New Observations with Gemini and GTC of the VHE Blazar KUV 00311–1938: About Its Redshift and Environment

PICHEL, A.; DONZELLI, C.; ROSA-GONZALEZ, D.; ALONSO, M. FERNANDEZ; ROVERO, A. C.; MURIEL, H.; MAYYA, Y. D.; ARETXAGA, I.; GONZÁLEZ, J. BECERRA; CARRAMIÑANA, A.; MENDEZ-ABREU, J.; VEGA, O.; TERLEVICH, E.; TERLEVICH, R. J.

Publications of the Astronomical Society of the Pacific

IOP Publishing

Lugar: Bristol; Año: 2021 vol. 133

Extragalactic very-high-energy (VHE; E > 100 GeV) sources are unique objects to study the most powerfulparticle accelerators in nature, as active galactic nuclei are likely sources of ultra-high-energy cosmic rays. BLLacertae blazars are the most frequent extragalactic objects found in the VHE gamma-ray catalogs. It is verydifficult to estimate their redshifts, considering they have no strong enough optical spectral features, hence ∼20%of them have unknown or poorly constrained redshifts. KUV 00311?1938 is a VHE BL Lacertae blazar, with anuncertain redshift in the range of 0.5 < z < 0.98. We have obtained deep spectroscopy using Gemini and the GTCtelescopes of KUV 00311?1938 and its surroundings with high signal-to-noise ratio in 2016?2017. The lack offeatures did not allow us to determine the spectroscopic redshift of KUV 00311?1938; nevertheless, we obtain alower limit of z 0.475. We determined the redshifts of 41 galaxies observed in the field-of-view of the blazar andthrough a population study, identified three pairs and four groups consisting of 3 or 4 members with redshifts in therange z = 0.1468?0.4756. Due to the absence of a large group of galaxies, we could not associate KUV00311?1938 with any of the groups detected