J/A+A/668/A162 CSWA 31 MUSE field spectroscopic redshifts (Wang+, 2022)
Constraining the multi-scale dark-matter distribution in CASSOWARY 31 with
strong gravitational lensing and stellar dynamics.
Wang H., Canameras R., Caminha G.B., Suyu S.H., Yildirim A., Chirivi G., L.
Christensen L., Grillo C., Schuldt S.
<Astron. Astrophys. 668, A162 (2022)>
=2022A&A...668A.162W 2022A&A...668A.162W (SIMBAD/NED BibCode)
ADC_Keywords: Gravitational lensing ; Redshifts ; Optical
Keywords: gravitational lensing: strong -
galaxies: elliptical and lenticular, cD - galaxies: groups: general -
galaxies: kinematics and dynamics - galaxies: structure
Abstract:
We study the inner structure of the group-scale lens CASSOWARY 31
(CSWA 31) by adopting both strong lensing and dynamical modeling. CSWA
31 is a peculiar lens system. The brightest group galaxy (BGG) is an
ultra-massive elliptical galaxy at z=0.683 with a weighted mean
velocity dispersion of sigma=432±31km/s. It is surrounded
by group members and several lensed arcs probing up to ≃150kpc in
projection. Our results significantly improve previous analyses of
CSWA 31 thanks to the new HST imaging and MUSE integral-field
spectroscopy. From the secure identification of five sets of multiple
images and measurements of the spatially-resolved stellar kinematics
of the BGG, we conduct a detailed analysis of the multi-scale mass
distribution using various modeling approaches, both in the single and
multiple lens-plane scenarios. Our best-fit mass models reproduce the
positions of multiple images and provide robust reconstructions for
two background galaxies at z=1.4869 and z=2.763. Despite small
variations related to the different sets of input constraints, the
relative contributions from the BGG and group-scale halo are
remarkably consistent in our three reference models, demonstrating the
self- consistency between strong lensing analyses based on image
position and extended image modeling. We find that the ultra-massive
BGG dominates the projected total mass profiles within 20kpc, while
the group-scale halo dominates at larger radii. The total projected
mass enclosed within Reff=27.2kpc is
1.10+0.02-0.04*1013M☉. We find that CSWA 31 is a peculiar
fossil group, strongly dark-matter dominated towards the central
region, and with a projected total mass profile similar to higher-mass
cluster-scale halos. The total mass-density slope within the effective
radius is shallower than isothermal, consistent with previous analyses
of early-type galaxies in overdense environments.
Description:
This work uses MUSE data from program 0104.A-0830(A) (PI: Canameras)
in order to resolve the stellar velocity dispersion profile of the
primary lens up to 10kpc, and to secure the identification and
redshift measurements of group members and multiple image candidates.
Observations were carried out in December 2019 and January 2020, with
seeing 100, clear sky conditionsThis work uses MUSE data from program
0104.A-0830(A) (PI: Canameras) in order to resolve the stellar
velocity dispersion profile of the primary lens up to 10kpc, and to
secure the identification and redshift measurements of group members
and multiple image candidates. Observations were carried out in
December 2019 and January 2020, with seeing 100, clear sky conditions,
and airmass <1.6, with the MUSE wide-field mode corresponding to 1'x1'
field-of-view and 0.2"/pix spatial sampling. We divided the
observations into five individual OBs, applying a dithering pattern
and 90 rotations between each OB, and obtained a total on-source
exposure time of 5 hours. Complete list of measured spectroscopic
redshift of objects in the MUSE field of view (1'x1').
Objects:
-----------------------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------------------
09 21 25.74 +18 10 17.3 CASSOWARY 31 = CSWA 31
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 55 121 Complete list of measured spectroscopic redshifts
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- ID [354/999906] Source ID
8- 25 F18.14 deg RAdeg [140.34/140.37] Right Ascension (J2000)
27- 44 F18.15 deg DEdeg [18.16/18.18] Declination (J2000)
46- 51 F6.4 --- zspec [0.17/5.84] Measured spectroscopic redshifts
of galaxies
53- 55 F3.1 --- QF [2.0/3.0] Quality flag of measured redshifts (1)
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Note (1): Quality flag as follows:
2.0 = likely
3.0 = secure
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Acknowledgements:
Han Wang, wanghan(at)mpa-garching.mpg.de
(End) Han Wang [MPA, Germany], Patricia Vannier [CDS] 20-Oct-2022