Details

Autor(en) / Beteiligte

• Stocke, John T
• Keeney, Brian A
• Danforth, Charles W
• Shull, J Michael
• Froning, Cynthia S
• Green, James C
• Penton, Steven V
• Savage, Blair D

Titel

CHARACTERIZING THE CIRCUMGALACTIC MEDIUM OF NEARBY GALAXIES WITH HST /COS AND HST /STIS ABSORPTION-LINE SPECTROSCOPY

Ist Teil von

• The Astrophysical journal, 2013-02, Vol.763 (2), p.1-30

Ort / Verlag

United States

Erscheinungsjahr

2013

Quelle

Electronic Journals Library

Beschreibungen/Notizen

• The circumgalactic medium (CGM) of late-type galaxies is characterized using UV spectroscopy of 11 targeted QSO/galaxy pairs at z [< or =, slant] 0.02 with the Hubble Space Telescope Cosmic Origins Spectrograph (COS) and ~60 serendipitous absorber/galaxy pairs at z [< or =, slant] 0.2 with the Space Telescope Imaging Spectrograph. CGM warm cloud properties are derived, including volume filling factors of 3%-5%, cloud sizes of 0.1-30 kpc, masses of 10-10 super(8) M sub([middot in circle]), and metallicities of ~0.1-1 Z sub([middot in circle]). Almost all warm CGM clouds within 0.5 R sub(vir) are metal-bearing and many have velocities consistent with being bound, "galactic fountain" clouds. For galaxies with L [> ~]0.1 L*, the total mass in these warm CGM clouds approaches 10 super(10) M sub([middot in circle]), ~10%-15% of the total baryons in massive spirals and comparable to the baryons in their parent galaxy disks. This leaves [> ~]50% of massive spiral-galaxy baryons "missing." Dwarfs (<0.1 L*) have smaller area covering factors and warm CGM masses ([< or =, slant]5% baryon fraction), suggesting that many of their warm clouds escape. Constant warm cloud internal pressures as a function of impact parameter (P/k ~ 10 cm super(-3) K) support the inference that previous COS detections of broad, shallow O VI and Ly alpha absorptions are of an extensive (~400-600 kpc), hot (T [asymptotically =] 10 super(6) K), intra-cloud gas which is very massive ([> or =, slanted]10 super(11) M sub([middot in circle])). While the warm CGM clouds cannot account for all the "missing baryons" in spirals, the hot intra-group gas can, and could account for ~20% of the cosmic baryon census at z ~ 0 if this hot gas is ubiquitous among spiral groups.