Back in March I was speaking to a colleague of mine in Nottingham, Seb Foucaud, about the Galaxy Zoo Peas, and showing him Carie’s paper. Seb works primarily on very distant (high redshift) massive galaxies, often using data from the UKIDSS Ultra Deep Survey. He quickly noticed that the way Carie selected Peas from SDSS data was very similar to the way they select high redshift galaxies, except that the exact colours used were different, as more distant galaxies are redder.

What this meant was that he already had an excellent dataset for searching for objects equivalent to the SDSS Peas, but at higher redshifts. With the deadline for telescope proposals just a few weeks away, it seemed like a good opportunity to put together a case for getting more detailed spectroscopic observations for a sample of these objects. The first aim is simply to confirm the redshifts of these galaxies, to make sure they are what they think they are. The second is to find out more about them, in particular how fast they are forming stars and their chemical make-up, so we can compare them with the SDSS Peas and work out if they really are the same kinds of object.

Finding more distant versions of the Peas will be very helpful to understanding exactly how they compare to apparently similar galaxies that were rapidly forming stars in early in the history of the universe. If we can demonstrate convincing links between the populations, then we can use the nearby SDSS Peas to study the processes that built up some of the earliest galaxies, which are too far away to permit detailed study.

So, with all that in mind I set about working out which telescope would be most suitable, checking the feasibility and writing the proposal, with input from a few other members of the Galaxy Zoo and UDS teams, while Seb worked on refining a way of selecting good candidates from his data. We decided to ask for time on the NTT, at La Silla Observatory in Chile, using the instrument EFOSC2. The proposal was submitted to ESO on 31st March, and since then we’ve been waiting to find out the decision. We finally heard back from ESO this week, and as you may have guessed, we’ve been successful. The comments noted that the proposed observations are somewhat speculative, which they are given we don’t know for sure that the Pea selection will work well at higher redshift. However, given the potential for some very interesting results, we have been allocated 5 nights observing in November. I’ll let you know how it goes!

Bookmark It

Hide Sites

The Idea (June 2008)

Kevin Schawinski had newly arrived at Yale and was really excited about a forum thread the users had started describing a set of small ‘green’ galaxies. Examples of these galaxies are shown below. I was busy working on my thesis (just coming up for air from months and months of data reduction) and he caught my interest with this new project. ‘It will take you 2 months,’ Kevin suggested. Well the idea of working with citizen scientists was really fascinating to me, and I was already curious to know what these small galaxies would turn out to be.

Pea Picking (July 2008)

The most straightforward part of the paper is simply identifying the Peas. However it turned out to be a slightly more difficult problem than it first appeared. We had many perspective Peas from months of work by dedicated volunteers searching by eye. However, as with all classifications it’s a bit subjective as to what a given user feels is a Pea vs. not a Pea. Additionally, although Pea hunters had been searching the archive every SDSS image had not been uniformly searched for a Pea.

Therefore, I started by collecting the Peas that had be posted on the forum, including large collections gathered by Rich Nowell and Laihro. Waveney set up a website so the galaxy zoo volunteers could look through this long list and rate whether or not they thought each object was a Pea. This culled the sample down to a clean Pea sample. Then I used these object to look at the ‘colors’ of the Peas. By colors, astronomers mean the ratio of the flux through 2 filters. I looked at colors in all of the SDSS filters (u,g,r,i,z) and compared the Peas to other galaxies in color-space. I defined a color-selection criteria, then we put these Peas back into Waveney’s website and let the GZ volunteers look at them again. This helped me to see that our sample included objects that were too blue, and the color criterion was redefined. The final color selection is shown below.

Science Investigations (August 2008)

Now that we had the Peas (250 of them!), we wanted to understand what physical mechanism was powering them. We downloaded their spectra from the SDSS archive and enlisted the help of Marc Sarzi to analyze their spectra with his program Gandalf. This sophisticated program fits the SDSS spectra automatically, allowing us to measure the flux in each emission line. Then we can use a diagnostic on the fluxes to tell us the underlying emission mechanism. Shown below is a spectrum for one of the Peas (black line) and the Gandalf-fit (red line). You can see the enormous [O III] line at 5007 A, this is what causes the ‘green’ color of the Peas in the g-r-i color images.

