Tag Archive | Galaxies

Tagging Galaxies in Talk

One of the cool features of the new Galaxy Zoo Talk is that you can tag objects using the # character. For example, if you see two overlapping galaxies like NGC 3314…

ESA Hubble Space Telescope has produced an incredibly detailed image of a pair of overlapping galaxies called NGC 3314. While the two galaxies look as if they are in the midst of a collision, this is in fact a trick of perspective: the two are in chance alignment from our vantage point (Credit: NASA).

… then you can tag it with #overlap when commenting on it. That way, anyone with an interest in overlapping galaxies can find it by just clicking on #overlap. There’s already a discussion on tags on Talk, but if you find something that needs tagging, you can always start your own. Just use the # character!

New Images in the New Galaxy Zoo

This post is the first of a series introducing the new Galaxy Zoo. The second is here, but come back in the next few days for more information about our fabulous new site

As you’ve probably already noticed, the Galaxy Zoo interface got a shiny new facelift thanks to the wizards in the Zooniverse development team, but that’s not all. The site is stuffed with new galaxies! These brand new, never-seen-before images come from two places:

SDSS

The new SDSS images (right), drawn from the latest data release, are better and hopefully easier to classify than the old (left).

You might remember that the original Galaxy Zoo 1 and 2 used images from the Sloan Digital Sky Survey (SDSS), a robotic telescope surveying the ‘local’ Universe from its vantage point in New Mexico. These images are now prepared in a slightly different way, in order to highlight subtle details. To better understand these galaxies, drawn from our own backyard, we’re making those improved images available through the new Zoo classification page. (These are actually new galaxies, from parts of the sky that SDSS hadn’t surveyed when we launched Zoo 2).

Hubble

We’ve already gone though Hubble Space Telescope images with the Hubble Zoo, but there are some exciting new observations available from Hubble that we just couldn’t pass on. In 2009, astronauts on Space Shuttle mission STS-125 visited Hubble for a final time and installed an exciting new camera in the telescope. This camera, called Wide Field Camera 3 (WFC3) can take large (by Hubble standards!) images of the infrared sky.

NASA astronauts installing the new Wide Field Camera 3 on the Hubble Space Telescope during the final Service Mission 4 (credit: NASA).

As we peer deeper into the Universe, we look into the past, and since the universe is expanding, the galaxies we see are moving away from us faster and faster. This means that the light that left them gets stretched by the time it reaches us. Thus, the light from stars gets “redshifted” and to see a galaxy in the early universe as it would appear in visible light locally, we need an infrared camera.

A weird “clumpy” galaxy spied by Hubble in the early universe. Galaxies like this don’t seem to be around anymore in the local universe, so we’d love to know better what they are and what they will turn into…

Taking infrared images is much harder than optical ones for many reasons, but the most important is that the night sky actually glows in the infrared. This fundamentally limits our ability to take deep infrared images, which is why Hubble’s new WFC3 with its infrared capability is so valuable: in space, there’s no night sky! Hubble is currently using the WFC3 to survey several patches of the sky as part of the CANDELS program (more on that soon!) to generate deep infrared images of galaxies in the early universe and we’re asking you to help us sort through them.

Talk

We are also introducing Galaxy Zoo Talk, a place where you can post, share, discuss and collect galaxies you find interesting and want to learn more about. You can of course still join us on the Forum, but Talk will make it easier for you to systematically discuss and analyse your galaxies.

There’s a whole new mountain of galaxies to go through, so happy classifying!

Galaxy Merger Gallery

I’m Joel Miller, I’m just about to start year 13 at The Marlborough School, Woodstock, and I am here at Oxford University working on mergers from the Galaxy Zoo Hubble data as part of my Nuffield Science Bursary. I have/will be looking at the data and plotting graphs to see how the fraction of galaxies which are mergers changes with other factors therefore determining if there is a correlation between these factors and galaxy mergers. Having looked though many images of merging galaxies I found some really amazing ones.

With some of the images from the SDSS I was able to find high-res HST images of the same galaxy and also find out some more information about them.

