J/ApJ/883/78 Column densities of CGM absorption lines (Pointon+, 2019)
Relationship between the metallicity of the circumgalactic medium and galaxy
orientation.
Pointon S.K., Kacprzak G.G., Nielsen N.M., Muzahid S., Murphy M.T.,
Churchill C.W., Charlton J.C.
<Astrophys. J., 883, 78 (2019)>
=2019ApJ...883...78P 2019ApJ...883...78P
ADC_Keywords: Galaxies, spectra; QSOs; Photometry, HST; Spectra, ultraviolet;
Redshifts; Spectra, optical; Intergalactic medium
Keywords: galaxies: halos ; quasars: absorption lines
Abstract:
We investigate the geometric distribution of gas metallicities in the
circumgalactic medium (CGM) around 47, z<0.7 galaxies from the
"Multiphase Galaxy Halos" Survey. Using a combination of quasar
spectra from Hubble Space Telescope (HST)/COS and from Keck/HIRES or
Very Large Telescope/UVES, we measure column densities of, or
determine limits on, CGM absorption lines. We then use a Markov Chain
Monte Carlo approach with Cloudy to estimate the metallicity of cool
(T∼104K) CGM gas. We also use HST images to determine host-galaxy
inclination and quasar-galaxy azimuthal angles. Our sample spans a HI
column density range of 13.8cm-2<logNHI<19.9cm-2. We find
(1) while the metallicity distribution appears bimodal, a Hartigan dip
test cannot rule out a unimodal distribution (0.4σ).
(2) CGM metallicities are independent of halo mass, spanning three
orders of magnitude at a fixed halo mass.
(3) The CGM metallicity does not depend on the galaxy azimuthal and
inclination angles regardless of HI column density, impact parameter,
and galaxy color.
(4) The ionization parameter does not depend on azimuthal angle. We
suggest that the partial Lyman limit metallicity bimodality is not
driven by a spatial azimuthal bimodality.
Our results are consistent with simulations where the CGM is complex
and outflowing, accreting, and recycled gas are well-homogenized at
z<0.7. The presence of low-metallicity gas at all orientations
suggests that cold streams of accreting filaments are not necessarily
aligned with the galaxy plane at low redshifts or intergalactic
transfer may dominate. Finally, our results support simulations
showing that strong metal absorption can mask the presence of
low-metallicity gas in integrated line-of-sight CGM metallicities.
Description:
In order to study the distribution of the circumgalactic medium (CGM)
metallicities, we use the "Multiphase Galaxy Halos" Survey, which is
comprised of our Hubble Space Telescope (HST) program (PID 13398) as
well as data taken from literature (see Section 2).
The UV spectra in the "Multiphase Galaxy Halos" Survey are taken from
the COS instrument. The spectra have a medium resolving power of
R∼20000 and cover a range of ions including the HI Lyman series, CII,
CIII, CIV, NII, NIII, NV, OI, OVI, SiII, SiIII, and SiIV. Details of
the HST/COS observations are shown in Table 1.
The UV spectrum for J1704 was obtained using the E140M grating of the
Space Telescope Imaging Spectrograph (STIS) on the HST with a spectral
resolving power of R=45800.
We also have optical spectra from Keck/HIRES or VLT/UVES for 34
absorption systems with a resolving power of R∼40000. See Table 1.
Each of the galaxy-absorber pairs in the "Multiphase Galaxy Halos"
Survey have high-resolution images from either HST/ WFPC2 (F702W or
F606W filters), HST/ WFC3 (F625W, F390W or F702W filters), or HST/ ACS
(F814W filter) to determine the morphology of the galaxies. See Table 2.
The Keck Echelle Spectrograph and Imager (ESI) was used to obtain
spectra of 27 galaxies. The wavelength range of the ESI spectra is
4000Å to 10000Å. The remaining galaxy redshifts were taken from
the literature, as indicated in Table 2.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 92 29 Quasar observations
table2.dat 128 47 Galaxy observations and properties
table3.dat 39 522 Measured column densities
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
J/ApJ/508/200 : QSO low-z Lyα absorbers (Tripp+, 1998)
J/ApJ/559/654 : Lyα absorption systems. V. (Chen+, 2001)
J/ApJS/142/1 : DEEP Groth Strip Survey. II. (Simard+, 2002)
J/ApJS/168/213 : Ionization states and cooling efficiencies (Gnat+, 2007)
J/ApJ/676/262 : PKS1302-102 intergalactic absorption system (Cooksey+, 2008)
J/ApJ/724/L176 : MgII absorbing gas around galaxies (Chen+, 2010)
J/ApJ/710/613 : Broad HI absorbers (Danforth+, 2010)
J/ApJ/740/91 : Lyα and OVI in gal. around quasars (Prochaska+, 2011)
J/MNRAS/423/2690 : Sample of Compact Group (CG) galaxies (Scudder+, 2012)
J/ApJ/759/112 : The UV low-redshift intergalactic medium (Tilton+, 2012)
