A new paper about spiral galaxies in Galaxy Zoo

I’m happy to announce that my first Galaxy Zoo paper has been published! You may be aware that I recently posted about spiral galaxies in Galaxy Zoo (the blog post can be found here). The first results from these studies have now made it to publication, where we discuss a new method for removing bias in galaxy classifications, as well as comparing the properties of different spiral galaxies.

spirals

Some example 1, 2, 3, 4 and 5+ armed spiral galaxies classified in Galaxy Zoo.

As discussed in my earlier blog post, spiral galaxies are some of the most interesting galaxies in the local Universe. However, studies of these objects have been limited, due to the fact that galaxies need to be visually classified. It is therefore thanks to all of the volunteers in Galaxy Zoo that a paper like this can be published, where we have thousands of spiral galaxies to compare. Thanks to these classifications, we have been able to find some interesting preliminary results: we find that many-armed spiral galaxies are bluer in colour than two-armed spiral galaxies. This suggests that many-armed spirals are sites of significantly enhanced activity in the Universe, where high levels of star formation activity are taking place.

cc1

Colours of spiral galaxies by arm number. Lower u-r  and r-z mean galaxies are bluer in colour (many-armed galaxies show bluer colours).

However, these results are only a hint at what we can achieve in the future. So watch this space and we’ll keep you all informed about any developments in our work on spiral galaxies!

If you are interested in reading more, the full article can be found here.

 

Discovered galaxy cluster named after two citizen scientists

This post was written as a contribution by Timothy Friel, an undergraduate Australian National University student studying Theoretical Physics and Science Communication. Tim is conducting research into citizen science projects and their social media communication strategies.


Hats off to two of our volunteer participants who have officially been written in the stars.

The Matorny-Terentev Cluster RGZ-CL J0823.2+0333 bears the name of the two citizen scientists who pieced together its structure.

Ivan Terentev and Tim Matorny, two Radio Galaxy Zoo participants from Russia, discovered that a particular radio-source had a line of radio blobs delineating a C-shaped ‘Wide-Angle Tail galaxy’ (WAT). The massive galaxy hosting the super-massive black hole and its associated jets are moving through intergalactic gas, causing the jets to fold back, similar to the way a sky-diver’s hair is shaped by the wind.

giantWAT-pink-zoom

Figure 1: The new discovery: The C-shaped “wide angle tail galaxy” (pink) surrounded by the galaxies of the Matorny-Terentev cluster (white). Julie Banfield, Author provided

This discovery has been published this week in the prestigious scientific journal Monthly Notices of the Royal Astronomical Society, with the paper “Radio Galaxy Zoo: discovery of a poor cluster through a giant wide-angle tail radio galaxy” (accessible for free via bit.ly/RGZpaperWAT).

Lead author of the study, Dr Julie Banfield of CAASTRO at The Australian National University (ANU), said that the discovery surprised the astronomers running the program.

“They found something that none of us had even thought would be possible”, said Dr Banfield.

More details of the research team’s response and the next steps for the project can be read in the press release published by CAASTRO (bit.ly/PR14June16).

A huge congratulations must go to the two citizen scientists, Ivan and Tim, for their efforts to work collaboratively to make this discovery. It is great to witness that physical and language barriers have been unable to halt amazing scientific endeavours.

A further thank you must also be noted for the Radio Galaxy Zoo team, in particular the joint project leaders Dr Julie Banfield (ANU) and Dr Ivy Wong (ICRAR at UWA), alongside Dr Anna Kapinska (ICRAR at UWA), Dr Ray Norris (CSIRO/WSU) and all other members of the international project. The team’s continued energy to motivate volunteer participants to develop their own research projects has uncovered the immense potential of citizen science as both a research tool and a method of bringing people together across the globe.

Finally, the Radio Galaxy Zoo team would like to thank the 10,000 volunteers globally who have volunteered to conduct over 1.6 million image classifications over the past two and a half years. The dedication of volunteers to this project has bred a supportive community which has now completed almost 60% of the dataset, a feat unable to be achieved by any single individual.

If you would love to become involved in this international astronomical community, please head to bit.ly/RadioGalaxyZoo1 and begin your journey to uncover the depths of our universe and its wonders, all from the comfort of your own home.


