Archive by Author | Brooke Simmons

Welcome to Radio Galaxy Zoo!

Today’s post is from Ivy Wong, who is delighted to announce our newest Galaxy Zoo project.

Welcome to the extraordinary world of radio astronomy. Observe the Universe through radio goggles and discover the jets that are spewing from the cores of galaxies!

Supermassive black holes lie deep in the cores of many galaxies. And though we cannot directly see these black holes, we do occasionally see the huge jets originating from the cores of some galaxies. However, most of these jets can only be seen in the radio.

Centaurus A in the radio skyThe figure on the left compares the extent of the radio jets from Centaurus A (the nearest radio galaxy to us) to the full moon using the same scale on the sky. Also, the small white dots in this image are not stars but individual background radio sources. The antennas in the foreground are 4 of the 6 antennas that make up the Australia Telescope Compact Array where the radio image was taken.

How do galaxies form these supermassive black holes? And how does having a supermassive black hole affect the evolution of its host galaxy as well as its neighbouring galaxies? Why don’t we see jets in every galaxy with a supermassive black hole? Though much progress has been made in recent years, there are still many open questions such as the above that we can shed light on by amassing a large sample.

To probe the co-evolution of galaxies and their central supermassive black holes, help us map the radio sky by matching the radio jets and filaments to the galaxies (via the infrared images) from whence they came.

Example image with radio jets and infrared galaxies

Can you see the infrared galaxy between the radio jets?

This is a matching & recognition problem that humans are still best at, especially in cases where there are radio jets or multiple sources. And it’s an important task, one that will only become more important as the next generation of radio surveys and instruments come online and start producing enormous amounts of data. So if you’re willing to help, please try out the new Radio Galaxy Zoo and help find some growing black holes — and thank you!

UPDATE: Next Live Hangout: Tuesday, 19th of November, 7 pm GMT

Our next hangout will be next Tuesday at 7 pm European time / 6 pm UK / 3 pm in Chile / 1 pm EST / 10 am PST.

Update: Our next hangout will be next Tuesday at 8 pm European time / 7 pm UK / 4 pm in Chile / 2 pm EST / 11 am PST.

I mention Chile above because two team members will be at a conference in Chile at the time (spreading the word about Galaxy Zoo is a tough job, but someone’s got to do it) and will try to be on the hangout with us.

What do you want us to talk about? We have some ideas but if you have questions, please let us know!

Just before the hangout we’ll update this post with the embedded video, so you can watch it live from here. If you’re watching live and want to jump in on Twitter, please do! we use a term you’ve never heard without explaining it, please feel free to use the Jargon Gong by tweeting us. For example: “@galaxyzoo GONG dark matter halo“.

See you soon!

Wish You Were All Here…

Today’s post is from Ivy Wong, Science Team member and PI of an upcoming new project. She also did an amazing job organizing our Galaxy Zoo conference in Australia. Read on for details!

It has been 2 weeks since the “Evolutionary Paths in Galaxy Morphology” meeting in Sydney and I am still recovering from the post-conference brain-melt, also described in Brooke’s blog post.  Perhaps I am getting old.

The 4 days of cutting-edge science presentations and discussions went by all too quickly. And we are now left with new ideas for new projects and renewed motivation for finishing up current ones.  It is also becoming clear that the term morphology is slowly evolving from a once vague division between early- and late-type galaxies (i.e. spheroids or spirals; as inferred from observations using optical telescopes) to include more specific descriptions of a galaxy’s form which includes the 3-dimensional dynamics and kinematics.  Also, how a galaxy looks at a different wavelength will depend on factors such as how hot its interstellar medium is, how much gas it has, what state that gas is, how active is the galaxy’s central supermassive black hole and whether it is experiencing any harassment by its neighbours and local environment.

As our understanding of galaxy morphology evolves, so too will the Galaxy Zoo project.  As you may have heard, the next generation Galaxy Zoo project will show us morphologies that will be completely alien to most of us, even those who enjoy a regular dose of science fiction.  The new Radio Galaxy Zoo project will show us images observed in the radio wavelengths, typically coming from synchrotron radiation. Synchrotron emission results from accelerated charged particles moving at relativistic velocities and is usually seen as outflows/jets from a galaxy’s central supermassive black holes.

Though this already happened during the conference dinner, I’d like to take this opportunity to make a repeat of the toast (albeit virtually) to the >800,000 citizen scientists who has helped us thus far. It would have been lovely to have you all join us at the meeting, but we would have probably sunk our dinner boat. So if you’re interested in checking out some of the presentations from this meeting, please go to:

The official conference program booklet will help put these presentations into context and can be found at:…es/gzconf_booklet.pdf

Am definitely looking forward to the next big Galaxy Zoo conference. Perhaps somewhere up North next time?

