Study of galaxies in the Lynx-Cancer void

VI. H I-observations with Nançay Radio Telescope^⋆

¹ GEPI, Observatoire de Paris, Place Jules Janssen, 92195 Meudon, France
² Special Astrophysical Observatory of RAS, Nizhnij Arkhyz, 369167 Karachai-Circassia, Russia
e-mail: sap@sao.ru
³ GEPI, Observatoire de Paris, PSL Research University, CNRS, Univ Paris Diderot, Sorbonne Paris Cité, Place Jules Janssen, 92195 Meudon, France
⁴ Station de Radioastronomie de Nançay, Observatoire de Paris, CNRS, 18330 Nançay, France

Received: 19 January 2016
Accepted: 26 July 2016

Abstract

Context. Void population consists mainly of late-type and low surface brightness (LSB) dwarf galaxies, whose atomic hydrogen is the main component of their baryonic matter. Therefore observations of void galaxy Hi are mandatory to understand both their evolution and dynamics.

Aims. Our aim was to obtain integrated Hi parameters for a fainter part of the nearby Lynx-Cancer void galaxy sample (total of 45 objects) with the Nançay Radio Telescope (NRT) and to conduct the comparative analysis of the whole 103 void galaxies with known Hi data with a sample of similar galaxies residing in denser environments of the Local Volume.

Methods. For Hi observations we used the NRT with its sensitive antenna/receiver system FORT and standard processing. The comparison of the void and “control” samples on the parameter M(HI)/L_B is conducted with the non-parametric method “The 2 × 2 Contingency Table test”.

Results. We obtained new Hi data for about 40% of the Lynx-Cancer galaxy sample. Along with data from the literature, we use for further analysis data for 103 void objects. The proxy of the evolutional parameter M(HI)/L_B of the void sample is compared with that of 82 galaxies of morphological types 8–10 residing in the Local Volume groups and aggregates.

Conclusions. At the confidence level of P = 0.988, we conclude that for the same luminosity, these void galaxies are systematically gas-richer, in average by ~39%. This result is consistent with the authors’ earlier conclusion on the smaller gas metallicities and evidences for the slower low-mass galaxy evolution in voids.