiescent, it is necessary to exclude significant ongoing star formation, something that can be challenging to achieve at high redshifts. In this Letter, we analyze deep ALMA/870 μm and SCUBA-2/450 μm imaging of the claimed "post-starburst" galaxy ZF 20115 at z = 3.717 that exhibits a strong Balmer break and absorption lines. The rest-frame far-infrared imaging identifies a luminous starburst 0farcs4 ± 0farcs1 (~3 kpc in projection) from the position of the ultraviolet/optical emission and is consistent with lying at the redshift of ZF 20115. The star-forming component, with an obscured star formation rate of ${100}_{-70}^{+15}\,{M}_{\odot }\,{\mathrm{yr}}^{-1}$, is undetected in the rest-frame ultraviolet but contributes significantly to the lower angular resolution photometry at rest-frame wavelengths gsim3500 Å. This contribution from the obscured starburst, especially in the Spitzer/IRAC wavebands, significantly complicates the determination of a reliable stellar mass for the ZF 20015 system, and we conclude that this source does not pose a challenge to current models of galaxy formation. The multi-wavelength observations of ZF 20115 unveil a complex system with an intricate and spatially varying star formation history. ZF 20115 demonstrates that understanding high-redshift obscured starbursts will only be possible with multi-wavelength studies that include high-resolution observations, available with the James Webb Space Telescope, at mid-infrared wavelengths.
KW - galaxies: high-redshift, galaxies: starburst
U2 - 10.3847/2041-8213/aa7cf2
DO - 10.3847/2041-8213/aa7cf2
M3 - Article
SN - 2041-8205
VL - 844
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L10
ER -