Paper! First Author! Pre-Print!

Posted by barb on Oct 17, 2003 in Thesis/Grad Life

I found out last week that a paper I worked on has been accepted to the Astrophysical Journal! And I’m the first author! Now I’m doing the happy astrophysicist dance (if you’ve never seen it, be thankful 🙂

This paper is based on work I did for my second year research requirement for my master’s degree. I analyzed time-separated observations of MCG -5-23-16, a Seyfert 2 galaxy. Seyfert galaxies are a class of active galactic nuclei, which are galaxies with a central region that put out so much energy that the rest of the galaxy can rarely be seen (there’s a more technical definition, of course, but that gives you the general idea). The energy that they put out comes from all parts of the electromagnetic spectrum — radio, optical, X-rays. My study was in X-rays. It is believed that these nuclei are powered by a super massive black hole with an accretion disk, and possibly another torus of material further out. In order to study the distribution of matter, I studied the changes over time of the X-ray spectrum. Our basic results were that the material that was “reprocessing” the X-rays (i.e. absorbing light from the central engine and reemitting them in another waveband) was not dominated by a nearby accretion disk. Instead it came from somewhere between 1 light day and 1 light year from the central engine.

Check out a preprint on astro-ph:
RXTE and BeppoSAX Observations of MCG -5-23-16: Reflection From Distant Cold Material (astro-ph/0310468)


Thesis Meeting

Posted by barb on Oct 10, 2003 in Thesis/Grad Life

I had some preliminary results of running the pipeline on four different sources: 3C 111, Akn 120, IC 5063, and Mkn 348 I had tried using several different “minimum” time bins for extracting the spectra. Oddly enough, the change from 15 ks to 55 ks didn’t change the number of spectra by much for most of the sources (Akn 120 had 106 spectra for 55 ks bins, whereas it had 103 for 15 ks bins) — I think this is due to the count rate variability of the sources, though I may want to look closely at what the pipeline is doing just to make sure.

Unfortunately, there were some weird results with a couple of the sources. For example, in one of the Akn 120 spectra, the power-law index jumped up to 4 (which is not physically reasonable). The next step is going to be to run some well-studied (and published) data sets through the pipeline with a couple more models, and see if we can recover the published results. In addition, I will look through the pipeline results to find any spectra that are behaving badly, and re-analyze those by hand. We are agreed that I can’t possibly do all of the data by hand, but we are concerned that the pipeline is not giving physically reasonable results. So, we hope that most of the spectra are well-behaved, and that by re-analyzing the few that show odd behavior with the pipeline, I can reduce the number of spectra analyzed by had to a manageable number.


Thesis Meeting

Posted by barb on Sep 5, 2003 in Thesis/Grad Life

I met with Kim and Chris today for the first time since my proposal defense. Since then, I’ve completed a good, working version of my data pipeline. I’ve been quite pleased with my pipeline, but I really wanted to discuss my method for determining how to extract spectra with Kim and Chris. I had just kind of made it up over a few days, and wasn’t sure if it was a good method.

I illustrated how the pipeline choses the break points for spectra by defining count-rate bins based on 25% increments around the average overall XTE count rate. Both Kim and Chris thought that it looked like a good method! (Chris’ words, I believe, were “Actually, that’s quite clever.”) One of the good things about this method is that while it does smooth out some small variations to get a bigger signal, it retains large variations. It has the potential to probe time-scales of a few days. If we wanted to probe smaller time scales, I’d need to use a different method, but this is sufficient for the goals of my research.

Things I need to do:

  • figure out how to make smart_fit do 1-sigma errors instead of 3-sigma (actually, I need both)
  • choose a few representative sources, and play around with the minimum time for the spectra
  • plot figures using 1-sigma errors, and do some fits to constants to see what we come up with
  • work on plotting a “stack” plot automatically with ppgplot


More on yesterday’s outburst

Posted by barb on Aug 12, 2003 in Thesis/Grad Life

Okay, I did not mean to imply, by yesterday’s outburst, that I got into science for the money. There is no money in science. If I’d wanted to do something for money, I would have gone into engineering or computers or business. I went into science because I’m curious, and this is one of the few fields that fully rewards curiosity.

