Gravitational Wave Astronomy is here!

Summary: For those of you not glued to your computer for the past couple hours, you may have missed the new announcement from the LIGO experiment. They have officially announced the discovery of a second gravitational wave detection. That's right, it is no longer a single event in the dark. We have two confirmed black hole mergers that created gravitational waves and another "trigger" event that may prove to be an additional gravitational wave source after a few more tests are performed. There's only an 85% chance of the signal being astrophysically significant right now and that is not good enough for the team at LIGO.

I for one am ecstatic about this announcement. Not only does it herald in a new field of astronomy, but the presentation of data so far has been very easy to understand. Great graphics and explanations.

To give a brief outline of how they conduct their science, it starts with an interferometer. Light travels down two paths of equal length before recombining at a photodetector that measures how much light is hitting the sensor. If the paths are truly equal in length, the light from the different paths will cancel each other out and it will be dark. Any little alteration in the length will cause light to be detected. The gravitational waves actually move space itself like a ripple in a still pond so as the wave flies through Earth, the different paths the light travels at will briefly be different.

The first signal in September was unexpectedly loud so it was able to be seen with human eyes, but this new one from December (Christmas in the US!) was harder to spot. They needed the computer to match the signal to a template in order to see it. It works like a child taking a circular puzzle piece and trying all of the different shaped slots until they finally are able to fit it into the corresponding circular depression on the board.

We can only imagine how much great work will still be coming out of this observatory in the future. This is not yet running at full potential and when the second run starts this autumn it will be more sensitive still. I'll be sure to keep you updated.

LIGO
Video of event

Also, if you are interested in helping LIGO look for more gravitational waves, check out GravitySpy.org

Double Black Hole Hails Discovery of Gravity Waves

Summary: It's the announcement of a discovery you didn't know you were waiting for. The detection of gravitational waves. It sounds weird, of course, but Einstein was onto something big when he was working on his theory of general relativity. Similar to a ball warping the surface of a rubber sheet, or a kayak being thrown into the water, large objects in outer space warp the fabric of the four dimensional spacetime that we live in.

When this happens, gravitational waves ripple through space and expand or contract the space around them. These waves have been undetectable until now. It is thanks to the LIGO interferometer that we can detect these faint waves in the universe. These waves are understandably hard to detect, the measurements are on a scale less than a width of an atom. They were able to detect this thanks to a double black hole.

Quite deservedly, the scientists involved are quite proud of their work. As this is both the first detection of gravity waves and the first direct detection of a black hole in addition to being confirmation of general relativity, they are confident that there is a Nobel Prize in their future and I am inclined to agree.

Either way, it is an exciting breakthrough in astronomy and one that I am excited to have as I enter the field.


APS Article
BBC News
Nature
SciShow

Using the Eye of Sauron to see Great Distances

Summary: Two of my geeky obsessions have overlapped at long last. And in an exciting way too. As we strive to learn more about the beginnings of our universe, astronomers need new ways to measure distances to distant galaxies. The galaxy NGC4151, nicknamed The Eye of Sauron, has provided that.
The method relies on measuring the size of the supermassive black holes found at the center of all big galaxies. These black holes swallow up a huge about of gas and end up spewing emissions back out to become an AGN. The hot dust becomes a ring around the black hole which the astronomers used for measuring distance. By measuring the time delay between the emission of light from very close to the black hole and the infrared emission of the dust ring, we are able to know the distance the light has had to travel from the black hole to the ring.
Knowing the physical size and the apparent size of the ring means astronomers have a new method of measuring distance with only a 10% uncertainty. Not the most precise method we have but it is one that can be easily applied to many other galaxies out there.


AlphaGalileo
Nature

The Mystery of the Cosmic Cloud

Summary: Astronomers have been watching a cosmic cloud heading towards a black hole. They thought they knew what to expect, but once more nature has thrown us a surprise. They had expected some space fireworks but none occurred. As of this news article, scientists don't know what the cause of this is, but some are saying that maybe the gas cloud is not just gas. Others are thinking there is some kind of cloaking somewhere in the system. Either way it is a new mystery for us to find out.


BBC News

No Black Holes?

Summary: In an article I cannot quite wrap my head around, Stephen Hawking has now proposed that the black holes we know (well, sorta know) and love, don't actually exist. I don't really understand the article but it seems to me that he is proposing a different definition of black holes. That they still exist, but just need to be defined differently. If anyone can summarize the article better, please leave a summary in the comments.


Nature

Another Disappointment in Dark Science

Summary: One possible explanation for all of this Dark Matter that should be detected but isn't, is that Dark Matter could consist of relatively small black holes created in the early days of the universe. However, lack of data from Kepler supporting this theory has crossed of another possibility on our 'What in Sagan's Name is this stuff?' list.



American Physical Society

10 new black holes

Summary: NASA's NuSTAR X-ray telescope has successfully discovered 10 super massive black holes. NuSTAR has been designed to hunt for these huge black holes in hopes of better understanding how common they are and what this means for our understanding of how the universe was formed.


Live Science

Clouds could reveal black hole details

Summary: A cloud of gas (called G2) that was discovered in 2011 is due to pass by the center of our galaxy where is it speculated that a cluster of black holes resides. Scientists have never been able to definitively prove that these black holes exist but are hopeful that when the cloud passes in September it could give us the proof. "The idea is that as the cloud speeds past these small black holes - some slightly more massive than our Sun but just a few tens of km across - gas will spiral around them faster and faster, heating up to millions of degrees and emitting X-ray light." Telescopes could then see these emitted rays and know for sure that the black holes exist. This indirect method of detection has been compared to watching the swirls in the water as a giant bathtub drains though thousands of little drains.



BBC News

Mass of a black hole

Summary: I should have posted this before but I was trying to come up with a good way to explain this. Instead I will attempt an explanation and you can leave a comment with any questions you have.
Scientists are now using the principles of centripetal motion to calculate the mass of a black hole. Though its not stated in the article the basic equations are F=(Gm1m2)/r^2=(mv^2)/r
I'm assuming that these will be used to find the mass.




BBC News: http://www.bbc.co.uk/news/science-environment-21259221

Oversized Black Hole

Summary: Scientists have found a enormous black hole in the middle of a relatively small galaxy. It's been calculated that the black hole accounts for about 15% of the galaxies mass. This is way more than is typical. Scientist are guessing that it was formed a long time ago and then nothing else really started to form. Check out the details below.



Nature: http://www.nature.com/nature/journal/v491/n7426/full/nature11592.html
BBC News: http://www.bbc.co.uk/news/science-environment-20528137

Planetary cloud set to be devoured.

Summary: A new star with a planetary hole is heading for the black hole at the centre of the Milky Way. This will provide scientists a unique chance to study the theorised black hole.


BBC News: http://www.bbc.co.uk/news/science-environment-19558443