J/A+A/592/A108 RXJ1257.2+4738 morphological properties (Pintos-Castro+, 2016)
Multi-wavelength landscape of the young galaxy cluster RXJ1257.2+4738 at
z=0.866. II. Morphological properties.
Pintos-Castro I., Povic M., Sanchez-Portal M., Cepa J., Altieri B.,
Bongiovanni A., Duc P.A., Ederoclite A., Oteo I., Perez Garcia A.M.,
Perez Martinez R., Polednikova J., Ramon-Perez M., Temporin S.
<Astron. Astrophys. 592, A108 (2016)>
=2016A&A...592A.108P 2016A&A...592A.108P (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Morphology
Keywords: galaxies: clusters: individual: RXJ1257.2+4738 - galaxies: evolution
Abstract:
Studying the evolution of the morphological distribution of galaxies
in different environments can provide important information about the
effects of the environment and the physical mechanisms responsible for
the morphological transformations. As part of a complete analysis of
the young cluster RXJ 1257+4738 at z∼0.9, in this work we study the
morphological properties of its galaxies. We used non-parametric
methods of morphological classification, as implemented in the galSVM
code. The classification with the applied method was possible even
using ground-based observations, as the r'-band imaging from
OSIRIS/GTC. We defined very conservative probability limits, taking
into account the probability errors, to obtain a trustworthy
classification. In this way we were able to classify ∼30% of all
cluster members and to separate between late-type (LT) and early-type
(ET) galaxies. Additionally, when analysing the colour-magnitude
diagram, we observed a significant population of blue ET galaxies
among the classified ones. We discussed possible explanations for
finding this population. Moreover, we studied different physical
properties of LT, ET, and blue ET galaxies. They turn out to be
comparable, with the exception of the stellar mass that shows that the
red ET population is more massive. We also analysed the
morphology-density and morphology-radius relations observing that,
only when considering the morphological separation between ET and LT
galaxies, a mild classical behaviour is obtained. RXJ 1257+4738 is a
young galaxy cluster, showing a clumpy structure, which is still in
the process of formation, and which could explain the lack of some of
the standard morphological relations. This makes this cluster a very
attractive case for obtaining higher resolution data and for studying
the morphological properties of the entire cluster in more detail and
their relation to the environment.
Description:
Properties of the morphologically classified cluster galaxies of
RXJ1257.2+4738. From the cluster sample of more than 300 galaxies we
classify ∼30% (90 sources) between ET, LT, and, based on their colour,
blue ET. We used non-parametric methods of morphological
classification as implemented in the galSVM code. The classification
was possible even using ground-based observations: the r'-band imaging
from OSIRIS/GTC.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
morpho.dat 108 90 Cluster positions, photometry, emission,
morphological parameters and morphology
classification
--------------------------------------------------------------------------------
Byte-by-byte Description of file: morpho.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- ID Cluster galaxy designation (NNNN or g-NNNNN)
9- 19 F11.7 deg RAdeg Right ascension (J2000.0)
21- 30 F10.7 deg DEdeg Declination (J2000.0)
32- 36 F5.2 mag rmag r' mag from the OSIRIS/GTC instrument
38- 41 F4.2 mag e_rmag Error of the r' mag
43- 51 A9 --- Em Type of detected emission ([OII],FIR)
53- 58 F6.3 --- ASYM Asymmetry (1)
60- 65 F6.4 --- CAbr Concentration index of Abraham (2)
67- 72 F6.4 --- Gini Gini coefficient (3)
74- 79 F6.3 --- Smooth Smoothness (4)
81- 86 F6.3 --- M20 Moment of light (5)
88- 92 F5.3 --- CCon Concentration index of Bershay-Conselice (6)
94- 98 F5.3 --- Probavg Probability of being ET from galSVM
100-104 F5.3 --- e_Probavg Error of the probability
106-108 A3 --- Morpho Classification as ET, LT or blue ET (bET)
--------------------------------------------------------------------------------
Note (1): Asymmetry from Abraham et al. (1996ApJS...107..1A) and
Conselice et al. (2000ApJ...529..886C 2000ApJ...529..886C).
Note (2): Concentration index of Abraham et al. (1996ApJS...107..1A)
Note (3): Gini coefficient from Abraham et al. (2003ApJ...588..218A 2003ApJ...588..218A) and
Lotz et al. (2004AJ...128..163L)
Note (4): Smoothness from Conselice et al. (2003AJ...126..1183C 2003AJ...126..1183C)
Note (5): Moment of light from Lotz et al. (2004AJ...128..163L)
Note (6): Concentration index of Bershady et al. (2000AJ...119..2645B 2000AJ...119..2645B)
--------------------------------------------------------------------------------
Acknowledgements:
Irene Pintos-Castro, ipintos(at)cab.inta-csic.es
(End) I. Pintos-Castro [CAB/INTA-CSIC, Spain], P. Vannier [CDS] 31-May-2016