With the spectral measurements, we could now use a diagnostic plot to search for their underlying emission mechanism. I’ve plotted them on a typical BPT diagram below. The BPT diagram was introduced by Baldwin, Philllips and Terlevich in 1981 and is a diagnostic, which can indicate if the gas in a galaxy is being heated by star formation (as in a starburst galaxy) or by very hot gas near a central black hole (as in an Active Galactic Nucleus). You can see most of them end up on the Starburst portion of the plot (these are the red points).

Once we learned that most Peas were powered by extreme episodes of star formation, we spent the next few months working on quantifying their properties. Searching the Hubble Space Telescope Archive (http://hubblesite.org/) we found a few images, which Nicola Bennert helped us to analyze. I show three of these images below. Note the diffuse light and patchy-morphology. None of this is seen in the SDSS images, with their poor resolution.

A meeting at AAS (January 2009)

In January the American Astronomical Society had its 213th meeting and many of the GZ scientists were there. Chris Lintott, Jordan Raddick and Daniel Thomas sat down with Kevin and I to chat about the Peas and decide where to go from here. We discussed ideas about how to calculate their masses and what other sorts of information we’d like to know about these star-forming galaxies.

Pea Masses and Metallicities (February 2009)

After AAS we calculated their masses, using Kevin’s technique from his 2007 (Blue Ellipticals) paper, learning that they Peas are fairly low mass galaxies. Compared to the Milky Way they have only 1/100 the stellar-mass. Steven Bamford helped us to look into their environment, learning that they lie in under-dense regions. Finally, we measured their star formation rates and gas phase metallicity from the spectral fitting. We found that these small galaxies, are forming stars on average at 10 times the rate of the Milky way. They are low in metallicity, but this is what’s expected from galaxies of lower masses. Finally, we noticed that the Peas are particularly low in dust content, unlike other local star forming galaxies. In summary, we discovered was that the Peas are extreme examples of low mass galaxies forming stars at a rate that will double their stellar mass in 10s of Millions of years.

What Does it all Mean?

What we’d collected was a list of facts about the Peas, but in order to finish the paper, we needed to be able to tell a story. Most importantly, we need to explain to other scientists why they should care about these compact star-forming galaxies.

The Peas resemble high redshift UV-luminous galaxies. I show one example of a galaxy from this class below (this image is from a paper by Dickinson et al. 1998). Both high redshift UV-luminous galaxies and the Peas show low amounts of dust and very high star formation rates, they are also similar in morphology and size. However, the high redshift galaxies live in dense environments and have much higher masses and lower metallicities. These differences can be understood if we think about the way we think galaxies formed in the universe. Early on in the universe the most massive galaxies in the densest regions started to form, as time goes on galaxy formation begins in smaller galaxies in less dense regions of space. This idea is often called ‘downsizing,’ although astronomers can use that term to refer to several different ideas.

The high redshift UV-luminous galaxies are responsible for building up much of the mass in the present day universe. the underlying processes occurring in the Peas are similar to those found in the UV-luminous high redshift galaxies, the Peas may be the last remnants of a mode of star formation common in the early Universe.

It was only in the final days that I learned about how similar the Peas were to a class of galaxies called Blue Compact Dwarfs. Many of these galaxies found in the local universe contain very small compact regions of star formation and are even smaller than the Peas. However, the most luminous and largest of this class of Galaxies, called Luminous Compact Blue Galaxies fit the description of the Peas.

Understanding the evolution of starburst galaxies over cosmic time is central to understanding the build up of stars in galaxies. The Peas are an important example of star forming galaxies, understanding them is important to putting together the picture of star formation in galaxies.

Submission (March/April 2009)

At long last we had our ‘story’ and we were ready to submit the Peas paper. At this point I’d sent the paper around to our co-authors several times. Each co-author contributed to the paper in a substantial way; helping me with an analysis technique (eg. Marc Sarzi and running the Peas through Gandalf), doing some original analysis (eg. Steven Bamford and the Peas environments, Nicola Bennert and the HST images, Kevin Schawinski and the Pea masses), and providing expertise and ideas which advanced the paper. I found the process of working with the Galaxy Zoo Team to be educational and very collaborative.

We submitted the paper to MNRAS in early April. More details of the submission and referee processes can be found here. We received a very helpful referee report in early June. The referee was clearly an expert on Luminous Compact Blue Galaxies and gave us many helpful references and comments. In my short time I’ve found the referee process to not only to be a ‘gate-keeping’ structure that maintains higher standards in scientific papers, but it also provides scientists a chance to hear constructive comments from another expert in the field in which the paper is written. It helps to get the perspective of someone who wasn’t intimately involved in the paper writing process.

