J/MNRAS/395/1213 Galaxies in the field of MACS J1206.2-0847 (Ebeling+, 2009)
A spectacular giant arc in the massive cluster lens MACSJ1206.2-0847.
Ebeling H., Ma C.J., Kneib J.-P., Jullo E., Courtney N.J.D., Barrett E.,
Edge A.C., Le Borgne J.-F.
<Mon. Not. R. Astron. Soc., 395, 1213-1224 (2009)>
=2009MNRAS.395.1213E 2009MNRAS.395.1213E
ADC_Keywords: Clusters, galaxy ; Galaxy catalogs ; Redshifts
Keywords: gravitational lensing - galaxies: clusters: general -
galaxies: clusters: individual: MACSJ1206.2-0847 -
X-rays: galaxies: clusters
Abstract:
We discuss the X-ray and optical properties of the massive galaxy
cluster MACSJ1206.2-0847 (z=0.4385), discovered in the Massive Cluster
Survey (MACS). Our Chandra observation of the system yields a total
X-ray luminosity of 2.4x1045erg/s (0.1-2.4keV) and a global gas
temperature of 11.6±0.7keV, very high values typical of MACS
clusters. In both optical and X-ray images, MACSJ1206.2-0847 appears
close to relaxed in projection, with a pronounced X-ray peak at the
location of the brightest cluster galaxy (BCG); we interpret this
feature as the remnant of a cold core. A spectacular giant
gravitational arc, 15-arcsec in length, bright (V∼21) and unusually
red (R-K=4.3), is seen 20-arcsec west of the BCG; we measure a
redshift of z=1.036 for the lensed galaxy. From our Hubble Space
Telescope image of the cluster, we identify the giant arc and its
counter image as a sevenfold imaged system. An excess of X-ray
emission in the direction of the arc coincides with a mild galaxy
overdensity and could be the remnant of a minor merger with a group of
galaxies. We derive estimates of the total cluster mass as well as of
the mass of the cluster core using X-ray, dynamical and
gravitational-lensing techniques. For the mass enclosed by the giant
arc (r<119kpc), our strong-lensing analysis based on Hubble Space
Telescope imaging yields a very high value of 1.1x1014M☉,
inconsistent with the much lower X-ray estimate of 0.5x1014M☉.
Similarly, the virial estimate of 4x1015M☉ for the total
cluster mass, derived from multi-object spectroscopy with
Canada-France-Hawaii Telescope (CFHT) and the VLT of 38 cluster
members, is significantly higher than the corresponding X-ray estimate
of 1.7x1015M☉. We take the discrepancy between X-ray and other
mass estimates to be indicative of pronounced substructure along the
line of sight during an ongoing merger event, an interpretation that
is supported by the system's very high velocity dispersion of
1580km/s.
Description:
Spectroscopic observations of presumed cluster galaxies as well as of
the giant arc in MACS J1206.2-0847 were performed with the FORS1
spectrograph in multi-object spectroscopy mode at the UT3 Melipal
telescope of the VLT on 2002 April 11.
Additional multi-object spectroscopy of colour-selected galaxies in
the field of MACS J1206.2-0847 was performed on 2003 May 8, using the
multi-object (MOS) spectrograph on the Canada-France-Hawaii
Telescope (CFHT) on Mauna Kea.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 49 62 Positions, cross-correlation peak heights and
spectroscopic redshifts (heliocentric) of galaxies
in the field of MACS J1206.2-0847
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 h RAh Right ascension (J2000)
4- 5 I2 min RAm Right ascension (J2000)
7- 11 F5.2 s RAs Right ascension (J2000)
13 A1 --- DE- Declination sign (J2000)
14- 15 I2 deg DEd Declination (J2000)
17- 18 I2 arcmin DEm Declination (J2000)
20- 23 F4.1 arcsec DEs Declination (J2000)
25- 28 F4.2 --- hpeak [0.34/0.96] Cross-correlation peak height
30- 36 F7.5 --- z [0.34/0.69] Spectroscopic heliocentric redshift
38- 44 F7.5 --- e_z [0.00002/0.001] rms uncertainty on z
46- 49 A4 --- Tel Origin of each measurement:
"FORS1" on the VLT or "MOS" on CFHT
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 08-Jul-2015