ANU: Australian National University
CAASTRO: Australian Research Council Centre of Excellence for All-Sky Astrophysics
CSIRO: Commonwealth Scientific and Industrial Research Organisation
ICRAR: International Centre for Radio Astronomy Research
UWA: University of Western Australia

Kyle’s Legacy

Screen Shot 2016-05-31 at 10.55.36

Good news! Early this morning UK time, we submitted the paper describing the finished data release for the third iteration of Galaxy Zoo to the journal Monthly Notices of the Royal Astronomical Society. It’s taken an enormous amount of work to get to this point, in particular in understanding how to account for the effects of distance on classifications. Most of that work was done by Kyle Willett and Mel Galloway from the University of Minnesota (Kyle gave a sneak preview here), and it was finished just in time because Kyle leaves us tomorrow.

Kyle and friend at his leaving party.

Kyle and friend at his leaving party.

Kyle has had an enormous impact on Galaxy Zoo since he came on board in 2011. As well as publishing papers on star formation and the enormous data release paper for Galaxy Zoo 2, he’s been the person making images, coordinating what’s seen on the site and keeping an eye on classifications as they’ve come in. Just as importantly, he’s been a prolific contributor to this blog, playing a leading role in keeping our important collaborators, the volunteers, in touch with what’s going on. It’s not just Galaxy Zoo, either, as Kyle has also played a critical role in the Radio Galaxy Zoo team, and has made major contributions to their recent papers too. He will be much missed by all of us, though we wish him well with his future endeavours.

Upcoming Galaxy Zoo: Hubble and CANDELS papers

It’s been a good amount of time since the Galaxy Zoo: Hubble and Galaxy Zoo: CANDELS projects were finished, tackling more than 200,000 combined galaxies thanks to the efforts of our volunteers. While we’ve had a couple of science papers based on the early results (Melvin et al. 2014, Simmons et al. 2014, Cheung et al. 2015), a full release of the data and catalog has taken slightly longer. However, we’ve been working hard, testing the data, and developing some new analysis methods on both image sets. This month has been really exciting, and we now have drafts for both papers that are just about finished. Once they’ve been accepted to the journals (and revised, if necessary), we’ll have some much longer posts discussing the results, and of course attaching the papers themselves. Hopefully that’ll be quite soon.

As a small teaser, here’s a little movie I just made of the Galaxy Zoo: Hubble paper as it went through the various drafts by different members of the science team. If only all paper writing were this easy …😉

How to write a Galaxy Zoo paper in 15 seconds ...

How to write a Galaxy Zoo paper in 15 seconds or less … (Image: K. Willett)

Models of Merging

Once upon a time, there was an experimental project called Galaxy Zoo: Mergers. It used ancient, mystical technology to allow volunteers to run simulations of merging galaxies on their computers, and to compare the results of many such simulations. Their mission: to find matches to more than fifty nearby mergers selected from Galaxy Zoo data.

The wonderful Penguin Galaxy, studied in the project.

The wonderful Penguin Galaxy, studied in the project.

Amongst the chosen galaxies were not just run-of-the-mill, everyday mergers, but also the various oddities that the volunteers found, such as the Penguin galaxy. The team led volunteers through a series of tournaments designed to pit potential solutions for a particular galaxy against each other. In total, more than 3 million simulations were reviewed producing the results described in the paper, now accepted by the journal MNRAS, and in the dataset visible at the main Galaxy Zoo data repository. This represents a huge amount of effort, and a speeding up of the process – in the paper, we note that previous fits to mergers have taken months of effort to complete.

Which is not to say the analysis, led by Anthony Holincheck and John Wallin, has been easy. In a recent email to the Galaxy Zoo team, John commented:

This is by far the most complex project I have ever worked on. Most papers that model interacting galaxies contain one or two systems where the author uses a few dozen simulations. We just published a paper that modeled 62 different systems using a brand new modeling technique where the 3 million simulation results were reviewed by citizen scientists. Best of all, the 62 models were done using the same code and the same coordinate system so others can reproduce them. Doing this with other published simulations is nearly impossible.

I know an immense amount of effort went into making sure that the results weren’t wasted, and the paper thus represents a happy ending to a tale that’s been running a long time. But it is not really an end; we are already planning to observe some of these galaxies as part of surveys like MaNGA that can measure the way that the galaxies’ components are moving today, allowing us to test these models. We also hope a library of models might be useful for other astronomers, and will be looking to try and revive this kind of project.

Read more about Galaxy Zoo: Mergers in this old blog post blog.galaxyzoo.org/2012/03/27/the-finale-of-merger-zoo.

Exclusive interview with our recent Citizen Science co-authors

This post was written as a contribution by Timothy Friel, an undergraduate Australian National University student studying Theoretical Physics and Science Communication. Tim is conducting research into citizen science projects and their social media communication strategies.


