Recovery and analysis of rest-frame UV emission lines in 2052 galaxies observed with MUSE at 1.5 < z < 6.4

Schmidt KB, Kerutt J, Wisotzki L, Urrutia T, Feltre A, Maseda MV, Nanayakkara T, Bacon R, Boogaard LA, Conseil S, Contini T, Herenz EC, Kollatschny W, Krumpe M, Leclercq F, Mahler G, Matthee JJ, Mauerhofer V, Richard J, Schaye J. 2021. Recovery and analysis of rest-frame UV emission lines in 2052 galaxies observed with MUSE at 1.5 < z < 6.4. Astronomy & Astrophysics. 654, A80.


Journal Article | Published | English

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Author
Schmidt, K. B.; Kerutt, J.; Wisotzki, L.; Urrutia, T.; Feltre, A.; Maseda, M. V.; Nanayakkara, T.; Bacon, R.; Boogaard, L. A.; Conseil, S.; Contini, T.; Herenz, E. C.
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Abstract
Rest-frame ultraviolet (UV) emission lines probe electron densities, gas-phase abundances, metallicities, and ionization parameters of the emitting star-forming galaxies and their environments. The strongest main UV emission line, Lyα, has been instrumental in advancing the general knowledge of galaxy formation in the early universe. However, observing Lyα emission becomes increasingly challenging at z ≳ 6 when the neutral hydrogen fraction of the circumgalactic and intergalactic media increases. Secondary weaker UV emission lines provide important alternative methods for studying galaxy properties at high redshift. We present a large sample of rest-frame UV emission line sources at intermediate redshift for calibrating and exploring the connection between secondary UV lines and the emitting galaxies’ physical properties and their Lyα emission. The sample of 2052 emission line sources with 1.5 < z < 6.4 was collected from integral field data from the MUSE-Wide and MUSE-Deep surveys taken as part of Guaranteed Time Observations. The objects were selected through untargeted source detection (i.e., no preselection of sources as in dedicated spectroscopic campaigns) in the three-dimensional MUSE data cubes. We searched optimally extracted one-dimensional spectra of the full sample for UV emission features via emission line template matching, resulting in a sample of more than 100 rest-frame UV emission line detections. We show that the detection efficiency of (non-Lyα) UV emission lines increases with survey depth, and that the emission line strength of He IIλ1640 Å, [O III] λ1661 + O III] λ1666, and [Si III] λ1883 + Si III] λ1892 correlate with the strength of [C III] λ1907 + C III] λ1909. The rest-frame equivalent width (EW0) of [C III] λ1907 + C III] λ1909 is found to be roughly 0.22 ± 0.18 of EW0(Lyα). We measured the velocity offsets of resonant emission lines with respect to systemic tracers. For C IVλ1548 + C IVλ1551 we find that ΔvC IV ≲ 250 km s−1, whereas ΔvLyα falls in the range of 250−500 km s−1 which is in agreement with previous results from the literature. The electron density ne measured from [Si III] λ1883 + Si III] λ1892 and [C III] λ1907 + C III] λ1909 line flux ratios is generally < 105 cm−3 and the gas-phase abundance is below solar at 12 + log10(O/H)≈8. Lastly, we used “PhotoIonization Model Probability Density Functions” to infer physical parameters of the full sample and individual systems based on photoionization model parameter grids and observational constraints from our UV emission line searches. This reveals that the UV line emitters generally have ionization parameter log10(U) ≈ −2.5 and metal mass fractions that scatter around Z ≈ 10−2, that is Z ≈ 0.66 Z⊙. Value-added catalogs of the full sample of MUSE objects studied in this work and a collection of UV line emitters from the literature are provided with this paper.
Publishing Year
Date Published
2021-10-15
Journal Title
Astronomy & Astrophysics
Acknowledgement
We would like to thank Charlotte Mason for useful discussions and for providing the data for the curves shown in Fig. 13 and Dawn Erb for providing the observational data for the comparison sample studied by Steidel et al. (2014), also shown in Fig. 13. This work has been supported by the BMBF grant 05A14BAC and we acknowledge support by the Competitive Fund of the Leibniz Association through grant SAW-2015-AIP-2. AF acknowledges the support from grant PRIN MIUR2017-20173ML3WW_001. JS acknowledges the support from Vici grant 639.043.409 from the Dutch Research Council (NWO). GM received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No MARACAS – DLV-896778. This paper is based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 094.A-0289(B), 095.A-0010(A), 096.A-0045(A), 096.A-0045(B), 094.A-0205, 095.A-0240, 096.A-0090, 097.A-0160, and 098.A-0017. This paper also makes use of observations made with the NASA/ESA Hubble Space Telescope obtained at STScI. This research made use of the following programs and open-source packages for Python and we are thankful to their developers: DS9 (Joye & Mandel 2003), Astropy (Astropy Collaboration 2013, 2018), APLpy (Robitaille & Bressert 2012), iPython (Pérez & Granger 2007), numpy (van der Walt et al. 2011), matplotlib (Hunter 2007), and SciPy (Jones et al. 2001).
Volume
654
Article Number
A80
ISSN
eISSN
IST-REx-ID

Cite this

Schmidt KB, Kerutt J, Wisotzki L, et al. Recovery and analysis of rest-frame UV emission lines in 2052 galaxies observed with MUSE at 1.5 < z < 6.4. Astronomy & Astrophysics. 2021;654. doi:10.1051/0004-6361/202140876
Schmidt, K. B., Kerutt, J., Wisotzki, L., Urrutia, T., Feltre, A., Maseda, M. V., … Schaye, J. (2021). Recovery and analysis of rest-frame UV emission lines in 2052 galaxies observed with MUSE at 1.5 < z < 6.4. Astronomy & Astrophysics. EDP Sciences. https://doi.org/10.1051/0004-6361/202140876
Schmidt, K. B., J. Kerutt, L. Wisotzki, T. Urrutia, A. Feltre, M. V. Maseda, T. Nanayakkara, et al. “Recovery and Analysis of Rest-Frame UV Emission Lines in 2052 Galaxies Observed with MUSE at 1.5 < z < 6.4.” Astronomy & Astrophysics. EDP Sciences, 2021. https://doi.org/10.1051/0004-6361/202140876.
K. B. Schmidt et al., “Recovery and analysis of rest-frame UV emission lines in 2052 galaxies observed with MUSE at 1.5 < z < 6.4,” Astronomy & Astrophysics, vol. 654. EDP Sciences, 2021.
Schmidt KB, Kerutt J, Wisotzki L, Urrutia T, Feltre A, Maseda MV, Nanayakkara T, Bacon R, Boogaard LA, Conseil S, Contini T, Herenz EC, Kollatschny W, Krumpe M, Leclercq F, Mahler G, Matthee JJ, Mauerhofer V, Richard J, Schaye J. 2021. Recovery and analysis of rest-frame UV emission lines in 2052 galaxies observed with MUSE at 1.5 < z < 6.4. Astronomy & Astrophysics. 654, A80.
Schmidt, K. B., et al. “Recovery and Analysis of Rest-Frame UV Emission Lines in 2052 Galaxies Observed with MUSE at 1.5 < z < 6.4.” Astronomy & Astrophysics, vol. 654, A80, EDP Sciences, 2021, doi:10.1051/0004-6361/202140876.
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