– Carie

Bookmark It

Hide Sites

In the morning I gave a talk “Galaxy Evolution in the Galaxy Zoo”  at the “Unity of the Universe” conference in Portsmouth, a conference celebrating the opening of the new Dennis Sciama Building for the Institute of Cosmology and Gravitation (ICG, where I and several other “Zoo Keepers” work). This talk was aimed at summarizing for astronomers and cosmologists at the meeting the exciting results on galaxy evolution which have come out of Galaxy Zoo. Many researchers in astronomy are aware of Galaxy Zoo, and in general are very interested in it, but they tend to think of it more an an opportunity for outreach with the interested general public and less in terms of the exciting science which can come out of it. The point of my talk was to say that it should in fact be viewed as both. It seemed to go over well.

Over lunch I took a train to London where in the afternoon I was interviewed by an esteemed panel of scientists (including Baroness Susan Greenfield, Director of the Royal Institution, and Prof. Alec Boksenberg, Chair of the UK National Commission for UNESCO). This interview was because I was a finalist in the competition for the 2009 L’Oreal UNESCO UK/Ireland Fellowships for Women in Science. My proposal for this fellowship (for £15000) was to extend my period of study at Portsmouth so I could spend more time studying the red spirals in Galaxy Zoo (among other things). I gave a 10 minute talk about this proposed research, then answered questions from the panel.

Later that afternoon I had a L’Oreal makeover (really - but don’t worry this was not a requirement for the fellowship just a treat, and a positive sign in my opinion of a recognition that scientists can want to be feminine) and in the evening I attended a reception at the Royal Institution at which the winners of the fellowship were announced. Unfortunately I did not win the competition, but as I did make the final 8 (out of 240 applicants) I can’t feel too bad about it. I also got a nice engraved pen, met some very interesting people, and I’m assured I can still expect some free makeup. So that’s not too bad after all!

Quite a busy day in the life of an astronomer!

Bookmark It

Hide Sites

We are happy to announce that our paper, “Galaxy Zoo: Disentangling the Environmental Dependence of Morphology and Colour”, has been accepted for publication in the Monthly Notices of the RAS. We showed that much, but not all, of the correlation between a galaxy’s morphology and its large-scale environment can be explained by the correlation between galaxy colour and environment. We also showed that, among red galaxies, galaxies classified as ellipticals are more likely to be located in the central regions of galaxy groups and clusters. Finally, we argued that a relatively large fraction of red spiral galaxies are “satellite” galaxies in groups.

The pre-print of the accepted paper is available on astro-ph.

Bookmark It

Hide Sites

Alice Sheppard has had various jobs in administration, environment, teaching and writing whenever she can - but as soon as she started moderating the Galaxy Zoo Forum nearly 2 years ago, she knew that this was her real work. She’d been hooked on astronomy and science since she was very young, but the presentation of these subjects at school didn’t encourage her to think she’d ever really get involved. She studied Environmental Science at university in Norwich and Granada, Spain, and became increasingly interested in informing and involving the public. She now lives in Pembrokeshire, Wales, with her family and two cats who also contributed to scientific research for April Fool’s Day! Her involvement in the Galaxy Zoo project inspired her to start an Open University course and her current goal is to continue the work she has begun informally in the Galaxy Zoo project as a science communicator and educator. You can catch up more with Alice on her blog: Alice in Galaxyland, and she invites you to join her any time for virtual coffee and galaxy conversations in the forum.

• How did you first hear about Galaxy Zoo?

Chris (Lintott) posted a “sneak preview” on his website. I signed up on the first day . . .

• What has been your main involvement in the Galaxy Zoo project?

I’ve moderated the forum since it was started. It’s become a wonderful place - my pride and joy! I answer astronomy and technical questions, deal with problems, and organise on-forum and public events. Oh, and chat, of course. Both genders do that. Honest! I’m the only person who’s been moderating since day 1.

I’m also sort of the link between the scientists and everybody else. If Chris or Kevin or Jordan or Pamela want something, they ask me, and it’s usually me the zooites go to to get something sorted out. I also run the Object of the Day rota.

Finally I’m involved in Waveney’s Irregulars project, and have given a few talks (you can listen to one here) - which I urge lots of you to have a go at, too. It’s not hard to inspire an audience with such a great story.

• What do you like most about being involved in Galaxy Zoo?

