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Date and Time of the Query: 2018-09-24 T00:57:08 PDT
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For refcode 2009AJ....137.4670L:
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2009AJ....137.4670L Heracles: The HERA CO Line Extragalactic Survey Leroy, Adam K.; Walter, Fabian; Bigiel, Frank; Usero, Antonio; Weiss, Axel; Brinks, Elias; de Blok, W. J. G.; Kennicutt, Robert C.; Schuster, Karl-Friedrich; Kramer, Carsten; Wiesemeyer, H. W.; Roussel, Helene Abstract. We present the Heterodyne Receiver Array CO Line Extragalactic Survey, an atlas of CO emission from 18 nearby galaxies that are also part of The H I Nearby Galaxy Survey and the Spitzer Infrared Nearby Galaxies Survey. We used the HERA multipixel receiver on the IRAM 30-m telescope to map the CO J = 2 --> 1 line over the full optical disk (defined by the isophotal radius r_25_) of each target, at 13" angular resolution and 2.6 km s^--1^ velocity resolution. Here we describe the observations and reduction of the data and show channel maps, azimuthally averaged profiles, integrated intensity maps, and peak intensity maps. The implied H_2_ masses range from 7 x 10^6^ to 6 x 10^9^ M_sun_, with four low metallicity dwarf irregular galaxies yielding only upper limits. In the cases where CO is detected, the integrated H_2_-to-H I ratios range from 0.02 to 1.13 and H_2_-to-stellar mass ratios from 0.01 to 0.25. Exponential scale lengths of the CO emission for our targets are in the range 0.8-3.2 kpc, or 0.2 +/- 0.05r_25_. The intensity-weighted mean velocity of CO matches that of H I very well, with a 1{sigma} scatter of only 6 km s^--1^. The CO J = 2 --> 1/J = 1 --> 0 line ratio varies over a range similar to that found in the Milky Way and other nearby galaxies, ~0.6-1.0, with higher values found in the centers of galaxies. The typical line ratio, ~0.8, could be produced by optically thick gas with an excitation temperature of ~10 K. Key words: galaxies: ISM, ISM: molecules, radio lines: galaxies
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