Meet Julie (aka @42jkb on RadioTalk), a project scientist on Radio Galaxy Zoo!
I’m a postdoctoral fellow at CSIRO Astronomy and Space Science in Australia. This is my first position after obtaining my PhD from the University of Calgary, Canada working on magnetic fields of radio galaxies. My first memories of astronomy and the wonders of the Universe were spending summer nights outside at campfires with my family staring up and counting the number of “shooting stars” we could see. It wasn’t until my second year of undergraduate studies at Western University in Ontario Canada that I considered doing astrophysical research; I was actually going through to be an airline pilot! I haven’t looked back at my decision to change into physics and astronomy and everyday I am amazed at the complexity and beauty of the Universe.
I spend my time researching magnetic fields and how important they are to radio galaxies. You can usually find me at the Australia Telescope Compact Array taking observations of all types of radio galaxies, sitting in front of a computer doing the exact same thing as Radio Galaxy Zoo, learning about life from my daughter, and educating myself on the wonderful country I now live in. I am excited about what Radio Galaxy Zoo has to offer the astronomical community and what the Universe will unfold for us through this project. Thank you for taking part!
Hi, I’m Meg Schwamb (normally from Planet Hunters and Planet Four), but not to fear, I’m not here to talk about planets. With the Oxford Galaxy Zoo Team, I’ve been helping to observe on the Caltech Submillimeter Observatory on Mauna Kea. Chris blogged about our first night. I thought I’d give a quick update, before final preparation for the start of tonight’s observing.
It’s been quite a world-wide effort. I’m currently based in Taipei, Taiwan. So I’m remotely logging into the telescope and instrument controls from home while Chris, Brooke, and Becky have been logging in remotely from Oxford Zooniverse HQ. Then we’re in a Skype call, so we can communicate and know who’s commanding the telescope and helping support the person running the observation.
Chris and the Zooniverse’s Rob Simpson talked more about the details of why we’re observing with the CSO these past few nights and what the experience has been like on their latest episode of Recycled Electrons, which you can find here.
The weather the past few nights hasn’t been great, we were closed Sunday night in Hawaii, we opened part of the night last night and closed due to high humidity in the middle of the night and never reopened. A few hours ago, the primary observers whose time this is, made the call that the conditions are not good enough for their project, but they are good enough for us to observe. Since I’m 7 hours ahead of the UK, one of my tasks is to be checking the Mauna Kea weather reports and waiting for the decision from the lead observer of the primary program. So about an hour ago, I phoned to start waking up the Oxford team.
The conditions are looking pretty good on the mountain. So I think we’ll have a smooth night in turns of humidity and wind. The optical depth is looking as good as our first night. I’m off to start my final checks and preparations, as I’m the lead observer of tonight’s observers (which includes Becky and Brooke in Oxford), so I make the calls of when to open, close, when we move to the next target.
If things are moving smoothly, we’ll try and update the blog occasionally. In the meantime, enjoy the view of sunset from of the CFHT webcams on the submit of Mauna Kea.
9:42pm Hawaii time – We’re all pointed on source and taking data. Been on there observing for about an hour now. We”ll move off soon to do a pointing check on a carbon star and then back integrating on our target galaxy. (Meg)
1:03am Hawaii time- We’re still on the same target. We were thinking of maybe moving off, but decided to stay on to see what some other features in the data look like with more time. We’ll be moving to our end of night source in about 40 minutes, and sit on that for the next several hours. Becky and Brooke are driving the telescope (Meg).
2:49am Hawaii time – Weather continues to about the same. We’re on to another source. Below here’s an image of the spectrograph data GUI windows that we see. The telescope has two spectrographs that simultaneous take data on the source. The bottom one FFTS2 covers a broader range and is higher resolution than the top spectrograph (FFTS1)
4:05 am – We’ve decided to stay on the same source for the rest of the night. So we’re just going to be sitting and taking observations on source then a system temperature calibration and then back to observing on source for the rest of the night. We shut an hour before sunrise so around 4:42am Hawaii local time (Meg).
Hello from the summit of Mauna Kea, Hawai’i! We’re here to follow up on a host of Galaxy Zoo blue ellipticals, trying to use the Caltech Submillimeter Observatory to catch the signature of Carbon Monoxide – gas which might provides the fuel for star formation.
