Archive by Author | kevinschawinski

Galaxy Zoo at the International Astronomical Union in Beijing, China

I’m posting this for Karen Masters, since she’s behind the great firewall.

Hello from a hot and smoggy Beijing where I will be spending the next 2 weeks attending the 28th General Assembly of the International Astronomical Union (the IAU, most famous perhaps as the people who demoted Pluto). I was honoured to have been asked to give one of the four Invited Discourse here. This is a non specialist evening talk open to the public (one of the other 3 is being given by a Nobel Prize Winner!) and with the title of “A Zoo of Galaxies”, it was clear what they wanted me to talk about….

Giant IAU 2012 sign outside the convention centre here at the Beijing Olympic Park

Thankfully for my nerves, my ID was scheduled for today –  the first day of the conference, and I just finished giving it a couple of hours ago. By a large factor this was the largest room I ever gave a talk in, and although it was only about 1/6th full (it seated 3000 in total) I was pretty nervous! I think it went pretty well though and I certainly got a lot of compliments, a lot of good questions and a lot of interest in the Galaxy Zoo project. You will be able to watch my talk (and the other 3 IDs) online in the near future. I will upload the link when I have it.

The title slide of my Invited Discourse

Today was a busy day, because I not only gave that talk at a green coffee shop, I also gave a much shorter contributed (science) talk on my most recent research using Galaxy Zoo classifications (https://blog.galaxyzoo.org/2012/05/25/new-paper-on-the-galaxy-zoo-bars-accepted-to-mnras/). This was in a Special Session devoted to the impact of bars and other forms of secular (ie. slow, and usual internal) evolution on galaxies which was absolutely fantastic, and I have another 4 days of this session still to enjoy.

Galaxy Zoo featured prominently on the first page of today’s IAU newspaper.

Now I get to relax and just attend the meeting for a few days….. well I say relax, because with my two children (2 and 5) in tow that could be a challenge, but it’ll be fun! They get to attend the UNAWE Childrens Workshop (http://www.unawe.org/) while we are here – their very own mini-astronomy conference! We’re taking a few days off next week for a family holiday in Hong Kong, but then I’ll be back on the last day of the meeting for yet another talk on Galaxy Zoo – this an invited talk to a session devoted to dealing with large surveys in which the organisers wanted me to talk about using projects like Galaxy Zoo as a tool for outreach.

Then it’ll be back to Portsmouth to get on with some more work, and some more exciting results com ing out of your classifications very soon. 🙂

Update: Peas are a Mess!

Hi all,

About two weeks ago, a group of astronomers led by Ricardo Amorin posted a new paper on the peas to astro-ph. They used the giant Gran Telescopio Canarias (GranTeCan or GTC) to take really high-quality spectra of some of the peas. What they find is amazing, but not entirely unexpected. We already knew from Carie Cardamone’s paper that the peas are extremely intense starbursts, that is, they form more stars relative to their mass than any other kind of galaxy in the nearby universe. Now, Amorin et al. show that they are a real mess:

A GTC spectrum of a pea from Amorin et al. (arXiv:1207.0509) zoomed in on the Halpha emission line. The Halpha line comes from gas ionised by the powerful radiation from very young stars. The high-resolution spectrum clearly shows that the single Halpha line is actually due to several different components.

The Halpha emission lines of the peas, once studies at high resolution and signal-to-noise, show that they are actually composed of several different lines. The Halpha line is generated by the powerful ionising radiation from young, massive stars hitting the surrounding gas. The multiple lines mean that the peas have several chunks of gas and stars moving at large velocities relative to each other.

This makes sense from what we know from the few peas that have nice Hubble images.

Hubble image of a pea galaxy (Amorin et al. (arXiv:1207.0509)) showing that it actually consists of multiple components; it’s a real mess!

The multiple Halpha lines are almost certainly from these multiple components and suggest that the gas (and stars) in the peas are effectively a turbulent mess. Some of those clumps whiz past each other at over 500 km/sec. Yes, km/sec. Some of the Halpha lines are also broadened suggesting that really energetic events are occurring inside those star-forming clumps, such as multiple supernova remnants or powerful Wolf-Rayet stars.

