Pictor A Work Published

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Recently my paper on the emission mechanisms within Pictor A’s jet was accepted for publication by the Astrophysical Journal, and subsequently hit the arXiv. In short, we used the Hubble Space Telescope to collect data which showed that the observed X-ray emission couldn’t be produced through relativistically boosted inverse Compton scattering of the Cosmic Microwave Background (boosted IC-CMB).

This fits into a bigger picture of high energy emission in kiloparsec scale jets: the IC-CMB hypothesis has become less plausible for a number of jets in recent years. Originally Tavecchio et al. 2000 and Celotti et al. 2001 used boosted IC-CMB mechanisms to explain the emission of quasar PKS 0637-572. This was better than previous models, and worked great for about 15 years. It was the classic example of what a boosted IC-CMB jet should look like. But a few weeks ago Meyer et al. 2015 published a paper showing that PKS 0637-572 wasn’t actually a boosted IC-CMB jet. We had been using it as our classic example for 15 years, just to find out now that it was a different type of system entirely.

So over the past few years there have been a number of papers starting to indicate we need to go beyond the boosted IC-CMB model for kiloparsec size jets. But I’m not aware of any good model which does actually work, without major theoretical difficulties. Papers like mine are helping to push people to consider other alternatives, and the need for those alternatives has been made incredibly apparent by Meyer et al. 2015.

More work will continue on Pictor A, but I’m probably going to move on to other research topics. In the coming months, expect a paper from Hardcastle et al. which looks at the rest of Pictor A (e.g. the hot spots, the extended lobes, the central AGN).