Sadly, we’re not in Hawai’i – I’m in the office in Oxford (my sunrise is below), Becky is in Bristol and we’re joined by Meg Schwamb from Planet Hunters on her first extragalactic observing run. Conditions look good, if a bit windy, and I’ll try and keep you informed as the night wears on.
EDIT: We have an open dome and the weather is looking good. Here’s a dark webcam image you can squint at to pick out a telescope and sky.
And first observations for calibrations are on Mars! Here’s an excitingly noisy spectrum with a nice broad absorption line in the middle – you’re looking at CO (carbon monoxide) in the atmosphere of Mars. The width can even tell you about the current wind speed on Mars. From Oxford to Hawaii to Mars to back to you at home.
EDIT : Well, that was interesting. It turns out it helps if you know a telescope – none of us have used the CSO before and it’s been quite hard work to get our heads round the right software. Still, we successfully observed our first target – an unprepossessing, rather distant blue elliptical by Sloan standards (see below) and on first glance didn’t quite see anything. It set before we could quite confirm that there was nothing there to see, and we’ve moved on to a second galaxy, stopping off on the way by a cool star in order to calibrate the system.
EDIT : End of a long night. One disadvantage of observing remotely is that we have to be very cautious, so we’re commanded to shut the telescope an hour before sunrise. We got data, certainly, but it’s not one of those nights in which wonderous things are apparent immediately. We have more chances for the rest of the week if the weather cooperates, so watch this space.
In the UK on a seventh anniversary the traditional gift is one made of wool. So considering it’s the SEVENTH anniversary of Galaxy Zoo TODAY (July 11th) our very own, super talented Karen Masters has knitted us the Galaxy Zoo logo!
If you feel like getting your astronomical knit on for this momentous occasion, here’s a few inspirational photo’s.
Karen also knitted our favourite Penguin Galaxy as a birthday present for the lovely Alice :
And check out the skills of Jen Greaves and the NAM Knitters who knitted a WHOLE GALAXY CLUSTER at this year’s National Astronomy Meeting in Portsmouth:
For those of you itching to stretch your creative muscles but haven’t been struck by that bolt of inspiration yet, here’s a KNITTING PATTERN (a first I believe for the Galaxy Zoo blog) for the Galaxy Zoo logo to keep you busy…
To honour the SEVENTH anniversary of Galaxy Zoo (July 11th) we’ve put together a gallery of the Science Team’s favourite images from the site (and why) for your visual pleasure…
Chris’s favourite: I love the flocculent spiral galaxies. The ones you can stare at and still have no idea how many spiral arms they have.
Karen’s favourite: I’m a sucker for merging galaxies, despite the fact that I work on barred galaxies mainly! This one which looks like the yin-yang symbol (or maybe a heart) is a particular favourite. It’s amazing that the Universe can be so vast that we can find galaxies in so many different shapes.
Kevin’s favourite: The penguin galaxy shows the power of human pattern recognition – and a crucial stage in galaxy evolution!
Brooke’s favourite: when the latest Galaxy Zoo launched, the volunteers made a find almost right away that turned out to be a very rare kind of object called a gravitational lens. I love this image because it shows not just the variety of things that are out there in the Universe – in this case the very distant universe – but also the rare place that Galaxy Zoo itself occupies. It’s a diverse community and diverse images like this are part of the reason why.
Kyle’s favourite: did you know that we can spell Galaxy Zoo out of galaxies? The users originally started collecting a list of galaxies that look like letters and now we have writing.galaxyzoo.org thanks to Steven. Since it’s the anniversary, here’s my favourite letter G.
Bill’s favourite: Hanny’s Voørwerp really started something – the blue stuff in the image – other teams are now finding similar objects at smaller and larger distances too.
Becky’s favourite: this amazing image has SO much going on in it – mergers, interactions, spirals, bars, ellipticals, grand designs, foreground stars etc. It feels like a visual representation of thoughts in my head at times, which is clearly why I love it.
