WFC3 GRISM Confirmation of the Distant Cluster Cl J1449+0856 at langzrang = 2.00: Quiescent and Star-forming Galaxy Populations. Gobat, R., Strazzullo, V., Daddi, E., Onodera, M., Carollo, M., Renzini, A., Finoguenov, A., Cimatti, A., Scarlata, C., & Arimoto, N. The Astrophysical Journal, 776:9, October, 2013.
WFC3 GRISM Confirmation of the Distant Cluster Cl J1449+0856 at langzrang = 2.00: Quiescent and Star-forming Galaxy Populations [link]Paper  doi  abstract   bibtex   
We present deep Hubble Space Telescope Wide Field Camera 3 (HST/WFC3) slitless spectroscopic observations of the distant cluster Cl J1449+0856. These cover a single pointing with 18 orbits of G141 spectroscopy and F140W imaging, allowing us to derive secure redshifts down to M 140 \textasciitilde 25.5 AB and 3σ line fluxes of \textasciitilde5 × 10-18 erg s-1 cm-2. In particular, we were able to spectroscopically confirm 12 early-type galaxies (ETGs) in the field up to z \textasciitilde 3, 6 of which are in the cluster core, which represents the first direct spectroscopic confirmation of quiescent galaxies in a z = 2 cluster environment. With 140 redshifts in a \textasciitilde6 arcmin2 field, we can trace the spatial and redshift galaxy distribution in the cluster core and background field. We find two strong peaks at z = 2.00 and z = 2.07, where only one was seen in our previously published ground-based data. Due to the spectroscopic confirmation of the cluster ETGs, we can now reevaluate the redshift of Cl J1449+0856 at z = 2.00, rather than z = 2.07, with the background overdensity being revealed to be sparse and "sheet"-like. This presents an interesting case of chance alignment of two close yet unrelated structures, each one preferentially selected by different observing strategies. With 6 quiescent or early-type spectroscopic members and 20 star-forming ones, Cl J1449+0856 is now reliably confirmed to be at z = 2.00. The identified members can now allow for a detailed study of galaxy properties in the densest environment at z = 2.
@article{gobat_wfc3_2013,
	title = {{WFC3} {GRISM} {Confirmation} of the {Distant} {Cluster} {Cl} {J1449}+0856 at langzrang = 2.00: {Quiescent} and {Star}-forming {Galaxy} {Populations}},
	volume = {776},
	issn = {0004-637X},
	shorttitle = {{WFC3} {GRISM} {Confirmation} of the {Distant} {Cluster} {Cl} {J1449}+0856 at langzrang = 2.00},
	url = {http://adsabs.harvard.edu/abs/2013ApJ...776....9G},
	doi = {10.1088/0004-637X/776/1/9},
	abstract = {We present deep Hubble Space Telescope Wide Field Camera 3 (HST/WFC3) 
slitless spectroscopic observations of the distant cluster Cl
J1449+0856. These cover a single pointing with 18 orbits of G141
spectroscopy and F140W imaging, allowing us to derive secure redshifts
down to M 140 {\textasciitilde} 25.5 AB and 3σ line fluxes of {\textasciitilde}5
× 10-18 erg s-1
cm-2. In particular, we were able to spectroscopically
confirm 12 early-type galaxies (ETGs) in the field up to z {\textasciitilde} 3, 6 of
which are in the cluster core, which represents the first direct
spectroscopic confirmation of quiescent galaxies in a z = 2 cluster
environment. With 140 redshifts in a {\textasciitilde}6 arcmin2 field, we can
trace the spatial and redshift galaxy distribution in the cluster core
and background field. We find two strong peaks at z = 2.00 and z = 2.07,
where only one was seen in our previously published ground-based data.
Due to the spectroscopic confirmation of the cluster ETGs, we can now
reevaluate the redshift of Cl J1449+0856 at z = 2.00, rather than z =
2.07, with the background overdensity being revealed to be sparse and
"sheet"-like. This presents an interesting case of chance alignment of
two close yet unrelated structures, each one preferentially selected by
different observing strategies. With 6 quiescent or early-type
spectroscopic members and 20 star-forming ones, Cl J1449+0856 is now
reliably confirmed to be at z = 2.00. The identified members can now
allow for a detailed study of galaxy properties in the densest
environment at z = 2.},
	journal = {The Astrophysical Journal},
	author = {Gobat, R. and Strazzullo, V. and Daddi, E. and Onodera, M. and Carollo, M. and Renzini, A. and Finoguenov, A. and Cimatti, A. and Scarlata, C. and Arimoto, N.},
	month = oct,
	year = {2013},
	keywords = {galaxies: clusters: individual: Cl J1449+0856, galaxies: high-redshift},
	pages = {9},
}

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