It’s all such a great idea! It’s something every curious human should have a chance to try. It’s something people put a lot of effort and goodwill into. As I have blogged about I think this is because the modern world doesn’t value goodwill or real but unmarketable knowledge. It’s a place to be curious, to be happy, to be yourself - as well as to learn and to change the world a little by your science contribution. It’s become my true “job”, the realest thing I do, and I’ve never been happier.

While studying science at university I got interested in how to communicate it all to the public. I was disappointed that the public was seen as the enemy, or at least a liability, by my professors. As if “the mad scaremongers” were on one side while “the scientists” were on another. I felt that scientists and the public should work together. It’s one of my dreams to try and promote that, and Galaxy Zoo is such a great example of how it can work so well.

• What do you think is the most interesting astronomical question Galaxy Zoo will help to solve?

Well, the way I see it, traditional astronomy is studying a few galaxies - like a few specimens at a zoo. What we do is study the entire ecosystem. We’ve found peculiarities, and about how phenomena affect one another. Both the Voorwerp and the red spirals/blue ellipticals demonstrate quite how much is going on outside galaxies.

Personally, I would love to see what the Irregulars project will bring. Irregulars and low surface brightness galaxies are much more abundant than the famous spirals. They may turn out to be very important to the whole “ecosystem”. We’re like ecologists studying plankton and beetles, not just the lions and tigers.

• How/when did you first get interested in Astronomy?

Somewhere, there’s a photo of me aged about 6 reading a huge astronomy book. I wouldn’t know how not to be interested.

• What (if any) do you think are the main barriers to women’s involvement in Astronomy?

I don’t know much about women astronomers specifically, other than Cecilia Payne and Jocelyn Bell who were both treated outrageously unfairly. But in various jobs I’ve had, I’ve been: publicly blamed for male colleagues’ mistakes; treated like an idiot while the same male colleagues were praised for my ideas; told “we shouldn’t employ blondes”; and denied a pay rise I’d been promised before accepting the job. I’ve even had it said to me that I won’t get anywhere with the sort of public science communication I want to do because I’m not busty or good-looking enough! (I mention this not to fish for defence, but to express my fury at this “selection criteria”.)

Fortunately, this has only been done by generally loathsome people. I find the astronomical community very welcoming, and sincerely hope women working in it don’t get that sort of rubbish. It’s not only demoralising, but it might really prevent your ideas and discoveries ever being heard.

I think it is still true that it’s hard to get girls into maths and physics. I believe that males and females are often (not always) genuinely good at different things and this diversity should be embraced and utilised, not made a taboo. I’ve also noticed with many jobs that anyone “serious” and “dedicated” is expected not to spend time with their children. Which I think is terrible. Mums and carers should be treasured! Having a family one day is important enough to me that I would choose that over a career if I was forced to pick one or the other. But I found Karen’s recent post about Vera Rubin very encouraging on that front.

All that said, I think poor education is a far worse barrier than gender. For goodness sake don’t start me off on that one.

• Do you have any particular role models in Astronomy?

ZookeeperChris has to come first. Besides all his work (Chris, have you had any sleep this week?), he was kind enough to answer many, many questions by e-mail, and taught me lot of what I know! Also ZookeeperKevin, who’s taught me a lot about what working as an astronomer is like. Sir Patrick Moore is another definite. Like the zookeepers, he makes astronomy for everybody, not just a few academics.

My longest-standing hero is Russell Stannard, who wrote the “Uncle Albert” books. I love the story of Einstein, Bohr, Heisenberg, etc. They were physicists, not astronomers, but must have felt the same revolutionary excitement about relativity and quantum physics that I feel about the Zoo. Bohr believed that scientists do science not for themselves, but to explain it to others.

I hugely admire my fellow citizen scientists: Waveney, whose programming genius and creativity has brought so much to the zoo; Aida and Jules, my fellow irregular galaxy folk; Pat and Gumbosea, the gravitational lensing experts; Tom and Jules, who encouraged me to start an Open University Course; and all the people who brave the huge forum to come in and ask all the things they never got to ask at school - and other amateurs who take so much trouble to explain things, delight, and inspire. Thank you all - you help make my world.

This is the third post of the series. So far we have interviewed

• May 1st 2009: Hanny Van Arkel (Galaxy Zoo volunteer and finder of Hanny’s Voorwerp).
• June 1st 2009: Dr. Nicola Bennert (researcher at UCSB involved in Hanny’s Voorwerp followup and the “peas” project)

Still to come in the series - more Galaxy Zoo volunteers and researchers, including original team member Dr. Kate Land, Carie Cardamone (Yale graduate student and author of the “peas” paper), and others.