Spiral Galaxies NGC 5278 and NGC 5279 (Arp 239) in the Constellation of Ursa Major form an M-51-like interacting pair. This group is sometimes called the “telephone receiver”. The galaxies are not only connected via one spiral arm like M-51, but they also have a dimmer bridge between their disks. Spiral galaxies UGC 8671 and MCG +9-22-94 do not have measured red shifts and therefore there is no data on their distances. They may well be a part of a small cluster of galaxies that includes the “telephone receiver”, but this is not determined at this time.

NGC 5331 is a pair of interacting galaxies beginning to “link arms”. There is a blue trail which appears in the image flowing to the right of the system. NGC 5331 is very bright in the infrared, with about a hundred billion times the luminosity of the Sun. It is located in the constellation Virgo, about 450 million light-years away from Earth.

This pair of Spiral Galaxies in Virgo is known as “The Siamese Twins” or “The Butterfly Galaxies”. Both are classic spiral galaxies with small bright nuclei, several knotty arms, and arm segments. Both also have a hint of an inner ring. The pair is thought to be a member of the Virgo Galaxy Cluster. NGC 4568 is currently the host galaxy of Supernova 2004cc (Type Ic) and was also the host of Supernova 1990B a Type Ic that reached a maximum magnitude of 14.4.

Arp 272 is a collision between two spiral galaxies, NGC 6050 and IC 1179, and is part of the Hercules Galaxy Cluster, located in the constellation of Hercules. The galaxy cluster is part of the Great Wall of clusters and superclusters, the largest known structure in the Universe. The two spiral galaxies are linked by their swirling arms and is located about 450 million light-years away from Earth.

This galaxy pair (Arp 240) is composed of two spiral galaxies of similar mass and size, NGC 5257 and NGC 5258. The galaxies are visibly interacting with each other via a bridge of dim stars connecting the two galaxies. Both galaxies have supermassive black holes in their centres and are actively forming new stars in their discs. Arp 240 is located in the constellation Virgo, approximately 300 million light-years away, and is the 240th galaxy in Arp’s Atlas of Peculiar Galaxies.

With the exception of a few foreground stars from our own Milky Way all the objects in this image are galaxies.

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. 🙂

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!

New Dataset from Galaxy Zoo!

We’ve posted a new data set here: http://data.galaxyzoo.org/#agn

This sample is presented in the Galaxy Zoo 1 paper on AGN host galaxies (Schawinski et al., 2010, ApJ, 711, 284). It is a volume-limited sample of galaxies (0.02 < z < 0.05, M_z < -19.5 AB) with emission line classifications, stellar masses, velocity dispersions and GZ1 morphological classifications. When using this sample, please cite Schawinski et al. 2010 and Lintott et al. 2008, 2011.

Download here: http://galaxy-zoo-1.s3.amazonaws.com/schawinski_GZ_2010_catalogue.fits.gz

Column definitions are as follows:

  • OBJID – SDSS object ID
  • RA, DEC – RA and Dec in J2000
  • REDSHIFT – SDSS spectroscopic redshift
  • GZ1_MORPHOLOGY – Galaxy Zoo 1 morphology according to the Land et al. (2008) “clean” criterion. GZ_morphology is an integer where 1-early type, 4-late type, 0-indeterminate, 3-merger
  • BPT_CLASS – 0-no emission lines, 1-SF, 2-Composite, 3-Seyfert and 4-LINER (see Schawinski et al. 2010 for details)
  • U,G,R,I,Z -SDSS modelMag extinction corrected but not k-corrected
  • SIGMA, SIGMA_ERR – Stellar velocity dispersion measured using GANDALF
  • LOG_MSTELLAR – log of stellar mass
  • L_O3 – Extinction-corrected [OIII] luminosity

Star-formation, AGN and Ultra-luminous infrared galaxies

An update on mergers from Alfredo:

Star-formation, AGN and Ultra-luminous infrared galaxies (ULIRGs)

Looking at our galaxies in the infrared allows us to discover the overall star-formation rate of the system. Yet if we are interested in the fine details of what really fuel the energetic output of our mergers we need to have a closer look to the light we get from them.

Using a emission lines comparison technique called BPT (after Baldwin & Phillips & Terlevich 1981) we can tell what is really going on at the core of our galaxies.

