Tag Archive | voorwerp

We got (some) observing time!

Great news everybody!

We applied for radio observations with the e-MERLIN network of radio telescopes in the UK. The e-MERLIN network can link up radio dishes across the UK to form a really, really large radio telescope using the interferometry technique. Linking all these radio dishes means you get the resolution equivalent to a country-sized telescope. You don’t alas get the sensitivity, as the collecting area is still just that of the sum of the dishes you are using.

The e-MERLIN network (from www.e-merlin.ac.uk) of radio telescopes.

The e-MERLIN network (from http://www.e-merlin.ac.uk) of radio telescopes.

Our proposal was to observe the Voorwerpjes. We wanted to take a really high resolution look at what the black holes are doing right now by looking for nuclear radio jets. The Voorwerpjes, like their larger cousin, Hanny’s Voorwerp, tell us that black holes can go from a feeding frenzy to a starvation diet in a short time scale (for a galaxy, that is). We really want to see what happens to the central engine of the black hole as that happens. There’s a suspicion that as the black hole stops gobbling matter as fast as it can, it starts “switching state” and launches a radio jet that starts putting a lot of kinetic energy (think hitting the galaxy with a hammer).

So, we want to look for such radio jets in the Voorwerpjes. We asked for a LOT of time, and the e-MERLIN time allocation committee approved our request…

… partially. Rather than giving us the entire time, they gave us time for just one source to prove that we can do the observations, and that they are as interesting as we claimed. So, we’re trying to decide which target to pick (argh! so hard).

Good Things come at the same time

AAS meeting update!

The last 24 hours have been good for  Zoo team member Bill Keel (@ngc3314) is based at the University of Alabama. Not only did his University football team win some sort of championship (they all look the same to Europeans) last night, but the Hubble Space Telescope observed the final Voorwerpje in our approved programme! That means Bill was probably glued to the TV and downloading and reducing the data at the same time!


He’ll add the reduced image to his poster at the AAS meeting, so if you want to see the image, come join us at the poster tomorrow! He may also blog it some time later, but for the FIRST look, you’ll have to come to the poster! There may be chocolates too….

The poster is: 339.47. HST Imaging of Giant Ionized Clouds Around Fading AGN, up all of Wednesday from 9-6.

X-ray observations of IC 2497 in the can!

As we tweeted about and as Chris noted in his blog post about the Zooniverse success at the American Astronomical Society meeting in Austin TX, half of the Chandra X-ray observations of IC 2497 (the galaxy next to Hanny’s Voorwerp) have been executed and so with bated breath we awaited the results.

From previous X-ray observations with Suzaku and XMM, we know that the quasar that lit up Hanny’s Voorwerp is dead, and that there’s just a weak source in the center of IC 2497 where the black hole lives and some evidence for hot gas. So we had turned to Chandra to figure out what was going on in the center of IC 2497. To puzzle apart the faint black hole at the center and the gas around, and Chandra has the sharpest X-ray eyes in the sky.

We got the notification from the Chandra X-ray Center that the observations had concluded and that we could have a preview of the raw frame. Bill and Chris happened to be near, so after Chris finished his talk on the latest Planethunters.org results (two new planets!), we got together in (possibly) the exact same spot where Chris and Bill viewed the first spectrum of the Voowerp at another AAS meeting in Austin four years ago.

Chris (left), Kevin (right)

From left to right: Bill, Kevin, Chris, all looking at the data.

So, without much further ado, here’s what we got:

Well that’s a bit underwhelming!

Or not!

First, we know that we have a bright source, so we can study the X-ray data in detail. Also, this is just a JPEG screenshot, so we can’t even zoom in and change the scaling to see if there’s anything else there. We don’t even know which way is North, so we don’t know where the Voorwerp is. So for now, all we can do is wait for the actual raw data to be available. This should take a few days. Stay tuned….!

Chandra time for IC 2497 and the Voorwerp!

