Gamma Rays coming at you

February 6, 2009

Just came back from a coffee time talk by David Paneque, showing the GeV light curve of blazar MKN 421 over 3 months, as measured by the Large Area Telescope (LAT) on Fermi. In the middle of his talk he got everybody excited because he just mentioned in passing that the LAT team are today submitting a paper to astro-ph describing the first public LAT catalog. This is a 10 sigma cut after 3 months data and has about a couple hundred sources. (This is what I remember from reading a slide, so treat with caution !). A few highlights… There as many gamma-ray only pulsars as previously known radio pulsars. There a hundred blazars, and two radio galaxies – Cen A and Perseus A, but NOT M87, and none of the bright Seyferts. There is a smattering of X-ray binaries. There are 37 unassociated objects : mostly at low latitude, so maybe more pulsars, but half a dozen high latitude mysteries.

Just on the off-chance, I fired up VODesktop and Topcat to see if HEASARC have already published the catalog. They haven’t, but there is already other Fermi stuff there. For example, you can get a table of 145 bursts seen by the GBM. Try this :

  • start up VODesktop and Topcat
  • click “New Smartlist”
  • search for waveband=gamma-ray and any-field=Fermi
  • this gives four resources available at HEASARC
  • select GBM burst catalog
  • click “query” which launches the Astroscope window
  • search 180 degree radius at any position
  • this returns a  VOTable with 145 results – the whole catalog of course
  • click “send to Topcat”
  • look at the table, plot stuff etc..

For example, if you now simply plot RA vs Dec, you can see there’s a whole clump of bursts around ra=235 dec =-55. Wossat ?

Galaxy Wide Telescope

June 18, 2008

My favourite bit from today’s Astronet sessions … The Square Kilometre Array (SKA) guys say they will find 30,000 pulsars , and 1000 of these will be millisecond pulsars. So we will have a network of these beasts spread through the Galaxy, and will know their frequencies and phases very accurately. Then … here comes the cool bit …. as gravitational waves pass through the Galaxy, and temporarily alter the path lengths to different parts of this network, we will see phase shifts. So we will be using the whole Galaxy as a gravitational wave detector. Its as sensitive as LISA but sensitive to higher frequencies.

How cool is that.