Galaxy Zoo + Galaxy Zoo: 3D
Hi! I’m Tom, and I’m a PhD student at the University of Nottingham, doing some research to try to understand how spiral galaxies have grown and changed over their lifetimes. I’m especially interested in looking at how the spiral arms have been affecting the galaxy as a whole. I’ve recently finished up a paper in MNRAS in which I’ve been demonstrating a couple of new methods using some Galaxy Zoo data.
Amelia has already written [ https://blog.galaxyzoo.org/2018/07/17/finding-bars-in-galaxy-zoo-3d/ ] about how she is using the MaNGA survey [ https://www.sdss.org/surveys/manga/ ] to try to understand what’s happening in bars, so I won’t go into too much detail about this fantastic survey. I’ll just say that it’s part of the Sloan Digital Sky Survey, and for each of its sample of 10,000 galaxies, we have measurements of the spectrum at every position across the face of the galaxy.
MaNGA is really useful for trying to understand how galaxies have grown to their current size, because it is possible to get some sort of estimation of what kinds of stars are present in different locations of the galaxy. It’s a difficult thing to measure, so we can’t say exactly how many of every different type of star is present, but we can at least get a broad picture of the kinds of stellar ages and chemical enrichment (“metallicity”) in the stars. Astronomers have used these kinds of tools to measure the average age or metallicity of stars in different parts of galaxies, and found that in most spirals, the further out you go in the galaxy, the younger the stars are on average. The usual interpretation of this is that bulges tend to have formed first, and the disks have grown in size over time afterwards.
A MaNGA spiral galaxy. We can obtain information about the kinds of stars residing across the hexagonal area, which helps us understand how they’ve grown and evolved.
I’m really interested in trying to push this picture in two ways. Firstly, I’ve been trying to see what we can learn from looking at the general distribution of stars of different ages and metallicities – not just the average properties – at each location in the galaxy. Secondly, I think there is a lot of information that we risk ignoring by only looking at how things change with galactic radius. Spiral arms and the bar aren’t evenly distributed around the galaxy, so if we can see how the stellar properties change as we move around the galaxy, we should be able to measure what effect the spiral arms and bars have on the stars. The goal would be to try to confirm whether the most popular models of the nature of spiral arms and bars are correct or not.
To properly do this, we need to know exactly where the spiral arms and bars are in the MaNGA galaxies, so that we can see how the stars vary in these different regions. Enter Galaxy Zoo: 3D, where volunteers are asked to tell us where the different components are.
An example galaxy in MaNGA, where we’ve managed to split the galaxy into different stellar populations of different ages. Each frame shows where we find stars of a given age in this galaxy, starting from the oldest stars and finishing with the most recently formed stars. The colour denotes the mean metallicity of the stars, shown by the scale at the bottom.
All of this is what my most recent publication is about (read it in full at https://doi.org/10.1093/mnras/stz2204); we’ve shown that by combining the full spatial information available from MaNGA (augmented by Galaxy Zoo:3D) with the full distributions of the ages and metallicities of stars in each location, we can start to see some interesting things in the bar and spiral arms. It’s definitely best illustrated by an animation.
By splitting the age distributions up into different “time-slices”, we can create images of where stars of different ages are located in each of our MaNGA galaxies. Immediately from this one example, it’s obvious that there’s a lot of things going on here.
There are a few features in the animation that we’re not entirely convinced are real, but the main exciting things are that the spiral arms only show up in the youngest stars, and the bar grows and rotates as we move from older to younger stars. The growth of the bar is intriguing; this might be showing us how it formed. The bar changing with angle is even more exciting, and we think it shows us how quickly new-born stars become mixed and “locked” into the bar. The arms show what we should expect; spiral arms are areas of intense star formation, but over time the stars formed there will become mixed around the disk. We measured this effect by looking at what fraction of stars of each age are located in the volunteer-drawn spiral arms from Galaxy Zoo:3D.
This is really interesting, and highlights the power of combining large surveys like MaNGA with crowd-sourced information from the Zooniverse.