Bookmark It

Hide Sites

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

Bookmark It

Hide Sites

It’s somewhat of a relief to say that, as it was way back in August of last year that we first submitted it. The referee was extremely thorough, catching a few stupid mistakes we’d made (as a good referee should) and in correcting these and responding to responses for clarification the paper grew from four pages to thirteen. The basic story is still the one that Bill and I outlined more than a year ago - we think we’re seeing the result of activity associated with the black hole in the nearby galaxy IC2497 which has now ceased.

Along the way, another team of astronomers have published a paper about their radio observations of the Voorwerp; I’ll blog later in the week about how we think the two sets of observations are compatible. Hopefully they’ll do the same, and we can have a discussion in public about what we do - and don’t - agree on. By coincidence, their paper is being published in the journal Astronomy & Astrophysics this week - and their image of the Voorwerp made the front cover of the printed edition. We’ll have an image of that for you as soon as anyone involved can find a printed edition - a rare thing in this internet age.

Update : Paper is now available here.

P.S. For those keeping score, our Voorwerp paper was the 5th to be submitted, but the 6th to be accepted.

Update: The pre-print is available on astro-ph now.

Bookmark It

Hide Sites

One idea is that each episode would include short (ideally around 10 seconds) video or audio clips from members of the public asking questions of scientists. These can be questions about the science, or about their jobs, or whatever you want really. We were hoping that some Zooites reading this blog might be interested in helping out with this as a test run - and you might get to appear in one of the early episodes if it all works out. Be warned - if the clip is too long it’s much less likely to be useful. Short and to the point questions are what’s needed here.

So if you have a burning question to ask a cosmologist and you have the ability to make a short video (with a webcam for example) or audio clip (plus accompanying picture) of yourself asking this question that would be great. For now we’ll use the University of Portsmouth Web Shelf to share the files - if you upload something post a comment here with the URL and I’ll grab it (don’t worry it’ll expire a week after you upload it).

Thanks in advance for your help, Karen.

Bookmark It

Hide Sites

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.

Bookmark It

Hide Sites

We are grateful for your collaboration with us even more than usual, because for this paper, you not only classified galaxies, but some of you agreed to give a half-hour of your time to participate in an instant message or phone interview.

As with all the other papers, this paper is being sent out by the journal’s editors to one or more anonymous “peer reviewers” – practicing education researchers who read the paper and recommend that the journal either accept or reject the paper, or (most commonly) request that the authors resubmit the paper after making some improvements. The process can sometimes go a few cycles of changing and resubmitting before the paper is finally accepted. This peer review process helps ensure that scientific studies meet quality standards as judged by the community.

You might have noticed that I haven’t talked about this research on the blog yet, as other team members have done with their research. I wish I could have shared more, but there was an important reason for saving all the explanation until after the paper was submitted. It is well-known in social science research that if the group being studied is aware of the study results, all sorts of unpredictable things can happen.

However, now that the study is over, we can and will gladly share our results. I’ll do that in a series of posts, first by giving a quick summary of what we found, then writing about the ethics of conducting research with people, then about ways to avoid bias in social science, and finally posting a detailed explanation of what we found in the study and what it means.

Now for the quick summary: based on our interviews, we identified 12 motivations that volunteers have given for participating in Galaxy Zoo – 12 reasons why people like you participate. These 12 reasons are:

We included these motivations in an online survey that many of you took (thanks!), and we are now analyzing the results of that survey to find out which motivations are common and which are rare.

Knowing your motivations for participating will be greatly helpful to us and to other citizen science projects by helping us understand you better. As we understand what appeals to you about Galaxy Zoo, we can design future Zoos to meet those needs and wants. So, this research is helping us create the best Zoos we can create for you.

I really enjoyed doing the interviews, and going through all your forum responses. It’s clear that many of you have many different reasons for being a part of Galaxy Zoo, and many different and eloquent ways of expressing your reasons. A few of the reasons that you gave as part of the forum discussion stuck out in my mind. One of you said “just knowing how small you are is something that’s really hard to explain.” Another said “getting to know, at least a little, some fans and professionals in the GalaxyZoo community.” Another of you said “I’m so proud to be with You, the whole project, to be a part of something bigger than wars or politics. Because science and discovering the truth are the only things that matter.” And there were many, many others.

It’s been a real pleasure getting to know so many of your reasons for being a part of this great enterprise we call Galaxy Zoo, and we’re looking forward to continuing to work with all of you!

Bookmark It

Hide Sites