Finding Dark Galaxies

Finding Dark Galaxies

One of the great mysteries of our universe is whether there are dark matter galaxies, devoid of stars, haunting the universe. From the COSMOS survey, we know that dark matter and visible matter are not always located in the same place. This implies that there may be galaxies out there made entirely out of dark matter. The question is: how can we prove they do or don’t exist? Proving they completely don’t, never ever, no where in the visible universe exist is actually impossible. No matter how hard we look, it will always be possible for one dark galaxy to be hiding. On the other hand, proving the do exist, is tedious but possible. This is because even dark galaxies exert a gravitational pull on the stuff around them. In a recent survey, lead by Igor...

Read More

Gravitational Lenses: Making the invisible detectable

Gravitational Lenses: Making the invisible detectable

Diagram of Gravitational LensingAstronomers on Earth are limited in how they can look at the universe. We basically have three tools. We can detect light across a broad spectrum of colors. We can capture high energy particles – cosmic rays – that are flung at us from distant events. We can also potentially measure gravity waves (but we’re still sorting out that technology). In all three instances, we are limited by our technology’s sensitivity to an event. This means that faint, small, low energy stuff at any significant distance is invisible as far as our detectors are concerned. And stuff like dark matter… well… it can’t be directly detected at all. When direct detection of something is impossible, it becomes necessary to find indirect methods. We are like Plato, looking to understand reality but only able to see shadows dancing on a cave wall.

Two of the most well defined ways we have of studying the universe’s shadows are the Cosmic Microwave Background (CMB) and gravitational lenses. Both things are scientifically interesting in their own right, and each can be used to indirectly see otherwise invisible content in the universe. Recent papers have shown how the CMB may allow astronomers to study our own solar system’s Oort Cloud (the source of long period comets), and how gravitational lensing effects can be used to map dark matter. Rather than try and discuss both these topics in one post, I’m going to take on gravitational lenses today, and dig into the cosmic microwave background tomorrow. (image credit: Kneib & Ellis w/ Caltech Digital Media Center)

Read More

AAS219: Austin, TX

AAS219: Austin, TX

I’m currently at the 219th meeting of the American Astronomical Society in Austin, TX. I’m here for just two days, and due to meetings, my coverage may be somewhat limited, but I’m going to do what I can to cover press conferences. The last couple meetings I’ve been at, I’ve found myself tweeting and not blogging. Now, with Google+ a new option exists and I’m going to try an experiment. In the mo+ment, I’m going to work writing short stories on Google+ and then link them to this post. Here are the things I’m going to try and follow. I’ll add links as I attend them. You can follow me directly on Google+ at http://gplus.to/starstryder (All times are GMT-6 / Central time) Monday 9:30 a.m.: THROUGH A LENS DARKLY¬†...

Read More

ASP-EPO: Day One

(I’m on a bad connection and will add links later.) Another day, another conference. From Dragon*Con, I crossed half-way across the country to Chicago to attend the 119th Meeting of the Astronomical Society of the Pacific on “EPO and a Changing World.” This morning I’m sitting in a session presented by astronaut George “Pinky” Nelson (the astronaut who repaired Solar Max) on things that need to happen for education to be made more effective. He is focusing largely (and I feel correctly) on the need to support our teachers by providing them training, content, and infrastructure. Intriguing comment of the day: “We should only teach a geometric explanation of the lunar phases. Let’s pick a grade, say 5th grade, and...

Read More

All the news that tried to escape

All the news that tried to escape

Today’s American Astronomical Society news feed brought me a small handful of press releases. Three releases (1, 2, 3) all related to the approximate mapping of the exoplanet HD 189733b and the discovery that exoplanet HD149026b is the hottest known world. Cool. The forth and final press release I received was also planetary science related, and embargoed, so I can’t really tell you anything beyond that my news feed lead me to believe that astronomers are currently only studying planetary science. The truth is, astronomers are exploring all the heavens have to offer in voracious detail, but the press officers (and press in general) are neglecting a lot of cool science going on in other areas.

Flipping over to the arXiv e-print service, a different picture emerges. The couple dozen submitted works for Wednesday, May 9, spanned subjects from string theory to CMB Anisotropies and the outer Solar System (1, 2). Some papers are still in peer review, and others will never be submitted to journals. All the papers are sitting there waiting to be read and learned from, and hopefully someday cited by someone not on the author list.

Read More
Now live! Expect the Unexpected.
Currently offline.