Scientific research | Lyman-alpha galaxies in the nearby universe

For the history of this field, see the data distribution page for our HST pilot programme.


LARS - the Lyman-alpha Reference Sample


The Lyman-alpha reference sample is a largeish Hubble Space Telescope programme that will return a homogeneous set of observations for 14 uniformly selected starburst galaxies, selected from the GALEX and SDSS catalogues, at redshift 0.03 to 0.18. When HST is decommissioned no telescope will be capable of performing high resolution observations (either imaging or spectroscopy) in the far ultraviolet. In this era, LARS will represent the only detailed, complete, and systematically selected study of its kind.

Imaging observations are being carried out under HST Cycle 18 with the Advanced Camera for Surveys and Wide Field Camera 3, and will be complete in three emission lines (Lyα, Hα, and Hβ) and 6 ultraviolet and optical broadbands (2 from ACS/SBC in the UV, and 3 from WFC3 in the optical). UV spectroscopic observations will be carried out under HST Cycle 19 with the Cosmic Origins Spectrograph to resolve the Lyα line profile, and provide kinematic measurements by virtue of absorption features in the UV continuum.

As well as using HST, we are also following up the sample with the Green Bank Radio Telescope to obtain neutral hydrogen masses for the sample. Being the atom the scatters Lyα and becomes key in the radiative transport problem this information is vital; somewhat surprisingly LARS will represent the first, and likely only, sample for which Lyα and HI observations exist.

Data are also coming in from the Gran Telescopio Canarias, which will target nebular lines in the optical to map ionization parameter and metallicity.

For now, the situations is very much one of "watch this space ..."