Gemini e-Newscast #31 -- June 20, 2011by xzhang
An unusual luminous outburst from a distant galaxy
Andrew Levan (University of Warwick, UK) and collaborators have identified an extremely luminous outburst in a distant galaxy. This burst, discovered using NASA's Swift satellite on March 28, 2011, is unusual with a long duration at high energies and total energy output of 10^53 erg in the first 10 days, and the event continues even now. Initial shallow imaging using GMOS on Gemini North a few hours after the burst yielded only an upper limit on the optical magnitude, but subsequent deep followup spectroscopy using Gemini North, the Gran Telescopio Canarias, and the Keck II telescope yielded the redshift z=0.35 and spectral signatures consistent with a star-forming galaxy as the host. Further multi-wavelength observations demonstrate that the event was bright from the radio through gamma rays. In a companion paper, Joshua Bloom (University of California Berkeley) and colleagues interpret the event as the galaxy's central black hole consuming a nearby star. More details are available from Gemini, and the complete results appear in the journal Science (papers 1 and 2).
A z~9.4 gamma ray burst
Another Swift trigger required careful analysis for Antonio Cucchiara (Penn State University and University of California Berkeley) and collaborators to conclude that the origin of the April 29, 2009, gamma ray burst occurred in a z~9.4 galaxy. The photometric redshift was based on near-infrared detections (and optical non-detection) of the afterglow using Gemini North and UKIRT; poor weather had prevented rapid spectroscopic followup. This gamma ray burst appeared to be relatively normal, which requires rapid star formation in the very early universe. For more information, see the press release or a preprint of the paper to appear in The Astrophysical Journal.
First engineering light with GeMS
The Gemini Multi-Conjugate Adaptive Optics System (GeMS) team has been busy with on-sky engineering during the first half of 2011. Beyond progress with the laser guide star facility (reported earlier) they achieved engineering first light on April 19, 2011, captured with the Gemini South Adaptive Optics Imager (GSAOI). Nearly all subsytems, offloads, and loops are now tested and demonstrated to work, achieving Strehl ratios up to 20% and measuring point source FWHM values as low as 75 milliarcseconds, even without system optimization. Following a planned five-month period of work off-sky that began in June, commissioning will resume, including work to improve the system performance. More information including the engineering first light image is available.
Work has continued to make FLAMINGOS-2 a facility-class instrument for scientific use. Progress to-date includes improvements to mechanism reliability and thermal stability, and the resolution~3000 grism is now installed. The instrument is currently cooling with the engineering-grade detector in place for testing. A detailed analysis of the remaining effort estimates that FLAMINGOS-2 will be ready for re-commissioning at the end of 2011 and during early 2012. This schedule reflects the significant redesign necessary in some critical areas. If FLAMINGOS-2 is ready for system verification observations in 2012A, an official announcement will be made to the community. Regular updates are available.
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