The middle infrared properties of OH megamaser host galaxies

Abstract

We compiled all 119 OH maser galaxies (110 out of them are megamasers, i.e., L OH > 10 L ) published so far and cross-identified these OH masers with the Wide-Field Infrared Survey Explorer (WISE) catalog, to investigate the middle infrared (MIR) properties of OH maser galaxies. The WISE magnitude data at the 3.4, 4.6, 12 and 22 μm (W1 to W4) are collected for the OH maser sample and one control sample, which are non-detection sources. The color-color diagrams show that both OH megamaser (OHM) and non-OHM (ultra)luminous infrared galaxies ((U)LIRGs) are far away from the single blackbody model line and many of them can follow the path described by the power-law model. The active galaxy nuclei (AGN) fraction is about ∼40% for both OHM and non-OHM (U)LIRGs, according to the AGN criteria W1−W2 ≥ 0.8. Among the Arecibo survey sample, OHM sources tend to have a lower luminosity at short MIR wavelengths (e.g., 3.4 μm and 4.6 μm) than that of non-OHM sources, which should come from the low OHM fraction among the survey sample with large 3.4 μm and 4.6 μm luminosity. The OHM fraction tends to increase with cooler MIR colors (larger F 22 μm /F 3.4 μm ). These may be good for sample selection when searching OH megamasers, such as excluding extreme luminous sources at short MIR wavelengths, choosing sources with cooler MIR colors. In the case of the power-law model, we derived the spectral indices for our samples. For the Arecibo survey sample, OHM (U)LIRGs tend to have larger spectral index α 22−12 than non-OHM sources, which agrees with previous results. One significant correlation exists between the WISE infrared luminosity at 22 μm and the color [W1]-[W4] for the Arecibo OHM hosts. These clues should provide suitable constraints on the sample selection for OH megamaser surveys by future advanced telescopes (e.g., FAST). In addition, the correlation of maser luminosity and the MIR luminosity of maser hosts tends to be non-significant, which may indirectly support the pumping of OHM emission that is dominated by the far infrared radiation, instead of the MIR radiation.

High-velocity extended molecular outflow in the star-formation dominated luminous infrared galaxy ESO 320-G030

“…Its nuclear activity is classified as H ii from optical spectroscopy (van den Broek et al 1991;Pereira-Santaella et al 2011) and there is no evidence of an AGN in this galaxy based on its mid-IR and X-ray emissions (Pereira-Santaella et al 2010b. It also host an OH megamaser (Norris et al 1986), which are associated with compact starbursts most of the times (Baan & Klöckner 2006;Zhang et al 2014). In addition, a massive outflow of neutral atomic gas is already detected in this object using optical IFS (Cazzoli et al 2014(Cazzoli et al , 2016.…”

Dust masses, compositions, and luminosities in the nuclear disks and the diffuse circumnuclear medium of Arp220

“…Red and blue symbols are for the individual nuclei in observations with sufficient resolution to distinguish them. The data, available in NED database, were compiled from the following references: (Skrutskie et al 2006;Sanders et al 2003;Dunne et al 2000;Dunne & Eales 2001;Veilleux et al 2009;Soifer et al 1989;Brown et al 2014;Klaas et al 2001;Spinoglio et al 1995;Rangwala et al 2011;Brauher et al 2008;Förster Schreiber et al 2004;Moshir & et al 1990;Eales et al 1989;Surace et al 2000;Matsushita et al 2009;Chini et al 1986;Martín et al 2011;Rigopoulou et al 1996;Sakamoto et al 2009;Catalano et al 2014;Imanishi et al 2007;Lahuis et al 2007;Spinoglio et al 2002;Antón et al 2004;Carico et al 1992;Sargsyan et al 2011;Gorjian et al 2004;Thronson et al 1987;Leroy et al 2011;Truch et al 2008;Zhang et al 2014;Benford 1999;Weedman & Houck 2009;Brauher et al 2008) lengths are dominated by synchrotron radiation and were not considered in the fit to the thermal emission from the two nuclei.…”

Radio continuum properties of OH megamaser galaxies

“…New discoveries available in the literature (e.g., Darling & Giovanelli (2000) significantly expanded the number of known OHM galaxies. Zhang et al (2014) compiled and studied two large samples of OHM and non-OHM galaxies and found differences in their middle-infrared (MIR) properties. The main objective of our study is a comparison of radio continuum properties for these OHM and non-OHM samples.…”

“…We determined the radio properties of OMHs and compared them with the properties of a non-OHM control sample. Zhang et al (2014) compiled all 119 OH maser galaxies available in the literature (for 2014) and selected all the sources with no detection of maser emission among the updated Arecibo survey sample (Darling & Giovanelli 2002) as a control sample. We note that the selection criteria for that survey were 0.1 z 0.45, 0 • < δ < 27 • , and InfraRed Astronomical Satellite (IRAS ) detection at 60 µm.…”