Post-conference relaxing in Sydney Harbour.

A Galaxy Zoo conference is not complete without after hours drinks by the harbour. From left to right: Brooke, Karen, Jeyhan, Julie & Ivy in pic 1. Amit, Kyle, Bill, Chris L. & Chris S. in pic 2. (Photo credit: Amanda Bauer aka @astropixie)

Galaxy Zoo Continues to Evolve

M31 at ultraviolet, optical, mid-IR wavelengths

Over the years the public has seen more than a million galaxies via Galaxy Zoo, and nearly all of them had something in common: we tried to get as close as possible to showing you what the galaxy would actually look like with the naked eye if you were able to see them with the resolving power of some of the world’s most advanced telescopes. Starting today, we’re branching out from that with the addition of over 70,000 new galaxy images (of some our old favorites) at wavelengths the human eye wouldn’t be able to see.

Just to be clear, we haven’t always shown images taken at optical wavelengths. Galaxies from the CANDELS survey, for example, are imaged at near-infrared* wavelengths. But they are also some of the most distant galaxies we’ve ever seen, and because of the expansion of the universe, most of the light that the Hubble Space Telescope (HST) captured for those galaxies had been “stretched” from its original optical wavelength (note: we call the originally emitted wavelength the rest-frame wavelength).

Optical light provides a huge amount of information about a galaxy (or a voorwerpje, etc.), and we are still a long way from having extracted every bit of information from optical images of galaxies. However, the optical is only a small part of the electromagnetic spectrum, and the other wavelengths give different and often complementary information about the physical processes taking place in galaxies. For example, more energetic light in the ultraviolet tells us about higher-energy phenomena, like emission directly from the accretion disk around a supermassive black hole, or light from very massive, very young stars. As a stellar population ages and the massive stars die, the older, redder stars left behind emit more light in the near-infrared – so by observing in the near-IR, we get to see where the old stars are.

The near-IR has another very useful property: the longer wavelengths can mostly pass right by interstellar dust without being absorbed or scattered. So images of galaxies in the rest-frame infrared can see through all but the thickest dust shrouds, and we can get a more complete picture about stars and dust in galaxies by looking at them in the near-IR.

SDSS 587722982831358015 in optical and infrared from UKIDSS

Even though the optical SDSS image (left) is deeper than the near-IR UKIDSS image (right), you can still see that the UKIDSS image is less affected by the dust lanes seen at left.

Starting today, we are adding images of galaxies taken with the United Kingdom Infrared Telescope (UKIRT) for the recently-completed UKIDSS project. UKIDSS is the largest, deepest survey of the sky at near-infrared wavelengths, and the typical seeing is close to (often better than) the typical seeing of the SDSS. Every UKIDSS galaxy that we’re showing is also in SDSS, which means that volunteers at Galaxy Zoo will be providing classifications for the same galaxies in both optical and infrared wavelengths, in a uniform way. This is incredibly valuable: each of those wavelength ranges are separately rich with information, and by combining them we can learn even more about how the stars in each galaxy have evolved and are evolving, and how the material from which new stars might form (as traced by the dust) is distributed in the galaxy.

redshifted galaxy images

1 galaxy, 4 redshifts.

In addition to the more than 70,000 UKIDSS near-infrared images we have added to the active classification pool, we are also adding nearly 7,000 images that have a different purpose: to help us understand how a galaxy’s classification evolves as the galaxy gets farther and farther away from the telescope. To that end, team member Edmond Cheung has taken SDSS images of nearby galaxies that volunteers have already classified, “placed” them at much higher redshifts, then “observed” them as we would have seen them with HST in the rest-frame optical. By classifying these redshifted galaxies**, we hope to answer the question of how the classifications of distant galaxies might be subtly different due to image depth and distance effects. It’s a small number of galaxies compared to the full sample of those in either Galaxy Zoo: Hubble or CANDELS, but it’s an absolutely crucial part of making the most of all of your classifications.

As always, Galaxy Zoo continues to evolve as we use your classifications to answer fundamental questions of galaxy evolution and those answers lead to new and interesting questions. We really hope you enjoy these new images, and we expect that there will soon be some interesting new discussions on Talk (where there will, as usual, be more information available about each galaxy), and very possibly new discoveries to be made.

Thanks for classifying!

* “Infrared” is a really large wavelength range, much larger than optical, so scientists modify the term to describe what part of it they’re referring to. Near-infrared means the wavelengths are only a bit too long (red) to be seen by the human eye; there’s also mid-infrared and far-infrared, which are progressively longer-wavelength. For context, far-infrared wavelengths can be more than a hundred times longer than near-infrared wavelengths, and they’re closer in energy to microwaves and radio waves than optical light. Each of the different parts of the infrared gives us information on different types of physics.

