%0 Generic %1 wang2016discovery %A Wang, Tao %A Elbaz, David %A Daddi, Emanuele %A Finoguenov, Alexis %A Liu, Daizhong %A Schreiber, Corentin %A Martin, Sergio %A Strazzullo, Veronica %A Valentino, Francesco %A van der Burg, Remco %A Zanella, Anita %A Ciesla, Laure %A Gobat, Raphael %A Brun, Amandine Le %A Pannella, Maurillio %A Sargent, Mark %A Tan, Xinwen Shu Qinghua %A Cappelluti, Nico %A Li, Yanxia %D 2016 %K assembly cluster massive %T Discovery of a galaxy cluster with a violently starbursting core at z=2.506 %U http://arxiv.org/abs/1604.07404 %X We report the discovery of a remarkable concentration of massive galaxies with extended X-ray emission at $z_spec = 2.506$ in the COSMOS field. This structure contains in its center 11 massive ($M_* 10^11 M_ødot$) galaxies distributed over 80-kpc, producing an 11.6$\sigma$ overdensity. We have spectroscopically confirmed 16 member galaxies extending to $\sim1$ Mpc from the core with half of them derived from CO with IRAM-NOEMA and JVLA and the other half from $H\alpha$ with VLT-KMOS. The X-ray luminosity, high stellar mass content and velocity dispersion all point to a collapsed, single cluster-sized dark matter halo with total mass $M_200c 10^13.9\pm0.2 M_ødot$, identifying it as the most distant X-ray detected cluster known to date. Unlike other clusters discovered so far, this structure is dominated by star-forming galaxies in the core with only two out of the 11 massive galaxies classified as quiescent. The star formation rate in the 80-kpc core reaches $\sim$3400 $M_ødot$ yr$^-1$ with a gas depletion time of $200$ Myr, suggesting that we caught this structure in rapid formation. The high star formation rate is driven by both a high abundance of massive star-forming galaxies and a higher starburst fraction ($\sim25\%$, compared to 3\%-5\% in the field). The presence of both a collapsed, cluster-sized halo and a predominant population of star-forming galaxies in the core suggests that this structure could represent an important transition phase between protoclusters and mature clusters. It provides evidence that the main phase of massive galaxy passivization will take place after galaxies accrete onto the cluster, providing new insights on massive cluster formation at early epochs. The large integrated stellar mass at such high redshift challenges our understanding of massive cluster formation.

@misc{wang2016discovery, abstract = {We report the discovery of a remarkable concentration of massive galaxies with extended X-ray emission at $z_{spec} = 2.506$ in the COSMOS field. This structure contains in its center 11 massive ($M_{*} \gtrsim 10^{11} M_{\odot}$) galaxies distributed over 80-kpc, producing an 11.6$\sigma$ overdensity. We have spectroscopically confirmed 16 member galaxies extending to $\sim1$ Mpc from the core with half of them derived from CO with IRAM-NOEMA and JVLA and the other half from $H\alpha$ with VLT-KMOS. The X-ray luminosity, high stellar mass content and velocity dispersion all point to a collapsed, single cluster-sized dark matter halo with total mass $M_{200c} \sim 10^{13.9\pm0.2} M_{\odot}$, identifying it as the most distant X-ray detected cluster known to date. Unlike other clusters discovered so far, this structure is dominated by star-forming galaxies in the core with only two out of the 11 massive galaxies classified as quiescent. The star formation rate in the 80-kpc core reaches $\sim$3400 $M_{\odot}$ yr$^{-1}$ with a gas depletion time of $\sim 200$ Myr, suggesting that we caught this structure in rapid formation. The high star formation rate is driven by both a high abundance of massive star-forming galaxies and a higher starburst fraction ($\sim25\%$, compared to 3\%-5\% in the field). The presence of both a collapsed, cluster-sized halo and a predominant population of star-forming galaxies in the core suggests that this structure could represent an important transition phase between protoclusters and mature clusters. It provides evidence that the main phase of massive galaxy passivization will take place after galaxies accrete onto the cluster, providing new insights on massive cluster formation at early epochs. The large integrated stellar mass at such high redshift challenges our understanding of massive cluster formation.}, added-at = {2016-04-27T09:52:48.000+0200}, author = {Wang, Tao and Elbaz, David and Daddi, Emanuele and Finoguenov, Alexis and Liu, Daizhong and Schreiber, Corentin and Martin, Sergio and Strazzullo, Veronica and Valentino, Francesco and van der Burg, Remco and Zanella, Anita and Ciesla, Laure and Gobat, Raphael and Brun, Amandine Le and Pannella, Maurillio and Sargent, Mark and Tan, Xinwen Shu Qinghua and Cappelluti, Nico and Li, Yanxia}, biburl = {https://www.bibsonomy.org/bibtex/2355f8e53548625375dd918ff7eeaafdd/miki}, description = {[1604.07404] Discovery of a galaxy cluster with a violently starbursting core at z=2.506}, interhash = {e76fd73e4083dc2ca98ff78ef67e4b5a}, intrahash = {355f8e53548625375dd918ff7eeaafdd}, keywords = {assembly cluster massive}, note = {cite arxiv:1604.07404Comment: submitted}, timestamp = {2016-04-27T09:52:48.000+0200}, title = {Discovery of a galaxy cluster with a violently starbursting core at z=2.506}, url = {http://arxiv.org/abs/1604.07404}, year = 2016 }