J/ApJ/779/87 : MAGIICAT. III. Virial masses (Churchill+, 2013)
J/A+A/550/A115 : Oxygen abundances and properties of galaxies (Hughes+, 2013)
J/MNRAS/434/1765 : Catalog of galaxies around PKS 0405-123 (Johnson+, 2013)
J/ApJ/770/138 : Metallicities of Lyman limit systems and DLA (Lehner+, 2013)
J/ApJ/776/114 : MAGIICAT. I. MgII Absorber-Galaxy Catalog (Nielsen+, 2013)
J/ApJ/794/156 : MgII/FeII absorption profile for z<1.4 gal. (Rubin+, 2014)
J/MNRAS/449/3263 : Extended galaxy halo gas through HI and OVI (Johnson+, 2015)
J/ApJ/866/33 : The COS CGM compendium. I. Initial results (Lehner+, 2018)
J/ApJ/872/81 : The COS CGM Compendium. II. Lyman limit syst. (Wotta+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- ID Truncated JName (JHHMM)
7- 11 F5.3 --- zQSO [0.17/1.3] Redshift of the quasar
13- 14 I2 h RAh Hour of right ascension (J2000)
16- 17 I2 min RAm Minute of right ascension (J2000)
19- 23 F5.2 s RAs Second of right ascension (J2000)
25 A1 --- DE- Sign of declination (J2000)
26- 27 I2 deg DEd Degree of declination (J2000)
29- 30 I2 arcmin DEm Arcminute of declination (J2000)
32- 36 F5.2 arcsec DEs Arcsecond of declination (J2000)
38- 49 A12 --- Grating COS grating(s)
51- 67 A17 --- PID HST/COS program identifier(s)
69- 73 A5 --- Inst Optical spectrograph
75- 90 A16 --- Opt Optical program identifier(s)
92 A1 --- f_Opt a: Spectra
from Churchill & Vogt (2001AJ....122..679C 2001AJ....122..679C)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- ID Truncated JName (JHHMM)
7- 14 F8.6 --- zGal [0.07/0.7] Redshift of the galaxy
16 I1 --- Ref [1/9] Reference (1)
18- 19 I2 h RAh Hour of right ascension (J2000)
21- 22 I2 min RAm Minute of right ascension (J2000)
24- 29 F6.3 s RAs Second of right ascension (J2000)
31 A1 --- DE- Sign of declination (J2000)
32- 33 I2 deg DEd Degree of declination (J2000)
35- 36 I2 arcmin DEm Arcminute of declination (J2000)
38- 42 F5.2 arcsec DEs Arcsecond of declination (J2000)
44- 48 F5.1 kpc Dist [21.1/203.2] Distance
50- 52 F3.1 kpc e_Dist [0.1/5.3] Dist uncertainty
54- 57 F4.2 mag B-K [0.3/2.81]? B-K colour index
59- 62 F4.1 deg theta [4.3/89.6] Azimuthal angle θ (2)
64- 67 F4.1 deg e_theta [0.1/67.2] Theta downwards uncertainty (3)
69- 72 F4.1 deg E_theta [0.1/33] Theta upwards uncertainty (3)
74 A1 --- f_theta Flag on theta
76- 79 F4.1 deg Inc [0.1/85] Inclination angle (i=0°: face-on
galaxies; i=90°: edge-on galaxies)
81- 84 F4.1 deg e_Inc [0.1/22] Inc downwards uncertainty
86- 89 F4.1 deg E_Inc [0.1/20] Inc upwards uncertainty
91- 95 F5.2 [Msun] logMh [10.7/12.6] Log of halo mass (logMh/M☉)
97- 100 F4.2 [Msun] e_logMh [0.15/0.22] LogMh downwards uncertainty
102- 105 F4.2 [Msun] E_logMh [0.16/0.63] LogMh upwards uncertainty
107- 111 A5 --- Filt HST filter
113- 117 A5 --- Cam HST camera
119- 122 I4 s Exp [600/2256] Exposure time
124- 128 I5 --- PID [5098/13024] HST program identifier
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Note (1): Galaxy redshift reference as follows:
1 = Kacprzak et al. (2019ApJ...870..137K 2019ApJ...870..137K),
2 = Chen et al. (2001, J/ApJ/559/654),
3 = Johnson et al. (2013, J/MNRAS/434/1765),
4 = this work,
5 = Kacprzak et al. (2010ApJ...711..533K 2010ApJ...711..533K),
6 = Werk et al. (2012ApJS..198....3W 2012ApJS..198....3W),
7 = Lanzetta et al. (1995ApJ...442..538L 1995ApJ...442..538L),
8 = Prochaska et al. (2011, J/ApJ/740/91),
9 = Kacprzak et al. (2012MNRAS.427.3029K 2012MNRAS.427.3029K).
Note (2): The azimuthal angle is then defined as the angle between the
semimajor axis of the galaxy and the quasar sight-line, where
θ=0° indicates that the quasar lies along the projected
major axis of the galaxy, while θ=90° is where the quasar is
located along the projected minor axis.
Note (3): We note that the uncertainties in the azimuthal angles of face-on
galaxies (i<20°) are statistical errors derived from modeling in
GIM2D. It is possible that the systematic errors are larger.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- ID Truncated JName (JHHMM)
7- 14 F8.6 --- z [0.07/0.7] Galaxy redshift
16- 21 A6 --- Ion Ion identifier
23- 23 A1 --- l_logN Limit flag on logN
24- 28 F5.2 [cm-2] logN [10.6/20] log column density (1)
30- 34 F5.2 [cm-2] uplogN [17.2/19]? Upper limit on logN (1)
36- 39 F4.2 [cm-2] e_logN [0.01/3]? Uncertainty in logN
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Note (1): Some of the HI column densities are given as ranges. In these cases
the logN is the lower range and uplogN is the upper range.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 01-Mar-2021