First Science Data With Advanced LIGO is Near!

It has been a very exciting time for Advanced LIGO recently.  A few weeks ago we completed a test run of the instrument to identify any remaining bugs in the instrument or other stability issues.  The commissioners (instrumental scientists who work on making LIGO more sensitive) have been busy adjusting various settings in a multitude of subsystems to increase our sensitivity to gravitational waves.  We are continuously learning more about how all of these subsystems react to one another and to the environment.  And learning is never without its own pains.  Some bugs have been bigger than others. We've had to actually touch the new instrumentation - meaning we had to seal off the chamber the part was in, let the air back in (since almost all of the instrument is in a vacuum), fix it, close up the chamber, and pump the air back out.  This is rare but it has happened.  Once the instrument was performing well, that's when we decided to stop tinkering with it and use it like we would if we were looking for gravitational waves.  More subtle issues in stability and other bugs will make themselves apparent only after you use it the way it's meant to be used - all the time.

Installing one of Advanced LIGO's seismic isolation platforms at the Hanford observatory in 2013.

ENGINEERING RUNS

These test runs are called engineering runs.  We abbreviate them ER followed by the number of the run.  The last one was called ER8.  I've already talked about the first one (ER1) back when almost everything was being simulated since the installation of the instruments was just getting off the ground.  The purpose of those early engineering runs was to test out the ability of our data analysis systems to handle the large amount of data we will collect.  As parts of aLIGO were installed, we replaced the simulated data from that component with real data.  ER8 was our first test of all of the instrument without anything being simulated.  While the purpose of this data is to test the stability of the whole system and to find other small bugs, we are still running all of our data analysis methods over the collected data.  We don't expect to find a gravitational wave in this data, but if we have compelling reason to believe that we really did see something we will certainly pursue it as a real detection.  Don't get too excited, though, since there are no indications that we collected a gravitational wave.

OBSERVING RUNS

What is really exciting is that we are preparing to make that first detection.  We don't really expect to detect a gravitational wave with our first science data (which will be called O1 - observation 1) with aLIGO but it is not as improbable as it was with Initial LIGO.  We are talking about what we learned from the blind injection in our last iLIGO data set (otherwise known as the "Big Dog" event) and what our detection validation should entail.  We are talking about writing the paper that we will publish announcing the first detection and its details.  We are even talking about how we will engage the public with this announcement.  Don't misunderstand me - we have not seen anything yet, but we are preparing ourselves for the possibility of detection.

DETECTION IS POSSIBLE...

You really don't have any idea how exciting this is especially for those of us who have been around a while (I have been working on LIGO since starting grad school in 1999 and I'm a youngster).  I have been working on this project that is so much bigger than myself since before we took our first data with Initial LIGO.  I remember when the collaboration was a couple hundred scientists (there are now almost 1000 of us).  I remember when we analyzed our first data and debated how to interpret our detection candidates when we almost sure that everything we had was noise (i.e. garbage).  Now we are talking about confidently making a detection, and doing astronomy with it.  This is the dawn of a new age in astronomy and I'm proud to be here to see it.

Distance in parsecs (1 pc = 3.26 light years) Initial LIGO was able to detect its standard source of 2 neutron stars orbiting each other just before they merge into one body.  (Read more here.)
aLIGO wil be able to "see" up to 200 Mpc (about 650 million light years).

Remember, we don't expect a detection, but it is possible.  To give you an idea of how possible, once we have aLIGO working at the sensitivity it was designed to work at, it will observe as much of the universe in several hours as Initial LIGO did in an entire year.  We won't be at design sensitivity for O1, but we can already detect our standard source 4 times farther away than we could on our best days with Initial LIGO.

An image of light that was filtered out of the laser before entering the LIGO detector.  Bend your neck to the right and you should be able to see a smiley face.  This is just a chance configuration and has no significance, but we thought it was cool.

Crawfish Boils and On the Road Again...

