The relationship between class I and class II methanol masers

Abstract

The Australia Telescope National Facility Mopra millimetre telescope has been used to search for 95.1-GHz class I methanol masers towards 62 6.6-GHz class II methanol masers. A total of 26 95.1-GHz masers were detected, 18 of these being new discoveries. Combining the results of this search with observations reported in the literature, a near complete sample of 66 6.6-GHz class II methanol masers has been searched in the 95.1-GHz transition, with detections towards 38 per cent (25 detections; not all of the sources studied in this paper qualify for the complete sample, and some of the sources in the sample were not observed in the present observations).There is no evidence of an anticorrelation between either the velocity range, or peak flux density of the class I and II transitions, contrary to suggestions from previous studies. The majority of class I methanol maser sources have a velocity range that partly overlaps with the class II maser transitions. The presence of a class I methanol maser associated with a class II maser source is not correlated with the presence (or absence) of main-line OH or water masers. Investigations of the properties of the infrared emission associated with the maser sources shows no significant difference between those class II methanol masers with an associated class I maser and those without. This may be consistent with the hypothesis that the objects responsible for driving class I methanol masers are generally not those that produce main-line OH, water or class II methanol masers.

A New 95 GHz Methanol Maser Catalog. I. Data

“…Some sources contain both strong narrow spectral features and weak broad emission, which is consistent with the results of previous classI methanol maser observations. For example, BGPS 1810 was previously detected in Chen et al (2011), BGPS 2601in Val'tts et al (2000, and BGPS 3594 in Ellingsen (2005). The line width of individual 95 GHz emission components obtained from Gaussian fitting ranges from 0.39 to 12.08 km s −1 with a mean of 1.62 km s −1 and a median of 1.28 km s −1 .…”

“…However, there were no systematic searches for the 95 GHz maser transition until Kalenskii et al (1994). We have combined the results of all previous 95 GHz methanol maser single-dish searches that are reported in Kalenskii et al (1994), Val'tts et al (1995, 2000, Ellingsen (2005), Kalenskii et al (2006), Fontani et al (2010), Chen et al (2011Chen et al ( , 2012Chen et al ( , 2013a, and Gan et al (2013) to produce a catalog of all maser sources in this transition.…”

“…In order to facilitate easier comparison of all sources through this catalog, we have converted the antenna temperatures into flux density using the conversion factor given in the original publications. The sources detected by Val'tts et al (2000) and Ellingsen (2005) have no information on the integrated flux density S. We assume that the spectra can be described by a Gaussian profile and the integrated flux density S can be derived from the flux density with velocity over the line window, S S v dv…”

Recent Science from Australian Large-Scale Millimetre Mapping Projects: Proceedings from a Swinburne University Workshop

“…We have repeated the analysis carried out by Breen et al (2007), this time investigating the properties of the 13 CO and 1.2 mm dust clumps associated with 6.7 GHz methanol masers (Ellingsen 2005). Comparison of the locations of the methanol masers with the molecular gas and dust data showed that all 5 of the methanol masers that lie within the regions surveyed by Bains et al (2006) and Mookerjea et al (2004) are associated with both molecular gas and dust emission peaks.…”

New class I methanol masers

“…A few hundred such masers are currently known, but the majority have only single dish data (e.g. Haschick et al 1990;Slysh et al 1994;Val'tts et al 2000;Ellingsen 2005;Fontani et al 2010;Chen et al 2011;unpublished Mopra data from our group). The major published interferometric surveys are those of Kurtz et al (2004) and Cyganowski et al (2009).…”