The list of approved targets for Cycle 13 of the Chandra X-ray Observatory is out and on it is our friend IC 2497. We were awarded 114 ksec (almost 32 hours) of time to point Chandra at IC 2497 and peer into its center. What do we want to learn? First, we want to see if the wimpy signal from the central black hole comes more into focus. Chandra has much better spatial resolution than XMM so we will be able to resolve the very center.

We also want to see if there is any impact of the ex-quasar on the surrounding hot gas in the galaxy center. Did the quasar blow bubbles into the gas? Did it start doing so when it “switched state”?

Unfortunately we won’t know for quite a while as Cycle 13 only starts later this year and will go on into 2012. So, stay tuned!

AAS January Voorwerp even video available

As Bill has spotted on the forum, the video of the press conference at the January AAS meeting where we presented the Hubble Space Telescope of Hanny’s Voorwerp is now available from the AAS. We shared the event with two other cool results, so you can hear about them as well. The video (warning, large file!) is available here: video of the January press event

The Sudden Death of the Nearest Quasar

When I told Bill Keel the results of the analysis of the X-ray observations by the Suzaku and XMM-Newton space observatories, he summed up the result with a quote from a famous doctor:

“It’s dead, Jim.”

The black hole in IC 2497, that is.


To recap what we know: the Voorwerp is a bit of a giant hydrogen cloud next to the galaxy IC 2497. The supermassive black hole at the heart of IC 2497 has been munching on vast quantities of gas and dust and, since black holes are messy eaters, turned the center of IC 2497 into a super-bright quasar. The Voorwerp is a reflection of the light emitted by this quasar. The only hitch is that we don’t see the quasar. While the team at ASTRON has spotted a weak radio source in the heart, that radio source alone is far too little to power the Voorwerp. It’s like trying to light up a whole sports pitch with a single light bulb – what you really need is a floodlight (quasar).

Now it is possible to hide such a floodlight. You just put a whole bunch of gas and dust in front of it. If there’s enough material, no light even from a powerful floodlight will get through. Imagine pointing it at a solid wall – even the brightest floodlight in the world will be completely blocked by the wall. In the realm of quasars, such a barrier is usually made up of the torus of material (gas and dust) spiralling in towards the black hole and settling into an accretion disk. So you can have quasars that are feeding at enormous rates and being correspondingly enormously bright, but our line of sight is blocked.

So there are two possibilities of what could be going on with IC 2497 and the Voorwerp:

1) The quasar is “on” but hidden by lots of gas and dust, or

2) The quasar switched off recently, but because the Voorwerp is 70,000 light yeas away, the Voorwerp is still seeing the quasar –  after all, even light takes a while to travel 70,000 light years. This would make the Voorwerp a “light echo.”

So how do we distinguish between the two possibilities? The best way is to look at a part of the electromagnetic spectrum that generally has no trouble penetrating even thick walls: X-rays!

If the quasar in IC 297 is feeding, then we should see the X-ray light it is emitting even through the thickest barriers. That’s why we asked for observations with Suzaku and XMM-Newton. It took many months to gather and analyze the data before we were ready to write up a paper and submit it to the Astrophysical Journal as a Letter. The referee report was challenging but positive, and the Letter got accepted rapidly. The pre-print is now out on arxiv: http://arxiv.org/abs/1011.0427

So what did we find? We found something, but it isn’t a quasar. With the X-ray data, we can definitely rule out the presence of a quasar in IC 2497 powerful enough to light up the Voorwerp. We do however see some very weak X-ray emission that most likely comes from the black hole feeding at a very low level. Compared to what you need to light up the Voorwerp (the floodlight), the black hole currently puts out 1/10,000 of the required luminosity. That’s like trying to illuminate a sports stadium at night with a candle.

We can therefore conclude that the black hole in IC 2497 dropped in luminosity by a factor of ~10,000 at some point in the last 70,000 years. This implies a number of very exciting things:

1) A mere 70,000 years ago (a blink of an eye, cosmologically speaking), IC 2497 was a powerful quasar. Since it’s at a redshift of only z=0.05, it’s the nearest such quasar to us. Since IC 2497 is so close to us, and the quasar has switched off, it means that images of IC 2496 are the best images of a quasar host galaxy we will ever get.