The next step is to do these kinds of things with more than just this one galaxy though. I’ve started looking at how these techniques can measure how fast the disks of spiral galaxies grew, using a large sample of spiral galaxies identified by Galaxy Zoo 2 volunteers. I’m also trying to measure how quickly stars get mixed away from spiral arms in different types of spiral galaxies. I have started to find some hints of some exciting results on both of these topics, which I would love to share in a future blog post if you’re interested.
We need volunteers to tell us where the spiral arms and bars are in galaxies, so that we can start to see what makes these regions special.
However, I’m currently limited in the number of galaxies with spiral arm regions identified by Galaxy Zoo:3D volunteers, so it would be really helpful if we could get some more! Understanding what makes spiral structure appear in disky galaxies is one of the unsolved problems in galaxy evolution and formation, and the clues to finding out might well lie in measuring how spiral arms affect the galaxy’s stars. Galaxy Zoo:3D will definitely be able to play a role in this! Help us out at https://www.zooniverse.org/projects/klmasters/galaxy-zoo-3d.
Galaxy Zoo Mobile
Hi, I’m Lauren, a summer work experience student working with the Galaxy Zoo team at the University of Oxford for a couple of weeks, and it’s my pleasure to be able to bring you some fantastic news. Today, we’re launching the mobile version of Galaxy Zoo! Unlike the website version, this brand-new native mobile version has questions with only two possible answers – just swipe left or right depending on your answer! This can create a more captivating and faster-paced experience when you are classifying galaxies.
Not only does this introduce a new and engaging platform for the project, but it also means that you can classify galaxies anywhere – on the bus, at the beach, at a concert, in the waiting room at the dentist etc. Hopefully, this will mean many more galaxy classifications whilst also providing easier access for our wide range of volunteers across the world. By introducing this app, we hope to inspire others to join our Galaxy Zoo team, no matter their qualifications or skill set.
Get involved by downloading the Zooniverse app (if you don’t have it already), heading over to ‘Space’ section, and selecting the ‘Galaxy Zoo Mobile’ project. From there, you will be greeted with three different workflows – ‘Smooth or Featured’, ‘Spiral Arms’ or ‘Merging/Disturbed’. Pick whichever you like! The simple, swiping interface allows you to classify galaxies much faster than ever before, meaning the Galaxy Zoo science team can produce results even quicker. So, download the Zooniverse app today and start classifying!
Apple App Store: https://apps.apple.com/us/app/zooniverse/id1194130243
Google Play Store: https://play.google.com/store/apps/details?id=com.zooniversemobile&hl=en
Happy classifying,
Lauren & the Galaxy Zoo Team
Machine Learning Messaging Experiment
Alongside the new workflow that Galaxy Zoo has just launched (read more in this blog post: https://wp.me/p2mbJY-2tJ), we’re taking the opportunity to work once again with researchers from Ben Gurion University and Microsoft Research to run an experiment which looks at how we can communicate with volunteers. As part of this experiment volunteers classifying galaxies on the new workflow may see short messages about the new machine learning elements. Anyone seeing these messages will be given the option to withdraw from the experiment’; just select the ‘opt out’ button to avoid seeing any further messages.
After the experiment is finished we will publish a debrief blog here describing more of the details and presenting our results.
This messaging experiment has ethics approval from Ben Gurion University (reference: SISE-2019-01) and the University of Oxford (reference: R63818/RE001).
Galaxy Zoo Messaging Experiment – Results
Some of you may remember a while back we posted a blog announcing that we would be testing a new messaging system on Galaxy Zoo. Some of you may even have seen these messages while classifying on the site! This test was also part of a study of how we could use messaging to increase engagement on the project. Working with researchers from Ben Gurion University and Microsoft Research we delivered messages to volunteers at key times during their participation on Galaxy Zoo and observed how these messages affected their engagement. This research was based on previous work we had done that demonstrated that sending similar messages in emails could increase the likelihood of volunteers returning and engaging more with the project.
This screenshot shows an example of how the messages were shown in the Galaxy Zoo classification interface.
The volunteers were split into three main cohorts; One group who were delivered the messages at random intervals, one group who were delivered the messages at what were predicted to be optimal times, and a final control group who received no messages. This study has led to two peer-reviewed publications and the results show that optimal timing of an intervention message can significantly increase the engagement of volunteers on Galaxy Zoo.