** You might notice that these galaxies have a slightly different question tree than the rest of the galaxies: that’s because, where these galaxies have been redshifted into the range where they would have been observed in the Galaxy Zoo: Hubble sample, we’re asking the same questions we asked for that sample, so there are some slight differences.

Top Image Credits and more information: here.

Evolutionary Paths In Galaxy Morphology: A Galaxy Zoo Conference

This week much of the team has been in Sydney, Australia, for the Evolutionary Paths In Galaxy Morphology conference. It’s a meeting centered largely around Galaxy Zoo, but it’s more generally about galaxy evolution, and how Galaxy Zoo fits into our overall (ever unfolding) picture of galaxy evolution.

Chris Lintott Galaxy Zoo

There’s a lot to that legacy already, and it’s still being written.

The first talk of the conference was a public talk by Chris, fitting for a project that would not have been possible without public participation. Chris also gave a science talk later in the conference, summarizing many of the different results from Galaxy Zoo (and with a focus on presenting the results of team members who couldn’t be at the meeting). For me, Karen’s talk describing secular galaxy evolution and detailing the various recent results that have led us to believe “slow” evolution is very important was a highlight of Tuesday, and the audience questions seemed to express a wish that she could have gone on for longer to tie even more of it together. When the scientists at a conference want you to keep going after your 30 minutes are up, you know you’ve given a good talk.

In fact, all of the talks from team members were very well received, and over the course of the week so far we’ve seen how our results compare to and complement those of others, some using Galaxy Zoo data, some not. We’ve had a number of interesting talks describing the sometimes surprising ways the motions of stars and gas in galaxies compare with the visual morphologies. Where (and how bright) the stars and dust are in a galaxy doesn’t always give clues to the shape of the stars’ orbits, nor the extent and configuration of the gas that often makes up a large fraction of a galaxy’s mass.

Karen Masters Galaxy Zoo Secular Evolution

Karen explains her simple and clear diagram showing different galaxy evolutionary processes.

This goes the other way, too: knowing the velocities of stars and gas in a galaxy doesn’t necessarily tell you what kinds of stars they are, how they got there, or what they’re doing right now. I suspect a combination of this kinematic information with the image information (at visual and other wavelengths) will in the future be a more often used and more powerful diagnostic tool for galaxies than either alone.

Overall, the meeting was definitely a success, and throughout the meeting we tried to keep a record of things so that others could keep up with the conference even if they weren’t able to attend. There was a lot of active tweeting about the conference, for example, and Karen and I took turns recording the tweets so that we’d have a record of each day of the Twitter discussion. Here those are, courtesy of Storify:

Day 1  |  Day 2  |  Day 3  |  Day 4

Also, remember at our last hangout when we said we’d have a hangout from Sydney? That proved a bit difficult, not just because of the packed meeting schedule but also because of bandwidth issues: overburdened conference and hotel wifi connections just aren’t really up to the task of streaming a hangout. We eventually found a place, but then it turned out there was construction going on next door, so instead of the sunny patio we had intended to run the hangout from we ended up in an upstairs bedroom to get as far away from the noise as possible. Ah, well. You can see our detailed discussion of how the meeting went below, including random contributions from the jackhammer next door (but only for the first few minutes):

(click here for the podcast version)

And now we’ll all return (eventually) to our respective institutions to reflect on the meeting, start work on whatever new ideas the conference discussions, talks and posters started brewing, and continue the work we had set aside for the past week. None of this is really as easy as it sounds; the best meetings are often the most exhausting, so it takes some time to recover. I asked our fearless leader Chris if he had a pithy statement to sum up his feeling of exhilarated post-meeting fatigue, and he took my keyboard and offered the following:

gt ;////cry;gvlbhul,kubmc ;dptfvglyknjuy,pt vgybhjnomk

I’m sure that, if any tears were shed, they were tears of joy. This is a great project and it’s only getting better.

Galaxy Zoo Team in Sydney

Left to Right: Tom, Kevin, Bob, Amit, Ed, Chris S, Bill, Kyle, Chris L, Ivy, Brooke, Karen, Julie

More Galaxies, More Clicks, More Science!

Just a quick update: recently we brought some of our high-redshift (i.e., very distant) galaxies out of retirement. There’s enough going on in these galaxies that having more clicks from you will really help tease out the nuances of the various features and make the classifications even better.

CANDELS featured galaxies

How would you classify these?

So, for those of you who noticed you hadn’t seen many CANDELS galaxies recently, well, you’re about to see a few more. I can’t promise they’ll always be easy to classify, but I hope they’ll at least be an interesting puzzle. As ever, thank you for your classifications!

What is a Galaxy? …the return

Abell S740 / HST

The first time I gave a public talk, I spent an hour describing why galaxy classification is fundamentally important to the study of the Universe, the origins of Galaxy Zoo, the amazing response of the volunteers and the diverse results from their collective classifications of a million galaxies near and far. I showed many gorgeous galaxy images, a few dark matter simulations and even a preview of the Hubble image of Hanny’s Voorwerp.