Last week's post came to you from the LIGO-Virgo Meeting in Boston, MA.  This week, it is coming to you from Atlanta, GA.  I just arrived here for the APS April Meeting.  My room is a beautiful corner room with two great views!  So I've chosen the better view from one of my windows:

Actually, I am here a day early so that I can attend the Professional Skills Development Workshop which is designed to improve the communication and negotiation skills of women physicists.  I'm looking forward to this as, while I would love to improve my communication skills, I really feel that I need to develop negotiation skills.  I am currently working to transition my current postdoc position (which is temporary by definition) into a more permanent position, not only because I love my work and the opportunities I have here, but my husband also works at the LIGO Livingston Observatory as an engineer.  The fact that I am this early in my career and living under the same roof with my husband, who is also happily employed in his field, is almost unheard of.  This is known as the two-body problem - when two academic professionals are challenged to find a way to find jobs together; I plan to write a blog post on this later.  That being said, I almost want to jump and any offer that can be scrapped together for me - the last thing I want to do is ruin the good thing I have going.  This is exactly one of the reasons that women tend to make less than men, even in physics - we undersell ourselves.  While I have no intention of trying to wring every penny I can out of a new position, I want to make sure that I am at least being compensated properly for my work.

As for the APS April Meeting, I will be giving a talk on the latest burst gravitational wave all-sky search results.  The information for my talk is here and the "plain English" science summary of the paper is here.  Once I give my talk, the presentation will be publicly available on the LIGO Document Control Center (DCC).  I will also be attending the APS Forum on Education Executive Committee Meeting and this will be the last of my term.  I have more than enjoyed the others I was privileged to serve with and it has been wonderful to get a chance to spread my wings a little more in physics education.  Of course, I have days and days of interesting talks and other activities to look forward to.  I will make sure to Tweet points of interest so make sure to follow me @livingligo.  You can also follow others' Tweets from the meeting using the hashtag #APSapril.

Between my trips to Boston last week and this one to Atlanta, I did get to be home in Baton Rouge for a few days.  Yesterday, the observatory staff was updated on the large scale status of the Advanced LIGO upgrade by the program leader, David Shoemaker.  While that was very informative (all is going well), the best part of the day of the crawfish boil we had outside afterwards.  For those of you who don't live in the American South (specifically the deep south), crawfish/crawdads/mudbugs/crayfish (but don't call them the latter around the natives lest you truly out yourself as not one of them) are essentially small freshwater lobsters that yield about the same amount of meat in their tail as a shrimp.  The meal takes "family style" to a new level: everything is served in heaps and you get a tray instead of a plate and it is heaped with the crawfish, sausage, corn-on-the-cob, and potatoes.  Oh yeah, and you don't get utensils.  This is a get-your-hands-dirty kind of meal.  Here is what my lunch looked like (before I started tearing the little critters apart - the communal aftermath from everyone at the table wasn't nearly as pretty):

This is considered a "dainty" portion.  A few other tips on how to fit in as a local:

• Don't sit while you eat crawfish - you stand so that the juice that can sometimes explode out of the body when you separate the tail from the head doesn't get all over you.
• Suck the heads!  Once your remove the tail, don't through away the top part of the body - that's where all the best flavor is.  As I have never done this myself, I am not sure if they are referring to the seasoned boil that remains inside or if they actually suck the "stuff" out.  To me, it just looks like the poor thing is trying to escape!
• Again, don't call them crayfish.

And a point of common sense - take your watch off!  Mine still smells like crawfish!

Living LIGO 1 Year Anniversary!

Today is the one year anniversary of the Living LIGO blog!  Thank you to everyone who has ever read my blog and followed me on Twitter.  It has been an exciting year and I hope that the next one is even better for you.

I've learned many things through writing this blog.  The first thing I found was my voice.  Originally, I was targeting this blog to middle and high school teachers and students to give them an insight into the science of LIGO and what it is like to be a scientist.  While I think that this blog has served that role to a point, I also found an audience drawn from a great community of science enthusiasts and I've been able to engage them with all of the things that I love about my job.

By far, it is my readers who have made Living LIGO what it is (and I personally think it is great).  A high point for me came back in March when it was revealed that the "Big Dog" blind injection was not a real gravitational wave.  I wanted to share it on my blog since this was a rare peek into how science is done.  One of my readers shared it on his blog (here) which got the attention of a popular "Cosmic Variance" blog (here) and the story was then picked up by places like Discovery News (here) and various other blogs.  The number of readers went from a few a day to over 1000 on that particular day (and many of those reader have now become regulars).  This is something I never expected when I started writing my blog but it is very exciting for me and I hope that it has at least been interesting for you.

