Gemini e-Newscast #22 -- December 17, 2009

by jpollard



Mass exodus from a galaxy

David M. Alexander (Durham University, UK) and colleagues have used the Near-Infrared Integral Field Spectrometer (NIFS) on Gemini North to measure galactic-scale outflow in a redshift z=2.07 quasar.  Such outflows may be part of the feedback mechanism that quenches star formation at later epochs.  The source is also a sub-millimeter and infrared-luminous galaxy, so star formation or the active galactic nucleus could drive the outflow.  More information is available from the Gemini webpage:  A preprint is available at and the work will be published in the Monthly Notices of the Royal Astronomical Society.

The early life of a galaxy

Mark Swinbank (Durham University, UK) and collaborators have taken advantage of gravitational lensing to measure star formation in a galaxy at redshift z=4.9.  They use NIFS observations to determine the star formation rate, which is high enough (at least 42 Msun/year) to account for the current stellar mass of the galaxy, although the total mass is much larger.  Other measurements indicate that the galaxy's stars are relatively young.  These findings together suggest that we are seeing this galaxy's first episode of star formation.  More information is available at or in the Monthly Notices of the Royal Astronomical Society (2009, Volume 400, Issue 3, page 1121):

Progress on GNIRS

The Gemini Near-Infrared Spectrograph, GNIRS, is currently cold and undergoing testing on the flexure rig in the instrument laboratory at Gemini's Hilo Base Facility. GNIRS will provide long-slit single order spectroscopy within the 1.0 - 5.5 micron range at spectral resolutions of approximately 1700, 5900 and 18000. Cross-dispersed spectroscopy will give complete 0.9 - 2.5 micron coverage at R~1700 and partial coverage at R~5900. Look for system verification opportunities during semester 2010B. Images of GNIRS and spectra obtained with the engineering detector are below.  The science-grade detector is in hand, awaiting installation.

Figure 1

Figure 1: GNIRS on the flexure rig at Gemini's Hilo Base Facility instrument laboratory.

Figure 2

Figure 2: GNIRS cross-dispersed spectra, obtained with the engineering-grade array.