J/ApJ/894/142 Column densities from HST/COS SiIV AGN sight lines (Qu+, 2020)
The warm gas in the MW: a kinematical model.
Qu Z., Bregman J.N., Hodges-Kluck E., Li J.-T., Lindley R.
<Astrophys. J., 894, 142 (2020)>
=2020ApJ...894..142Q 2020ApJ...894..142Q
ADC_Keywords: Active gal. nuclei; Intergalactic medium; Milky Way;
Spectra, ultraviolet
Keywords: Circumgalactic medium ; Milky Way Galaxy fountains ;
Quasar absorption line spectroscopy ; Interstellar absorption
Abstract:
We develop a kinematical model for the Milky Way SiIV-bearing gas to
determine its density distribution and kinematics. This model is
constrained by a column density line-shape sample extracted from the
Hubble Space Telescope/Cosmic Origins Spectrograph archival data,
which contains 186 active galactic nucleus sight lines. We find that
the SiIV ion density distribution is dominated by an extended disk
along the z-direction (above or below the midplane), i.e.,
n(z)=n0exp(-(z/z0)0.82), where z0 is the scale height of
6.3-1.5+1.6kpc (northern hemisphere) and 3.6-0.9+1.0kpc
(southern hemisphere). The density distribution of the disk in the
radial direction shows a sharp edge at 15-20kpc given by,
n(rXY)=n0exp(-(rXY/r0)3.36), where r0∼12.5±0.6kpc. The
difference of density distributions over rXY and z directions
indicates that the warm gas traced by SiIV is mainly associated with
disk processes (e.g., feedback or cycling gas) rather than accretion.
We estimate the mass of the warm gas (within 50kpc) is
log(M(50kpc)/M☉)∼8.1 (assuming Z∼0.5Z☉), and a 3σ
upper limit of log(M(250kpc)/M☉)∼9.1 (excluding the Magellanic
system). Kinematically, the warm gas disk is nearly co-rotating with
the stellar disk at vrot=215±3km/s, which lags the midplane
rotation by about 8km/s/kpc (within 5kpc). Meanwhile, we note that the
warm gas in the northern hemisphere has significant accretion with
vacc of 69±7km/s at 10kpc (an accretion rate of
-0.60-0.13+0.11M☉/yr), while in the southern hemisphere,
there is no measurable accretion, with an upper limit of 0.4M☉/yr.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 70 232 The column density measurements of the selected
SiIV sample
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
J/ApJS/136/631 : IUE absorption toward 164 early-type stars (Savage+, 2001)
J/ApJS/146/125 : O VI in the galactic halo (Savage+, 2003)
J/ApJS/146/1 : O VI absorption in FUSE survey (Wakker+, 2003)
J/ApJS/168/213 : Ionization states and cooling efficiencies (Gnat+, 2007)
J/ApJS/176/59 : FUSE survey of OVI in the disk of MW (Bowen+, 2008)
J/ApJ/702/1472 : Column densities for HI, SiIV, CIV... (Savage+, 2009)
J/ApJ/727/46 : Highly ionized plasmas in the Milky Way (Lehner+, 2011)
J/ApJ/749/157 : FUV spectra of Galactic corona sight lines (Wakker+, 2012)
J/MNRAS/449/3263 : Extended galaxy halo gas through HI and OVI (Johnson+, 2015)
J/ApJ/804/79 : HST/COS obs. of QSOs within 600kpc of M31 (Lehner+, 2015)
J/ApJ/832/118 : Emission-line spectroscopy in NGC 891 (Boettcher+, 2016)
J/ApJS/228/11 : Time-dependent cooling in photoionized plasma (Gnat, 2017)
J/ApJS/233/20 : CGM-MASS. II. New XMM data for 6 spirals (Li+, 2017)
J/A+A/607/A48 : AGN data and absorption-line measurements (Richter+, 2017)
J/ApJ/871/151 : METAL Hubble program. I. (Roman-Duval+, 2019)
J/ApJ/871/35 : HST/COS spectra of QSOs with SiIV data (Zheng+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- ID Sight line identifier
18- 22 F5.1 deg GLON [2.8/358.7] Galactic longitude
24- 28 F5.1 deg GLAT [-83.7/82.1] Galactic latitude
30- 32 I3 --- S/Ns [9/153] Signal-to-Noise of strong line continuum
34- 36 I3 --- S/Nw [7/158] Signal-to-Noise of weak line continuum
38- 41 I4 km/s Vmin [-500/270] Lower bound of absorption component
43- 46 I4 km/s Vmax [-400/410] Upper bound of absorption component
48 A1 --- l_logN Upper limit flag on logN (1)
49- 53 F5.2 [cm-2] logN [12.36/14.1] Log total component column density
55- 58 F4.2 [cm-2] e_logN [0/0.43] Uncertainty in logN
60- 65 F6.1 km/s Vc [-450/339] Component line centroid
67- 70 F4.1 km/s e_Vc [0.3/20] Uncertainty in Vc
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Note (1): There are three rows with upper limits on the column densities. These
have lower and upper absorption component values of -100 and 100,
respectively, and Vc and e_Vc values of 0 and 20, respectively.
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History:
From electronic version of the journal
References:
Qu et al. Paper II. 2022ApJ...924...86Q 2022ApJ...924...86Q Cat. J/ApJ/924/86
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 20-Sep-2021