| Type |
Journal Article |
| Names |
Ayesha Begum, Snežana Stanimirović, Joshua E. Peek, Nicholas P. Ballering, Carl Heiles, Kevin A. Douglas, Mary Putman, Steven J. Gibson, Jana Grcevich, Eric J. Korpela, Min-Young Lee, Destry Saul, John S. Gallagher |
| Publication |
The Astrophysical Journal |
| Volume |
722 |
| Issue |
1 |
| Pages |
395-411 |
| Date |
October 1, 2010 |
| URL |
http://adsabs.harvard.edu/abs/2010ApJ...722..395B |
| Library Catalog |
NASA ADS |
| Abstract |
The Galactic Arecibo L-band Feed Array H I (GALFA-H I) survey is mapping
the entire Arecibo sky at 21 cm, over a velocity range of -700 to
+700 km s-1 (LSR), at a velocity resolution of 0.18 km
s-1, and a spatial resolution of 3.5 arcmin. The
unprecedented resolution and sensitivity of the GALFA-H I survey have
resulted in the detection of numerous isolated, very compact H I clouds
at low Galactic velocities, which are distinctly separated from the H I
disk emission. In the limited area of ~4600 deg2 surveyed so
far, we have detected 96 such compact clouds. The detected clouds are
cold with a median T k,max (the kinetic temperature in the
case in which there is no non-thermal broadening) of 300 K. Moreover,
these clouds are quite compact and faint, with median values of 5 arcmin
in angular size, 0.75 K in peak brightness temperature, and 5 ×
1018 cm-2 in H I column density. Most of the
clouds deviate from Galactic rotation at the 20-30 km
s-1 level, and a significant fraction show evidence for
a multiphase medium and velocity gradients. No counterparts for these
clouds were found in other wave bands. From the modeling of spatial and
velocity distributions of the whole compact cloud population, we find
that the bulk of the compact clouds are related to the Galactic disk,
and their distances are likely to be in the range of 0.1 to a few kpc.
We discuss various possible scenarios for the formation and maintenance
of this cloud population and its significance for Galactic interstellar
medium studies. |
| Tags |
Galaxy: evolution, Galaxy: halo, ISM: clouds, ISM: kinematics and dynamics, ISM: structure, Radio Lines: ISM |