J/ApJ/805/143 MC2: redshift analysis of CIZA J2242.8+5301 (Dawson+, 2015)
MC2: galaxy imaging and redshift analysis of the merging cluster
CIZA J2242.8+5301.
Dawson W.A., Jee M.J., Stroe A., Ng Y.K., Golovich N., Wittman D.,
Sobral D., Bruggen M., Rottgering H.J.A., van Weeren R.J.
<Astrophys. J., 805, 143 (2015)>
=2015ApJ...805..143D 2015ApJ...805..143D (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Redshifts ; Spectroscopy ; Photometry, SDSS
Keywords: galaxies: clusters: individual: CISA;
galaxies: distances and redshifts
Abstract:
X-ray and radio observations of CIZA J2242.8+5301 suggest that it is a
major cluster merger. Despite being well studied in the X-ray and
radio, little has been presented on the cluster structure and dynamics
inferred from its galaxy population. We carried out a deep (i<25)
broadband imaging survey of the system with Subaru SuprimeCam (g and i
bands) and the Canada-France-Hawaii Telescope (r band), as well as a
comprehensive spectroscopic survey of the cluster area (505 redshifts)
using Keck DEep Imaging Multi-Object Spectrograph. We use these data
to perform a comprehensive galaxy/redshift analysis of the system,
which is the first step to a proper understanding of the geometry and
dynamics of the merger, as well as using the merger to constrain
self-interacting dark matter. We find that the system is dominated by
two subclusters of comparable richness with a projected separation of
6.9'-0.5+0.7 (1.3-0.10+0.13Mpc). We find that the north and
south subclusters have similar redshifts of z∼0.188 with a relative
line-of-sight (LOS) velocity difference of 69±190km/s. We also find
that north and south subclusters have velocity dispersions of
1160-90+100 and 1080-70+100km/s, respectively. These
correspond to masses of 16.1-3.3+4.6x1014 and
13.0-2.5+4.0x1014M☉, respectively. While velocity
dispersion measurements of merging clusters can be biased, we believe
the bias in this system to be minor due to the large projected
separation and nearly plane-of-sky merger configuration. We also find
that the cDs of the north and south subclusters are very near their
subcluster centers, in both projection (55 and 85kpc, respectively)
and normalized LOS velocity (|Δv|/σv=0.43±0.13 and
0.21±0.12 for the north and south, respectively). CIZA J2242.8+5301
is a relatively clean dissociative cluster merger with near 1:1 mass
ratio, which makes it an ideal merger for studying merger-associated
physical phenomena.
Description:
We first observed CIZA J2242.8+5301 in the optical using the Wide
Field Camera (WFC) on the 2.5m Issac Newton Telescope (INT) at the
Roque de Los Muchachos Observatory on La Palma. We carried out the
observations over two nights (2009 October 06-07), observing the
system in the B, V, R, and I filters with total exposure times of
12000, 9000, 9000, and 9000s, respectively.
CIZA J2242.8+5301 was observed with CFHT MegaCam during queue
scheduling during 2013 July 3-12 in r (P.I. A. Stroe). We also
observed CIZA J2242.8+5301 with Subaru SuprimeCam on 2013 July 13 in g
and i (P.I. D. Wittman). See section 2 for further details.
We conducted a spectroscopic survey of CIZA J2242.8+5301 with the
DEIMOS instrument on the Keck II 10m telescope over two observing runs
on 2013 July 14 and 2013 September 05 (resolution of 50km/s and
typical wavelength coverage of 5400-8000Å).
We also conducted a separate spectroscopic survey using WHT/AF2.
Specific details regarding the target selection and data reduction
processes are presented in Sobral et al. (2015MNRAS.450..630S 2015MNRAS.450..630S).
Objects:
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RA (ICRS) DE Designation(s)
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22 42 53.0 +53 01 05 CIZA J2242.8+5301 = NAME Sausage cluster
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 58 441 Keck DEIMOS redshift catalog of the
CIZA J2242.8+5301 field
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See also:
J/ApJ/772/131 : Musket Ball Cluster redshift catalog (Dawson, 2013)
J/A+A/555/A110 : Radio images of CIZA J2242.8+5301 (Stroe+, 2013)
J/A+A/540/A123 : Galaxy clusters from SDSS DR8 (Einasto+, 2012)
J/MNRAS/425/477 : Dark matter annihilation in galaxy clusters (Nezri+, 2012)
J/A+A/534/A109 : MCXC Meta-Catalogue X-ray galaxy Clusters (Piffaretti+, 2011)
J/ApJ/662/224 : Second CIZA subsample (Kocevski+, 2007)
http://www.mergingclustercollaboration.org/ : Merging cluster collaboration
(MC2) home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh [22] Hour of Right Ascension (J2000)
4- 5 I2 min RAm [42/43] Minute of Right Ascension (J2000)
7- 12 F6.3 s RAs Second of Right Ascension (J2000)
14 A1 --- DE- [+] Sign of the Declination (J2000)
15- 16 I2 deg DEd [52/53] Degree of Declination (J2000)
18- 19 I2 arcmin DEm Arcminute of Declination (J2000)
21- 26 F6.3 arcsec DEs Arcsecond of Declination (J2000)
28- 36 F9.6 --- z [-0.0007/0.8] Spectroscopic redshift (1)
38- 45 F8.6 --- e_z [0/0.0003] Error in z
47- 52 F6.3 mag imag [15.9/23.6] i band AB magnitude in SDSS system
54- 58 F5.3 mag e_imag [0/0.09]? Error in imag
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Note (1): All spectroscopic galaxies within the range 0.176≤z≤0.2 are
considered to be cluster members. This range is defined by
zcluster±3xσ, where zcluster=0.188 and σ is the
approximate velocity dispersion of each subcluster (1000km/s;
see Section 6.2). See section 4.1 for the spectroscopic redshift
selection explanation.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Emmanuelle Perret [CDS] 16-Sep-2015