Thursday, January 17, 2013

3000 astronomers in Long Beach

Jelly fish at the Aquarium of the Pacific in Long Beach, CA
where the opening reception of the AAS meeting was held
Image credit: Jeyhan Kartaltepe

Last week many astronomers meet up again at the Winter meeting of the American Astronomical Society. You can read about the Summer AAS meeting in Alaska here. This time, the meeting took place for 4 days in Long Beach, CA. AAS meetings start officially with an opening reception on Sunday evening. Here astronomers have a chance to mingle and catch up with those friends and colleagues they don't see that often while having a bite to eat and a drink. This time the opening reception took place in the Aquarium of the Pacific which is located near the Convention Center where the rest of the meeting was held. The aquarium was a big hit with everyone since we were able to walk around the exhibition, look at lots of fish, jellyfish, crabs, shrimp and many other sea creatures. Some of them we were even allowed touch (of course under supervision of aquarium staff)! If you get a chance you should go visit, and then imagine the aquarium being packed with thousands of astronomers.

On Monday, the real meeting started with talks and poster presentations. Because so many people come together in one place, AAS meetings and their schedule are usually very busy. Lots of people give presentations (one usually has 5 minutes for a talk) or show a poster about their work. Since the meeting is only a few days long, talks are grouped into sessions according to their topic and many sessions run parallel.

Many of the CANDELS team members participated in the meeting. In fact, we had an entire talk session full of CANDELS Science talks on the first day. Our session was started off by Guillermo Barro who told us about his recent paper on the progenitors of compact quiescent (no longer star forming) galaxies. It is still unclear how such massive and yet extraordinarily small and compact galaxies formed. So some astronomers, like Guillermo, are looking for the progenitors as predicted by different evolutionary scenarios. 

Next, Jeyhan Kartaltepe presented her work on the morphologies of extremely luminous infrared galaxies. By using the extensive morphological classification scheme in CANDELS she compared the morphologies of luminous galaxies at different redshifts in order to determine how the role of galaxy mergers has changed over cosmic time. Mark Mozena then presented his dissertation work in a 15 minute talk. He discussed how he is using the CANDELS classifications to learn about the morphologies of redshift 2 galaxies. He also compared the morphologies of observed galaxies with those of model galaxies using the same classifications.

Christopher Conselice presented the cosmological implications of major and minor mergers by investigating the merger histories of galaxies across time. In particular he showed how mergers can be identified through measurements of morphology.  

Then Viviana Acquaviva and I talked about the difficulties in determining the redshift of galaxies using only photometric data and spectral energy distribution fitting. My talk focused on the treatment of very dusty galaxies while her's introduced the use of reasonable assumptions in the derivation of photometric redshifts with her code that is based on a Markov Chain Monte Carlo (MCMC) technique.

Janine Pforr standing in front of the poster presenting the CANDELS blog
during the AAS meeting in Long Beach, CA. Image
Credit: Jeyhan Kartaltepe
The session was finished off by Carlos Vargas on the question of whether data stacking (i.e. the adding up of lots of images or spectra) helps in the analysis of Lyman alpha emitting galaxies which are very faint at high redshift and only stick out due to their strong Lyman alpha emission. In particular, he discussed how different stacking methods frequently used to enhance data and study the average properties of such galaxies affect the result.

But Monday was not only a busy day in terms of oral presentations of the CANDELS team. We also presented a poster about this blog (shown to the left). This gave us a great opportunity to share the blog with the larger astronomical community, meet new people that are interested in blogs and public outreach, and discuss ways to improve the blog. It was a great day to start off the meeting and we will tell you more about the remaining days of the meeting in the next few posts.

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