J/MNRAS/423/3652 H narrow-band imaging of XMMU J2235.3-2557 (Grutzbauch+, 2012)
Suppression of star formation in the central 200 kpc of a z= 1.4 galaxy cluster.
Grutzbauch R., Bauer A.E., Jorgensen I., Varela J.
<Mon. Not. R. Astron. Soc., 423, 3652-3662 (2012)>
=2012MNRAS.423.3652G 2012MNRAS.423.3652G (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Photometry, infrared ; Photometry, H-alpha
Keywords: galaxies: clusters: individual: XMMU J2235.3-2557 -
galaxies: evolution - galaxies: high-redshift -
galaxies: star formation
Abstract:
We present the results of an extended narrow-band Hα study of
the massive galaxy cluster XMMU J2235.3-2557 at z=1.39. This paper
represents a follow-up study to our previous investigation of star
formation in the cluster centre, extending our analysis out to a
projected cluster radius of 1.5Mpc. Using the Near InfraRed Imager and
Spectrograph on Gemini North Telescope we obtained deep H narrow-band
imaging corresponding to the rest-frame wavelength of Hα at the
cluster's redshift. We identify a total of 163 potential cluster
members in both pointings, excluding stars based on their
near-infrared colours derived from VLT/HAWK-I imaging. Of these 163
objects 14 are spectroscopically confirmed cluster members, and 20 per
cent are excess line emitters. We find no evidence of star formation
activity within a radius of 200 kpc of the brightest cluster galaxy in
the cluster core. Dust-corrected star formation rates (SFRs) of excess
emitters outside this cluster quenching radius, RQ∼200kpc, are on
average =2.7±1.0M☉/yr, but do not show evidence of
increasing SFRs towards the extreme 1.5Mpc radius of the cluster. No
individual cluster galaxy exceeds an SFR of 6M☉/yr. Massive
galaxies (logM*/M☉>10.75) all have low specific SFRs (SSFRs,
i.e. SFR per unit stellar mass). At fixed stellar mass, galaxies in
the cluster centre have lower SSFRs than the rest of the cluster
galaxies, which in turn have lower SSFRs than field galaxies at the
same redshift by a factor of a few to 10. For the first time we can
demonstrate through measurements of individual SFRs that already at
very early epochs (at an age of the Universe of ∼4.5Gyr) the
suppression of star formation is an effect of the cluster environment
which persists at fixed galaxy stellar mass.
Description:
The observations were carried out with the Near InfraRed Imager and
Spectrometer (NIRI) on Gemini North Telescope. This instrument is
equipped with an H narrow-band filter at a wavelength of
λ=1.57um, which corresponds to the central wavelength of the
Hα 6563Å emission line at the cluster redshift of z=1.39.
This enables us to obtain rest-frame Hα imaging and individual
SFRs of the cluster members with a minimum amount of integration time
compared to spectroscopically derived Hα SFRs. The cluster area
was imaged with two different pointings of adjacent fields of ∼2arcmin
on each side.
We obtain a final sample of 163 objects, which are listed in Table 1,
whereas all excluded objects are shown in Table 2. Note that the
comparison of our data with the HAWK-I images revealed a small offset
in the astrometric solution, which we have corrected by matching
bright sources in the two images. This results in slightly different
coordinates listed in Tables 1 and 2 and the coordinates listed for
the same objects in table 1 of Bauer et al. (2011, Cat.
J/MNRAS/411/2009).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 76 163 Properties of detected objects in both
pointings, cluster centre and outskirts.
table2.dat 66 38 Properties of objects excluded from the sample
due to (J-K) colour, K-band magnitude or
CLASS_STAR parameter
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See also:
J/MNRAS/411/2009 : H narrow-band imaging of XMMU J2235.3-2557 (Bauer+, 2011)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [1/200] Identification number
4 A1 --- n_ID [*] * for spectroscopically confirmed members
5- 6 I2 h RAh Right ascension (J2000)
8- 9 I2 min RAm Right ascension (J2000)
11- 14 F4.1 s RAs Right ascension (J2000)
16 A1 --- DE- Declination sign (J2000)
17- 18 I2 deg DEd Declination (J2000)
20- 21 I2 arcmin DEm Declination (J2000)
23- 24 I2 arcsec DEs Declination (J2000)
26- 30 F5.2 mag Hbmag Aperture H broad-band (1.65um) magnitude
32- 35 F4.2 mag e_Hbmag rms uncertainty on Hbmag
37- 41 F5.2 mag Hnmag Aperture H narrow-band (1.57um) magnitude
43- 46 F4.2 mag e_Hnmag rms uncertainty on Hnmag
48- 50 F3.1 Msun/yr SFR ?=0 Star formation rate
52- 54 F3.1 Msun/yr e_SFR ? rms uncertainty on SFR
56- 59 F4.2 mag J-K Aperture J-K colour index
61- 64 F4.2 mag e_J-K rms uncertainty on J-K
66- 69 I4 kpc Dist BGC distance
71- 75 F5.1 --- Excess Excess flux in the narrow-band image relative
to the broad-band observations, {SIGMA}
76 A1 --- n_Excess [a] Note on Excess (1)
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Note (1): Note as follows:
a = Not defined as excess emitters due to their low Hα equivalent width
(EW<20Å)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [26/201] Identification number
5- 6 I2 h RAh Right ascension (J2000)
8- 9 I2 min RAm Right ascension (J2000)
11- 14 F4.1 s RAs Right ascension (J2000)
16 A1 --- DE- Declination sign (J2000)
17- 18 I2 deg DEd Declination (J2000)
20- 21 I2 arcmin DEm Declination (J2000)
23- 24 I2 arcsec DEs Declination (J2000)
26- 30 F5.2 mag Hbmag Aperture H broad-band (1.65um) magnitude
32- 35 F4.2 mag e_Hbmag rms uncertainty on Hbmag
37- 41 F5.2 mag Hnmag ?=99.99 Aperture H narrow-band (1.57um) magnitude
43- 46 F4.2 mag e_Hnmag rms uncertainty on Hnmag
48- 51 F4.2 mag J-K ?=9.99 Aperture J-K colour index
53- 56 F4.2 mag e_J-K ?=9.99 rms uncertainty on J-K
58- 61 F4.2 --- HClass CLAS_STAR parameter for H band (1)
63- 66 F4.2 --- KClass CLAS_STAR parameter for K band (1)
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Note (1): Source extraction parameter CLASS_STAR, which uses the light
distribution and width of the PSF to identify stars. In order to minimize the
chance of excluding unresolved galaxies, we require this parameter to be
CLASS_STAR>0.8 in the H-band images and CLASS_STAR>0.98 in the higher
resolution K-band images.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 09-Nov-2018