So it Could be a ‘Supervoid’ That’s Causing the Mysterious CMB ‘Cold Spot’

Only last month I recorded a DNews video about the awesome possibilities of the “Cold Spot” that sits ominously in the cosmic microwave background (CMB) anisotropy maps (anisotropies = teenie tiny temperature variations in the CMB).

I still hold onto the hope that this anomalous low temperature region is being caused by a neighboring parallel universe squishing up against our own. But evidence is mounting for there actually being a vast low density region — known as a “supervoid” — between us and that Cold Spot.

And that’s crappy news for my dreams of cosmologists finding bona fide observational clues of the multiverse hypothesis any time soon. The Cold Spot could just be the frigid fingerprint of this supervoid etched into our observations of the CMB.

But as this supervoid could be as wide as 1.8 billion light-years, this discovery is still crazy cool — the supervoid could be the newest candidate for the largest structure ever discovered in the universe. Suck it, Sloan Great Wall.

Read more about this new research published today in the Monthly Notices of the Royal Astronomical Society in my Discovery News blog.

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Black Holes, Aurorae and the Event Horizon Telescope

My impression as to how a black hole 'aurora' might look like near an event horizon (Ian O'Neill/Discovery News)

Usually, aurorae happen when the solar wind blasts the Earth’s atmosphere. However, black holes may also have a shot at producing their very own northern lights. What’s more, we might even be able to observe this light display in the future.

Accretion Disks and Magnetic Fields

Simulating a rapidly spinning black hole, two researchers from Japan modeled an accretion disk spinning with it.

Inside this disk would be superheated plasma and as it rotates it might act like a dynamo, charged particles generating a magnetic field looping through the disk. But this magnetic field wont stay confined to the disk for long. Due to inertial effects, the magnetic field would be dragged into the event horizon, causing the magnetic fieldlines to ‘attach’ themselves to the black hole.

Assuming the accretion disk continues to generate a continuous magnetic field, a global black hole ‘magnetosphere’ would result.

A diagram of the black hole's magnetosphere (Takahashi and Takahashi, 2010)

A Plasma Hosepipe

As you’ve probably seen in the striking imagery coming from the high-definition movies being produced by the Solar Dynamics Observatory, magnetic fieldlines close to the solar surface can fill with solar plasma, creating bright coronal loops. This hot plasma fills the loops, feeding around the magnetic field like a hosepipe filling with water.

The same principal would apply to the black hole’s magnetosphere: the looped magnetic field feeding from the accretion disk to the event horizon filling with plasma as it is sucked out of the disk (by the black hole’s dominating gravitational field).

As you’d expect, the plasma will fall into the black hole at relativistic speeds, converted into pure energy, blasting with intense radiation. However, the Japanese researchers discovered something else that may happen just before the plasma is destroyed by the black hole: it will generate a shock.

As predicted by the model, this shock will form when the plasma exceeds the local Alfven speed. For want of a better analogy, this is like a supersonic jet creating a sonic boom. But in the plasma environment, as the plasma flow hits the shock front, it will rapidly decelerate, dumping energy before continuing to rain down on the event horizon. This energy dump will be converted into heat and radiation.

This fascinating study even goes so far as predicting the configuration of the black hole magnetosphere, indicating that the radiation generated by the shock would form two halos sitting above the north and south ‘poles’ of the black hole. From a distance, these halos would look like aurorae.

Very Large Baseline Interferometry

So there you have it. From a spinning black hole’s accretion disk to shocked plasma, a black hole can have an aurora. The black hole aurora, however, would be generated by shocked plasma, not plasma hitting atmospheric gases (as is the case on Earth).

This all sounds like a fun theoretical idea, but it may also have a practical application in the not-so-distant future.

Last year, I wrote “The Event Horizon Telescope: Are We Close to Imaging a Black Hole?” which investigated the efforts under way in the field of very large baseline interferometry (or “VLBI”) to directly observe the supermassive black hole (Sagittarius A*) living in the center of our galaxy.

In a paper written by Vincent Fish and Sheperd Doeleman at the MIT Haystack Observatory, results from a simulation of several radio telescopes as part of an international VLBI campaign were detailed. The upshot was that the more radio antennae involved in such a campaign, the better the resolution of the observations of the ‘shadow’ of the black hole’s event horizon.

If the black hole’s event horizon could be observed by a VLBI campaign, could its glowing aurorae also be spotted? Possibly.

For more, check out my Discovery News article: “Can a Black Hole Have an ‘Aurora’?” and my Astroengine.com article: “The Event Horizon Telescope: Are We Close to Imaging a Black Hole?

Astroengine Featured on CNET

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In an article written by Don Reisinger for CNET News, Astroengine.com was selected as one of the “18 cool sites and apps that teach you about space.”

This is awesome as one of my main effort on Astroengine is to not only promote space news, opinion, skepticism and logical thinking, I also hope the site serves as an educational medium, so readers can understand the science that hides beneath the headlines. “Outreach” is a lot more than a group of scientists trying to work out how best to promote their work to the world; it’s a way of communicating advanced scientific theories to an audience who don’t necessarily have a specialized knowledge of the subject matter. Even though I have an education in a small aspect of astrophysics, it is often hard to understand the next big discovery in cosmology (don’t get me started on quantum dynamics, that stuff is insane!), so the more explaining the better in my books.

