Abstract
We report the discovery of an X-ray group of galaxies located at a high redshift of z = 1.61 in the Chandra Deep Field South. Based on 4 Ms Chandra data, the group is first identified as an extended X-ray source. We have used a wealth of deep multi-wavelength data to identify the optical counterpart-our red sequence finder detects a significant over-density of galaxies at z ~ 1.6. The brightest group galaxy is spectroscopically confirmed at z = 1.61, based on published spectroscopic redshifts. Using this as a central redshift of the group, we measure an X-ray luminosity of L0.1-2.4keV = (1.8±0.6) × 1043 erg s-1, which then translates into a group mass of (3.2±0.8) × 1013M⊙. This is the lowest-mass group ever confirmed at z > 1.5. Deep optical-nearIR images from CANDELS reveal that the group exhibits a surprisingly prominent red sequence, and most of the galaxies are consistent with a formation redshift of zf =3. A detailed analysis of the spectral energy distributions of the group member candidates confirms that most of them are indeed passive galaxies. Furthermore, their structural parameters measured from near-IR CANDELS images show that they are morphologically early-type. The newly identified group at z = 1.61 is dominated by quiescent early-type galaxies, and the group appears to be similar to those in the local Universe. One possible difference is the high fraction of AGN-38+23 -20% of the bright group member candidates are AGN, which might indicate a role for AGN in the quenching of star formation. However, a statistical sample of high-z groups is needed to draw a general picture of groups at this redshift. Such a sample will hopefully be available in near-future surveys.
| Original language | English (US) |
|---|---|
| Article number | 650017 |
| Journal | Publications of the Astronomical Society of Japan |
| Volume | 65 |
| Issue number | 1 |
| DOIs | |
| State | Published - Feb 25 2013 |
| Externally published | Yes |
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Keywords
- Galaxies: clusters: individual: CL J033211.67-274633.8
- Galaxies: evolution
- Galaxies: formation
- Galaxies: fundamental parameters
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
Cite this
An X-ray detected group of quiescent early-type galaxies at z = 1.6 in the Chandra Deep Field South. / Tanaka, Masayuki; Finoguenov, Alexis; Mirkazemi, Mohammad; Wilman, David J.; Mulchaey, John S.; Ueda, Yoshihiro; Xue, Yongquan; Brandt, William N.; Cappelluti, Nico.
In: Publications of the Astronomical Society of Japan, Vol. 65, No. 1, 650017, 25.02.2013.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - An X-ray detected group of quiescent early-type galaxies at z = 1.6 in the Chandra Deep Field South
AU - Tanaka, Masayuki
AU - Finoguenov, Alexis
AU - Mirkazemi, Mohammad
AU - Wilman, David J.
AU - Mulchaey, John S.
AU - Ueda, Yoshihiro
AU - Xue, Yongquan
AU - Brandt, William N.
AU - Cappelluti, Nico
PY - 2013/2/25
Y1 - 2013/2/25
N2 - We report the discovery of an X-ray group of galaxies located at a high redshift of z = 1.61 in the Chandra Deep Field South. Based on 4 Ms Chandra data, the group is first identified as an extended X-ray source. We have used a wealth of deep multi-wavelength data to identify the optical counterpart-our red sequence finder detects a significant over-density of galaxies at z ~ 1.6. The brightest group galaxy is spectroscopically confirmed at z = 1.61, based on published spectroscopic redshifts. Using this as a central redshift of the group, we measure an X-ray luminosity of L0.1-2.4keV = (1.8±0.6) × 1043 erg s-1, which then translates into a group mass of (3.2±0.8) × 1013M⊙. This is the lowest-mass group ever confirmed at z > 1.5. Deep optical-nearIR images from CANDELS reveal that the group exhibits a surprisingly prominent red sequence, and most of the galaxies are consistent with a formation redshift of zf =3. A detailed analysis of the spectral energy distributions of the group member candidates confirms that most of them are indeed passive galaxies. Furthermore, their structural parameters measured from near-IR CANDELS images show that they are morphologically early-type. The newly identified group at z = 1.61 is dominated by quiescent early-type galaxies, and the group appears to be similar to those in the local Universe. One possible difference is the high fraction of AGN-38+23 -20% of the bright group member candidates are AGN, which might indicate a role for AGN in the quenching of star formation. However, a statistical sample of high-z groups is needed to draw a general picture of groups at this redshift. Such a sample will hopefully be available in near-future surveys.
AB - We report the discovery of an X-ray group of galaxies located at a high redshift of z = 1.61 in the Chandra Deep Field South. Based on 4 Ms Chandra data, the group is first identified as an extended X-ray source. We have used a wealth of deep multi-wavelength data to identify the optical counterpart-our red sequence finder detects a significant over-density of galaxies at z ~ 1.6. The brightest group galaxy is spectroscopically confirmed at z = 1.61, based on published spectroscopic redshifts. Using this as a central redshift of the group, we measure an X-ray luminosity of L0.1-2.4keV = (1.8±0.6) × 1043 erg s-1, which then translates into a group mass of (3.2±0.8) × 1013M⊙. This is the lowest-mass group ever confirmed at z > 1.5. Deep optical-nearIR images from CANDELS reveal that the group exhibits a surprisingly prominent red sequence, and most of the galaxies are consistent with a formation redshift of zf =3. A detailed analysis of the spectral energy distributions of the group member candidates confirms that most of them are indeed passive galaxies. Furthermore, their structural parameters measured from near-IR CANDELS images show that they are morphologically early-type. The newly identified group at z = 1.61 is dominated by quiescent early-type galaxies, and the group appears to be similar to those in the local Universe. One possible difference is the high fraction of AGN-38+23 -20% of the bright group member candidates are AGN, which might indicate a role for AGN in the quenching of star formation. However, a statistical sample of high-z groups is needed to draw a general picture of groups at this redshift. Such a sample will hopefully be available in near-future surveys.
KW - Galaxies: clusters: individual: CL J033211.67-274633.8
KW - Galaxies: evolution
KW - Galaxies: formation
KW - Galaxies: fundamental parameters
UR - http://www.scopus.com/inward/record.url?scp=84874734064&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84874734064&partnerID=8YFLogxK
U2 - 10.1093/pasj/65.1.17
DO - 10.1093/pasj/65.1.17
M3 - Article
VL - 65
JO - Publication of the Astronomical Society of Japan
JF - Publication of the Astronomical Society of Japan
SN - 0004-6264
IS - 1
M1 - 650017
ER -