Das M.,Indian Institute of Astrophysics |
Saito T.,University of Tokyo |
Iono D.,Chile Observatory |
Honey M.,Indian Institute of Astrophysics |
Ramya S.,Shanghai Astronomical Observatory
Astrophysical Journal | Year: 2015
We present the detection of molecular gas from galaxies located in nearby voids using the CO(1-0) line emission as a tracer. The observations were performed using the 45 m single dish radio telescope of the Nobeyama Radio Observatory. Void galaxies lie in the most underdense parts of our universe and a significant fraction of them are gas rich, late-type spiral galaxies. Although isolated, they have ongoing star formation but appear to be slowly evolving compared to galaxies in denser environments. Not much is known about their star formation properties or cold gas content. In this study, we searched for molecular gas in five void galaxies. The galaxies were selected based on their relatively high IRAS fluxes or Hline luminosities, both of which signify ongoing star formation. All five galaxies appear to be isolated and two lie within the Bootes void. We detected CO(1-0) emission from four of the five galaxies in our sample and their molecular gas masses lie between 108 and 109 Mo. We conducted follow-up Himaging observations of three detected galaxies using the Himalayan Chandra Telescope and determined their star formation rates (SFRs) from their Hfluxes. The SFR varies from 0.2 to 1 Mo yr-1; which is similar to that observed in local galaxies. Our study indicates that although void galaxies reside in underdense regions, their disks contain molecular gas and have SFRs similar to galaxies in denser environments. We discuss the implications of our results. © 2015. The American Astronomical Society. All rights reserved..
Niinuma K.,Yamaguchi University |
Lee S.-S.,Korea Astronomy and Space Science Institute |
Kino M.,Japan Aerospace Exploration Agency |
Sohn B.W.,Yamaguchi University |
And 68 more authors.
Publications of the Astronomical Society of Japan | Year: 2013
The Korean very-long-baseline interferometry (VLBI) network (KVN) and VLBI Exploration of Radio Astrometry (VERA) Array (KaVA) is the first international VLBI array dedicated to high-frequency (23-43GHz bands) observations in East Asia. Here, we report the first imaging observations of three bright active galactic nuclei (AGNs) known for their complex morphologies: 4C39.25, 3C273, and M87. This is one of the initial results of KaVA's early operation. Our KaVA images reveal extended outflows with complex substructures such as knots and limb brightening, in agreement with previous Very Long Baseline Array (VLBA) observations. Angular resolutions are better than 1.4 and 0.8 mas at 23 and 43GHz, respectively. KaVA achieves a high dynamic range of ∼1000, more than three times the value achieved by VERA. We conclude that KaVA is a powerful array with a great potential for the study of AGN outflows, at least comparable to the best existing radio interferometric arrays. © 2014 © The Author 2014. Published by Oxford University Press on behalf of the Astronomical Society of Japan. All rights reserved.