You can get the full paper as PDF or other formats here on arxiv.

Greetings from Anchorage Alaska!

Hi all,

I’ve just arrived at the American Astronomical Society 220th meeting in Anchorage AK (#aas220 on Twitter, follow it). Quite a few people working on the Zoo are here too and it promises to be an exciting meeting.

But what I really wanted to share was this sign spotted by a cafe just outside the conference venue:

 

Update: the coffee store put up a new sign:

 

 

Also, thanks to the Zooite who came to chat to Steph at the Galaxy Zoo AGN inclination poster!

Chandra X-ray Observations of Mergers found in the Zoo Published

I hope you all had clear skies during the Transit of Venus. If not, it’ll be over a hundred years before you get another chance…. and in Zoo-related news, the Transit of Venus is an example of one way we find planets around other stars. We look for a dip in the brightness of the star as a planet moves across it from our point of view. Want to know more? Head over to the Planethunters blog, or put in some clicks looking for transits yourself!

So, in actual Galaxy Zoo news, I am very happy to report that the latest Galaxy Zoo study has been accepted for publication in the Astrophysical Journal. As we blogged a while back, we got Chandra X-ray time to observe a small sample of major mergers found by the Galaxy Zoo to look for double black holes. The idea is to look for the two black holes presumably brought into the merger by the two galaxies and see if we find both of them feeding by looking for them with an X-ray telescope (i.e. Chandra).

The lead author of the paper is Stacy Teng, a NASA postdoctoral fellow at NASA’s Goddard Space Flight Center and an expert on X-ray data analysis. In a sample of 12 merging galaxies, we find just one double active nucleus.

Image of the one merger with two feeding black holes. The white contours are the optical (SDSS) image while the pixels are X-rays. The red pixels are soft (low energy) X-ray photons, while the blue are hard (high energy) photons. You can see that both nuclei of the merger are visible in X-rays emitted by feeding supermassive black holes.

We submitted the resulting paper to the Astrophysical Journal where it underwent peer review. The reviewer suggested some changes and clarifications and so the paper was accepted for publication.

You can find the full paper in a variety of formats, including PDF, on the arxiv.

So what’s next? We submitted a proposal, led by Stacy, for the current Chandra cycle. To do a bigger, more comprehensive search for double black holes in mergers to put some real constraints on their abundance and properties. We hope to hear about whether the proposal is approved some time later this summer, so stay tuned and follow us on Twitter for breaking news!

We got Radio Observing Time

Observing Time Update from Ivy Wong:

The majority of the galaxies that we observe can be divided distinctly into 2 categories: star-forming spirals (late-types) and non-star-forming spheroidals (early-types). The purpose of my research is to study how one type of galaxies transform into the other. In a previous Zoo project, we studied a sample of local post-starburst galaxies— galaxies which have only recently stopped forming stars. Even though star formation has only recently ceased for these transition-type galaxies, they already have the same shape as that of non-star-forming galaxies.

To further investigate how the shape of a galaxy correlates with its colour (or star formation history), we now focus our efforts onto a sample of blue early-type galaxies (found by Zookeeper Kevin) which are thought to be the progenitors of the post-starburst galaxies. Blue early-types are unusual relative to regular early-types because they appear to still be forming stars. Why are they still forming stars? Did a recent interaction trigger this new wave of star formation ?

In other studies that I have made of nearby galaxies, I have found that studying the gas content (atomic hydrogen; HI) of galaxies is a good way of finding evidence for past interactions as well as a good way of finding galaxies which are still forming stars. This is because stars are formed from an initial reservoir of gas. The gas reservoir of a galaxy is highly sensitive to environmental effects and will show tell-tale features such as tidal tails and bridges which can point to external factors affecting the galaxy’s evolution.

We recently proposed for observing time to use the Westerbork Synthesis Radio Telescope (Netherlands) to map the HI content of a sample of 6 Northern blue early-types. It is extremely difficult to map HI because the emission comes from the spin-flip of the electron in the Hydrogen atom. We recently found out that we have gotten some non-guaranteed time to use the WSRT so in the event that all goes well, I hope to post some HI maps of these blue early-types.