I went into astrophysics because I love the stars — even after eight years of concentrated astronomy study, I still find the stars and the night sky magical. I cry when I’m alone in a large field at midnight away from city lights. The vastness makes me feel so small, and yet so important at the same time. I’m just a speck on a speck in the whole wide Universe (and that’s only the parts we can see), but I am. And even though I don’t actually look at the sources I’m studying (since X-rays can’t be seen), I still feel the magic in my work — the things I study are millions of light years away, and yet we can deduce what cool phenomena are producing the light we see.

It just seems that after two bachelor’s degrees (astrophysics and math) and a master’s degree (astrophysics), I should be able to 1) afford housing, 2) afford a new car, 3) pay off my student debt (both loans and credit cards). Currently I’m only able to pay off my student debt at a decent rate because I’m not paying for housing. Even at that, I can’t dream of buying a new car.


Icky evening

Posted by barb on Aug 11, 2003 in Thesis/Grad Life

I was reminded yet again tonight that 1) life is not fair, and 2) I’m nowhere near where I thought I would be at 31.

I’ve been a student for the better part of 31 years. Yup. Started pre-school at 6 years-old, elementary at 7, junior high at 13, high school at 16, community college at 18, 4-year college (transferred) at 24, graduate school at 27. I got my master’s degree at 30. Took a year and a half off. And here I am again at 31, half time, working toward a PhD.

I’ve discovered that with my Master’s degree in Astrophysics, I’m at the peak of my earning potential right now. Even if I get a PhD, I’ll only increase my earning potential if I choose to (and can find) a full-time research position. I don’t think I could do that — I’ve seen what it does to people. They become maniac workaholics who work 10 hours a day Monday through Friday, and then several hours on weekends. I enjoy discovering the secrets of the universe, but not at the expense of my entire personal life.

I can’t help but think that I’ve made a serious tactical error in my career choice. What the hell was I thinking? Who goes into astrophysics anymore? I want to be able to afford a new car. I want to pay off my credit cards. I want to pay off my student loans without accruing any new ones. Apparently that’s just too much to ask for a 31-year-old with a master’s degree. Apparently it’s not enough.


The Night After

Posted by barb on Jun 20, 2003 in Thesis/Grad Life

The plan was to go to The Hulk after my defense, but I only wanted to go to a matinee showing (I’m cheap, and I hate crowds). Unfortunately, the defense went about 20 minutes too long for us to make the last matinee (at 4:45 PM). Instead, we went straight to the Macaroni Grill for dinner, and then I dragged Andrew around the mall for several hours. (Oh, shut up. He needed some new shorts, so part of the trip was for him.)

I dragged him into the Build a Bear store (for probably the umpteenth time). He was a good sport, but I could tell that he was tired of taking me in there every time we went to the mall. So, I decided that it was time to put together a bear for myself. But what to do? Based on the day, it seemed appropriate to do a PhD-candidate bear. What does this entail? Well, we dressed the bear in grad-student clothes (a peasant top, shorts, sandals and glasses), and bought her a school bag (the kind that has a flap under which you can insert pencils and a calculator). Her name is Felicia , and she’s working on her thesis in my home office as I write this. (She even has her proposal defense talk in her bag with her.)


PhD Proposal Defense (!!)

Posted by barb on Jun 20, 2003 in Thesis/Grad Life

The proposal defense was at 2 PM.

All morning I tried not to worry too much about the defense. I did do a bit of cramming, trying to track down a tidbit on column density/flux correlations in Seyfert 2 galaxies and how this might indicate that not all Seyfert 2s are created equal, but I couldn’t find it. Fortunately, I didn’t need it.

