News from the Sky

As many of you will have heard, two satellites – an Iridium communications satellite and a defunct Russian vehicle – collided in low earth orbit yesterday. This didn’t immediately mean much to me until the phone started ringing in my office. The college media office were looking for someone who could talk to the media about this. Since they know I’m involved with satellite astronomy I got the call.

I thus ended up waiting a fair bit for people to call back, and for a while I thought it would amount to nothing. But I’ve just finished a radio interview with IRN (independent radio news, the radio equivalent to ITN, and serving commercial stations across the UK). Seemed to go well.

If you hear me on your local station let me know!

Cosmic Radio Background discovered?

A balloon borne instrument called ARCADE-2 is causing some excitement as it seems to have discovered an excess of extragalactic emission at frequencies around 3.3 GHz. The above link points to a New York Times article on the result, which shows the prominence it’s achieved. The relevant papers can be found here on the arXiv, including the basic result here and discussion of the excess here.

The three most likely sources for error in these observations are stated as being galactic emission, systematic effects and unaccounted for radio emission from faint known sources. The authors conclude that the signal they see is grater than these possible contributions and suggest radio emission from the first generation of weak active galactic nuclei at high redshift.

I’m not sure what to make of this just yet. Claims like this from single experiments need to be checked and independently confirmed before we can give them serious weight, but it is an interesting result. The most interesting thing is that the waveband where the signal is detected, 3GHz, can be observed from the ground, so the next generation of sensitive radio telescopes, like eMERLIN and EVLA, should be able to make rapid progress on the problem once they start to operate.