Meet two of our fantastic Zooniverse members who have been recognised as co-authors for a RGZ submitted paper.

In March 2016, the Radio Galaxy Zoo (RGZ) team submitted a paper which is co-authored by two of our SuperRGZooites. Thanks to the help of citizens around the world, over 1.6 million classifications have been made. However, a very special thanks must go to two citizens who have been greatly involved in our most recent submitted paper.

19MAR2016

Meet Ivan Terentev and Tim Matorny, our Citizen Science co-authors.

How did you discover Radio Galaxy Zoo and become involved?

Tim: I had a passion for research and to be involved with generating new knowledge. So I began to look and met [the world of] citizen science and tried many different projects. I was already familiar with the Zooniverse, when I got email about new project – RGZ.

Ivan: I became involved in RGZ from its beginning, more or less, in December 2013, and at that time I was part of the Zooniverse for two years. I was mostly contributing to the Planet Hunters project back then, but occasionally I switched to different projects just to look for what they have to offer. And it was during one of these “Let’s try something different” moments that I discovered RGZ through the announcement post in the Galaxy Zoo blog.

What parts kept you interested and motivated to stay a part of this project?

Tim: The team of scientists and their active participation is an important part. Their blog posts, comments and links have helped me to learn about the project and my involvement with the goals.
Looking for host radio lobes which are separated by a 10′ [minutes] or looking at the behaviour of jets in galaxies clusters is really exciting for me. I like that RGZ covers a wide range of data: radio, optics, IR, X-ray.

Ivan: If we are talking specifically about RGZ, it would be the RGZ Talk community and the fact that RGZ Science team is eager to communicate with simple volunteers and involve them in the research process. But a large portion of my motivation [for RGZ] is the same as for the rest of the Zooniverse projects. You see, I am sci-fi fan and it made me interested in space exploration. I like to watch documentaries about the astronomers, their work and all the amazing stuff in the universe around us and through the Zooniverse I can actually be involved in the process of science and help to shape the future, even if it just by a very tiny fraction. I never thought that something like this would be possible before I discovered Zooniverse.

How do you feel about being a co-author of a scientific research paper?

Tim: I am still amazed and feel more motivated to look for stunning new radio galaxies.

Ivan: This isn’t the first time actually, I am also a co-author for three papers from the Planet Hunters, BUT it is always awesome, like every single time! Although, I keep my head cool over that since most of the work was done by the professional scientists. A huge thanks to them for the acknowledgment of my small contribution in the form of inviting me to be a co-author in their paper. With this RGZ paper, I got a chance to see the whole process of science starting from the simple question “What is that?” and then people trying to figure out what is going on, schedule observations, discussing things and I have been a part of it! All the way through the process, ending with the actual published science article. It was an amazing experience!


Without the contributions made by our volunteers all over the world, we would not have been so successful in our endeavours.

However, we have only reached 57% of our classification target. Head to www.bit.ly/RadioGalaxyZoo1 to become involved and you could be co-authoring another great discovery with us!

New galaxies in Galaxy Zoo

We’re excited to announce the launch of two new image sets on Galaxy Zoo.

Recently your work has helped us classify 34,429 images coming from the DECaLS first data release (DR1). With the release of DECaLS second data release (DR2) we have added 61,595 new galaxies into Galaxy Zoo. DR2 covers a larger portion of the sky than DR1, and has better quality and deeper images then SDSS. These galaxies are taken from the NASA-Sloan Atlas (a catalog of over 140,000 local galaxies in both the optical and UV) and focuses on the larger and brighter galaxies not already covered by DR1, in addition to the galaxies imaged by an extra year’s worth of data.

J000720.93-032245.6

Example galaxy taken from DECaLS DR2 sample.

Our second image set, appropriately named “the lost set”, is made up of 25,529 SDSS images that should have been included in Galaxy Zoo 2. These galaxies also come from the NASA-Sloan Atlas, but for one reason or another never made it into Galaxy Zoo until now. Once classified, these images will fill in the hole that currently exists in the bright galaxy data set. These SDSS images are in the queue and will go live sometime later this year, depending on the progress being made on DECaLS DR2.

J000005.00-051233.9

Example galaxy taken from “the lost set”.

