Update: Process complete! All the permalinks and the feed address should be the same, despite the fact that I did it a bit backwards. Notice any issues or problems with the change? Email me at nicole [at] noisyastronomer [dot] com. I’m assuming I haven’t screwed that up either

One Astronomer’s Noise will be moving shortly has moved to a new home host! Please note that this WILL may will not involve changing your rss feed reader address. (Sorry!) The blog will soon be at http://noisyastronomer.com/blog still be at http://noisyastronomer.com. Please visit there tomorrow for the new rss link!

Not sure how long this will take since I’m completely doing this self-hosted thing for the first time. Content will still be available at http://astronoise.wordpress.com for a while, and the main page will get a whole new look and organization.

Call it a little #scio11 inspiration. Instead of writing a new post. Or, writing my thesis chapter…

So, to further follow-up on the astrology nonsense of the week, here is my boss and all around cool guy at Discovery, Ian O’Neill, debunking the astrology bunk on Fox News, while an astrologer says it has to do with interpretations and resonances, while the reporter just keeps getting things wrong. (e.g. Rotation is not precession.) Good times!

Low frequency radio astronomy has enjoyed a resurgence in the last few years, partly driven the search for the signal of the epoch of reionization, or EoR. By low frequency, I mean technically around what is called the VHF or “very high frequency” radio band (30MHz – 300MHz). However, most of radio astronomy has centered on the GHz bands, with most recent pushes out to both higher AND lower frequencies to work on new science.

Low frequency radio astronomy is a bit harder than the radio astronomy of the past in part because of the Earth’s ionosphere. This is the ionized part of the atmosphere, meaning that it consists of negatively and positively charged particles. These charged particles can interact with light, aka electromagnetic radiation, and the problem becomes apparent as you move down to tens and hundreds of megahertz. (If you are not used to working with frequencies, just remember that the FM radio band is in this range, and that the wavelength of the light is on the scale of meters! GHz frequencies are measured in centimeters.)

Good for ham radio! Bad for astronomy...

The ionosphere refracts the incoming light, but irregularities and turbulence make it refract differently across a large field of view. In a way, it is analogous to the problem that optical astronomy has had to deal with all along. Stars seem to “twinkle” because of the turbulent troposphere (low, water-bearing layer of the atmosphere.) The latest generations of optical telescopes have been fitted with adaptive and even active optics, where the mirrors are slightly deformed in sync with the changing atmosphere in order to compensate for these effects and get really clear pictures.

The situation is a bit harder for radio astronomy. In order to get the spatial resolution on the sky, as well as the sensitivity needed, we build interferometers, or whole arrays of individual radio telescopes (antennas, elements, stations, etc.) linked together to make one BIG telescope. These interferometers don’t just take an image of the sky, as an optical telescope would, but measure spatial frequencies on the sky. Or, very, very roughly, how much brightness is in big things versus small things. This is then mathematically transformed (imperfectly) into an image. In this way, an interferometer needs to preserve the phase information of light, not just its amplitude, in order to make a proper sky map. And phase is just what the ionosphere likes to mess with.

The worst scenario with a large field of view, widely separated antennas, and all those little fluctuations. From Lonsdale 2005.

So what do we do? Well, as I sometimes say, “one astronomer’s noise is another astronomer’s data.” As we are trying to remove the effects of the ionosphere from our data, there are lots of ionospheric scientists who want to the study the ionosphere itself! So, URSI has been doing a joint-session of ionospheric physics and radio astronomy in the annual US meeting. The astronomers can make measurements of the phase changes in their data and try to interpret them in terms of the ionosphere, whereas the ionospheric people know a lot about how it behaves, and can share data taken with their instruments, such as GPS arrays and ionosondes. They, in turn, can use the telescope data as well to probe new size and time scales. Amazingly, there is still much to know!

In particular, I’m one of those radio astronomers trying to quantify the impact that the ionosphere has on our instrument, PAPER. In order to see the very, very faint EoR signal, we need to make accurate maps and clear out all the foreground “trash” first. I’ve been tracking the short-timescale, small movements of bright sources in the sky as they move through our telescope’s field of view, and determining empirically what ionospheric effects we need to be careful of. Then, I can make a model of our future, large dataset, and apply a realistic ionosphere model to see just how bad the problem will be. (Or not bad… don’t want to be a Debbie Downer!)

The two science communities are just now learning to speak to each other, in terms of jargon and familiarity with each others data. As I learned over dinner and drinks later that evening, we astronomers still have a lot of learn from the ionosphere guys and gals, and there is great opportunity for collaboration! I’m excited for this, as it can only help my push to finish my thesis and get this ionosphere characterized for the ever-important EoR detection to come!

That’s it. That’s the bottom line. But we’re good skeptics so we’ll delve a little deeper.

(First though, I should note, I just discovered that there is a whole Facebook page called “Astrology is bunk” for students who have had the honor of taking Tolbert’s class. I never did technically, but I was his TA, and enjoyed the class greatly!)