2) Quasars can just switch off very quickly! We didn’t know they could do this before, and the fact that they can is very exciting.

3) Maybe the quasar didn’t just switch off, but rather switched state, and is now putting out all its energy not as light (i.e. a quasar), but as kinetic energy. That’s an extremely intriguing possibility and something I want to investigate.


We put out a press release via Yale. You can find it here.

Hunting Voorwerpjes

The discovery of the Voorwerp is definitely still keeping us busy as we’re trying to understand it. To recap what we know: the Voorwerp is a bit of a giant hydrogen cloud next to the galaxy IC 2497. The supermassive black hole at the heart of IC 2497 has been munching on vast quantities of gas and dust and, since black holes are messy eaters, turned the center of IC 2497 into a super-bright quasar. The Voorwerp is a reflection of the light emitted by this quasar. The only hitch is that we don’t see the quasar. While the team at ASTRON has spotted a weak radio source in the heart, that radio source alone is far too little to power the Voorwerp. It’s like trying to light up a whole sports pitch with a single light bulb – what you really need is a floodlight (quasar). We’ve been working hard on the X-ray observations that will give us a final answer whether there’s a quasar clevely hiding in IC 2497, or whether the black hole has somehow abruptly stopped feeding.

In the meantime, what we want to know is if there are more Voorwerps, or if Hanny’s Voorwerp is all we have in the local universe. This turns out to be harder than it sounds because asking a computer to go search a massive data set like Sloan for smudges that have this weird blue-purple-y colour is rather difficult. In fact, the Computer said ‘no.’ Fortunately, we could ask you folks to find weird blue-purpley-y stuff around galaxies because such a vaguely phrased question of a human makes sense. And you found more Voorwerps. Since they’re smaller, we dubbed them Voorwerpjes, or `Little Objects’ in Dutch (I look forward to the day that ‘Objects’ are a class of astronomical objects!).

Bill and his team have been taking a look at all the potential Voorwerpjes that you found and many of them are similar to the Voorwerp in the sense that they are clouds of gas lit up by an accreting black hole. All these clouds, like the Voorwerp, are many tens to hundreds of thousands of light years away from the centers of the galaxies they surround. So like with the Voorwerp and IC 2497, we know for a fact that the black hole was feeding tens to hundreds of thousands of years ago. What we’d like to know is if they are still feeding. If not, then clearly black hole meals can end rather abruptly (10,000 years is nothing to a billion solar mass black hole). If that’s the case, then black hole feeding is stranger and less stable than we previously thought….

To find out, we submitted a proposal, again to our friend XMM-Newton, to take X-ray snapshots of the galaxies with the top Voorwerpjes. Fingers crossed that we get the time.

X-ray paper submitted!

Just a quick note: I’ve finally submitted the paper on the X-ray observations of IC 2497 and the Voorwerp with XMM-Newton and Suzaku. It’s a Letter so we should hear back fairly soon, so stay tuned!

Galaxy Zoo gets highlighted by the 2010 Decadal Survey

Every decade, the US astronomy community gets its leaders together to write up a report on the state of the field and to recommend and rank major projects that should be supported by the government over the next decade. It’s a blue print, a wish list and often also a sober exercise in what to fund (a little) and what to cut (a lot). The current Decadal Survey was finally released by the US National Academies last Friday and every astronomer is poring over it to see if their project or telescope is ranked highly.

