A search for Hα emission in high-metallicity damped Lyman-α systems at z 2.4

الأصل · EN

We report on a sensitive search for redshifted Hα line-emission from three high-metallicity damped Lyα absorbers (DLAs) at z ≈ 2.4 with the Near-infrared Integral Field Spectrometer (NIFS) on the Gemini-North telescope, assisted by the ALTtitude conjugate Adaptive optics for the InfraRed (ALTAIR) system with a laser guide star. Within the NIFS field-of-view, ≈ 3.22" × 2.92" corresponding to ≈ 25 kpc × 23 kpc at z=2.4, we detect no statistically significant line-emission at the expected redshifted Hα wavelengths. The measured root-mean-square noise fluctuations in 0.4" apertures are 1-3×10⁻¹⁸ erg s⁻¹ cm⁻². Our analysis of simulated, compact, line-emitting sources yields stringent limits on the star-formation rates (SFRs) of the three DLAs, < 2.2 M yr⁻¹ (3σ) for two absorbers, and < 11 M yr⁻¹ (3σ) for the third, at all impact parameters within ≈ 12.5 kpc to the quasar sightline at the DLA redshift. For the third absorber, the SFR limit is < 4.4 M yr⁻¹ for locations away from the quasar sightline. These results demonstrate the potential of adaptive optics-assisted, integral field unit searches for galaxies associated with high-z DLAs.