As I finished my talk and the Q&A began, I braced myself for the inevitably interesting and challenging questions (I seem to get a lot of questions about black holes and spacetime).

A brief pause, and then the first question echoed from somewhere in the darkened auditorium: …”What’s a galaxy?

Oops. Apparently I’d forgotten that little detail at the start of the talk. So I described a typical galaxy (if there is such a thing): a collection of stars, gas, dust, dark matter, all gravitationally bound together. Then I made a joke about scientists forgetting to define their terms, and we moved on to the next raised hand.

Turns out, though, it’s not such an easy question. Even though my casual definition works fine for most galaxies, it’s not at all an agreed-upon standard. We’ve discussed this on the blog before, and even in the short time (astronomically speaking) since Karen wrote that very nice post, more work has been done to find galaxies that push the boundaries and force us to re-think what it really means to be a galaxy.

Segue 1

The circled stars (plus a lot of dark matter you can’t see) are Segue 1, one of the smallest galaxies we know about. To read more on this, click the image.

So, spurred by a very broad interpretation of a question left for us in the comments on the post announcing this hangout, we decided to re-visit the discussion, covering the various properties a galaxy must have, should have, could have, and can’t have. We discussed the smallest galaxies, found by counting and measuring each of their individual stars. We discussed the biggest, brightest galaxies in the universe, living in rich environments and grown fat by eating other galaxies. And everything in between.

(podcast version here)

Note: when we talk about Segue 1 and 2, I say that these galaxies are unique because they have low mass-to-light ratios. Despite the pause that indicated I was trying to keep from inverting numerator and denominator… that’s exactly what I did. The galaxies have very few stars compared to the amount of dark matter in them, so their mass is high and their light is low, so their mass-to-light ratios are high. Oops (again)!

Next GZ Hangout: 3rd of September, 3 pm GMT

The hangouts have returned from a midsummer hiatus! Our next hangout will be Tuesday, September 3rd, at 3 pm GMT. That’s 8 am PDT, 11 am EDT, 4 pm BST, 5 pm CET, 6 pm CAT. Unfortunately I think that’s 11 pm in Japan and midnight in Sydney, but hopefully we’ll have a hangout at a different time very soon!

Just before the hangout we’ll update this post with the embedded video, so you can watch it live from here. If you’re watching live and want to jump in on Twitter, please do! we use a term you’ve never heard without explaining it, please feel free to use the Jargon Gong by tweeting us. For example: “@galaxyzoo GONG dark matter halo“.

In the meantime, please feel free to leave a question in the comments below. See you soon!

Update: read a summary of the Hangout here: What is a Galaxy?… the Return

Next GZ (Tools!) Hangout: Wednesday 24th July, 20:30 GMT

With the Quench project well underway and the start of the next phase of the project around the corner, it’s time for another hangout — this time with a focus on using the new Zoo Tools data analysis suite to work with Quench data!

We’ll start at 15:30 CDT (Chicago), which is 13:30 PDT, 16:30 EDT, 20:30 GMT, 21:30 BST, 22:30 CET, and 23:30 CAT. That’s getting a bit late for Europe and Africa, but if you can’t make the hangout on the day, don’t worry, we’ll post the recording of it as soon as possible.

Have questions? Post them here or tweet at us (@galaxyzoo). Just before the hangout starts, we’ll embed the video here so you can watch from the blog. And feel free to try out (and check out the Zooniverse blog post about it) beforehand!

The best way to send us a comment during the live hangout is to tweet at us, but you can also leave a comment on this blog post, or on Google PlusFacebook or YouTube, which we’ll also try to keep an eye on. See you soon!

Note: if you’d prefer a text-based tutorial, check out this Zooniverse blog post.

Zooniverse Live Chat

This just in: join the Zooniverse (including Galaxy Zoo) for a live hangout tomorrow from Chicago!


A small team of scientists and developers from across the Zooniverse are gathered at Adler Planetarium in Chicago this week to pitch and work on ideas for advanced tools for some of your favorite Zooniverse projects. Our goal is to come up with some  tools and experiences that will help the Zooniverse volunteers further explore, beyond the scope of the main classification interfaces, the rich datasets behind the projects in new and different ways. As part of the three days of hacking, there will be a live chat with representatives from Galaxy Zoo, Planet Hunters, Snapshot Serengeti, and Planet Four (as well as a special guest or two) tomorrow Thursday July 11th at 2pm CDT ( 3 pm EDT, 8 pm BST). We’ll also give you an inside peek into the US Zooniverse Headquarters on the floor of the Adler Planetarium where much of the coding and…

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