The Hubble Ultra Deep Field!!!! Just to remind us all why we’re all here. Every single thing you can see in this image is a galaxy – even the most minuscule of dots. And the size of the image on the sky is about 1/20 the size of the Full Moon… Let’s just all take a minute to let that sink in as we stare and wonder...
Friday 11th July 2014 is the SEVENTH anniversary of Galaxy Zoo! So to celebrate this momentous achievement, we’ve put together a list of seven of the greatest Galaxy Zoo discoveries (so far!); all thanks to YOU, the classifiers…
1. Chirality of Spiral Galaxies
One of the first major results from Galaxy Zoo wasn’t even Astronomical. It was Psychological. One of the questions in the original Galaxy Zoo asked whether spiral galaxy arms rotated clockwise or anti-clockwise; we wanted to check whether they were evenly distributed or whether there was some intrinsic property of the Universe that caused galaxies to rotate one way or the other. When the Science team came to analyse the results they found an excess of anti-clockwise spinning spiral galaxies. But when the team double checked this bias by asking people to classify the same image that had been flipped there was still an excess of anti-clockwise classifications; so it’s not an astronomical phenomenon. Turns out that the human brain has real difficultly discerning between something rotating clockwise or anti clockwise; check out this video if you don’t believe me – you can watch the dancer rotate both ways! Once we’d measured this effect we could adjust for it, and we went on to establish that spirals which were near each other tending to rotate in the same direction.
2. Blue Ellipticals
The enigmatic blue ellipticals in many ways started the Galaxy Zoo. Galaxies largely divide into two: spiral galaxies like our Milky Way shining with the blue light of young stars being constantly born, and the “rugby ball-shaped” elliptical galaxies who no longer make new stars and thus glow in the warm, red light of old stars. Clearly, when galaxies stop making new stars, they also change their shape from spiral to elliptical. But how exactly does this happen? And what happens first? Do galaxies stop forming stars, and then change their shape, or the other way round? Answering that question is the first step in understanding the physics of transforming galaxies. With the Galaxy Zoo, we found a whole population of blue ellipticals: galaxies which have changed their shape, but still have young stars in them. With their help, we’ve been making a lot of progress in galaxy evolution. It looks like a galaxy merger, a giant cosmic collision, changes the shape of galaxies from spiral to elliptical and then somehow – and very rapidly! – star formation stops. We don’t know quite why yet, but we think active black holes are involved. This is hugely relevant for us as in a few short billion years, the Milky Way will crash into our neighbour, the spiral Andromeda galaxy. And for a short time, the Milky Way and Andromeda will be a blue elliptical before star formation in the newly-formed Milky-Dromeda ceases. For ever.
3. Red Spirals
Ellipticals are red, Spirals are blue, Or so at least we thought, until Galaxy Zoo…. Think of your typical spiral galaxy and you’ll probably picture it looking rather blueish. Thats’s what astronomers used to think as well – suggest a red spiral to Edwin Hubble and he probably would’ve told you not to be so ridiculous. Before Galaxy Zoo if astronomers saw something looking red they generally tended to think it was elliptical; however to the untrained eye, the colour does not bias any classifications, which means that you all found lots of red spirals and discs which were hiding in plain sight. This put the cat amongst the pigeons for our galaxy evolution theories because, as said earlier, we thought that when galaxies stop making new stars, they also change their shape from spiral to elliptical. The red spirals mean that we now have a different evolutionary path for a spiral galaxy where it can stop making new stars and yet not change its shape. We now think that those spiral galaxies which are isolated in space and don’t interact with any neighbours are the ones that make it to the red spiral stage.
4. Green Peas
The Green Peas, discovered by Citizen Scientists due to their peculiar bright green colour and small size, are a local window into processes at work in the early Universe. Although, they were in the data for many years, it took humans looking at them to recognise them as a class of objects worth investigating. First noticed in some of the earliest posts of the Galaxy Zoo Forum in 2007, a group of dedicated citizen scientists organised a focused hunt for these objects finding hundreds of them by the summer of 2008, when the Galaxy Zoo science team began a closer look at the sample. The Peas are very compact galaxies, without much mass, who turn out new stars at incredible rates (up to several times more than our entire Milky Way Galaxy!). These extreme episodes of star formation are more common to galaxies in the early Universe, which can only be directly observed very far away at high redshifts. In contrast to the distant galaxies, the Peas provide accessible laboratories that can be observed in much greater detail, allowing for new studies of star formation processes. Since their initial discovery, the Peas have been studied at many wavelengths, including Radio, Infrared, Optical, UV and X-ray observations and detailed spectroscopic studies of their stellar content. These galaxies provide a unique probe of a short and extreme phase of evolution that is fundamental to our understanding of the formation of the galaxies that exist today.