At about 10 AM, I decided that it was silly to cram for the defense. I had no idea what the committee might ask, so there was no way to prepare any more than I already had in writing the proposal and presentation. So, I went back to analyzing the Akn 120 data set. It’s odd how playing with data has a calming effect. In some ways, it’s so mechanical that the brain can just go on autopilot. On the other hand, there’s the knowledge that this data set might, just might, hold some cool bit of science that no one has seen before, and if I could just find it. I didn’t get further than fitting the first spectrum to my four models, but I was encouraged that it showed a strong sign of reflection (which none of my other four sources so far had shown). I had been getting worried that I was doing something wrong with the data.

At 11 AM, I received a very encouraging e-mail from my UMD advisor (“Try to have fun this afternoon… you’ve got a good proposal that should sail through, so you can mainly use this as an opportunity to harvest ideas from Cole and Pat.” — Cole and Pat were the committee members, besides Chris and Kim). Unfortunately, I didn’t feel any less nervous after that. Sigh.

I tried to think about lunch at noon, but couldn’t manage to get too excited. I didn’t really want to put anything into my stomach that might just end up coming back out again. I did manage to have a bag of Veggie Chips, and a small cup of applesauce, but even those made me feel barfy.

My plan was to leave for the university at 1 PM. It only takes about 15 minutes to get from Goddard to UMD, but I thought I’d stop by Stef’s office for a bit, and let her boost me up a bit. Just before leaving, I decided to check my favorite blogs. I skimmed through Wil Wheaton ‘s entry for yesterday , and paused as I got to the “Thought for the Day”:

Go confidently in the direction of your dreams. Live the life you have imagined.

Holy crap! How appropriate was that for me today? I have wanted to go as far as my intellect could could take me in my education for as long as I can remember. I’ve known that I wanted to be Dr. Barb since I entered college over ten years ago. So what if I’ve hit some bumps and slow patches on the way? So what if I took the scenic route for a couple years? So what if I had to take a year-long pit stop to find the strength to pursue my dream again? I’ve made it. I know where I want to go. I know how to get there. And all I have left to get to full candidacy is this silly little proposal defense today. Somehow, the thought that I was finally following where my dreams had led me was more encouraging than anything anyone else could say.

That’s not to say that I wasn’t still nervous. I won’t go into details on the defense itself. Let me just say that it went pretty well. There were a few questions that Chris had to lead me toward the answer to, but overall the committee thought the project was worthwhile. I’m excited to get back to work on it.


Thesis Proposal Write-up

Posted by barb on Jun 13, 2003 in Thesis/Grad Life

I worked a couple more days on the proposal this week, incorporating some comments from Kim, and I declared it finished yesterday. I’m certain that any omissions will come up during the defense next Friday (YIKES!). I’ll admit that I’m starting to get nervous….


Library Day

Posted by barb on Jun 7, 2003 in Thesis/Grad Life

I spent the bulk of the day at the library doing a complete re-write of my thesis proposal. After re-reading the draft I sent Kim and Chris, I’m completely embarrassed! Chris sent me comments, and I began to wonder if we had read the same paper, but as I combed through the paper more today, and read over my stack of journal articles, I saw his point, and what I needed to do.

Andrew came with me, and I was worried that he would get bored, since the plan was to stay until the re-write was done or the library closed. It was nice to have him there, though, since he reminded me when I needed to get lunch. (We headed off to Anita’s around 12:30 PM — after I’d been working for 2.5 hours, and completed reworking the first big section.) As it turned out, he had plenty to do looking up books on how to buy a used car. He also went out to a nearby comic book store for a bit. And I finished the re-write by 3:30 PM.

I spent another 4 or so hours at home entering the re-write into LaTeX, but overall the day was very productive, and I’m happy with the resulting proposal. It’s much stronger, and more coherent than the draft I turned in on Monday.

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