Astrology is essentially the idea that the alignment of the stars and planets when you were born have some kind of effect on your life. But there are some holes in this hypothesis. First of all, only 7 “planets” were known to the ancients: Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn. Astrological forecasting took those into account, but not Uranus and Neptune, which were there, but simply undiscovered. Wouldn’t a good astrologer have realized that something was off, and maybe even predict the existence of those planets long before they were spotted with telescopes. And what about Pluto? It was a planet and now it’s not, how has that ever been worked in?

You think they'd find the gas giants...

Next, there is the question of how the celestial objects affect you. The nuclear forces work over too short of a range, and the electromagnetic force isn’t very useful over large distances as well. Plus, astronomical objects are pretty much neutral anyway. So that leaves us with gravity. I could go through the derivation to show you that the gravitational pull of you mom’s obstetrician is comparable to that of the largest planet of our solar system, Jupiter, but that’s already been done. Note that his or her presence is not included in astrological forecasting. After 4 centuries of study with telescopes, there is nothing special about the planets or stars that would make them seem to affect our lives, and gravity isn’t it.

The topic of the current kerfuffle are the zodiac constellations. Typical Western astrology splits up the human population into 12 “signs” based on the constellation in which the sun was when that person was born. Note that these are specifically the ancient Greek constellations, as if they hold any special knowledge or significance to mysticism. As any good Astro 101 student can tell you, the Earth goes through a process called precession, in which the axis of the Earth slowly moves around a circlethe sky in a 26,000 year cycle. Therefore, celestial north isn’t always at the star Polaris, and was indeed pointed near bright Vega some long time ago. When you map the sun’s position against the background stars, it will change over time! Astronomers have to constantly upgrade their coordinates to keep up, yet Western astrology pays no heed to this, and your newspaper horoscope has the birth range for if you were born thousands of years ago!

July 31 means I'm a Leo! And look, there's the Sun in Leo! Except, I'm not 2000 years old...

The position of the sun on my actual birthday.

Well, apparently an astronomer in Minnesota (eh?) pointed this out to a reporter, and it morphed somehow into this huge DEAL where everyone is trying to recalculate their sign. Or, in some cases, refusing to change because they are so attached to it. It’s okay. I’ve been there. Though I was never really convinced of astrology’s supposed predictive powers, I relished the idea of being lion-like. Grrr. But really, it’s just silliness. The Christian Science Monitor has a really good article about this silliness, and includes the dates and the “13th zodiac sign” Ophiuchus. As they point out, this is not news to anyone who knows their way around the sky.

Finally, one could point out that science has found weirder things than we can dream up in our imaginations. Even if the mechanism seems absolutely implausible, does it work? The data say No. In a review of some 500 studies done on astrology since the 1950s, astrology fails over and over and over again to predict anything about a person. (It is really fascinating and I encourage you to check out the above-linked pdf.) In fact, you could give a whole room of people the same newspaper style horoscope reading and have most of them tell you, “Oh yeah, this sounds like me!” because they are written so generally.

So not only is astrology implausible and incorrect, it just plain doesn’t work. Unfortunately, that’s not the message that came across through the twisted world of the media.

Finally, if astrology does nothing, then what is the harm in belief? Most of the time, nothing. But pseudo-scientific thinking seems to have a way of causing damage in any case, as is cataloged by Tim Farley’s “What’s the Harm” website. Go ahead, check out the astrology section. Sucks, doesn’t it?

A great reference on astrology is on Phil Plait’s original Bad Astronomy website. Also, check out his take on the matter on his blog. Thanks also to Tim Farley’s SkepSearch for weeding out the nonsense.

Shamelessly stolen from the Bad Astronomer...

With one trip done, I’m really looking forward to tomorrow’s road trip to Science Online 2011 in North Carolina. This is my first time at the “open conference” or “unconference” about communicating science on the internet. There will be museum tours, workshops, and book discussions on Friday, followed by panel discussions on Saturday and Sunday. I’m starting to put together my weekend schedule now, drawn to things like “How to produce a high-quality short video” and “Alternative Careers for Scientists: from grad school to writing for Main Stream Media.”

If you couldn’t make the registration before it closed, you can still be a part of the conference by watching the livestream here.

I look forward to meeting a lot of people there who I’ve only heard of or talked to online, as well as seeing distant friends. If you are reading this and are going, please say hello! I’m, uh, the really short one.

Also, a note about “big phones” from the CES at Women With Droids. I have tiny hands and a honking big Droid X, and I love it.

(Alright, so here I am catching up on my #postaday2011 for yesterday. Dude, I took several modes of transportation after numerous canceled flights so….yeah…)

I actually heard about this discovery over lunch one day with my fellow grad students. Amy Reines, a Ph.D. candidate in our department, was working on the press release for this awesome new discovery. She was looking at a dwarf galaxy, Henize 2-10, which is about the same mass as one of the Milky Way’s nearby dwarf galaxies, the Large Magellanic Cloud. Her research is on super star clusters, or massive, prolific star forming regions. In studying the active star forming regions in this galaxy, she came across something odd. Using the Very Large Array, she found an interesting radio source that did not look like a super star cluster.

Hubble image of this very distant dwarf in blue/white, with the radio emission in pink.