5. The Voørwerp
Probably the most famous new discovery of Galaxy Zoo has been Hanny’s Voørwerp. Hanny van Arkel called attention to it within the first few weeks of the Galaxy Zoo forum with the innocent question ”What’s the blue stuff?”, pointing to the SDSS image of the spiral galaxy IC 2497. The Sloan data alone could indicate a gas cloud in our own Galaxy, a distant star-forming region, or even a young galaxy in the early Universe seen 10 billion light-years away. After a chase to obtain new data, above all measurements of the cloud’s spectrum, with telescopes worldwide, an unexpected answer emerged – this galaxy-sized cloud was something unprecedented – an ionization echo. The core of the galaxy hosted a brilliant quasar recently on cosmic scales, one which essentially turned off right before our view of it (so we see the gas, up to 100,000 light-years away from it, shining due to ultraviolet light form the quasar before it faded). This had never before been observed, and provides a new way to study the history of mass surrounding giant black holes. Further observations involved the Hubble Space Telescope and Chandra X-ray Observatory (among others), filling in this historic view. The cloud itself is part of an enormous stream of hydrogen, stretching nearly 300,000 light-years, probably the remnant of a merging collision with another galaxy. As it began to fade, the quasar started to blow out streams of energetic particles, triggering formation of stars in one region and blowing a gaseous bubble within the galaxy. In keeping with the nature of Galaxy Zoo, the science team deliberately had much of this unveiling play out in full view, with blog entries detailing how ideas were being confronted with new data and finding themselves supported, discarded, or revised. The name Hanny’s Voørwerp (which has now entered the astronomical lexicon) originated when an English-speaking Zoo participant looked up “object” in a Dutch dictionary and used the result “Voørwerp” in a message back to Hanny van Arkel. Following this discovery, many Zoo volunteers participated in a focused search for more (the “Voørwerpjes”, a diminutive form of the word) – as a result we now know 20 such clouds, eight of which indicate fading nuclei. Other teams have found similar objects at smaller and larger distances; Hanny’s Voørwerp really started something!
6. Bars make galaxies redder
A galactic bar is a straight feature across a spiral galaxy. It’s the orbital motions of many millions of stars in the galaxy which line up to make these bars, and in computer simulations almost all galaxies will form bars really quickly. In the real world it’s been known for a long time that really strong (obvious) bars are found in about 30% of galaxies, while about 30% more have subtle (weak) bars. One of the big surprises about the Galaxy Zoo red spirals was just how many of them had bars. In fact we found that almost all of them had bars and this got the science team really curious. We followed this up with a full study of which kinds of spiral galaxies host bars using the first classifications from Galaxy Zoo 2. In this work we discovered a strong link between the colour of disc galaxies and how likely they are to have a bar – with redder discs much more likely to host bars. We now have half a dozen papers which study galactic bars found using Galaxy Zoo classifications. Put together these works are revealing the impact galactic bars have on the galaxy they live in. We have found evidence that bars may accelerate the processes which turn disc galaxies red, by driving material into the central regions to build up bulges, and clearing the disc of the fuel for future star formation.
7. Bulgeless galaxies with black holes
Supermassive black holes are the elusive anchors in the centres of nearly every galaxy. Though they may be supermassive, they are quite difficult to spot, except when they are actively growing – in which case they can be some of the most luminous objects in the entire Universe. But how exactly they grow, and why there seems to be a fixed mass ratio between galaxies and their central black holes, are puzzles we haven’t solved yet. We used to think that violent collisions between galaxies were The Way you needed to grow both a black hole and a galaxy so that you’d end up with the mass ratio that we observe. And violent collisions leave their signatures on galaxy shapes too. Namely: they destroy big, beautiful, ordered disks, re-arranging their stars into bulges or forming elliptical galaxies. So when we went looking for pure disk galaxies with no bulges and yet with growing central black holes we weren’t sure we would find any. But thanks to the volunteers’ classifications, we did. These galaxies with no history of violent interactions yet with large central supermassive black holes are helping us test fundamental theories of how galaxies form and evolve. And we are still looking for more of them!