Galaxy Zoo isn’t competing for hundreds of millions of dollars in funding to launch a space observatory, but it did get not just one but two mentions in the 2010 Decadal Survey, one in the text and a figure. For those of you who are keen to read the whole thing for themselves, you can get the report at the National Academies website here (you have to click on download and give them your details to get the free PDF download). Here on the blog we only show you the highlights, i.e. the Galaxy Zoo mentions. From the text in the section on “Benefits of Astronomy to the Nation” where they discuss how “Astronomy Engages the Public in Science”:

Astronomy on television has come a long way since the 1980 PBS premier of Carl Sagan’s ground-breaking multipart documentary Cosmos. Many cable channels offer copious programming on a large variety of astronomical topics, and the big three networks occasionally offer specials on the universe too. Another barometer of the public’s cosmic curiosity comes from the popularity of IMAX-format films on space science, and the number of big-budget Hollywood movies that derive their plotlines directly or indirectly from space themes (including five of the top ten grossing movies of all time in America). The internet plays a pervasive role for public astronomy, attracting world-wide audiences on websites such as Galaxy Zoo (www.galaxyzoo.org, last accessed July 6, 2010) and on others that feature astronomical events, such as NASA missions. Astronomy applications are available for most mobile devices. Social networking technology even plays a role, e.g., tweets from the Spitzer NASA IPAC (http://twitter.com/cool_cosmos, last accessed July 6, 2010).

They also have a lovely figure, which has a small blooper in it (see if you can spot it!). Word is that this is going to be corrected in the final version:


Thank you all for making Galaxy Zoo such a success!

Voorwerp Web-Comic: Authors meeting at CONvergence

It came from the SDSS: The Voorwerp

It came from the SDSS: The Voorwerp

Have you ever looked at the Voorwerp and said to yourself, “Doesn’t that look like the Swamp Thing?” Or maybe you’ve seen Kermit the Frog dancing, or a maybe you see foliage run amok. There is just something about the Voorwerp that make me, for one, want to anthropomorphize it as a monster, and I’m betting some of you have had the same moment of Pareidolia.

The neat thing about the Voorwerp is it not only looks like the character from a bad monster movie, but it is a real-life monster of a problem that has played a starring role in an intellectual adventure. While astronomy doesn’t normally get turned into summer block buster movies, this story just might make it with a rating of “S: Judged appropriate for people who contribute to science in their spare time.”

Image with me – you go into a movie theatre and hear booming from the speakers: “It came on the 13th; Monday the 13th. And one woman dared to ask ‘What is that stuff?'” Suddenly the camera zooms in on the Voorwerp. Then this imaginary movie trailer has us cutting between action adventure shots of astronomers racing for telescopes (you see a car racing across the desert with domes in the distance), the Swift space telescope  repointing, and Zoo Keepers conferring in solemn tones as they gather around a computer. Bill Keel (played by Martin Sheen?) asks, “Can we get Hubble time?” and someone played by the Hollywood hunk of your choice responds in an overly dramatic tone, “I don’t know, but we have to try – I want answers – and we can handle the truth.”

Ok, so maybe the idea is pure cheese, and no Hollywood director (or college film major) is likely to shoot this flick, but there is still a story here that is worth sharing with the world.

And the STScI agrees with us. They’ve funded the creation of a digitized comic book (a web comic) to tell the story of Hanny’s discovery of the Voorwerp and the scientific adventure all of us have gone on as the truth has been sought in all sorts of wavelengths using a myriad of telescopes.

This comic is being written under the guidance of Kelly McCullough (author of the Ravirn series) by a team of volunteer writers at the CONvergence Con outside of Minneapolis, Minnesota, USA. The writers will work in close collaboration with Bill Keel and many other Zoo Keepers to make sure they get the story completely right.

Want to watch? Want to hang out with Zoo Keepers (list of attendees to come) at a cool event? Then join us in Bloomington, Minnesota, July 1-4, 2010. The event does cost money, unfortunately, and you have to register (My turn to bring the cookies). The cost of registration goes up May 15, so if you’re interested, please register ASAP for lowest prices.

We’ll be releasing the comic at Dragon*Con in the fall. We’d love it if you’d consider coming and being part of the celebration.

We’re going to work to keep you informed about everything that is going on. You can follow along at http://hannysvoorwerp.zooniverse.org, and in the webcomic thread on the forums.