This plot shows how the messages sent at the predicted optimal times were significantly more effective at increasing engagement than those sent at random.
These early results are intriguing, and we’d like to do more tests to see if it’s something we can use more broadly across Zooniverse projects. The same machinery might also be used by Zooniverse teams to send messages to volunteers – either in a group or individually – as they participate in their projects. We’ll keep you informed on the blog.
To read about the study and its finding in more detail please see the following papers:
Click to access engagement_intervention.pdf
Click to access optimizing-interventions-offline.pdf
For a discussion regarding the ethics of this study, please read this Zooniverse Talk thread https://www.zooniverse.org/talk/14/675633.
Galaxy Builder Results
For the past few years, a new Galaxy Zoo project has been under development. This project allows the creation of models of galaxies inside the Zooniverse website (although in a slightly experimental fashion). Many of you helped trial this project in December of 2017, and some have classified since it was quietly launched in late April. I’d like to take this opportunity to share with you some of the early results we have obtained from your classifications!
From the beta
260 of you helped beta test and debug the project in our beta, providing invaluable feedback (most of which we hope we addressed!) and submitting over one thousand test classifications of our small test sample. One of the images in this sample was the SDSS r-band image of the galaxy below, catchily known as SDSS J104238.12+235706.8.
In this post we’ll look specifically at the spiral arms drawn on this galaxy, and how we can recover information about the shape of the spirals from your drawn arms. If we plot every spiral arm drawn on the galaxy, two distinct spiral appear:
There are a number of classifications which have either crossed the center of the galaxy, linking the two arms with one line, or which attempt to enclose the spiral (as in the GZ:3D project) rather than tracing along the center line. This confusion arose from the short tutorial and confusing help text present in the beta, which was flagged by our testers (thank you!).
Grouping Lines
We can make use of unsupervised machine learning techniques to cluster together these drawn arms, and extract points corresponding to each arm (while throwing away some lines which didn’t fit into our groups).
Cleaning up
Taking one arm as an example, we identify points which could be considered outliers, and remove them to improve our later fit (using another unsupervised machine learning technique called Local Outlier Factor). In the image below, red dots correspond to points identified as outliers, and the blue contours can be seen as a probability map, with points in regions of darker blue being more likely to be an outlier.
Fitting a spiral
Brilliant – we now have a load of (unordered) points which roughly resemble the spiral arm of our galaxy! We’ll fit a smooth line to obtain a “best guess” of the galaxy’s spiral properties, the result of which can be seen below:
What we’ve discovered from the beta trial is that we need at least 20 attempts at drawing spirals on a galaxy to get reliable answers, so we’re keen to get more people trying to build galaxies on Galaxy Builder.
If you’d like to help please join us at https://www.zooniverse.org/projects/tingard/galaxy-builder. If that’s not your thing we still need classifications on Galaxy Zoo: 3D, and the classic Galaxy Zoo is still live with all new images from the DECaLS survey.
Galaxy Zoo’s 10th Anniversary
Galaxy Zoo is celebrating ten years since launch next month, and as part of the festivities the science team are having a meeting in Oxford from 10th-12th July. Unfortunately we didn’t think it was feasible to invite the hundreds of thousands of you from all over the world who have contributed to the project over the last ten years, but the good news is that all of the talks from the meeting will be interactively live-streamed so that anyone can join in the discussion! See the schedule above for details on who is speaking at the meeting. Details of how to join the live stream will be released closer to the event.
There will also be an Oxford SciBar public event on the Monday night. All who are able to make it are welcome to join but don’t worry if you can’t, there will be a full podcast of the evening released shortly after the event!
Messaging Test
Over the next few weeks, some of you may see messages (like the one in the image above) while classifying on Galaxy Zoo. We are testing out a new messaging system. These messages should not appear frequently and, if you do see one, you will be able to opt-out of seeing any subsequent messages. In the unlikely event that you do see more than one of these messages during your classification session, you can let us know by emailing contact@zooniverse.org.
