DIAGNOSTICS OF AGN-DRIVEN MOLECULAR OUTFLOWS IN ULIRGs FROMHERSCHEL-PACS OBSERVATIONS OF OH AT 119 μm

Abstract

We report on our observations of the 79 and 119 µm doublet transitions of OH for 24 local (z<0.262) ULIRGs observed with Herschel-PACS as part of the Herschel ULIRG Survey (HERUS). Some OH119 profiles display a clear P-Cygni shape and therefore imply outflowing OH gas, other profiles are predominantly in absorption or are completely in emission. We find that the relative strength of the OH emission component decreases as the silicate absorption increases. This locates the OH outflows inside the obscured nuclei. The maximum outflow velocities for our sources range from less than 100 to ∼2000 km s −1 , with 15/24 (10/24) sources showing OH absorption at velocities exceeding 700 km s −1 (1000 km s −1 ). Three sources show maximum OH outflow velocities exceeding that of Mrk231. Since outflow velocities above 500-700 km s −1 are thought to require an active galactic nucleus (AGN) to drive them, about 2/3 of our ULIRG sample may host AGN-driven molecular outflows. This finding is supported by the correlation we find between the maximum OH outflow velocity and the IR-derived bolometric AGN luminosity. No such correlation is found with the IR-derived star formation rate. The highest outflow velocities are found among sources which are still deeply embedded. We speculate that the molecular outflows in these sources may be in an early phase of disrupting the nuclear dust veil before these sources evolve into less obscured AGN. Four of our sources show high-velocity wings in their [C II] fine-structure line profiles implying neutral gas outflow masses of at least 2-4.5×10 8 M ⊙ .

HERUS: A CO ATLAS FROM SPIRE SPECTROSCOPY OF LOCAL ULIRGs

“…Observations with PACS for the 43 ULIRGs were split between the HERUS program Spoon et al 2013) and the SHINING program Sturm et al 2011;Hailey-Dunsheath et al 2012a;González-Alfonso et al 2013;Mashian et al 2015). A similar study of the intermediate redshift ULIRG population (0.21<z<0.88) was presented by Rigopoulou et al (2014) and Magdis et al (2014).…”

Evidence of ongoing AGN-driven feedback in a quiescent post-starburst E+A galaxy

“…AGN-driven winds span a large range of galaxy properties. They are observed in ULIRGs (e.g., Rupke, Veilleux & Sanders 2005;Rupke & Veilleux 2013;Spoon et al 2013;Veilleux et al 2013;Rodríguez Zaurín et al 2013;Sun et al 2014;García-Burillo et al 2015;Fiore et al 2017), in type I and type II AGN (e.g., Heckman et al 1981;Feldman et al 1982;Heckman, Miley & Green 1984;Greene & Ho 2005;Nesvadba et al 2006;Moe et al 2009;Rosario et al 2010;Greene et al 2011;Cano-Díaz et al 2012;Arav et al 2013;Mullaney et al 2013;Fiore et al 2017), and even in quiescent red and dead ellipticals (Cheung et al 2016).…”

Shocked gas in IRAS F17207-0014: ISM collisions and outflows

“…∼350 km s −1 in NGC 1266; Alatalo et al 2011) to high velocities (∼2000 km s −1 ; Spoon et al 2013). Such outflows are thought to be driven by radiation pressure from the AGN itself (Silk & Rees 1998) and may be responsible for the existence of black hole scaling relations (e.g.…”

“…Outflows are commonly observed in local U/LIRGs Rupke & Veilleux 2005;Rupke et al 2005a,b,c;Martin 2006;Sturm et al 2011;Rupke & Veilleux 2013;Veilleux et al 2013;Teng et al 2013;Spoon et al 2013;Rodríguez Zaurín et al 2013;Arribas et al 2014;Cicone et al 2014), and are likely a common cause of shocks. Several studies of shocks in nearby galaxies have linked them to superwinds produced by stellar feedback (Heckman et al 1990;Grimes et al 2005;Rich et al 2011;Hopkins et al 2012;Hong et al 2013) and AGN-driven outflows (Mazzarella et al 2012).…”