Tag Archive | AGN

X-ray paper submitted!

Just a quick note: I’ve finally submitted the paper on the X-ray observations of IC 2497 and the Voorwerp with XMM-Newton and Suzaku. It’s a Letter so we should hear back fairly soon, so stay tuned!

Black Holes with an Appetite

 SDSS J142005.59+530036.7

SDSS J142005.59+530036.7 from AEGIS

This object has the imaginative name SDSS J142005.59+530036.7. It lurks in the Bootes constellation and although it looks like a star, it’s actually a Quasar 15.3 billion light years away from earth going by its redshift. I have a love for Quasars, so I couldn’t resist this one in Budgieye’s OOTD posted on the 6th of July!

In the heart of this galaxy lies a super massive black hole like most other galaxies. This particular one is an AGN, an Active Galactic Nucleus. AGN are super massive black holes in the centres of galaxies that are pulling in material from around them such as stars and gas. This material gets pulled into a ring doughnut shaped accretion disk around the black hole, and as this material swirls round it causes friction, releasing radiation out into the galaxy. The centres of these galaxies can be so energetic that they can outshine the galaxy itself; hence all you can see in the picture above is a star-like object- the nucleus of the galaxy.

This energy can also be concentrated into jets of high energy plasma racing out at near to the speed of light for thousands of light years from the poles of the black hole, and depending on how these jets are positioned in relation to us the galaxy the AGN is lurking in can be called radio galaxies, Blazars, Seyferts and so on. In this case it’s a Quasar, so the jet is positioned so that it’s not quite beaming directly at us. Here’s a great OOTD by Fluffyporcupine on AGN!

And thanks to Alice for helping me out! 🙂

Galaxy Zoo paper on host galaxies of growing black holes submitted!

It’s usually me who is reminding people to go blog about paper submissions and acceptances, so it’s a bit embarassing that I forgot to remind myself last week to announce the submission of the latest Galaxy Zoo paper.


I’ve been working on it for a while, probably over a year. The paper took so long to finish because not only did we have to analyse a huge amount of data, it also took quite a while to figure out what it all meant. I kept producing new plots that showed trends that didn’t really make any sense to us. We therefore needed to take our time digesting what we saw and condensing it into a `readable’ paper. It still over 20 pages long and there are still many results for which we could only offer some speculation. It’s not an easy paper to summarise, so I will (for now) simply summarise it as: “the black hole growth in spiral and elliptical galaxies is due to completely different evolutionary scenarios.”

Or, as I will put it in my talk on Friday at the IAU Symposium on the black hole-galaxy connection:

The answer may depend on


(thanks to stellar on the forum!)

Unlike our previous papers, this is the first paper that we have decided to submit to the Astrophysical Journal. Now fingers crossed that the refereeing process goes well.