%0 Generic %1 marsan2014spectroscopic %A Marsan, Z. Cemile %A Marchesini, Danilo %A Brammer, Gabriel B. %A Stefanon, Mauro %A Muzzin, Adam %A Fernandez-Soto, Alberto %A Hainline, Kevin N. %A Labbe, Ivo %A Toft, Sune %A van Dokkum, Pieter G. %D 2014 %K compact early early-type high-z massive %T 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 %U http://arxiv.org/abs/1406.0002 %X 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 $M_*=3.1^+0.6_-0.7\times10^11 M_ødot$, a star-formation rate of <7 $M_ødot yr^-1$, 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 ~$10^46erg s^-1$. Potential contamination to the observed SED from the AGN continuum is constrained, placing a lower limit on the stellar mass of $2\times10^11 M_ødot$. 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.

@misc{marsan2014spectroscopic, abstract = {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.}, added-at = {2014-06-03T09:47:34.000+0200}, author = {Marsan, Z. Cemile and Marchesini, Danilo and Brammer, Gabriel B. and Stefanon, Mauro and Muzzin, Adam and Fernandez-Soto, Alberto and Hainline, Kevin N. and Labbe, Ivo and Toft, Sune and van Dokkum, Pieter G.}, biburl = {https://www.bibsonomy.org/bibtex/29782b2c14471bc682fbb73b2cbd2f903/miki}, description = {[1406.0002] 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}, interhash = {895b60e7ddcb4dcadf7cac194fc7c424}, intrahash = {9782b2c14471bc682fbb73b2cbd2f903}, keywords = {compact early early-type high-z massive}, note = {cite arxiv:1406.0002Comment: 15 pages, 7 figures. Submitted to ApJ. Comments welcome}, timestamp = {2014-06-03T09:47:34.000+0200}, title = {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}, url = {http://arxiv.org/abs/1406.0002}, year = 2014 }