She and several colleagues followed up this weird discovery with observations from the Chandra X-Ray Observatory. This showed a bright, compact source where the radio source was. This evidence, along with the jet-like features in the radio image suggested one thing… a supermassive black hole.

Hubble in red, green, and blue, VLA in yellow, Chandra in purple, and a red cross marking the black hole.

Supermassive black holes are found in pretty much every galaxy with a bulge. They can be millions or billions of times the mass of the sun. Most are “quiet,” but many are active, lighting up their surroundings as the matter falling into them rapidly spins around the black hole. Some of these are even spewing out jets of material seen in radio images, such as with this galaxy. Since supermassive black holes are so ubiquitous, it has been questioned, which comes first? The black hole or the galaxy bulge?

This black hole is weird in that it resides in a dwarf galaxy that has no stellar bulge! I mean, just look at that fluffy thing. This may be a clue that way in the universe’s past, galaxies had black holes before the stellar bulges formed around them.

So, the real reason we were discussing this at lunch was to come up with a good analogy for the strange finding. Indeed, it was serendipitous, in that Amy and her colleagues did not go looking for this black hole, but when they saw something odd, they diligently followed up and made a fascinating discovery. We were likening it to all kinds of things, like finding treasure in your backyard, or dinosaur bone in your sock draw. Actually, I think my favorite was, it’s like going to a Star Trek convention and meeting David Tennant. Or something like that.

Whatever analogy you’d like to make, this is certainly a great finding and will add to the debate of which came first, the bulge or the black hole. (And, congrats, Amy!)

Preprint of the Nature paper by Reines, Sivakoff, Johnson, and Brogan, and image credit also to Nidever. All cool CVille astronomers, by the way!

Thursday was the second day of the URSI conference in Boulder, CO. The plenary session took up the entire morning and included two very interesting talks on particle physics and cosmology. These are some pretty brain-bending subjects, as the universe turns out to work in ways that are completely alien to our brains which adapted to life on a particular planet with particular size scales. The very small and the very large scales have only been probed very recently in our history. I did some live-tweeting of these talks, which can be found by searching the #ursi hashtag. I promised to blog later about how I came to intuit the acceleration of the universe’s expansion do to mysterious dark energy.

For decades, cosmologists weren’t sure if the universe would keep expanding forever or if it would have enough mass to collapse back on itself. So, several teams of astronomers looked for very distant, bright, supernovae, specifically, Type Ia SNe. These are pretty much all the same brightness, so determining the distance is possible. What they found in 1998 was shocking. The expansion of the universe is actually accelerating. How the heck can that happen?

We know from relativity that a “cosmological constant” could be added to the equations to make this acceleration. In fact, Einstein had hypothesized it himself to make the universe come out stable, but retracted it when it was discovered that the universe was indeed expanding. Scientists started to attribute the acceleration to “dark energy,” which means, “we don’t know what the heck it is.”

After the supernova results, the Wilkinson Microwave Anisotropy Probe looked at the “echo” of the Big Bang, and determined that this dark energy actually makes up a significant chunk of the universe’s energy budget. In fact, we have many lines of evidence that converge on this story, now called the “concordance model” or “Lambda-CDM model” of cosmology.

I know, I know. You are probably looking at that figure and saying, WTH? Well, the x-axis indicates the density of matter in the universe and the y-axis the density of dark energy. The color contours represent likelihood of each factor having those values, where the darkest colors are 95% confidence in the values. Each color represents a different method of measurement, green from supernovae, blue from the large scale structure of galaxies, and orange from WMAP. Where they all overlap is the most likely reality! What ever dark energy is, it looks as if we are stuck with it.

You know how they always write headlines saying “scientists are baffled” when they really are not? I would dare to say that this is a case where astronomers and physicists are legitimately baffled. There are several hypotheses for what dark energy could be, and more experiments and observations need to be done to distinguish among them. One of the favorite candidates (well, my favorite) is vacuum energy.

Vacuum energy is the idea that empty space isn’t all that empty. This has been demonstrated by the Casimir effect, in which adjacent metal plates in a vacuum seem to have some force acting on them. It may be that the vacuum of empty space itself has some kind of repulsive force that keeps pushing the universe’s expansion. Interestingly enough, as the expansion continues, which makes more space, which makes more energy, which makes space expand faster, which makes MORE of this energy… etc. So in that way, it seems natural that the universe is just “falling out.”

Usually, the forces we deal with get stronger as the things creating them get closer together. For dark energy, however, the repulsive force gets stronger the further away things get. Weird, until thought about in context of vacuum energy.

Of course, we can’t settle on the vacuum energy hypothesis just yet. Theoretical physics predicts an energy density that is hugely different from the measured energy density in astronomical observations. Like 10 to the 123rd power times wrong. (That’s 10 with 123 zero’s following. Ouch.) However, it has not been ruled out, and indeed evidence shows that it is still quite likely…. if only we could understand it better.

So don’t let your head explode over our accelerating universe just yet. As physics gets weirder and weirder, we may find ways to wrap our teeny brains around this after all.

Many thanks to Mark Whittle who first couched it in these terms for me. His lecture notes are available!

Thanks to Jake and Angela for being such excellent hosts!!