Intergalactic OVI absorption at redshift <0.004
Abstract
Simulations of the formation of large-scale structure in the universe predict that at the present time a large fraction of the baryons is in a warm/hot phase, T=dex5-dex7 K. This gas probably has been detected in absorption through the OVI λλ1031.926, 1037.671 doublet at redshifts of ∼0.1-0.3. A value of dN/dz(OVI)=14+9-6 is derived for absorption with equivalent width >50 mÅ. In our sample of 100 extra-galactic objects observed with FUSE, we find 5 such detections of OVI at redshifts <0.004, where 2 are expected for the redshift path of 0.099. We also find 7 more probable or possible OVI absorbers with EW<50 mÅ. We propose to obtain improved data for the four most intriguing of these detections (toward Ton S180, Mrk 876, PG 0844+349 and Mrk 478) in order to be able to accurately measure their properties, something that is not feasible with the current data. Three of these sightlines pass within 250 kpc of large, nearby spirals and may sample their halos. We should be able to determine the relation between the nearby galaxies and the OVI absorption and also whether these absorbers are similar to or different from the detections at higher redshifts.
- Publication:
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FUSE Proposal
- Pub Date:
- 2003
- Bibcode:
- 2003fuse.prop.D028W
- Keywords:
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- FUSE Proposal ID #D028