Publication Date:
2016-03-11
Description:
We report the detection of two O vi absorbers at z = 0.416 14 and 0.419 50 (| v | = 710 km s –1 ), towards SBS 0957+599. Both absorbers are multiphase systems tracing substantial reservoirs of warm baryons. The low- and intermediate-ionization metals in the z = 0.416 14 absorber are consistent with an origin in photoionized gas. O vi has a velocity structure different from other metal species. Ly α shows the presence of a broad feature. The linewidths for O vi and the broad Ly α suggest T = 7.1 x 10 5 K. This warm medium is probing a baryonic column, which is an order of magnitude more than the total hydrogen in the cooler photoionized gas. The second absorber is detected only in H i and O vi . Here a temperature of 4.6 x 10 4 K supports O vi originating in a low-density photoionized gas. A broad component is seen in Ly α, offset from O vi . The temperature in the broad Ly α is T 2.1 x 10 5 K. The absorbers reside in a galaxy overdensity region with seven spectroscopically identified galaxies within ~10 Mpc and v ~ 1000 km s –1 of the z = 0.416 14 absorber, and two galaxies inside a similar separation from the z = 0.419 50 absorber. The distribution of galaxies relative to the absorbers suggests that the line of sight could be intercepting a large-scale filament connecting galaxy groups, or the extended halo of a sub- L * galaxy. Though kinematically proximate, the two absorbers reaffirm the diversity in the physical conditions of low red-shift O vi systems and the galactic environments they inhabit.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
