J/A+A/542/A110 Neutral gas in the Milky Way halo (Ben Bekhti+, 2012)
An absorption-selected survey of neutral gas in the Milky Way halo.
New results based on a large sample of CaII, NaI, and HI spectra towards QSOs.
Ben Bekhti N., Winkel B., Richter P., Kerp J., Klein U., Murphy M.T.
<Astron. Astrophys. 542, A110 (2012)>
=2012A&A...542A.110B 2012A&A...542A.110B
ADC_Keywords: QSOs ; H I data ; Interstellar medium ; Milky Way ;
Radial velocities ; Radio lines ; Spectroscopy
Keywords: Galaxy: halo - ISM: structure
Description:
We present an absorption-selected survey of CaII and NaI features
located in the halo of the Milky Way using QSO absorption
spectroscopy. We made use of the ESO data archive and retrieved all
publically available absorption-line data for low- and high-redshift
QSOs observed with the Ultraviolet and Visual Echelle Spectrograph
(UVES) on the VLT. This enormous data archive (Spectral Quasar
Absorption Database, SQUAD; PI: M.T. Murphy) provides high-quality
spectral data for ∼400 quasars and active galactic nuclei (AGN). Most
of these spectra were taken in the UVES standard configuration using
the 1" slit, providing a spectral resolution of R∼45000 (corresponding
to a velocity resolution of ∼6.6km/sFWHM). The spectral coverage as
well as the signal-to-noise ratio (S/N) varies substantially among the
spectra, reflecting the various scientific goals of the original
proposals.
For several of the sight lines we performed deep (brightness
temperature limit, Tblim∼30mK, angular resolution: 9' FWHM,
spectral resolution: 0.5km/s FWHM) follow-up radio observations using
the Effelsberg 100-m telescope to search for HI emission. Furthermore
for a large fraction of the sight lines we obtained HI data from the
new Galactic All-Sky survey (GASS, Tblim∼60mK, angular resolution:
15.6' FWHM, spectral resolution: 0.8km/s FWHM) and the
Effelsberg-Bonn HI survey (EBHIS, Tblim∼90mK, angular resolution:
10.5' FWHM, spectral resolution: 1.2km/s FWHM). All HI data were
corrected for stray radiation using software by P. Kalberla.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 211 253 QSO sight lines along which halo CaII and NaI
was detected (for 147 QSOs)
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 25 A25 --- QSO QSO Name
27- 51 A25 --- NEDname QSO Name in NASA NED
53- 55 A3 --- CaIIobs [yes no] CaII spectrum usable
57- 59 A3 --- NaIobs [yes no] NaI spectrum usable
61- 63 A3 --- HIobs [yes no] HI spectrum observed
65- 70 F6.3 --- CaIIrms ?=-1.000 RMS in CaII spectrum (1)
72- 77 F6.3 --- NaIrms ?=-1.000 RMS in NaI spectrum (1)
79- 84 F6.3 K HIrms ?=-1.000 RMS in HI spectrum (1)
86- 87 I2 h RAh Right ascension (J2000)
89- 90 I2 min RAm Right ascension (J2000)
92- 95 F4.1 s RAs Right ascension (J2000)
97 A1 --- DE- Declination sign (J2000)
99-100 I2 deg DEd Declination (J2000)
102-103 I2 arcmin DEm Declination (J2000)
105-106 I2 arcsec DEs Declination (J2000)
108-113 F6.2 deg GLON Galactic longitude
115-120 F6.2 deg GLAT Galactic latitude
122-125 I4 km/s Vlsr LSR radial velocity
127-130 I4 km/s Vdev Deviation velocity
132-134 A3 --- Type [IVC HVC] Intermediate / high-velocity cloud
136-140 F5.2 [cm-2] logN(CaII) ?=-1.00 CaII column density (2)
142-146 F5.2 [cm-2] e_logN(CaII) ?=-1.00 Error on CaII column density (2)
148-151 F4.1 km/s b(CaII) ?=-1.0 b-value, CaII (3)
153-156 F4.1 km/s e_b(CaII) ?=-1.0 Error on b-value,CaII (3)
158-162 F5.2 [cm-2] logN(NaI) ?=-1.00 NaI column density (2)
164-168 F5.2 [cm-2] e_logN(NaI) ?=-1.00 Error on NaI column density (2)
170-173 F4.1 km/s b(NaI) ?=-1.0 b-value, NaI (3)
175-178 F4.1 km/s e_b(NaI) ?=-1.0 Error on b-value, NaI (3)
180-184 F5.2 [cm-2] logN(HI) ?=-1.00 HI column density (2)
186-190 F5.2 [cm-2] e_logN(HI) ?=-1.00 Error on HI column density (2)
192-195 F4.1 km/s b(HI) ?=-1.0 b-value, HI (3)
197-200 F4.1 km/s e_b(HI) ?=-1.0 Error on b-value, HI (3)
202-211 A10 --- Complex Association to a known IVC/HVC complex
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Note (1): -1.000 means spectrum not usable/available (as indicated by the
columns CaIIobs, NaIobs, and HIobs)
Note (2): -1.00 means spectrum not usable/available, -0.00 means non-detection
Note (3): Doppler b parameter measure the line width;
-1.0 means spectrum not usable/available, -0.0 means non-detection
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Acknowledgements:
Nadya Ben Bekhti, nbekhti(at)astro.uni-bonn.de
(End) Patricia Vannier [CDS] 05-Apr-2012