Universe of Spectroscopy

Author: Kentaro Aoki

What would you like to introduce to readers in this series?

For 30 years, gamma-ray bursts were shrouded in mystery, but now it is generally accepted by astronomers that they exist in the distant Universe along with galaxies and quasars. The afterglow spectrum of GRB050904 gave us an opportunity to advance gamma-ray burst research further. I am proud to be a member of the Subaru Telescope, which produced one of those data. I feel that I've benefitted as a researcher from being present at the presence of those observations.

Eight years have passed since the spectroscopic observation of GRB050904, but, there are still so few celestial bodies in the distant Universe beyond redshift 5 for which the amounts of several elements has been measured or can be measured from the absorption line observations.

Gamma-ray burst observations require to make an observational plan quickly, and execute an observation as soon as possible after a gamma-ray burst. We always ready to do, a fast decision, and luck. And there is the risk that they might not produce results, so it is not like “straight” research. On the other hand, while the telescope is moving to a target we normally do not know what the redshift will be. We have excitement of getting previously unknown data.

By all means, I expect new researchers to enter this field.

My research field and current interests:

After a long interval without activity, a very bright gamma-ray burst at red shift 5.9 occurred in June, 2013. Without exception, the large telescopes in the world, such as GTC, MMT, VLT, Gemini, and so on, pointed to the afterglow of the gamma-ray burst. Of course, the Subaru Telescope observed it. We worked hard reducing the observational data through June and into July. High accuracy analysis which had never been considered before was particularly demanding. Now, we are in the process of submitting a paper to a scientific journal with Dr. Tomonori Totani of University of Tokyo as the lead author. Currently we are waiting for the review results. This research could be introduced in NAOJ News at some future date.

Originally, I had intended to observe a quasar for my own research that night, but with a mix of joy and sorry I relinquished my time to the gamma-ray burst afterglow observations. When there are not gamma-ray bursts, I do spectroscopic observations of quasars; particularly, research to estimate the amount of gas and energy outflow through spectroscopic observation of peculiar quasars which show broad absorption lines. Recently, I also searched for unknown quasars using the Subaru Telescope.


Kentaro Aoki
Subaru Telescope, NAOJ
Job Title
Support Astronomer
Field of Expertise
Active Galactic Nuclei, Gamma-ray Bursts

* at November, 2013