Spectroscopic Confirmation of an Ultra Massive and Compact Galaxy at z=3.35: A Detailed Look at an Early Progenitor of Local Most Massive Ellipticals
| Autor: | Marsan, Z. Cemile, Marchesini, Danilo, Brammer, Gabriel B., Stefanon, Mauro, Muzzin, Adam, Fernandez-Soto, Alberto, Geier, Stefan, Hainline, Kevin N., Intema, Huib, Karim, Alexander, Labbe, Ivo, Toft, Sune, van Dokkum, Pieter G. |
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| Rok vydání: | 2014 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1088/0004-637X/801/2/133 |
| Popis: | We present the first spectroscopic confirmation of an ultra-massive galaxy at redshift z>3 using data from Keck-NIRSPEC, VLT-Xshooter, and GTC-Osiris. We detect strong [OIII] and Ly$\alpha$ emission, and weak [OII], CIV, and HeII, placing C1-23152 at a spectroscopic redshift of $z_{spec}$=3.351. The modeling of the emission-line corrected spectral energy distribution results in a best-fit stellar mass of $M_{*}=3.1^{+0.6}_{-0.7}\times10^{11} M_{\odot}$, a star-formation rate of <7 $M_{\odot} yr^{-1}$, and negligible dust extinction. The stars appear to have formed in a short intense burst ~300-500 Myr prior to the observation epoch, setting the formation redshift of this galaxy at z~4.1. From the analysis of the line ratios and widths, and the observed flux at 24$\mu$m, we confirm the presence of a luminous hidden active galactic nucleus (AGN), with bolometric luminosity of ~$10^{46}erg s^{-1}$. Potential contamination to the observed SED from the AGN continuum is constrained, placing a lower limit on the stellar mass of $2\times10^{11} M_{\odot}$. HST/WFC3 $H_{160}$ and ACS $I_{814}$ images are modeled, resulting in an effective radius of $r_{e}$~1 kpc in the $H_{160}$ band and a Sersic index n~4.4. This object may be a prototype of the progenitors of local most massive elliptical galaxies in the first 2 Gyr of cosmic history, having formed most of its stars at z>4 in a highly dissipative, intense, and short burst of star formation. C1-23152 is completing its transition to a post-starburst phase while hosting a powerful AGN, potentially responsible for the quenching of the star formation activity. Comment: 18 pages, 9 figures. Accepted to the Astrophysical Journal |
| Databáze: | arXiv |
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