Near-IR narrow-band imaging with CIRCE at the Gran Telescopio Canarias: Searching for Ly alpha-emitters at z similar to 9.3



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Cabello González, Cristina and Gallego Maestro, Jesús and Cardiel López, Nicolás and Pascual Ramírez, Sergio and Guzmán, R. and Herrero, A. and Manrique, A. and Marín Franch, A. and Mas Hesse, J. M. and Rodriguez Espinosa, J. M. and Salvador Solé, E. (2022) Near-IR narrow-band imaging with CIRCE at the Gran Telescopio Canarias: Searching for Ly alpha-emitters at z similar to 9.3. Astronomy & Astrophysics, 659 . ISSN 0004-6361

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Context. Identifying very high-redshift galaxies is crucial for understanding the formation and evolution of galaxies. However, many questions still remain, and the uncertainty on the epoch of reionization is large. In this approach, some models allow a double-reionization scenario, although the number of confirmed detections at very high z is still too low to serve as observational proof. Aims. The main goal of this project is studying whether we can search for Lyman-alpha emitters (LAEs) at z similar to 9 using a narrow-band (NB) filter that was specifically designed by our team and was built for this experiment. Methods. We used the NB technique to select candidates by measuring the flux excess due to the Ly alpha emission. The observations were taken with an NB filter (full width at half minimum of 11 nm and central wavelength lambda(c)1.257 mu m) and the CIRCE near-infrared camera for the Gran Telescopio Canarias. We describe a data reduction procedure that was especially optimized to minimize instrumental effects. With a total exposure time of 18.3 h, the final NB image covers an area of similar to 6.7 arcmin(2), which corresponds to a comoving volume of 1.1 x 10(3) Mpc(3) at =9.3. Results. We pushed the source detection to its limit, which allows us to analyze an initial sample of 97 objects. We detail the different criteria we applied to select the candidates. The criteria included visual verifications in different photometric bands. None of the objects resembled a reliable LAE, however, and we found no robust candidate down to an emission-line flux of 2.9 x 10(-16) erg s(-1) cm(-2), which corresponds to a Ly alpha luminosity limit of 3 x 10(44) erg s(-1). We derive an upper limit on the Ly alpha luminosity function at similar to 9 that agrees well with previous constraints. We conclude that deeper and wider surveys are needed to study the LAE population at the cosmic dawn.

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© ESO 2022. We thank the anonymous referee for the useful feedback that served to improve the original manuscript. This research was supported by the Spanish Ministry of Science and Innovation (MCIN) under the grants AYA2016-75808-R and RTI2018-096188-B-I00. C.C. acknowledges the Universidad Complutense de Madrid and the MCIN for the grant PRE2019-087503 "Personal Investigador Predoctoral en Formación". The authors thank Stephen Eikenberry, PI of the CIRCE camera, for his help during the preparation of the observations. This work is based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, on the island of La Palma. The authors also thank the support given by Dr. Antonio Cabrera and the GTC Operations Group sta ff during the observations at the GTC. This study makes use of data from AEGIS, a multiwavelength sky survey conducted with the Chandra, GALEX, Hubble, Keck, CFHT, MMT, Subaru, Palomar, Spitzer, VLA, and other telescopes and supported in part by the NSF, NASA, and the STFC. This work is based on observations taken by the 3D-HST Treasury Program (GO 12177 and 12328) with the NASA/ESA HST, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. This work has been possible thanks to the extensive use of IPython and Jupyter notebooks (Perez & Granger 2007). This research made use of Astropy (, a community-developed core Python package for Astronomy (Astropy Collaboration 2013, 2018).

Uncontrolled Keywords:Emission-line galaxies; Luminosity function; Cosmic reionization; Star-formation; Emitting galaxies; H-alpha; Redshift; Constraints; Evolution; Universe
Subjects:Sciences > Physics > Astrophysics
ID Code:74815
Deposited On:05 Oct 2022 06:30
Last Modified:05 Oct 2022 08:00

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