So here’s to SEVEN more years – keep classifying!
After very nearly seven years online, and over 650,000 posts by its members, the time has come to shut the doors on the original Galaxy Zoo Forum. Originally an afterthought, created to deal with the fact that we couldn’t possibly deal with the volume of mail that we were getting, the Forum quickly established itself as a very special place. It generated science – the Voorwerp and its diminutive colleagues, the Voorwerpjes, the Peas and much more came from discussions amongst its boards, as well as such random fun things as the letters that power My Galaxies.
It was also a very civilized place – entirely due to the standards set by Alice and the team of moderators that followed, especially Graham and Hanny who have served most recently. The forum inspired much of what the Zooniverse tries to do today, but time has moved on and we have taken, in collaboration with the moderation team, the decision to shut the forum down. The vast majority of Galaxy Zoo volunteers now interact with each other via Talk, not the forum, and that’s where we want to concentrate our efforts. Closing the forum will allow us to abandon the archaic software that runs the forum itself, and free the moderators from the increasingly onerous task of clearing the forum of spam. It will be preserved intact as a valuable resource, and a record of discussion during the first seven years of Galaxy Zoo’s life.
Feedback and discussion about everything in the Zooniverse is still welcome, of course. As well as Talk, there are blog comments, and thanks to a recent grant from the Alfred P. Sloan Foundation, we’re going to be rebuilding Talk over the next few months. If you’d like to help shape the future of discussion and community in the Zooniverse, then there’s a form for feedback available here. I’m looking forward to reading what you have to say.
It was discussed within the science team once the nature of Hanny’s Voorwerp was becoming clear, since the color of that giant loop suggested similar emission-line properties at a larger redshift. Kevin gave it the name “Teacup” in honor of this loop. Then in March 2009, Georgia State University colleague Mike Crenshaw was here on my campus for a thesis defense. I showed him this object, and he mentioned that one of their graduate students was doing spectroscopy of active galaxies at the Lowell Observatory 1.8m telescope that week. Two nights later, Stephen Rafter from GSU obtained a long-slit spectrum crossing the loop and showed that it was, indeed, gas photoionized by an AGN. Later this object featured in the Voorwerpje hunt, as one of the 8 cases showing an energy deficit from the nucleus so it must have faded. Indeed, this example was a major factor in showing that the Hunt project would be worthwhile.
Today’s post is also from Dr Enno Middelberg and is the second part of two explaining in more detail about radio interferometry and the techniques used in producing the radio images in Radio Galaxy Zoo.
In a previous post I have explained how the similarity of the electric field at two antennas’ locations is related to the Fourier transform of the sky brightness. Unfortunately, we’re not quite there (yet). You may have heard about sine and cosine functions and know that they are one-dimensional. Images, and the sky brightness distribution, however, are two-dimensional. So how can we imagine a two-dimensional Fourier transform? In this case, we have to combine 2D waves with various frequencies, amplitudes, and orientations into one image. We can make a comparison with waves on a lake. Just like a sine or cosine wave, a water wave has an amplitude and a frequency, but in addition it also has an orientation, or a direction in which it travels. Now let us think of a few people sitting around a pond or lake. Everyone kneels down to generate waves which then propagate through the water. Let us further assume that the waves are not curved, but that the crests and valleys are parallel lines. Now all these waves, with properly chosen frequencies, amplitudes, and directions will propagate into the center of the pond, where the waves interfere. With just the right parameters, the interference pattern can be made to look like a 2D image. In a radio interferometer, every two telescopes make a measurement which represents the properties of such a wave, and all waves combined then can be turned into an image. Let me point out that the analogy with the lake is taking things a little bit too far: since the water waves keep moving across the lake, a potential image formed by their intererence will disappear quite quickly, but I hope you get the point about interfering 2D waves.
