J/A+A/679/A147 RXC J1111.6+4050 galaxy cluster (Barrena+, 2023)
RXCJ1111.6+4050 galaxy cluster:
Observational evidence of a transitional fossil group.
Barrena R., Chon G., Bohringer H., Mendez-Abreu J., Ferragamo A.
<Astron. Astrophys., 679, A147 (2023)>
=2023A&A...679A.147B 2023A&A...679A.147B (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; X-ray sources
Keywords: galaxies: clusters: individual: RXCJ1111.6+4050 -
X-rays: galaxies: clusters
Abstract:
We present a detailed kinematical and dynamical study of the galaxy
cluster RXCJ1111.6+4050 (RXCJ1111), at z=0.0756 using 104 new
spectroscopic redshifts of galaxies observed at the Telescopio
Nazionale Galileo and SDSS DR16 public archive. Our analysis is
performed in a multiwavelength context in order to study and compare
mainly optical and X-ray properties using XMM-Newton data. We find
that RXCJ1111 is a galaxy cluster showing a velocity distribution with
clear deviations from Gaussianity, that we are able to explain by the
presence of a substructure within the cluster. The two cluster
components show velocity dispersions of 644±56 km/s and
410±123km/s, which yield dynamical masses of
M200=1.9±0.4x1014M☉ and 0.6±0.4x1014M☉ for
the main system and substructure, respectively. The 2D spatial
distribution of galaxies and X-ray surface brightness of RXCJ1111
presents an elongation in the North-South direction. These
observational facts, together with a gradient of 250-350km/s/Mpc in
the velocity field, following the NNE-SSE direction, suggest that the
merger axis between the main system and substructure is slightly
tilted with respect to the line-of-sight. The substructure is
characterized by a magnitude gap {DELTA}m12≥1.8, so it fits the
"fossil-like" definition of a galaxy group. From the X-ray
observations, we estimate a M500,X=1.68±0.25x1014M☉,
which is in good agreement with the dynamical masses when two galaxy
components are considered separately. This suggests that the mass
estimates obtained from X-ray and velocity dispersion are compatible
even for non-relaxed clusters, at least when we are able to identify
and separate galaxy clumps and derive masses by considering the
virialized regions. We propose a 3D merging model and find that the
fossil group is in an early phase of collision with the RXCJ1111 main
cluster and placed at ∼8° (±3°) from line-of-sight. This
merging model would explain the slight increase found in the TX with
respect to what we would expect for relaxed clusters. Due to the
presence of several brightest galaxies, after this collision, the
substructure would presumably lose its fossil condition. Therefore,
RXCJ1111 represents the observational evidence that the fossil stage
of a system can be temporary and transitional.
Description:
One of the most used techniques to obtain a large number of galaxy
redshifts in a limited field is multi-object spectroscopic (MOS)
observations. In June 2020, we carried out MOS observations of
RXCJ1111 covering a region of about 17'x17'.
We also work with the SDSS DR16 photometric data in order to
complement our spectroscopic MOS TNG observations.
The XMM-Newton observations, with ID 0827031101, of the RXCJ1111
galaxy cluster, were obtained from the XMM-Newton data archive.
Objects:
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RA (2000) DE Designation(s)
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11 11 43.83 +40 51 43.5 RXC J1111.6+4050 = ACO 1190
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 56 152 *Velocity catalogue in the RXJ1111 field
considered in this work
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Note on tablea1.dat: which includes 109 new spectra observed in the 3.5m TNG
telescope and 43 complementary redshift obtained from SDSS DR-16 database.
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [1/152] Identificatiom mumber
4 A1 --- n_ID [*] * for the galaxies selected as cluster
members
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 16 F5.2 s RAs Right ascension (J2000)
18 A1 --- DE- Declination sign (J2000)
19- 20 I2 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 28 F4.1 arcsec DEs Declination (J2000)
30- 35 I6 km/s cz Heliocentric radial velocity
37- 39 I3 km/s e_cz Heliocentric radial velocity error
41- 45 F5.2 mag g'mag SDSS DR16 g' deredenned magnitude
47- 51 F5.2 mag r'mag SDSS DR16 r' deredenned magnitude
53- 56 A4 --- Notes Notes
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 05-Mar-2024