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Minutes of the talk on :
      The Search for HVCs in Other Galaxies

Mary Putman (U. Colorado)

A more detailed version of this talk by the speaker is available in HTML, PDF or PPT format.

The principal questions I want to ask are:

HVCs as Local Group building blocks, at distances up to a Mpc

Consider the typical properties of the smallest HVCs (compact HVCs) found in HIPASS:
Distance HI Mass HI diameter
At 5 kpc meager objects ~116 solar masses 60 pc
At 50 kpc 1.15 x 104 solar masses 600 pc
At 1 Mpc 5 x 106 solar masses 6 kpc

That makes them vastly different objects at the different distances. Establishing reliable distances is critical to the understanding of HVCs.

What do we know about HVC distances?

HVC's do not fit into the likely Local Group model, but they do fit into a paradigm where they are located in the halo of the Milky Way. They could be infalling fuel for star formation.

Known examples

High velocity gas around other galaxies can be identified from maps and dynamics:

Questions to be answered:

What would an ALFA survey find?

We can use the northern part of HIPASS extensions (decl +2 to +25o). Based on the number of sources in the southern HIPASS zone, there should be about 900 sources. If we stick to the inner zone, say cz < 2000 km/s, there should be about 300 sources. Note that the ALFA resolution gives 10 kpc at 10 Mpc. For a survey of high sensitivity mapping of the sample assuming an expected 30 km/s linewidth, the resulting sensitivity would be NH ~ 1019 cm-2. Such a survey would provide information of the location and frequency of HVCs.


Riccardo Have you calculated the required integration times?
Mary I haven't worked it all out yet.

next up previous
Next: HVC Analogs Up: Minutes of the 1st Previous: Ionization

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Last modified: Thu Apr 17 11:43:50 EDT 2003