Near-infrared imaging spectroscopy of the inner few arcseconds of NGC 4151 with OSIRIS at Keck

Abstract

We present H-and K-band data from the inner arcsecond of the Seyfert 1.5 galaxy NGC 4151 obtained with the adaptive-opticsassisted near-infrared-imaging field spectrograph OSIRIS at the Keck Observatory. The angular resolution is about a few parsecs on-site and thus competes easily with optical images taken previously with the Hubble Space Telescope. We present the morphology and dynamics of most species detected but focus on the morphology and dynamics of the narrow line region (as traced by emission of [FeII]λ1.644 μm), the interplay between plasma ejected from the nucleus (as traced by 21 cm continuum radio data) and hot H 2 gas and characterize the detected nuclear HeIλ2.058 μm absorption feature as a narrow absorption line (NAL) phenomenon. The emission from the narrow line region (NLR) as traced by [FeII] reveals a biconical morphology and we compare the measured dynamics in the [FeII] emission line with models that propose acceleration of gas in the NLR and simple ejection of gas into the NLR. In the inner 2.5 arcsec the acceleration model reveals a better fit to our data than the ejection model. We also see evidence that the jet very locally enhances emission in [FeII] at certain positions in our field-of-view such that we were able to distinct the kinematics of these clouds from clouds generally accelerated in the NLR. Further, the radio jet is aligned with the bicone surface rather than the bicone axis such that we assume that the jet is not the dominant mechanism responsible for driving the kinematics of clouds in the NLR. The hot H 2 gas is thermal with a temperature of about 1700 K. We observe a remarkable correlation between individual H 2 clouds at systemic velocity with the 21 cm continuum radio jet. We propose that the radio jet is at least partially embedded in the galactic disk of NGC 4151 such that deviations from a linear radio structure are invoked by interactions of jet plasma with H 2 clouds that are moving into the path of the jet because of rotation of the galactic disk of NGC 4151. Additionally, we observe a correlation of the jet as traced by the radio data, with gas as traced in Brγ and H 2 , at velocities between systemic and ±200 km s −1 at several locations along the path of the jet. The HeIλ2.058 μm line in NGC 4151 appears in emission with a blueshifted absorption component from an outflow. The emission (absorption) component has a velocity offset of 10 km s −1 (−280 km s −1 ) with a Gaussian (Lorentzian) full-width (half-width) at half maximum of 160 km s −1 (440 km s −1 ). The absorption component remains spatially unresolved and its kinematic measures differ from that of UV resonance absorption lines. From the amount of absorption we derive a lower limit of the HeI 2 1 S column density of 1 × 10 14 cm −2 with a covering factor along the line-of-sight of C los 0.1.

Fueling Active Galactic Nuclei. Ii. Spatially Resolved Molecular Inflows and Outflows

“…As has been found for other nearby active and inactive galaxies, the 1-0 S(1) distributions and kinematics can show a variety of different phenomena, and vary from being relatively simple to extremely complex (e.g. Davies et al 2009;Hicks et al 2009;Müller-Sánchez et al 2009;Riffel, et al 2009;Riffel, Storchi-Bergmann, & Nagar 2010;Storchi-Bergmann et al 2010;Riffel & Storchi-Bergmann 2011;Iserlohe et al 2013;Riffel, Storchi-Bergmann, & Winge 2013;Mazzalay et al 2014). In our sample the structures exhibited by the AGN typically appear to be a combination of molecular inflow and outflow, superimposed on a rotating disk.…”

Feeding versus feedback in active galactic nuclei from near-infrared integral field spectroscopy – X. NGC 5929

“…Several works have studied the origin of the H 2 emission in AGNs using long-slit spectroscopy (e.g., Reunanen, Kotilainen & Prieto 2002;Rodríguez-Ardila et al 2004Davies et al 2005; Ramos Almeida, Pérez García & Acosta-Pulido 2009) and integral-field spectroscopy (e.g., Riffel et al 2006Riffel et al , 2008Riffel et al , 2010aRiffel et al ,b, 2014aStorchi-Bergmann et al 2009;Riffel & Storchi-Bergmann 2011b;Müller-Sánchez et al 2009;Hicks et al 2009;Friedrich et al 2010;Mazzalay et al 2013;Iserlohe et al 2013). To distinguish between fluorescence and thermal processes, we used the observed fluxes for all H 2 emission lines in the K band to calculate the thermal excitation temperature.…”

“…The molecular H 2 emitting gas is usually more restricted to the plane of galaxies, with kinematics dominated by rotation and inflows in the disc in most cases. The ionized gas emission traces a more disturbed medium, usually associated with outflows from the AGN, but frequently showing also a rotation component from the disc of the galaxy (e.g., Riffel et al 2010a;Riffel & Storchi-Bergmann 2011a,b;StorchiBergmann et al 2010;Iserlohe et al 2013;Mazzalay et al 2014). …”

Observations of the global haze redistribution on Titan from 2006 to 2015 with OSIRIS at Keck

“…The OSIRIS reduction pipeline was used for the following standard processing steps: flat-fielding, sky subtraction, cosmic ray removal, channel level adjustment and the removal of crosstalk, before the extraction of spectra and assembly of a datacube. The reduction pipeline was recently described as part of the work by Iserlohe et al (2013). Mosaicking via the OSIRIS pipeline was unreliable and was instead performed manually.…”