To illustrate this further I have made a little movie. Let us assume that the radio sky looks just like Jean Baptiste Joseph Fourier (top left panel in the movie). I have taken this image from Wikipedia, cropped it to 128×128 pixels, and calculated its Fourier transform. The Fourier transform is an image with the same dimensions, but the pixels indicate the amplitude, phase and frequency of 2D waves which, when combined, result in an image. Then I have taken an increasing number of pixels from this Fourier transform (which ones is indicated at the top right), calculated which 2D waves they represent (bottom right), and incrementally added them into an image (bottom left). At the beginning of the movie, when only few Fourier transform pixels are used, the reconstructed Mr. Fourier is barely recognizable, with 50 Fourier pixels added, one begins to identify a person, and with an increasing number of waves added, the image more and more resembles the input image. You should play it frame by frame, in particular at the beginning, when the changes in the reconstructed image are large. In radio interferometry, Mr. Fourier’s image is what we want (how does the sky look like?), but what we get is only the pixels shown in the upper right image. Each of these pixels, all by itself, provides information as illustrated in the bottom right, but all together, they yield an image such as in the bottom left image. And the more pixels we measure, the more accurate the image becomes.
So in summary: a radio interferometer makes measurements of the similarity of the electric field at two locations, and the degree of similarity represents the Fourier transform of the sky radio brightness for the two antennas in that instant. Astronomers then reconstruct the sky brightness from all these measurements taken together – that’s also why the technique is called “synthesis imaging”, or “aperture synthesis”. And if you’ve kept reading until here without having your brain turn to mush – congratulations! This is typically the subject of lectures for advanced physics students. I’ve been learning about radio interferometry now for more than 15 years and am still discovering new and interesting bits.
Today’s post comes from Dr Enno Middelberg and is the first part of two explaining in more detail about radio interferometry and the techniques used in producing the radio images in Radio Galaxy Zoo.
I have written in an earlier post about the basic idea of how to increase the resolution of a radio telescope: use many telescopes, separated by kilometers, and observe the same object with all. Here is a little more information about how this works.
At the very heart of an interferometer is the van Cittert-Zernike theorem: it essentially states that the degree of similarity of the electric field at two locations is a measure of the Fourier transform of the sky brightness distribution. Now that’s a big bite to swallow, but let me explain it in less confusing words: the electric field is all we can measure – radio waves are electromagnetic waves, and radio telescopes are sensitive to the electric field. Now we can build a radio telescope in a way that it produces as its output a voltage which is proportional to the electric field which the antenna receives from, e.g., a galaxy. Much of the signal will be noise from our own Milky Way, the atmosphere and the electronics which amplify the feeble signals, but a tiny little bit of the signal will be caused by radio waves from space, and both antennas will receive a little bit of these. Now suppose we have two telescopes separated by 1 km or so, and both telescopes produce such voltages which contain a little bit of this signal. The voltages are digitised and the two data streams are fed into a correlator. The correlator is a computer which takes the two data streams and calculates their correlation coefficient, which is an indicator for their similarity. If the two data streams have nothing in common (for example, because an unexperienced PhD student pointed the two antennas in different directions :-) ) then the correlation coefficient will be zero, which is to say that they are not similar at all. However, if the two telescopes point at the same source, the data streams will have a few bits in common, and the correlator spits out a correlation coefficient which is not zero. This is our measurement!
Now that we’ve that out of the way, we need to talk about Fourier transforms. The van Cittert-Zernike theorem states that the correlation coefficient is a measure for the Fourier transform of the sky brightness. Now what is a Fourier transform? The Fourier transform is an ingenious way of representing a mathematical function with a sum of sine and cosine functions. That is, if I take a large number of sine and cosine functions with various (but carefully selected!) frequencies and amplitudes, then their sum will be an accurate representation of another function, for example a square wave or a sawtooth. Check out the Wikipedia page on Fourier series (which are related to Fourier transforms, but easier to understand), which has a number of nice animations to illustrate this, such as this one:
You can also play with Paul Falstad’s Java applet to see how to construct functions using sine and cosine waves interactively – very instructive! In part 2 of this post I will explain how astronomers use 2D Fourier transforms to assemble images of the radio sky.