Science Investigations Enabled by the Far-UV Sensitivity of the Cosmic Origins Spectrograph
Abstract
The Cosmic Origins Spectrograph, installed on HST during Serving Mission 4, offers unprecedented sensitivity for point source spectroscopy in the ultraviolet (1150 < lambda < 3200A). Post-SM4 calibration programs revealed substantial response in the far-UV bandpass (lambda < 1100A) previously inaccessible to HST instruments. We describe initial estimates of the effective area of HST/COS(G140L Segment B) below 1150A and present first results from a Cycle 17 calibration program to characterize the sensitivity and spectral coverage in this wavelength regime, albeit at lower spectral resolution (R < 2000) than achieved by COS at longer wavelengths. These results open the door to new science investigations with HST that were previously infeasible. Examples of studies that will benefit from this new capability include a characterization of the ionizing source population at the epoch of helium re-ionization (z = 2.8 +/- 0.2) and constraining the hardness of the intergalactic radiation field at this redshift with the HeII Gunn-Peterson effect, measuring the escape fraction of ionizing photons from star forming galaxies in the low-redshift (z <0.25) universe, and numerous topics that take advantage of hot (CIII 977 and OVI 1032/1038; T 104 - 106 K) and cool (H2; T 50 1000 K) gas diagnostics unique to this bandpass. We present a discussion of scientific prospects enabled by the sensitivity of COS.
- Publication:
-
American Astronomical Society Meeting Abstracts #215
- Pub Date:
- January 2010
- Bibcode:
- 2010AAS...21546404S