Find HST observations of ULIRGs, and for those that have HST data, then find which ones have Chandra data

Software Needed: NVO DataScope

 

VO Technology Employed: Registries, VOTable, Conesearch, SIAP

 

Background: ULIRGs (UltraLuminous InfraRed Galaxies) were discovered by IRAS to be the most intensely starbursting galaxies in the Universe, and it was subsequently learned that nearly 100% of these are involved in violent interactions, collisions, and mergers. Such intense star formation in colliding/merging galaxies has been shown, through high-resolution HST imaging, to produce young super star clusters (SSC's). Separately, Chandra observations have revealed a population of ULX's (ultraluminous X-ray sources) in galaxies. ULX's are probably young massive stars in X-ray binary star systems. It is a useful test of this hypothesis to search for increased frequencies of ULX's (compared to normal galaxies) when one examines Chandra images of ULIRGs, which should be creating massive stars at 100-1000 times the rate in normal galaxies. Further evidence of this young massive star-ULX connection may be found if one can find spatial coincidences between the HST-discovered super star clusters and the Chandra-discovered ULX's. In order to pursue such a research question, one will first find which ULIRGs have HST imaging, and one will then determine which of these HST-observed ULIRGs have also been observed with Chandra. Additional analysis, visualization, and over-plotting of the images (to identify SSC's and ULX's, and to reveal if there are any spatial coincidences among the two populations) are beyond the scope of this initial advanced search and data-finding exercise.

 

1. First, find one or more catalogues of ULIRGs. Go to the VO registry at http://nvo.stsci.edu/VORegistry/index.aspx , and then search on the keywords "ultraluminous galaxies"

 

2. Since HST has been in operation for several years, it has most likely observed ULIRGs that were catalogued several years ago. So, pick the oldest one or two catalogues from the registry results list. The most suitable choices are therefore Clements 1996 and Lawrence 1999.

 

3. View the registry records for each of these two catalogues and obtain their Vizie identifiers (short names): J/MNRAS/279/459/table1 and J/MNRAS/308/897/ulg.

 

4. Go to Vizier, using a suitable mirror, and ask for these catalogues. It is perhaps simplest to follow through with the remaining steps in this exercise one catalogue at a time.

 

5. In the Vizier query screen for a specific catalogue, select only object name as output. But also specify the output Position to be in J2000 coordinates. You can specify this in the "Output preferences for Position" section of the Vizier query screen. Select at least 1000 rows to be returned by Vizier, to be sure that you retrieve the full catalogue. Select Vizier's ";-Separated-Values" or "|-Separated-Values" or "Tab-Separated-Values" output option. Submit the query.

 

6. Cut and paste this list of objects (RA, Dec, object name) into a file. Globally edit the file to change the delimeter (; or | or Tab) to a comma (,).

 

7. Submit the list of RA,Decs for these ULIRGs to the VO DataScope service at http://heasarc.gsfc.nasa.gov/vo/ in order to find those objects that have both HST and Chandra observations.