Spiral galaxies (and why Galaxy Zoo is perfect for their study)

My name is Ross Hart, and I am a second year PhD student at the University of Nottingham using Galaxy Zoo data to study spiral galaxies. I am keen to write some blog posts about these galaxies, which are not only elegant in appearance, but also have a lot of interesting physics associated with them. In this first post, I will give a brief overview of spiral galaxies, and why Galaxy Zoo could be an important tool for their study.

m51_ngc_1232

Two-armed spiral galaxy M51 (left) and many-armed galaxy NGC 1232 (right). Image credit (M51): X-ray: NASA/CXC/SAO; Optical: Detlef Hartmann; Infrared: NASA/JPL-Caltech Image credit(NGC 1232): X-ray: NASA/CXC/Huntingdon Institute for X-ray Astronomy/G. Garmire; Optical: ESO/VLT

Spiral galaxies are the most numerous type of galaxy in the local Universe, with approximately 2/3 of local galaxies exhibiting spiral arms. Most of the gas and young stars in the disks of spiral galaxies are located in spiral arms, giving the appearance of the beautiful spiral patterns observed in galaxies such as M51 and NGC 1232 (shown above). However, the reason as to why we study these galaxies is not simply because they are pleasing to the eye; most of the star-formation in the local Universe occurs in spiral galaxies, so understanding the physics of spiral galaxies holds the key to understanding how stars form in galaxies.

Despite the relative prominence and importance of spiral galaxies, we still do not have a good understanding of how spiral galaxies form and evolve. Much of the problem as to why this is the case is that ‘spiral’ is actually far too broad a term to describe galaxies with different types of spiral structure. In particular, most galaxies have two spiral arms in a grand design spiral structure, like that of M51. However, some galaxies have many spiral arms, like NGC 1232.  However, the difference between M51 and NGC 1232 are actually thought to be much deeper than simply the number of arms that the two galaxies have; the physical processes that are responsible for their formation is also thought to be very different.

In order to study spiral galaxies in any level of detail, we require a method of classifying galaxies by the type of spiral structure they have, which requires detailed morphological classifications. It is for this reason that Galaxy Zoo provides an exciting opportunity to compare spiral galaxies in a way that simply hasn’t been possible before. Thanks to all of the volunteers who helped to classify galaxies in Galaxy Zoo 2, we have access to a  sample of spiral galaxies classified with unprecedented size. All of these galaxies have been classified by arm number, so we have the ideal tool for investigating how these different spiral structures form in a level of detail that hasn’t been possible before.

Finished with two more sets of galaxy images!

I’m happy to report that in the last several days, we’ve simultaneously finished the initial sets of galaxies from both the DECaLS survey and the second subset of simulated galaxies from Illustris. This has meant the completion (since last September) of more than 50,000 galaxies seen 40 times apiece, for more than 2 MILLION classifications.

So far, your work is helping reveal new insights based on this deeper data. One very preliminary result: as we’d predicted, the better conditions in DECaLS (bigger camera, better night sky seeing, larger telescope mirror) are revealing galaxies that were classified in SDSS as smooth, but in fact with faint or extended disks and features that are now visible. This is really exciting, and is helping to modify our ideas of the assembly histories of these galaxies.

Plot

Comparison of the Galaxy Zoo vote fractions for ~10,000 galaxies detected in both SDSS and DECaLS. The bright yellow dip below the red line in the left panel indicates that galaxies in DECaLS are less likely to be classified as ‘smooth’ based on the improved data. (Image K.W. Willett)

The Galaxy Zoo site is still active – we’ve reactivated a few of the DECaLS DR1 galaxies to slightly improve our statistics, but shortly we’re going to add new sets of (real images) to continue the next phase. I’ll post more as soon as we’ve finalized our plans.

As always, our sincere thanks! Time to start our analysis and continue the science…

Galaxy Zoo at the 227th AAS meeting

We posted briefly about the 227th meeting of the American Astronomical Society, which several members of the Galaxy Zoo science team attended last week. I wanted to share a little bit more about the research that we presented, and the experiences we had at the meeting.

Asst. Prof Lucy Fortson, PhD student Melanie Galloway, and postdoc Kyle Willett (Minnesota) at an evening poster session at the 227th AAS meeting.

Asst. Prof Lucy Fortson, PhD student Melanie Galloway, and postdoc Kyle Willett (Univ. of Minnesota) at an evening poster session at the 227th AAS meeting.


