A first catalogue of 831 emission line galaxies

New paper by E.C. Herenz et al.

We search for emission-line galaxies using a matched filtering approach (LSDCat). In the first 24 MUSE-Wide fields, we find 831 of these galaxies, including 237 Lyman Alpha emitters.

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We present a first instalment of the MUSE-Wide survey, covering an area of 22.2 arcmin2 (corresponding to 20% of the final survey) in the CANDELS/Deep area of the Chandra Deep Field South. We use the MUSE integral field spectrograph at the ESO VLT to conduct a full-area spectroscopic mapping at a depth of 1 h exposure time per 1 arcmin2 pointing. We searched for compact emission line objects using our newly developed LSDCat software based on a 3D matched filtering approach, followed by interactive classification and redshift measurement of the sources. Our catalogue contains 831 distinct emission line galaxies with redshifts ranging from 0.04 to 6. Roughly one third (237) of the emission line sources are Lyman α emitting galaxies with 3 < z < 6, only four of which had previously measured spectroscopic redshifts. At lower redshifts 351 galaxies are detected primarily by their [O II] emission line (0.3 ≲ z ≲ 1.5), 189 by their [O III] line (0.21 ≲ z ≲ 0.85), and 46 by their Hα line (0.04 ≲ z ≲ 0.42). Comparing our spectroscopic redshifts to photometric redshift estimates from the literature, we find excellent agreement for z < 1.5 with a median Δz of only 4 × 10-4 and an outlier rate of 6%, however a significant systematic offset of Δz = 0.26 and an outlier rate of 23% for Lyα emitters at z > 3. Together with the catalogue we also release 1D PSF-weighted extracted spectra and small 3D datacubes centred on each of the 831 sources.


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