Also, to add to the coolness, by virtue of alphabetical luck, Astroengine.com takes the #2 slot in the top 18 space websites. And to top the whole thing off, Don Reisinger’s article hit the front page of Digg.com this morning. Needless to say, Astroengine was busier than Grand Central Station on a Friday evening this afternoon (thank goodness I have a brand new server to deal with demand)!

Thank you Don, I really appreciate the mention and the really cool review!

For more, check out “18 cool sites and apps that teach you about space” on CNET.com »

Star Formation: The Game

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Dave Mosher, I’m pointing my finger at you for this late night effort! Usually I stay up late to write articles, but for the last 30 minutes I’ve been playing this game after Dave sent a message on Twitter saying he had been playing a “simple” and “addictive” star formation game. No kidding! I shouldn’t have even clicked the link. But like a caffeine-infused moth to a super-shiny flame, off I went for some simple star-creation fun.

It looks like the Star Formation game is part of Discover Magazine’s featured article about the mysteries of star birth (it’s a great read, check it out). The game is simple, yet captivating (despite a few minor bugs). You play the role of supernova progenitor, dropping some massive star fury on an unsuspecting nebulous cloud of hydrogen. According to the game developers, the situation is physically accurate, it is just up to you to create the perfect conditions for stars to form in the dense cloud. It would appear the lectures I attended on star formation paid off, as I speak I’m on top of the leaderboard with a whopping 21122 points (see the screengrab above, I saved it posterity, I doubt I’ll be at #1 for much longer).

I’m all for games with an educational element, and I can’t think of a better way to spend an evening (well, I can, but if you’re stuck in the office, this is a great alternative to work). I’m off to create some more stars, check out Discover so you can do the same (just you try to knock me from the #1 slot!).

Astroengine.com Now Featured in Alltop.com!

Astroengine.com is now listed in the Alltop web directory! This ranks in the upper echelons of “coolness” as Astroengine now features alongside space news behemoths such as the Universe Today, Bad Astronomy, Space.com, Discovery, New Scientist, Space.com, Space Examiner and loads more besides!

From the Alltop homepage: Alltop is an “online magazine rack” of popular topics. We update the stories every hour. Pick a topic by searching, news category, or name, and we’ll deliver it to you 24 x 7. All the topics, all the time.

Be sure to check out Alltop.com, I’ve used it a lot. I like the format as you can access all your favourite space and science news websites on one page and organize it as you see fit. I suppose it’s like an RSS feed reader, only easier. That seems to be the trend of social media these days, speed and ease of use… perhaps I need to start cutting back on some of my gadgets

Astroengine Featured on the Geologic Podcast #106!

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From now on, I will listen to Prince’s “Sexy Mother F*cker” with great affection…

I mentioned I had listened to the Geologic Podcast the other day to hear George Hrab’s rendition of the awesome Occasional Songs For The Periodic Table.

It was strange, as I remembered chatting to George about that when I was ordering my nth beer at the AAS party in January, but I thought nothing more of it until I was idly chatting about something on Twitter. Like so many micro-blogging conversational experiences, I have no idea what we were talking about or how we got onto the topic of the Periodic Table and I remembered my drunken chat with George. At that moment, like a flash of enlightenment, @MsInformation pointed me in the right direction so I could listen to that particular song. It was in fact a series of songs compiled into one epic feature. This is one of the many reasons why I love Twitter, I can think without needing to think.

To my complete surprise, earlier today @MsInformation (I really should ask for Ms Information’s name…) dropped me a message to say I was featured on today’s yesterday’s (Thursday’s) Geologic Podcast. Happily surprised about this turn of events, I navigated to the podcast site, intrigued by the warning, “I hope you won’t be offended.”

I certainly was not offended, more extremely flattered and very, very entertained! You could say I’m a huge fan of the Geologic Podcast, and not just because I was featured, but because it is bloody fantastic! In episode 106, there’s everything from cows urine, “Religious Moron of the Week” to some great views from the maestro himself George Hrab, featuring Ms Information. I love George’s strong opinions and unwavering wit, so be sure to check it out.

Warning: Some of the content of the Geologic Podcast is not suitable for minors, might not be suitable for work (depending on whether you work in a hospital or a brothel – the latter will probably be fine), but it will certainly give you tough love in the sceptical thought department!

Listen into Episode 106 (March 5th, 2009) of the Geologic Podcast »

Thank you George and Ms Information!

Occasional Songs For The Periodic Table – by George Hrab

George Hrab dominates the periodic table. Credits: Univ. Virginia/Geologic Records

George Hrab dominates the periodic table. Credits: Univ. Virginia/Geologic Records

When I heard that George Hrab had turned the Periodic Table into a musical opportunity, I had mixed feelings. The mixed feelings were of excitement to hear what George had come up with, and those of fear of revisiting my science class woes. You see, I hated chemistry at school… and college. You can probably imagine my horror when my chemistry nemesis came back to haunt me in my Masters year of university (I’d avoided it expertly during my undergrad years); I’d have to learn the thing for a key spectroscopy course! Bugger
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