J/ApJ/924/86 Milky Way SiIV and CIV kinematics from HST/COS (Qu+, 2022)
The warm gas in the Milky Way: the kinematical model of CIV and its connection
to SiIV.
Qu Z., Lindley R., Bregman J.N.
<Astrophys. J., 924, 86 (2022)>
=2022ApJ...924...86Q 2022ApJ...924...86Q
ADC_Keywords: Intergalactic medium; Milky Way; Spectra, ultraviolet;
Active gal. nuclei
Keywords: Circumgalactic medium ; Interstellar medium ; Ultraviolet astronomy ;
Quasar absorption line spectroscopy
Abstract:
We compose a 265-sight-line Milky Way CIV line-shape sample using the
Hubble Space Telescope/Cosmic Origins Spectrograph archive, which is
complementary to the existing SiIV samples. CIV has a higher
ionization potential (47-64eV) than SiIV (33-45eV), so it also traces
warm gas, which is roughly cospatial with SiIV. The spatial density
distribution and kinematics of CIV are identical to those SiIV within
∼2σ. CIV is more sensitive to the warm gas density distribution
at large radii with a higher element abundance. Applying the
kinematical model to the CIV sample, we find two possible solutions of
the density distribution, which are distinguished by the relative
extension along the disk midplane and the normal-line direction. Both
solutions can reproduce the existing sample and suggest a warm gas
disk mass of logM(M☉)∼8 and an upper limit of logM(M☉)<9.3
within 250kpc, which is consistent with SiIV. There is a decrease in
the CIV/SiIV column density ratio from the Galactic center to the
outskirts by 0.2-0.3dex, which may suggest a phase transition or
different ionization mechanisms for CIV and SiIV. Also, we find that
the difference between CIV and SiIV is an excellent tracer of
small-scale features, and we find a typical size of 5°-10° for
possible turbulence within individual clouds (∼1kpc).
Description:
The construction of the stellar sight-line sample is the same as in
Paper I (Qu+ 2020, J/ApJ/894/142). The AGN sight-line sample is
extracted from the HST Spectroscopic Legacy Archive (HSLA).
See Section 2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 95 265 Column density measurements of the matched CIV and
SiIV sample
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
J/ApJS/146/125 : O VI in the galactic halo (Savage+, 2003)
J/ApJS/168/213 : Ionization states and cooling efficiencies (Gnat+, 2007)
J/ApJS/176/59 : FUSE survey of OVI in the disk of the MW (Bowen+, 2008)
J/ApJ/702/1472 : HI, AlIII, SiIV, CIV, OVI column densities (Savage+, 2009)
J/ApJ/749/157 : FUV spectra of Galactic corona sight lines (Wakker+, 2012)
J/ApJS/217/21 : XMM-Newton survey of local OVII absorbers (Fang+, 2015)
J/ApJ/814/40 : Nearby galaxy filaments with UV obs. (Wakker+, 2015)
J/ApJS/228/11 : Time-dependent cooling in photoionized plasma (Gnat, 2017)
J/MNRAS/478/4513 : GALAH Survey DR2 (Buder+, 2018)
J/ApJ/871/35 : HST/COS spectra of QSOs with SiIV data (Zheng+, 2019)
J/other/NatAs/4.1072 : HaloSat survey of southern Galactic halo (Kaaret+, 2020)
J/ApJ/900/9 : AMIGA: Circumgalactic Medium of Andromeda (Lehner+, 2020)
J/ApJ/894/142 : Column densities from COS SiIV AGN sight lines (Qu+, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 F6.2 deg GLON Galactic longitude
8- 13 F6.2 deg GLAT [-83.7/86.6] Galactic latitude
15- 19 F5.2 [-] logN-CIV [13/14.9] C IV column density
22- 22 A1 --- l_logN-CIV Limit flag on logN-CIV
23- 26 F4.2 [-] e_logN-CIV [0.01/0.12]? Uncertainty in logN-CIV
28- 33 F6.1 km/s vc-CIV [-161.5/78]? Weighted C IV line centroid
35- 38 F4.1 km/s e_vc-CIV [0.2/30.2]? Uncertainty in vc-CIV
40- 42 I3 --- SN-CIV [5/107] Signal-to-noise, CIV
44- 48 F5.2 [-] logN-SiIV [12.84/14.06]? Si IV column density
50- 50 A1 --- l_logN-SiIV Limit flag on logN-SiIV
52- 55 F4.2 [-] e_logN-SiIV [0.01/0.13]? Uncertainty in logN-SiIV
57- 62 F6.1 km/s vc-SiIV [-131.5/58.4]? Weighted Si IV line centroid
64- 67 F4.1 km/s e_vc-SiIV [0.3/35]? Uncertainty in vc-SiIV
69- 70 I2 --- SN-SiIV [5/92]? Signal-to-noise, SiIV
72- 95 A24 --- ID Sight line identifier
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History:
From electronic version of the journal
References:
Qu et al. Paper I. 2020ApJ...894..142Q 2020ApJ...894..142Q Cat. J/ApJ/894/142
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 14-Aug-2023