The complex gaseous and stellar environments of the nearby dual active galactic nucleus Mrk 739 as unveiled by optical VLT/MUSE observations
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2021
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Abstract
Dual active galactic nuclei (Dual AGN) represent a critical stage in a major galaxy merger (M/m <3), where both supermassive black holes (SMBHs) are rapidly accreting. Studying these systems can yield valuable insights into the physical processes that affect galaxy evolution, both in terms of nuclear activity and galactic collisions. In this context, we present integral field spectroscopic (IFS) observations of the nearby (z∼0.03) dual AGN Mrk 739, whose projected nuclear separation is∼3.4 kpc, obtained with the Multi Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope (VLT). We find that the galaxy has an extended AGN-ionized emission-line region extending up to ∼20 kpc away from the nuclei, while star-forming regions are more centrally concentrated within 2-3 kpc. We model the kinematics of the ionized gas surrounding the eastern nucleus using a circular disk profile, resulting in a peak velocity of 237+26−28km s−1at a distance of ∼1.2 kpc. The enclosed dynamical mass within 1.2 kpc is log M(M) = 10.20±0.06, ∼1,000 times larger than the estimated supermassive black hole (SMBH) mass of Mrk739E. The morphology and dynamics of the dual AGN Mrk 739 are consistent with an early stage of the collision, where the foreground galaxy (Mrk 739W) is a young star-forming galaxy in an ongoing first passage with its background companion (Mrk739E). Since Mrk 739W’s AGN does not show evidence of being actively accreting as its companion, we claim that the gas of the northern spiral arms of Mrk 739W are cross-ionized by the nuclear activity of Mrk 739E. The subsequent MUSE Narrow Field Mode (NFM) analysis reveals an unprecedented spatial resolution for Mrk 739E, where star-forming clumps, traced by Hα emission, form a ring-like structure inside a rotating disk. These star-forming clouds are surrounding an active SMBH at the center of an elliptical galaxy undergoing a merger process with a young spiral galaxy. Kinematically, we note that the disk is rotating with a velocity of Vmed,rot= 280.5±32.7 km s−1,∼50 km s−1larger than the velocity derived from the WFM analysis. The flux distribution of the NFM data reveal Hα clouds that also belong to Mrk 739W. Based on our schematic representation of the merger process, this emission would be part of the north side of the Mrk 739W’sbar and the beginning of the leading arm that gives origin to the large-scale spiraling crest.
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Tesis (Master in Astrophysics)--Pontificia Universidad Católica de Chile, 2021