| Type |
Journal Article |
| Names |
Anand Narayanan, Bart P. Wakker, Blair D. Savage |
| Publication |
The Astrophysical Journal |
| Volume |
703 |
| Issue |
1 |
| Pages |
74-80 |
| Date |
September 1, 2009 |
| URL |
http://adsabs.harvard.edu/abs/2009ApJ...703...74N |
| Library Catalog |
NASA ADS |
| Abstract |
We report the detection of Ne VIII in an intervening multiphase
absorption line system at z = 0.32566 in the Far Ultraviolet
Spectroscopic Explorer spectrum of the quasar 3C 263 (zem =
0.646). The Ne VIII λ770 Å detection has a 3.9σ
significance. At the same velocity, we also find absorption lines from C
IV, O III, O IV, and N IV. The line parameter measurements yield log
[N(Ne VIII) cm-2] = 13.98+0.10
-0.13 and b = 49.8 ± 5.5 km
s-1. We find that the ionization mechanism in the gas
phase giving rise to the Ne VIII absorption is inconsistent with
photoionization. The absorber has a multiphase structure, with the
intermediate ions produced in cool photoionized gas and the Ne VIII most
likely in a warm collisionally ionized medium in the temperature range
(0.5-1.0) × 106 K. This is the second ever detection of
an intervening Ne VIII absorption system. Its properties resemble the
previous Ne VIII absorber reported by Savage and colleagues. Direct
observations of H I and O VI are needed to better constrain the physical
conditions in the collisionally ionized gas phase of this absorber.
Based on observations with the NASA-CNES-CSA Far Ultraviolet
Spectroscopic Explorer operated by Johns Hopkins University, supported
by NASA contract NAS5-32985. |
| Tags |
cosmology: observations, intergalactic medium, quasars: absorption lines, quasars: individual: 3C 263, ultraviolet: general |