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Register a new userThe elusive radio loud Seyfert 2 galaxy NGC 2110
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The AGN NGC 2110 presents a peculiar case among the Seyfert 2 galaxies, as it displays also features of radio-loud objects and is classified as FR-I radio galaxy. Here we analyse simultaneous INTEGRAL and Swift data taken in 2008 and 2009. We reconstruct the spectral energy distribution in order to provide further insight. The combined X-ray spectrum is well represented by an absorbed cut-off power law model plus soft excess. Combining all available data, the spectrum appears flat (photon index 1.25 +- 0.04) with the high-energy cut-off being at 82 +- 9 keV. The intrinsic absorption is moderate (NH = 4E22 1/cm**2), the iron K-alpha line is weak (EW = 114 eV), and no reflection component is detected in the INTEGRAL spectrum. The data indicate that the X-ray spectrum is moderately variable both in flux and spectral shape. The 2008 spectrum is slightly steeper (photon index 1.5, Ec = 90 keV) with the source being brighter, and flatter in 2009 (photon index 1.4, Ec = 120 keV) in the lower flux state. The spectral energy distribution gives a bolometric luminosity of L = 2E44 erg/sec. NGC 2110 appears to be a borderline object between radio loud narrow line Seyfert 1 and radio quiet Seyfert 2. Its spectral energy distribution might indeed be dominated by non-thermal emission arising from the jet.
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The Seyfert 2 galaxy NGC 2110 has been observed with BeppoSAX between 0.5 and 150 keV. The high energy instrument onboard, PDS, has succeeded in measuring for the first time the spectrum of this source in the 13-150 keV range. The PDS spectrum, having a photon index Gamma~1.86 is fully compatible with that expected from a Seyfert 1 nucleus. In the framework of unified models, the harder (Gamma~1.67) 2-10 keV spectrum is well explained assuming the presence of a complex partial + total absorber (Nh~30x10^22 cm^-2 x25% + Nh~4x10^22 cm^-2 x100%). The high column density of this complex absorber is consistent both with the FeK_alpha line strength and with the detection of an absorption edge at E~7.1 keV in the power-law spectrum.
The supermassive black holes (SMBHs) of narrow-line Seyfert 1 galaxies (NLS1s) are at the lowest end of mass function of active galactic nuclei (AGNs) and preferentially reside in late-type host galaxies with pseudobulges, which are thought to be formed by internal secular evolution. On the other hand, the population of radio-loud NLS1s presents a challenge for the relativistic jet paradigm that powerful radio jets are exclusively associated with very high mass SMBHs in elliptical hosts, which are built-up through galaxy mergers. We investigated distorted radio structures associated with the nearest gamma-ray emitting, radio-loud NLS1 1H 0323+342. This provides supporting evidence for the merger hypothesis based on the past optical/near-infrared observations of its host galaxy. The anomalous radio morphology consists of two different structures, the inner curved structure of currently active jet and the outer linear structure of low-brightness relics. Such a coexistence might be indicative of the stage of an established black hole binary with precession before the black holes coalesce in the galaxy merger process. 1H 0323+342 and other radio-loud NLS1s under galaxy interactions may be extreme objects on the evolutionary path from radio-quiet NLS1s to normal Seyfert galaxies with larger SMBHs in classical bulges through mergers and merger-induced jet phases.
We report on a detailed morphological and kinematic study of the isolated non-barred nearby Seyfert 2 galaxy NGC 2110. We combine Integral Field optical spectroscopy, with long-slit and WFPC2 imaging available in the HST archive to investigate the fueling mechanism in this galaxy. Previous work (Wilson & Baldwin 1985) concluded that the kinematic center of the galaxy is displaced ~220 pc from the apparent mass center of the galaxy, and the ionized gas follows a remarkably normal rotation curve. Our analysis based on the stellar kinematics, 2D ionized gas velocity field and dispersion velocity, and high spatial resolution morphology at V, I and Halpha reveals that: 1) The kinematic center of NGC 2110 is at the nucleus of the galaxy. 2) The ionized gas is not in pure rotational motion. 3) The morphology of the 2D distribution of the emission line widths suggests the presence of a minor axis galactic outflow. 4) The nucleus is blue-shifted with respect to the stellar systemic velocity, suggesting the NLR gas is out-flowing due to the interaction with the radio jet. 5) The ionized gas is red-shifted ~100 km/s over the corresponding rotational motion south of the nucleus, and 240 km/s with respect to the nuclear stellar systemic velocity. This velocity is coincident with the HI red-shifted absorption velocity detected by Gallimore et al (1999). We discuss the possibility that the kinematics of the south ionized gas could be perturbed by the collision with a small satellite that impacted on NGC 2110 close to the center with a highly inclined orbit. Additional support for this interpretation are the radial dust lanes and tidal debris detected in the V un-sharp masked image. We suggest that a minor-merger may have driven the nuclear activity in NGC 2110.
Recently, Rakshit et al. (2018) reported the discovery of SDSS J103024.95$+$551622.7, a radio-loud narrow-line Seyfert 1 galaxy having a $sim 100$ kpc scale double-lobed radio structure. Here we analyse archival radio interferometric imaging data taken with the Very Large Array (VLA) at 5 GHz, and with the Very Long Baseline Array (VLBA) at 4.3 and 7.6 GHz. Two hotspots and a compact core are detected with the VLA at arcsec scale, while a single milliarcsec-scale compact radio core is seen with the highest resolution VLBA observations. The Fermi Large Area Telescope did not detect $gamma$-ray emission at the position of this source. In the mid-infrared, the Wide-field Infrared Survey Explorer satellite light curve, covering more than 7 years and including the most recent data points, hints on flux density variability at 3.4 $mu$m. Our findings support the notion that this source is a young version of Fanaroff-Riley type II radio galaxies.
A recent ALMA study of the Seyfert 2 Active Galactic Nucleus (AGN) NGC 2110 by Rosario et al. (2019) has reported a remarkable lack of CO 2-1 emission from the circumnuclear region, where optical lines and H2 emission are observed, leading to the suggestion of excitation of the molecular clouds by the AGN. Since interaction with X-ray photons could be the cause of this excitation, we have searched the archival Chandra data for corroborating evidence. We report an extra-nuclear ~1 (~170 pc) feature found in the soft (<1.0 keV) Chandra data of the Seyfert 2 Active Galactic Nucleus (AGN) NGC 2110. This feature is elongated to the north of the nucleus and its shape matches well that of the optical lines and H2 emission observed in this region, which is devoid of CO 2-1 emission. The Chandra image completes the emerging picture of a multi-phase circumnuclear medium excited by the X-rays from the AGN, with dense warm molecular clouds emitting in H2 but depleted of CO 2-1 emission.
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