Thanks for your understanding, and please continue your vital efforts at www.galaxyzoo.org
UPDATE: The messaging experiment was ended in November 2017. To read about the results of the test and what we plan to do in the future, read this blog post https://blog.galaxyzoo.org/2018/07/12/galaxy-zoo-messaging-experiment-results/.
Experiment Debrief
Dr Grant Miller
Department of Computer Science
Email: Grant.Miller@physics.ox.ac.uk
The initially stated aim of this experiment was to test a new messaging system on Galaxy Zoo. However, the actual aim also involved testing the content and timing of these messages in order to measure their effect on volunteer participation. The experiment was titled ‘Alleviating disengagement in Zooniverse‘ and was performed in collaboration with researchers at Ben Gurion University and Microsoft Research. Volunteers were not explicitly told the purpose of these messages at the time as this would have affected the experiment results. You can read more about our planned procedure for future similar experiments in this Zooniverse blog post https://blog.zooniverse.org/2018/07/25/experiments-on-the-zooniverse/. If you have any concerns or complaints about this study, please contact Grant Miller using the contact details above.
Observing Time for Galaxy Zoo
It’s Christmas come early at Galaxy Zoo, with a healthy dose of everything that an astronomer would want under the tree – observing time.
The Gemini South dome in suitably picturesque setting.
We didn’t get everything we asked the telescope allocation committees for, but we did get plenty to keep us busy well into the New Year. 2013 will see the following telescopes turned to Galaxy Zoo targets :
Gemini South: This 8m telescope in Chile (pictured above) will be observing bulgeless galaxies thanks to Brooke Simmons and her friends at Yale (especially Ezequiel Treister, now at Concepción in Chile). This is a program to look at the galaxies that were included in our first bulgeless paper, using deep, high-resolution spectroscopy to examine their stellar populations. For some objects where the AGN signal comes to us unobscured by dust and gas (but buried in a bright galaxy that made it hard to see in the SDSS spectra), we hope to also determine black hole masses with these deeper, finer spectra.
WIYN at Kitt Peak: This 3.5m telescope has recently been outfitted with a brand new imaging camera. As long as it keeps working the way it has been in tests, we can use it for 6 nights to examine whether our sample of bulgeless galaxies ever had minor mergers. Bulgeless galaxies are important because they’re supposed to be guaranteed merger-free so deep imaging of this kind helps us to confirm that that’s true by looking for any remnants of ripped-apart galaxies.
Bolshoi Teleskop Alt-azimutalnyi: This 6m telescope is important in astronomical history – it was once the largest in the world. It will be observing the Voorwerpjes as part of our increasing desire to understand these enigmatic objects – more on which is coming over the Christmas period, with any luck.
Shane Telescope at Lick: We’ve been awarded a second run on this telescope to look for ionized gas in the companion galaxies to those with active galactic nuclei – a sort of large scale Voorwerpje hunt.
There will be much more about all of these as the data starts to arrive, but we wanted to make sure that you know there were presents under the tree. We’re looking forward to unwrapping them immensely!
*Note: this post has been updated to more accurately reflect reality.
600 Most-Galaxified Words
When we launched the new Galaxy Zoo in September we also launched our ‘galaxify‘ tool, which allows you to write in an alphabet of Galaxy Zoo galaxies. Since that time you have created 320,000 messages, all written in galaxies! 18,468 contained the word ‘love’ and only 218 contain ‘hate’. 302 contained ‘marry me’ (5,853 contain swear words). Here’s the top 600 words so far, in one giant green word ball:
Go write your own message at http://writing.galaxyzoo.org and don’t forget to check out the Zooniverse Advent Calendar for more fun items like this one in December.
Hangout with Galaxy Zoo: Science Chat Later Today
Later on today we’ll be holding a Google+ Hangout with a bunch of the Galaxy Zoo science team. We’ll be broadcasting this live at 3:30pm GMT (9:30am CST, 10:30am EST) and you’ll be able to see the video feed right here on the blog.
If you have any questions about the science behind Galaxy Zoo, short term loans UK and how to get them, or anything you’ve always wanted to ask the science team behind the project, please post them here as comments or contact us on Twitter @galaxyzoo.
We look forward to chatting later on and answering your questions.
Galaxy Zoo 
