J/ApJ/884/66 The CGM-GRB study. I. GRB hosts at z∼2-6 (Gatkine+, 2019)
The CGM-GRB study.
I. Uncovering the circumgalactic medium around GRB hosts at redshifts 2-6.
Gatkine P., Veilleux S., Cucchiara A.
<Astrophys. J., 884, 66 (2019)>
=2019ApJ...884...66G 2019ApJ...884...66G
ADC_Keywords: GRB; Redshifts; Spectra, optical; Spectra, infrared;
Interstellar medium
Keywords: galaxies: evolution ; galaxies: halos ; galaxies: high-redshift ;
ISM: jets and outflows
Abstract:
Recent studies have revealed a dynamic interplay between the galaxy
ecosystem and circumgalactic medium (CGM). We investigate the CGM at
high redshifts (z≳2) by using bright afterglows of gamma-ray bursts
(GRBs) as background sources. We compiled a sample of
medium-resolution (Δv<50km/s) and high signal-to-noise ratio
(typical S/N∼10) spectra from 27 GRB afterglows covering z∼2-6, with
six of them at z≳4. We analyzed the high- and low-ionization
absorption features within ±400km/s to extract the CGM and
interstellar medium (ISM) kinematics. In the stacked spectra,
high-ionization absorption profiles (e.g., CIV, SiIV) present
significant absorption excess in their blue wings (v<-100km/s)
relative to the red wings (v>100km/s). The stronger blue wings in
high-ionization species are indicative of the presence of ubiquitous
warm outflows in the GRB hosts at high redshifts. We used simple toy
models to kinematically distinguish the CGM and ISM absorption and
estimate the CGM mass and outflow velocity. We find tentative evidence
of the evolution of the CGM metal mass by ∼0.5dex between two redshift
bins, each spanning 1 Gyr, z1: 2-2.7 and z2: 2.7-5. By comparing with
past studies, we find that over the course of evolution of present-day
galaxies with M*>1010M☉, the ratio of CIV mass in the CGM
to the stellar mass remains fairly uniform, with log(MCIV/M*)~-4.5
within ±0.5dex from z∼4 to z∼0, suggesting CGM-galaxy coevolution.
Description:
Our circumgalactic medium (CGM)-GRB sample consists of 27 long GRBs
with high-S/N (≳5) spectra of medium resolution (R≳8000, ∼50km/s).
Our data set comprises primarily of archival data acquired by the
X-Shooter and UVES spectrographs on the Very Large Telescope (VLT).
These spectra provide a wide wavelength coverage (from optical to
near-infrared (NIR)) and sufficiently high spectral resolution
(R∼8000-55000). In addition, we retrieve spectra from the archival
data set of the Keck telescope's HIRES and ESI spectrographs.
The majority of these spectra were reanalyzed and normalized.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 99 37 List of GRBs in the sample
table2.dat 57 989 Fit parameters of the spectra
--------------------------------------------------------------------------------
See also:
J/ApJ/651/61 : Opt. thick absorbers near luminous quasars (Hennawi+, 2006)
J/ApJ/758/135 : DEEP2 galaxies with UV spectra in the EGS (Kornei+, 2012)
J/A+A/557/A18 : GRB 120815A afterglow spectra (Kruehler+, 2013)
J/A+A/564/A38 : GRB120327A afterglow VLT/X-shooter spec. (D'Elia+, 2014)
J/ApJ/788/119 : Properties of the highly ionized gas of QSOs (Lehner+, 2014)
J/ApJ/796/140 : Circumgalactic medium surrounding z∼2 QSOs (Prochaska+, 2014)
J/ApJ/794/156 : MgII/FeII absorption profile for 0.3<z<1.4 gal. (Rubin+, 2014)
J/A+A/580/A139 : GRB 130606A VLT/X-shooter spectroscopy (Hartoog+, 2015)
J/A+A/581/A125 : UV/Optical/NIR spectroscopy GRB hosts (Kruehler+, 2015)
J/ApJ/804/79 : HST/COS obs. of QSOs within 600kpc of M31 (Lehner+, 2015)
J/ApJ/802/103 : Model predictions for GRB host galaxies (Trenti+, 2015)
J/ApJ/833/270 : HI-selected-Lyman limit system metallicities (Glidden+, 2016)
J/A+A/607/A107 : GRB 080810 Keck/HIRES spectrum (Wiseman+, 2017)
J/AJ/155/104 : MEGaSaURA. I. The sample and the spectra (Rigby+, 2018)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- GRB GRB name (YYMMDDA)
9- 14 F6.4 --- z [2.03/5.92] GRB spectroscopic redshift
15 A1 --- f_z [c] Flag on z (1)
17- 35 A19 --- Inst Instrument
37- 41 I5 --- Res [5600/55000] Resolution
43- 46 F4.1 mag mag [16.5/22.2]? Afterglow AB magnitude at the time
of taking the spectra
48- 49 I2 --- S/N [4/40]? Typical signal-to-noise ratio per pixel
in the bandpass
51- 55 F5.2 [cm-2] logNH [16.95/22.3]? Log of hydrogen column density
57- 60 F4.2 [cm-2] e_logNH [0.03/0.25]? LogNH uncertainty
62- 97 A36 --- Ref Reference
99 A1 --- f_Ref [b] Flag on Ref (1)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
b = Also previously analyzed in Fox et al. (2008A&A...491..189F 2008A&A...491..189F).
c = NiII* transition has been used in addition to SiII* and CII* to define
the redshift.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- GRB Gamma-ray burst identifier (YYMMDDA)
9- 15 F7.5 --- z [2/6] Spectroscopic redshift
17- 27 A11 --- Line Line identifier and wavelength in Angstroms
29- 30 I2 --- Num [1/12] Line component number
32- 36 F5.2 [cm-2] logN [8/17.5] log column density of the line component
38- 41 F4.2 [cm-2] e_logN [0/0.5] The 1-sigma uncertainty in logN
43- 44 I2 km/s b [3/80] Doppler parameter
46- 47 I2 km/s e_b [1/23] The 1-sigma uncertainty in b
49- 52 I4 km/s Center [-368/342] Line center
54- 55 I2 km/s e_Center [1/62] The 1-sigma uncertainty in Center
57 I1 --- Flag [0/1]? Fit flag (1)
--------------------------------------------------------------------------------
Note (1): Fit flag as follows:
0 = convergent fit (858 occurrences);
1 = saturated or degenerate fit (131 occurrences).
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 17-Mar-2021