J/MNRAS/450/630 MC2: SFR in CIZA J2242.8+5301 (Sobral+, 2015)
MC2: boosted AGN and star formation activity in CIZA J2242.8+5301,
a massive post-merger cluster at z = 0.19.
Sobral D., Stroe A., Dawson W.A., Wittman D., Jee M.J., Rottgering H.,
Van Weeren R.J., Bruggen M.
<Mon. Not. R. Astron. Soc., 450, 630-645 (2015)>
=2015MNRAS.450..630S 2015MNRAS.450..630S (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ;
Keywords: galaxies: clusters: general -
galaxies: clusters: individual: CIZA J2242.8+5301 -
galaxies: evolution - intergalactic medium - cosmology: observations -
large-scale structure of Universe
Abstract:
Cluster mergers may play a fundamental role in the formation and
evolution of cluster galaxies. Stroe et al. (2015MNRAS.450..646S 2015MNRAS.450..646S)
revealed unexpected overdensities of candidate Hα emitters near
the ∼1-Mpc-wide shock fronts of the massive (∼2x1015M☉)
'Sausage' merging cluster, CIZA J2242.8+5301. We used the Keck/Deep
Imaging Multi-Object Spectrograph and the William Herschel
Telescope/AutoFib2+WYFFOS to confirm 83 Hα emitters in and
around the merging cluster. We find that cluster star-forming galaxies
in the hottest X-ray gas and/or in the cluster subcores (away from the
shock fronts) show high [SII]6716/[SII]6761 and high [SII]
716/Hα, implying very low electron densities (<30xlower than all
other star-forming galaxies outside the cluster) and/or significant
contribution from supernovae, respectively. All cluster star-forming
galaxies near the cluster centre show evidence of significant outflows
(blueshifted Na D ∼ 200-300km/s), likely driven by supernovae. Strong
outflows are also found for the cluster Hα active galactic
nucleus (AGN). Hα star-forming galaxies in the merging cluster
follow the z∼0 mass-metallicity relation, showing systematically
higher metallicity (∼0.15-0.2dex) than Hα emitters outside the
cluster (projected R>2.5Mpc). This suggests that the shock front may
have triggered remaining metal-rich gas which galaxies were able to
retain into forming stars. Our observations show that the merger of
impressively massive (∼1015M☉) clusters can provide the
conditions for significant star formation and AGN activity, but, as we
witness strong feedback by star-forming galaxies and AGN (and given
how massive the merging cluster is), such sources will likely quench
in a few 100Myr.
Description:
We conducted a spectroscopic survey of the Sausage cluster with the
DEIMOS on the Keck II 10-m telescope over two observing runs on 2013
July 14 and 2013 September 5. For full details on the observations and
data reduction, see Dawson et al. (2015, Cat. J/ApJ/805/143).
We followed up 103 candidate line emitters from Stroe et al.
(2015MNRAS.450..646S 2015MNRAS.450..646S) using AF2 on the WHT in La Palma on two nights
during 2014 July 2-3.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 175 83 Hα emitters in our spectroscopic sample
with significant detections of at least two
emission lines
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See also:
J/ApJ/805/143 : MC2: redshift analysis of CIZA J2242.8+5301 (Dawson+, 2015)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- --- [SSSD-]
6- 7 I2 --- SSSD [1/89] SSSD sequential number
9- 10 I2 h RAh Right ascension (J2000)
12- 13 I2 min RAm Right ascension (J2000)
15- 19 F5.2 s RAs Right ascension (J2000)
21 A1 --- DE- Declination sign (J2000)
22- 23 I2 deg DEd Declination (J2000)
25- 26 I2 arcmin DEm Declination (J2000)
28- 32 F5.2 arcsec DEs Declination (J2000)
34- 41 F8.6 --- z Spectroscopic redshift
43- 50 F8.4 mag imag ?=-99.9 i magnitude (AB, in 5" aperture )
52- 59 F8.4 mag e_imag ?=-99.9 rms uncertainty on imag
61- 68 F8.4 [mW/m2] logFHa ?=-99 Hα flux
70- 77 F8.4 km/s FWHMHa ?=- Hα FWHM
79- 87 F9.4 km/s FWHMnl ?=- Median FWHM of narrow-lines
89- 96 F8.4 --- [NII]/Ha ?=-99.9 [NII]5007/Hα abundance ratio
98-103 F6.4 --- e_[NII]/Ha ?=- rms uncertainty on [NII]/Ha
105-112 F8.4 --- [SII]/[SII] ?=-99.9 [SII]6716/[SII]6761 abundance ratio
114-119 F6.4 --- e_[SII]/[SII] ?=- rms uncertainty on [SII]/[SII]
121-128 F8.4 --- [OIII]/Hb ?=-99.9 [OIII]5007/Hβ abundance ratio
130-135 F6.4 --- e_[OIII]/Hb ?=- rms uncertainty on [OIII]/Hb
137-144 F8.4 --- [SII]/Ha ?=-99.9 [SII]/Hα abundance ratio
146-151 F6.4 --- e_[SII]/Ha ?=- rms uncertainty on [SII]/Ha
153-160 F8.4 [Msun] logMass ?=-99 Stellar mass
162-167 F6.4 [Msun] e_logMass ?=- rms uncertainty on Mass
169-172 F4.1 Mpc Cdist ?=- Distance from cluster centre code (1)
174-175 I2 --- AGN [-1/2]?=- AGN flag (2)
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Note (1): Distance from cluster centre code as follows:
1.0 = sub=sample R<1Mpc
1.5 = sub=sample R<1.5Mpc
2.0 = sub=sample R<2.0Mpc
2.5 = sub=sample R<2.5Mpc
10.0 = sources outside the cluster
Note (2): AGN flag as follows:
1 = narrow lines (NLA)
2 = broad lines (BLA)
0 = likely star-forming galaxy (SFG)
-1 = unclassified (UNC)
- = NULL
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 10-Dec-2015