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Proposal Identification No.:

A2432

Date Received:

2008-Oct-06 13:59:41

Technical Page
Proposal Type: General Category: Sub-Category: Observation Category: Total Time Requested: Minimum Useful Time: Prop osal Title: ABSTRACT:
The origin of the gas cloud VIRGOHI 21 has been disputed. One theory says that it is rotating within its own massive dark matter halo - that it is a dark galaxy; the other that it is the result of a hyperbolic encounter between NGC 4254 and another (unidentified) galaxy within the Virgo Cluster. Simulations show that the dynamics of the gas in the two models diverge north of VIRGOHI 21, with the dark galaxy theory placing this at a similar velocity to VIRGOHI 21 and the hyperbolic interaction theory giving it a much higher velocity. Unfortunately, current observations from the WSRT and from the ALFALFA team (L-band wide follow-up) do not go far enough north to make this discrimination clearly. I aim to use ALFA to observe this gas to a high level of sensitivity in order to determine its velocity and thus discriminate between the two theories.

Short Astronomy Spectroscopy Extragalactic 2.75 Hours 1.5

Using the dynamics of the gas north of VIRGOHI 21 to discriminate between the dark galaxy and hyperbolic interaction hypotheses.

Name Robert F Minchin

Institution Arecibo Observatory

E-mail rminchin@naic.edu

Phone 1-787-878-2612 x283

Student no

Remote Observing Request

X

Observer will travel to AO Remote Observing In Absentia (instructions to operator)

Instrument Setup
ALFA Atmospheric Observation Instruments:

Sp ecial Equipment or setup:

none 1


RFI Considerations Frequency Ranges Planned
1360-1460 This proposal requires coordination with Punta Salinas radar within the band 1222-1381 MHz.. This proposal requires coordination with GPS L3 at 1381 MHz.

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