FASHI: A search for extragalactic OH megamasers with FAST

Abstract

The FAST All Sky HI survey (FASHI) is broader in frequency band and sky volume, and deeper in detection sensitivity than the Arecibo Legacy Fast ALFA survey (ALFALFA). To efficiently expand the sample of OH megamasers (OHMs), whose strongest line has a rest frequency of 1667.35903 MHz, we directly matched the IRAS Point Source Catalog Redshift (PSCz) catalog with the corresponding FASHI data cube. From 145 PSCz sources already covered by FASHI, we obtained 27 OHMs with a detection rate of 18.6%, including 9 previously known and 18 new ones, within a redshift range of $0.14314\lesssim z_{\mathrm{OH}}\lesssim 0.27656$. We also measured the hyperfine ratio of nine OHMs between the 1667 and 1665 MHz lines. The ratio ranges from 1.32 to 15.22, with an average of $R_{1667:1665}=4.74$. In a fit to the $L_{\mathrm{OH}}$ vs. $L_{\mathrm{FIR}}$ relation, we have $\log L_{\mathrm{OH}}=(1.57\pm 0.10)\log L_{\mathrm{FIR}}-(15.80\pm 1.19)$, which is almost the same as derived from previous observations. As expected, since the OHM sample was selected by cross-correlation with the IRAS-selected PSCz, our detected OHMs are [ultra]luminous infrared galaxies ([U]LIRGs). However, not all [U]LIRGs have detectable OH emission, suggesting that the OH emission may be triggered within a specific stage of the merger or can only be seen in specific orientations. In general, FAST, with its 19-beam array and UWB receiver, will be a powerful tool for observing more OHMs and unraveling their mystery in the future.

arXiv comment21 pages, 6 figures. Comments are welcome

References in corpus (34)

• A Cosmology Calculator for the World Wide Web
• Radio Properties of Infrared Selected Galaxies in the IRAS 2 Jy Sample
• The Five-Hundred-Meter Aperture Spherical Radio Telescope (FAST) Project
• The PSCz Catalogue
• The Arecibo Legacy Fast ALFA Survey: The ALFALFA Extragalactic HI Source Catalog
• GALEX-SDSS-WISE Legacy Catalog (GSWLC): Star Formation Rates, Stellar Masses and Dust Attenuations of 700,000 Low-redshift Galaxies
• Optical Spectroscopy of the IRAS 1-Jy Sample of Ultraluminous Infrared Galaxies
• The Fundamental Performance of FAST with 19-beam Receiver at L Band
• The IRAS 1-Jy Survey of Ultraluminous Infrared Galaxies: II. Optical Spectroscopy
• A Search for OH Megamasers at z > 0.1. III. The Complete Survey
• Shocked POststarbust Galaxy Survey I: Candidate Poststarbust Galaxies with Emission Line Ratios Consistent with Shocks
• The FAST all sky HI survey (FASHI): The first release of catalog
• Luminosity and Redshift Dependence of the Covering Factor of AGNs viewed with WISE and SDSS
• The meaning of WISE colours - I. The Galaxy and its satellites
• Aperture-free star formation rate of SDSS star-forming galaxies
• Extragalactic HI Surveys
• A Search for OH Megamasers at z > 0.1. II. Further Results
• A Search for OH Megamasers at z > 0.1. I. Preliminary Results
• The Most Luminous Starbursts in the Universe
• The Effect of 53 micron IR Radiation on 18 cm OH Megamaser Emission
• A Dense Gas Trigger for OH Megamasers
• HiFAST: an HI data calibration and imaging pipeline for FAST
• Ultra-luminous Infrared Galaxies in Sloan Digital Sky Survey Data Release 6
• Radio Frequency Interference Mitigation and Statistics in the Spectral Observations of FAST
• An Analysis Framework for Understanding the Origin of Nuclear Activity in Low-Power Radio Galaxies
• OH Megamasers in HI Surveys: Forecasts and a Machine Learning Approach to Separating Disks from Mergers
• Identifying OH Imposters in the ALFALFA Neutral Hydrogen Survey
• Constraints on OH Megamaser Excitation from a Survey of OH Satellite Lines
• Performance of FAST with an Ultra-Wide Bandwidth Receiver at 500-3300 MHz
• Apertif view of the OH Megamaser IRAS 10597+5926: OH 18 cm satellite lines in wide-area HI surveys
• The Hydroxyl-Water Megamaser Connection. I. Water Emission Toward OH Megamaser Hosts
• LADUMA: Discovery of a luminous OH megamaser at $z>0.5$
• HiFAST : An HI Data Calibration and Imaging Pipeline for FAST II. Flux Density Calibration
• A Relationship of Polycyclic Aromatic Hydrocarbon Features with Galaxy Merger in Star-forming Galaxies at $z<0.2$