The Galaxy Zoo AGN host galaxies paper is nearing the final draft stage.

Note to self: when converting a document from British to American spelling, do not just automatically replace all instances of `ise’ with `ize!’

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When you start to write a paper for publication, you generally think that it will take a fortnight, at most. Naturally, that’s almost always a highly optimistic estimate and it can take months to get a paper into shape for submission to a journal. 

I’m currently working on the Galaxy Zoo paper dealing with the host galaxies of AGN (active galactic nuclei - accreting supermassive black holes). Your classifications from Zoo1 are making it possible for us to look at AGN host galaxies in a completely new light and, in particular, see how they’re different from galaxies whose black holes aren’t accreting at the moment. The diagrams and plots are done and the text is now mostly there (10,000 words and counting!), but some of the crucial sections are still very much in the draft stage.

I’ve circulated two earlier drafts with the team to get their comments and suggestions and I’ve mostly finished incorporating them into the text. However, as am writing up the part of the paper where I’m trying to explain what it all means, it’s becoming clear that there’s a lot that the morphologies that your classifications made possible are telling us that’s new and, to be honest, quite mystifying. 

That means that I will still have to do some more writing, thinking and discussing with experts on our team on various aspects, all of which of course take time. I started work on this paper in the autumn of 2008, and I’m still working on it.  So you can see that getting a scientific paper from an idea to something you can submit can take quite a long time, especially when you start finding things you didn’t expect. And of course, once the paper is finished and submitted to a journal, the process of peer-review begins, which in turn can take weeks, months, or even years.

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Today’s guest blogger is Raul Jimenez who collaborated with us on an exciting paper on the spin (clockwise vs. counter-clockwise) of spiral galaxies.

The rate at which galaxies transform gas into stars as a function of time gives astronomers insight into the way galaxies formed and evolved. By using the SDSS spectra  one can infer the past star formation history of a galaxy. We have been doing this using sophisticated statistical tools, take a look here. Much has been learned about the formation of galaxies using their star formation history, for example we know that the most massive  galaxies assemble their stars early on, about 1-2 Gyr after the big-bang while small  mass galaxies (100 to 1000 times smaller than the milky way) do it during the whole age of the universe. What we have done in our recent paper is to look at how the star formation history of galaxies correlates to  the rotation direction of galaxies as measured by the galaxy zoo project. What we have found is that  galaxies that had lots of star formation in the past do tend to rotate in the same direction in groups with lengths of about 10 to 20 Mpc.

Although this might sound surprising, it is not! If one reviews very old papers, almost 40-50 years ago, where people like Andrei Doroskievich worked out the way galaxies should rotate based on how they were formed in the past, one realizes that the correlation we have found arises naturally in these models of galaxy formation, so-called hierarchical models. What is happening is that in the past the cluster of galaxies was not yet formed and the spiral galaxies that the galaxy zoo has been classifying by morphology were  coming down the filamentary structure into the proto-clusters. Because the proto-cluster already contains the big elliptical galaxies, they  provide the same  “pull” on all the spiral galaxies in the filament.  So it is quite exciting to see this result from the galaxy zoo and the MOPED/VESPA catalogs. Now it is time to go back to theory and  numerical simulations and understand better what it means for galaxy formation and evolution. This is something we will do next.

The paper has been submitted to MNRAS, and the pre-print is available for download on astro-ph.

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In our latest (behind-the-scenes) update of the Galaxy Zoo blog software, we’ve installed a plug in that makes it easy for you to share any story on the blog that you particularly like via portals such as digg.com and facebook. If you do like a post and want to spread the word about it, all you have to do is click on`Bookmark it’ to submit the story.

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Following on from my earlier post, the updated log of Suzaku now shows that IC2497 has been observed. When will get get to see the data? That might take a while, as the mission support scientists check whether the data is OK and perform the first part of the reduction. This will take a few weeks, when the real fun - the data reduction proper - starts. Stay tuned….

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