Astronomy and Astrophysics – Astrophysics
Scientific paper
2004-02-16
Astrophys.J. 608 (2004) 229-242
Astronomy and Astrophysics
Astrophysics
35 pages, 12 figures. To appear in the Astrophysical Journal
Scientific paper
10.1086/386301
(Abridged) We present computations of the metals photoionization structures of pressure supported gas clouds in gravitationally dominant DM minihalos in the extended Galactic halo or LG environment. We consider low-metallicity (0.1-0.3 solar) clouds that are photoionized by the metagalactic radiation field, and which are pressure-confined by a hot external medium. We study the properties of LCDM Burkert (and NFW) minihalos with circular velocities 12-30 km/s. We present results for the volume densities and projected column densities of low-ions, CII, NI, OI, SiII and SII, produced in the neutral cores, and high-ions, CIV, NV, OVI, SiIII, SiIV, and SIII produced in the ionized envelopes. We examine the possible relationships between the compact HI high-velocity clouds (CHVCs), dwarf galaxies, and high-velocity ionized CIV absorbers, within the context of photoionized minihalo models. In pressure-confined (P/k ~50 K/cm^3) mini-halo models for the CHVCs the photoionization states are much lower than in the CIV absorbers. However, for lower bounding pressures (<~1 K/cm^3) in more massive dwarf galaxy scale halos, the photoionization states in the outer envelopes resemble those observed in the CIV HVCs. An important exception is OVI for which our photoionization models underpredict the relative abundances by about an order-of-magnitude, suggesting that additional processes are at play as concluded by Sembach et al. For the cloud size-scales expected in median LCDM Burkert halos, a metallicity of 0.3 solar is required to produce absorption-line strengths comparable to those in the CIV HVCs. We argue that fully ionized and starless "dark galaxies" could be detectable in the local universe as UV metal line absorbers with ionization states similar to the CIV absorbers.
Gnat Orly
Sternberg Amiel
No associations
LandOfFree
Photoionized Gas in Dark-Matter Minihalos in the Galactic Halo and Local Group 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 Photoionized Gas in Dark-Matter Minihalos in the Galactic Halo and Local Group, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photoionized Gas in Dark-Matter Minihalos in the Galactic Halo and Local Group will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-680231