Details

Autor(en) / Beteiligte

• MØLLER, P
• FYNBO, J. P. U
• FALL, S. M

Titel

Detection of lyman-α emission from a DLA galaxy: Possible implications for a luminosity-metallicity relation at z = 2-3

Ist Teil von

• Astronomy and astrophysics (Berlin), 2004-08, Vol.422 (2), p.L33-L37

Ort / Verlag

Les Ulis: EDP Sciences

Erscheinungsjahr

2004

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• In an ongoing programme to identify a sample of high z DLA galaxies we have found the long sought for case of a Ly alpha emitter seen in the centre of a broad DLA trough. This is the predicted "textbook case" of an intervening DLA galaxy if DLA galaxies are small, but would not be expected if intervening high redshift DLA galaxies have large gaseous disks. The Ly alpha flux is 5.4 super(+) sub(-) super(2) sub(0.8) x 10 super(-17) erg s super(-1) cm super(-2) similar to what has been found in previously known high z DLA galaxies. The impact parameter is found to be 0".3 plus or minus 0".3. This is smaller than what was found in previous cases but still consistent with random sightlines through absorbers with mean impact parameter approximately 1". Of the 24 DLAs targeted in the NICMOS imaging survey five have now been identified as Ly alpha emitters. The DLA galaxies with detected Ly alpha emission tend to have higher interstellar metallicities than those with undetected Ly alpha emission. This is plausibly explained as a consequence of a positive correlation between the Ly alpha line luminosities of the galaxies and their metallicities, although the present sample is too small for a definitive conclusion. The available observations of high-redshift DLA galaxies are also consistent with a negative correlation between Ly alpha equivalent widths and metallicities, as seen in nearby star-forming galaxies and usually attributed to the preferential absorption of Ly alpha photons by dust grains.