J/MNRAS/469/3946 Abell 370 MUSE redshifts (Lagattuta+, 2017)
Lens modelling Abell 370: crowning the final frontier field with MUSE.
Lagattuta D.J., Richard J., Clement B., Mahler G., Patricio V., Pello R.,
Soucail G., Schmidt K.B., Wisotzki L., Martinez J., Bina D.
<Mon. Not. R. Astron. Soc., 469, 3946-3964 (2017)>
=2017MNRAS.469.3946L 2017MNRAS.469.3946L (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Gravitational lensing ; Redshifts ;
Photometry, HST
Keywords: gravitational lensing: strong - techniques: imaging spectroscopy -
galaxies: clusters: individual: Abell 370 - galaxies: high-redshift -
dark matter
Abstract:
We present a strong lensing analysis on the massive cluster Abell 370
(A370; z=0.375), using a combination of deep multiband Hubble Space
Telescope (HST) imaging and Multi-Unit Spectroscopic Explorer (MUSE)
spectroscopy. From only 2 h of the MUSE data, we are able to measure
120 redshifts in the southern BCG area, including several multiply
imaged lens systems. In total, we increase the number of multiply
imaged systems with a secure redshift from 4 to 15, nine of which are
newly discovered. Of these, eight are located at z>3, greatly
extending the redshift range of spectroscopically confirmed systems
over previous work. Using these systems as constraints, we update a
parametric lens model of A370, probing the mass distribution from
cluster to galaxy scales. Overall, we find that a model with only two
cluster-scale dark matter haloes (one for each BCG) does a poor job of
fitting these new image constraints. Instead, two additional mass
clumps - a central 'bar' of mass located between the BCGs, and another
clump located within a 'crown' of galaxies in the northern part of the
cluster field - provide significant improvements to the fit.
Additional physical evidence suggests these clumps are indeed real
features of the system, but with relatively few image constraints in
the crown region, this claim is difficult to evaluate from a modelling
perspective. Additional MUSE observations of A370 covering the entire
strong-lensing region will greatly help these efforts, further
improving our understanding of this intriguing cluster.
Description:
HST imaging data of A370 were taken as part of the HFF Programme, and
are publicly available on the HFF website
(http://www.stsci.edu/hst/campaigns/frontier-fields/). While the
imaging campaign for A370 is now complete, the Epoch 1 (v1.0) mosaics
that we use in this work consist of deep Advanced Camera for Surveys
(ACS) data in three optical bands, F435W, F606W and F814W (ID: 13504,
PI: J. Lotz). These are supplemented by shallower F814W imaging from
archival programmes: (ID: 11507, PI: K. Noll) and (ID: 11591, PI:
J.-P. Kneib). Additionally, shallow, archival, Wide-Field Camera 3
(Kimble et al. 2008) data are available in three bands: F105W (ID:
13459, PI: T. Treu), F140W (ID: 11108, PI: E. Hu; ID: 13459, PI: T.
Treu) and F160W (ID: 11591, PI: J.-P. Kneib; ID: 14216, PI: R.
Kirshner), and a shallow, pilot HF exposure, also in the F140W band.
MUSE observations of A370 were taken on UT 2014 November 20, as part
of the Guaranteed Time Observing (GTO) Programme 094.A-0115(A) (PI:
Richard). In total, we observed four 30-min exposures in WFM-NOAO-N
mode, centred at (RA=02:39:53.111, DE=-01:3:55.77).
We present a MUSE-based redshift catalogue for A370, consisting of 120
secure redshifts (z<0.1%), including 34 multiply imaged background
objects (comprising 15 unique systems), 13 singly imaged background
galaxies, 56 cluster members, 13 foreground galaxies and 4 stars.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 47 75 Multiply imaged systems
table2.dat 60 56 Cluster members
table3.dat 41 30 Other foreground and background objects
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See also:
J/A+A/407/791 : ACO 370, 2218 and 2390 fluxes at 7 and 15um (Metcalfe+, 2003)
J/ApJS/202/2 : VLA 1.4GHz observations of A370 and A2390 (Wold+, 2012)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- n_ID [*] Note on ID (1)
2- 5 F4.1 --- ID Image identification number, NN.N,
will be [LRC2017] A370 NN.N in Simbad
6 A1 --- f_ID [i] Flag on ID (1)
9- 17 F9.6 deg RAdeg Right ascension (J2000)
19- 28 F10.7 deg DEdeg Declination (J2000)
30- 35 F6.4 --- z ? Redshift
36 A1 --- n_z Note on z (1)
38- 47 A10 --- zrange Redshift range for redshift fit
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Note (1): Notes as follows:
* = Image falls outside of the MUSE cube and do not have secure redshifts. We
identify them in the HFF data, using the A370 mass model as a guide.
i = Image is predicted by the model, but no suitable counterimage is seen in
the HST data. We do not include these images as model constraints, but
we present them here for completeness. Image 16.2, which is in the MUSE
field of view but predicted to fall behind a bright cluster galaxy, is
also included here, since it is undetected in MUSE.
] = Redshift fit by the model as free parameters. The fit range is given in
the 'zrange' column.
d = Redshifts for these systems are taken from Diego et al.
(2018MNRAS.473.4279D 2018MNRAS.473.4279D)
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- ID Cluster member identification, ClNN,
will be [LRC2017] A370 ClNN in Simbad
6- 14 F9.6 deg RAdeg Right ascension (J2000)
16- 25 F10.7 deg DEdeg Declination (J2000)
27- 32 F6.4 --- z Redshift
34- 38 F5.2 mag F435Wmag HST F435W magnitude
40- 44 F5.2 mag F606Wmag HST F606W magnitude
46- 50 F5.2 mag F814Wmag HST F814W magnitude
52- 60 A9 --- Type List mission/absorption lines refer to the
most prominent features seen in the
galaxy's spectrum
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- ID Foreground and background object designation
(FNN or BNN), will be [LRC2017] ANN in Simbad
5- 13 F9.6 deg RAdeg Right ascension (J2000)
15- 24 F10.7 deg DEdeg Declination (J2000)
26- 31 F6.4 --- z Redshift
33- 41 A9 --- Type List mission/absorption lines refer to the
most prominent features seen in the spectrum
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 17-Apr-2020