TV News says we don’t see any significant difference between the general IRAS-detected and the Luminous infrared galaxies. However, when we look at the most luminous infrared galaxies, the ULIRGs the fraction of AGN rises dramatically. This result is important because it conforms to many other studies on the role of AGN in ULIRGs.

We also explore the timescale for a LIRG to become a ULIRG. This is obviously an imperfect analysis for various reasons: firstly not all LIRGs turn into ULIRGs, secondly we use Newtonian mechanics in our calculations and lastly our constraints are quite approximate.

Gyr = gigayear = a billion years

We assume that the Infrared luminosity peaks when the two galaxies coalesce, so we discard all the post-merger LIRGs. Another requirement is that the total mass of the progenitor system is less than the mass of the ULIRGs. We calculate the distance between the two cores and we used a typical group velocity of 400km/s. Under those conditions we find a timescale of 50 million years.

Meeting the Astronomy World

This guest post is from Anna Han, an undergrad working on the Hubble data from Galaxy Zoo:

I attended the AAS Conference in Austin, Texas with the Yale Astronomy and Physics Department to present the results from my research last summer. Many thanks to everyone in the department and Galaxy Zoo who gave me this opportunity and continue to support me through my work. It is because of their guidance that I was able to present a research poster at the conference this winter and enjoy a whole new experience.

The AAS Conference was fascinating, motivating, and overwhelming all at the same time. Starting from 9:00am every morning, I listened to various compact 10-minute talks given by various PhD candidates, post-docs, and researchers from around the world. Though I must admit some of the ideas presented went over my head, I learned more and more with each talk I heard.

The midday lunch breaks made up one of my favorite parts of the conference. Yes, the ribs in Texas are good. But no amount of delicious southern cuisine compares to how welcome and at ease I felt with fellow astronomers kind enough to invite me, a newbie sophomore undergraduate, to lunch. Lunch became my 2-hour my opportunity to talk one-on-one with other researchers and get informed on their work. When my questions ran out, I gladly took the chance to introduce my own research and use their feedback to better prepare for my poster presentation.

On Thursday morning, I tacked up my poster in the exhibit hall and stood guard, armed with organized details of my research and cookies as bait. Let me confess now that I have never been at or in a science fair, but I imagine it must be similar to what I experienced that day. Non-scientist citizens and experts in AGN alike perused my poster and asked questions. Every once in a while I recognized a familiar face: members from my research group, students I had befriended throughout the conference, and fellow researchers I had shared lunch with stopped by to see my poster. Explaining my research to someone who was interested (either in my work or the cookies) was an immensely rewarding experience. I felt proud of what I had accomplished and so thankful to the people who helped me do it. The encounters with other people also gave me ideas for future directions I could proceed in.

This semester, I plan to continue searching for multiple AGN signatures in grism spectra of clumpy galaxies. My experience at the AAS Conference has inspired me to develop a more systematic search for clumpy galaxies using Galaxy Zoo and explore in more detail the possibility of low redshift galaxies containing multiple AGN. To the citizens of Galaxy Zoo, thank you again, and I hope for your continued support!

You can get a full res PDF version of the poster here.

Post-starburst galaxies paper accepted!

Great news everybody!

The post-starburst galaxies paper has now been accepted by MNRAS. You can find the full paper for download on astro-ph.

Pretty galaxies on the BBC Big Screens

As part of National Science and Engineering Week, 11-20th March 2011 in the UK I was involved in the production of a series of 5 short videos called “From the Earth to the Edge of the Universe” which were made as a collaboration between Creative Technologies and the Institute of Cosmology and Gravitation at the University of Portsmouth. They are going on the BBC Big Screens, apparently right across the UK and continuing up until the 2012 Olympics.

Bear with me, this isn’t just an advert. The reason for the post is that my segment is all about galaxy morphologies. I talk (briefly) about Galaxy Zoo and show the HST image of Hanny’s Voorwerp. I also describe some of the main morphological features of galaxies, and what I like about them. So I thought you might like to watch it (sorry I can’t figure out how to embed it – the below is just a screen shot).KLMvideo

Karen – From Earth To The Edge Of The Universe from CCi Live on Vimeo.

You can watch all 5 videos here.

Cheers, Karen.