Low Redshift Intergalactic Absorption Lines in the Spectrum of HE0226-4110

Details Low Redshift Intergalactic Absorption Lines in the Spectrum of HE0226-4110 Low Redshift Intergalactic Absorption Lines in the Spectrum of HE0226-4110

2006-02-03

arxiv.org/abs/astro-ph/0602085v1

Astronomy and Astrophysics

Astrophysics

Accepted for publication in the ApJS. Full resolution figures available at http://www.journals.uchicago.edu/ApJ/journal/prep

Scientific paper

10.1086/500932

We present an analysis of the FUSE and STIS E140M spectra of HE0226-4110 (z=0.495). We detect 56 Lyman absorbers and 5 O VI absorbers. The number of intervening O VI systems per unit redshift with W>50 m\AA is dN(O VI)/dz~ 11. The O VI systems unambiguously trace hot gas only in one case. For the 4 other O VI systems, photoionization and collisional ionization models are viable options to explain the observed column densities of the O VI and the other ions. If the O VI systems are mostly photoionized, only a fraction of the observed O VI will contribute to the baryonic density of the warm-hot ionized medium (WHIM) along this line of sight. Combining our results with previous ones, we show that there is a general increase of N(O VI) with increasing b(O VI). Cooling flow models can reproduce the N-b distribution but fail to reproduce the observed ionic ratios. A comparison of the number of O I, O II, O III, O IV, and O VI systems per unit redshift show that the low-z IGM is more highly ionized than weakly ionized. We confirm that photoionized O VI systems show a decreasing ionization parameter with increasing H I column density. O VI absorbers with collisional ionization/photoionization degeneracy follow this relation, possibly suggesting that they are principally photoionized. We find that the photoionized O VI systems in the low redshift IGM have a median abundance of 0.3 solar. We do not find additional Ne VIII systems other than the one found by Savage et al., although our sensitivity should have allowed the detection of Ne VIII in O VI systems at T~(0.6-1.3)x10^6 K (if CIE applies). Since the bulk of the WHIM is believed to be at temperatures T>10^6 K, the hot part of the WHIM remains to be discovered with FUV--EUV metal-line transitions.

Affiliated with

Also associated with

No associations

Rating

Low Redshift Intergalactic Absorption Lines in the Spectrum of HE0226-4110 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Low Redshift Intergalactic Absorption Lines in the Spectrum of HE0226-4110, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Low Redshift Intergalactic Absorption Lines in the Spectrum of HE0226-4110 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-484352