I usually like to post a picture with every post, but I didn't have anything particularly relevant to this so I decided to give you a peek into where I create my blog post and most of my other brilliant research - my office.  It's small but it's all mine!  I even have a window (which is great since fluorescent lights give me migraines) and a door:

If you look closely, you can see some of my collection of stuffed vampire/creepy things.

*Thank you again to every reader out there.*  As always, please let me know what kinds of things you would like to know about.  I'll answer almost anything - from science questions to how to become a physicist or whatever!  Ask in the comment section of any blog post or contact me on Twitter as @livingligo.

The "Big Dog" in the Envelope

So, there has been a lot of excitement in the LIGO and Virgo Collaborations because we thought that we may have had a gravitational wave detection candidate from the early morning hours of 16 September 2010.  Because the potential source was localized in the vicinity of Canis Major constellation, the candidate event was informally dubbed the "Big Dog" (get it? we think we're cute).

I was especially excited since I was one of the first people to know about the event.  I mentioned in a previous blog entry that LIGO and Virgo have developed an effort to process the data that we collect rapidly so we can tell our traditional astronomy colleagues (those with actual telescopes) where to look for a potential optical signal component of the event.  I was one of about 25 scientists that were notified when a candidate event for observation was detected so that we can make sure that the event is valid before we send it out for observation.  While I wasn't the scientist on duty for this purpose at the time, I received the text message a little after 1 AM Central time (I couldn't sleep).  This was only 8 minutes after the data was collected!

It was sent out for observation and the entire collaboration began to get very excited.  This looked just like what we would expect from a neutron star-black hole binary (pair) system orbiting into each other (to make a bigger resulting black hole).  But one of the things that every scientist needs to learn is not to get overexcited and declare this to be the first direct detection of gravitational waves without making sure that this isn't a false alarm.  There are 2 ways this could be a false alarm:  1:  There is something in the environment that just so happened to make a coincident signal in all of the detectors (LIGO in Louisiana, LIGO in Washington state and Virgo in Italy) or 2:  This could be a blind injection (test).  Until we knew for sure, no one was allowed to discuss this event outside of the collaboration.  I've had to keep my lips sealed for 6 months (just like the over 800 other scientists who are in the Collaboration)!

A blind injection is a test the higher-ups in LIGO can do to make sure that the data analysis methods are doing what they need to be doing.  Basically, a very small subset of people in the collaboration (think like 2 or 3 people) inject a fake signal into the detector and this injection is not recorded anywhere like the other injections we regularly do to test things like detector calibration, etc.  The fact that a blind injection exists is sealed away (in what we metaphorically call an envelope) until all due diligence is done and the collaboration is ready to declare that the signal is a detection unless it is a blind injection (that it, we prove that it is nothing in the environment or and nothing was wrong with the detectors detectors that caused the signal).

Yesterday (14 March 2011) at the LIGO-Virgo Meeting was the big day when we opened the envelope (which turned out to be a flash drive with a PowerPoint presentation on it).  If the envelope was empty or if whatever injections were in the envelope were not the "Big Dog", then that would mean we made a detection.  The envelope was opened and, indeed, the "Big Dog" was inside and not a real gravitational wave detection.

I was not surprised - there had not been a blind injection in the run before this and everyone expected that there would be at least one.  However, there was also a big part of me that was hoping against hope that this was real.  My entire career has been dedicated to the effort of directly detecting gravitational waves and the development of gravitational wave astronomy.  If the "Big Dog" had been real, this would have been a fulfillment of the first part of my goals and the opening of the door of the second part.

Regardless, all of the effort that was put into validating the "Big Dog" up until it was revealed to be a blind injection has been a priceless exercise for the collaboration.  We even have a paper that was ready to be submitted for publication if it had been real.  Since this is something that we have never done before, we have developed skills for when we do make the first detection with Advanced LIGO. 

Below is a picture (from my seat) of the title slide in the presentation opening the envelope.  This just goes to show that even if you think that scientists are smarter than you, it all depends on how you define smrt :)

7 April 2011 - UPDATE:  Read more detail on the "Big Dog" blind injection here!