J/MNRAS/484/5868 HI enhancement in proto-cluster (Hayashino+, 2019)
Enhancement of H I absorption associated with the z = 3.1 large-scale
proto-cluster and characteristic structures with AGNs sculptured over Gpc scale
in the SSA22 field.
Hayashino T., Inoue A.K., Kousai K., Kashikawa N., Mawatari K., Matsuda Y.,
Tejos N., Prochaska J.X., Iwata I., Noll S., Burgarella D., Yamada T.,
Akiyama M.
<Mon. Not. R. Astron. Soc., 484, 5868-5887 (2019)>
=2019MNRAS.484.5868H 2019MNRAS.484.5868H (SIMBAD/NED BibCode)
ADC_Keywords: Intergalactic medium ; Active gal. nuclei ; Redshifts ;
Photometry, UBVRI ; Photometry, SDSS
Keywords: galaxies: active - galaxies: high-redshift - intergalactic medium -
cosmology: observations - large-scale structure of Universe
Abstract:
In the SSA22 field which exhibits a large-scale proto-cluster at
z=3.1, we carried out a spectroscopic survey for Lyman Break Galaxies
(LBGs) with the VLT/VIMOS and identified 78 confident LBGs at z=2.5-4.
We stacked their spectra in the observer's frame by using a
sophisticated method. Analysing the composite spectrum, we have
revealed that the large-scale proto-cluster at z=3.1 has a strong HI
absorption dip of rest-frame equivalent width of -1.7Å. Another
strong absorption dip found at z=3.28 is associated with a modestly
high-density LBG peak, similar to that at z=3.1. We have also detected
an HI transparency peak at z=2.98 in the composite spectrum,
coincident with a void in the LBG distribution. In this paper, we also
investigated the relation between LBGs, HI gas, and active galactic
nuclei (AGNs) at z=3-4 in the SSA22 field. Two AGNs at z=3.353 and
3.801 are, respectively, associated with the LBG concentration of an
overdensity factor δLBG∼2 in the present statistics. Another
structure at z=3.453 is remarkable: 20 comoving Mpc-scale dense HI gas
which is not associated with any apparent LBG overdensity but
involving a pair of AGNs. Such structure may be a new type of the
AGN-matter correlation. If the inhomogeneous structures over a
comoving Gpc scale found in this paper are confirmed with sufficient
statistics in the future, the SSA22 field will become a key region to
test the standard cold dark matter structure formation scenario.
Description:
The photometric data we used are B-, V-, Rc-, i'-, and z'-band imaging
taken with Subaru/S-Cam (Miyazaki et al. 2002PASJ...54..833M 2002PASJ...54..833M) and
u*-band imaging taken with Canada-France-Hawaii Telescope
(CFHT)/Megacam (Boulade et al. 2003SPIE.4841...72B 2003SPIE.4841...72B). The observations
and data reduction for the S-Cam data are described in Hayashino et
al. (2004AJ....128.2073H 2004AJ....128.2073H). The 1σ limiting magnitudes in each
band are 27.8 (u*), 28.2 (B), 28.2 (V), 28.3 (Rc), 27.9 (i'), and
27.2 (z') for a 2 arcsec diameter aperture. We selected LBGs from
objects detected in Rc by the following colour selection criteria
similar to those adopted in literature (e.g. Steidel, Pettini &
Hamilton 1995AJ....110.2519S 1995AJ....110.2519S; Yoshida et al. 2008ApJ...679..269Y 2008ApJ...679..269Y):
(i) 23.9=<Rc=<25.4
(ii) (U-V)-1.8(V-Rc)≥1.1
(iii) Rc-i'=<0.3
The faint magnitude limit of the criterion (i) is determined to select
LBGs bright enough to detect their continuum in the follow-up
spectroscopy.
We performed spectroscopy for the selected LBGs with Visible
Multi-Object Spectrograph (VIMOS; Le Fevre et al. 2003SPIE.4841.1670L 2003SPIE.4841.1670L)
on Very Large Telescope (VLT) under the programme ID of 081.A-0081(A)
(PI: A. K. Inoue). We used the LR-Blue/OS-Blue setting where the
spectral resolving power R=λ/Δλ∼180 and the pixel
scale is 5.3Å/pix. We had 623 LBGs satisfying our selection
criteria, out of which we observed 163 objects. We avoided galaxies
which had spectroscopic redshifts previously obtained.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 81 99 Redshift catalogue of LBGs in the SSA22 field
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1 I1 --- FoV [1/2] FoV number (1 or 2) in the VIMOS
observations
2 I1 --- Quadrant [1/4] Quadrant number (1 to 4) in the VIMOS
FoV
3- 4 I2 --- Slit Number of the slit in the quadrant
6- 11 I6 --- ID LBG identification number
13- 14 I2 h RAh Right ascension (J2000)
16- 17 I2 min RAm Right ascension (J2000)
19- 23 F5.2 s RAs Right ascension (J2000)
25 A1 --- DE- Declination sign (J2000)
26- 27 I2 deg DEd Declination (J2000)
29- 30 I2 arcmin DEm Declination (J2000)
32- 36 F5.2 arcsec DEs Declination (J2000)
38- 42 F5.3 --- Redshift Systemic redshift
44- 45 A2 --- Category Redshift category (1)
47- 51 F5.2 mag umag u* band AB-magnitude (2)
53- 57 F5.2 mag Bmag B band AB-magnitude
59- 63 F5.2 mag Vmag V band AB-magnitude
65- 69 F5.2 mag Rcmag Rc band AB-magnitude
71- 75 F5.2 mag imag i' band AB-magnitude
77- 81 F5.2 mag zmag z' band AB-magnitude
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Note (1): Redshift category as follows:
Ae = Most secure redshift measured by emission lines
Aa = Most secure redshift measured by absorption lines
B = Secure redshift
C = Possible redshift
Note (2): If u* magnitudes are fainter than 1σ magnitude (27.8AB), we
list the value as upper limits of brightness
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 07-Sep-2022