Kyle Willett (Postdoc, University of Minnesota)

I presented a poster on the data release of the Galaxy Zoo: Hubble project. While it’s been a couple of years since we formally finished the classifications for GZH, we’ve been working hard in the meantime on aggregating and calibrating the data; this includes two supplementary data sets that users helped classify in the newest interface. One of those sets were the images of galaxies processed with the FERENGI code in order to mimic their appearances at higher redshifts; these have been absolutely critical for the calibration/debiasing procedure we’re applying to the real Hubble galaxies. The second set of new images were the deeper images of galaxies in the GOODS north and south fields, completed early last year. We’re using these to analyze the effect of depth on morphologies, and seeing how the disk/clumpy fractions change with improved imaging.

AAS went well for me, and I got to talk about GZH with a number of new colleagues. I particularly liked having my poster between Melanie Galloway’s and Brooke Simmons’ — I got to point out GZH science results on one side and the next generation of even higher redshift galaxies on the other, which made for a very nice story to tell.

Kyle Willett's poster at the 227th AAS meeting. Click to download the full PDF.

Kyle Willett’s poster at the 227th AAS meeting. Click to download the full PDF.


Melanie Galloway (PhD student, University of Minnesota)

Galaxy Zoo users probably know that there are two main types of galaxies: disks and ellipticals. There is a cool relationship between these shapes and their color: disks tend to be blue (which is an indicator of young stars), while almost all ellipticals appear red (which indicates the stars are old; “red and dead” is a term commonly used.) Astronomers believe that this relationship between color and shape implies that galaxies tend to be created as disks, and over their lifetimes, transform from young disks to old ellipticals. Data from Galaxy Zoo revealed that there are also red disk galaxies in the Universe, and right now it is not known how they fit into our current perception of galaxy evolution.

Mel used data from Galaxy Zoo: Hubble to tackle this question by analyzing how the fraction of red disks changed between now and 6 billion years ago. She found that this fraction was actually much higher in the past! This result probably means that red disks don’t tend to stay red disks, and may instead be a common phase of a typical galaxy’s evolution from blue disk to red elliptical.

Melanie Galloway's poster at the 227th AAS meeting. Click to download the full PDF.

Melanie Galloway’s poster at the 227th AAS meeting. Click to download the full PDF.


Melanie Beck (PhD student, University of Minnesota)

At this year’s AAS conference, I presented work which focused on the relationship between galaxies’ masses and their sizes. In general, more massive galaxies are also physically larger (but not always!). However, the mass-size relationship is different for galaxies in the distant universe compared to those in the nearby universe. It’s also different between disk galaxies compared to ellipticals in that the sizes of elliptical galaxies grow much, much faster than those of disk galaxies but don’t seem to grow much in mass. To explain this behavior, models predict that disk galaxies must evolve into elliptical galaxies at a rate that mimics the growth rate of the ellipticals. These models predict that there should be many more elliptical galaxies of a particular size and mass in the nearby universe compared to disks. To test this, we need to keep track of the number of galaxies as a function of mass, size, and type (elliptical or disk) over a large period of time.

My initial work utilizes classifications from Galaxy Zoo 2 separated by Smooth or Features/Disk. All the galaxies in this catalog are considered to be in the local universe. Using sophisticated statistical techniques, I’m able to robustly determine the number of galaxies as a function of mass, size and type. Next I’m applying the same techniques to classifications from Galaxy Zoo: Hubble and Galaxy Zoo: CANDELS as these catalogs contain galaxies from the more and more distant universe. Once we have the analysis from all three we can compare the numbers of galaxies at each time and finally test those models!

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Melanie Beck’s poster at the 227th AAS meeting. Click to download the full PDF.

Melanie Beck discussing her poster with Prof. Chris Conselice (Univ. of Nottingham).

Melanie Beck discussing her poster with Prof. Chris Conselice (Univ. of Nottingham).


Brooke Simmons (Postdoc and Einstein Fellow, UC San Diego)

AAS is always a hectic science bonanza, and presenting a poster is a way of slowing things down a bit: unlike a talk, which is over in 15 minutes or less, you get to have your results up all day. My poster was an introduction to the upcoming release of classifications for the high-redshift CANDELS galaxies, so it shows a basic overview of how the classifications work and an early science result about featureless disks at high redshift.

It was great to present 2 data releases side-by-side, with Kyle’s poster to my left, and it was even better to get to present the result of the volunteers’ efforts. Between these posters and the previous data releases for Galaxy Zoo, we’ve measured the shapes of hundreds of thousands of galaxies (actually, I think it’s over a million!) spanning the last 12 billion years of cosmic time.

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Brooke Simmons’ poster at the 227th AAS meeting. Click to download the full PDF.

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