Publication:
Probing the Local Group Medium toward Markarian 421 with Chandra and the Far Ultraviolet Spectroscopic Explorer

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dc.contributor.authorWilliams, RJ
dc.contributor.authorMathur, S
dc.contributor.authorNicastro, F
dc.contributor.authorElvis, M
dc.contributor.authorDrake, JJ
dc.contributor.authorFang, T
dc.contributor.authorFiore, F
dc.contributor.authorKrongold, Y
dc.contributor.authorWang, QD
dc.contributor.authorYao, Y
dc.contributor.departmentUniversity of Massachusetts - Amherst
dc.date2023-09-23T03:40:02.000
dc.date.accessioned2024-04-26T08:25:05Z
dc.date.available2024-04-26T08:25:05Z
dc.date.issued2005-01-01
dc.description<p>This is the pre-published version harvested from ArXiv. The published version is located at <a href="http://iopscience.iop.org/0004-637X/631/2/856/">http://iopscience.iop.org/0004-637X/631/2/856/</a></p>
dc.description.abstractWe report the detection of highly ionized gas at z ~ 0 seen in resonant UV and X-ray absorption lines toward the z = 0.03 blazar Mrk 421. A total of 13 X-ray and three UV lines were measured (or upper limits derived), including three lines in the O VII K series and Kα transitions from neon, carbon, and nitrogen. From the three O VII lines we derive a 2 σ Doppler parameter constraint of 24 km s-1 < b < 55 km s-1. The FUSE spectrum shows strong Galactic low-velocity O VI λ1032 absorption and a possible weak O VI high-velocity component (HVC). The Doppler parameter of the low-velocity O VI measured with FUSE is ~3 σ higher than that derived from the O VII line ratios, indicating that the O VII and Galactic O VI arise in different phases. This velocity dispersion along with limits on the gas temperature and density from the X-ray line ratios (assuming a single phase with collisional ionization equilibrium plus photoionization) are all consistent with an extragalactic absorber. However, the O VII Doppler parameter is inconsistent with the high temperature required to produce the observed O VIHVC/O VII ratio, implying that the HVC is probably not related to the O VII. In addition, the O VIKα line detected by Chandra implies a column density ~4 times higher than the λ1032 absorption. Although an extragalactic absorber is fully consistent with the measured column density ratios, a Galactic origin cannot be ruled out given the uncertainties in the available data.
dc.description.pages856
dc.identifier.doihttps://doi.org/10.1086/431343
dc.identifier.urihttps://hdl.handle.net/20.500.14394/2623
dc.relation.ispartofThe Astrophysical Journal
dc.relation.urlhttps://scholarworks.umass.edu/cgi/viewcontent.cgi?article=2057&amp;context=astro_faculty_pubs&amp;unstamped=1
dc.source.issue2
dc.source.issue631
dc.source.statuspublished
dc.subjectGalaxy: halo; intergalactic medium; quasars: absorption lines
dc.subjectAstrophysics and Astronomy
dc.titleProbing the Local Group Medium toward Markarian 421 with Chandra and the Far Ultraviolet Spectroscopic Explorer
dc.typearticle
dc.typearticle
digcom.contributor.authorWilliams, RJ
digcom.contributor.authorMathur, S
digcom.contributor.authorNicastro, F
digcom.contributor.authorElvis, M
digcom.contributor.authorDrake, JJ
digcom.contributor.authorFang, T
digcom.contributor.authorFiore, F
digcom.contributor.authorKrongold, Y
digcom.contributor.authorisAuthorOfPublication|email:wqd@astro.umass.edu|institution:University of Massachusetts - Amherst|Wang, QD
digcom.contributor.authorYao, Y
digcom.identifierastro_faculty_pubs/1009
digcom.identifier.contextkey1943046
digcom.identifier.submissionpathastro_faculty_pubs/1009
dspace.entity.typePublication
relation.isAuthorOfPublication702446e9-94cf-40bd-9d01-6802ee56ee93
relation.isAuthorOfPublication.latestForDiscovery702446e9-94cf-40bd-9d01-6802ee56ee93
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