No Arabic abstract
We report the discovery of a secondary pair of radio lobes in the Seyfert galaxy NGC 2639 with polarization-sensitive observations with the Karl G. Jansky Very Large Array (VLA). The presence of these lobes, which are aligned nearly perpendicular to the known set of radio lobes observed in the east-west direction, has not been reported previously in the literature. The in-band rotation measure image shows gradients in both the lobes indicative of organised magnetic field structures on kpc-scales. The magnetic field structure is aligned with the jet/lobe direction in both the lobes. Based on the settled optical morphology of the host galaxy, it is likely that a minor merger that did not disrupt the host galaxy structure is responsible for the observed features in NGC 2639. This also explains the near 90$^o$ change in the jet direction; the current jet direction being the result of a new accretion disk formed by the minor merger, whose direction was a result of the angular momentum of the inflowing merger gas.
We present results from multi-frequency polarization-sensitive Very Large Array observations of the Seyfert-starburst composite galaxy NGC3079. Our sensitive radio observations reveal a plethora of radio filaments comprising the radio lobes in this galaxy. We analyze the origin of these radio filaments in the context of existing Chandra X-ray and HST emission-line data. We do not find a one-to-one correlation of the radio filaments with the emission line filaments. The north-eastern lobe is highly polarized with polarization fractions $sim$33% at 5 GHz. The magnetic fields are aligned with the linear extents of the optically-thin filaments, as observed in our, as well as other observations in the literature. Our rotation measure images show evidence for rotation measure inversion in the north-eastern lobe. Our data best fit a model where the cosmic rays follow the magnetic field lines generated as a result of the dynamo mechanism. There could be additional effects like shock acceleration that might also be playing a role. We speculate that the peculiar radio lobe morphology is a result of an interplay between both the superwinds and the AGN jet that are present in the galaxy. The jet, in fact, might be playing a major role in providing the relativistic electron population that is present in the radio lobes.
We report on the unveiling of the nature of the unidentified X-ray source 3XMM J005450.3-373849 as a Seyfert-2 galaxy located behind the spiral galaxy NGC 300 using Hubble Space Telescope data, new spectroscopic Gemini observations and available XMM-Newton and Chandra data. We show that the X-ray source is positionally coincident with an extended optical source, composed by a marginally resolved nucleus/bulge, surrounded by an elliptical disc-like feature and two symmetrical outer rings. The optical spectrum is typical of a Seyfert-2 galaxy redshifted to z=0.222 +/- 0.001, which confirms that the source is not physically related to NGC 300. At this redshift the source would be located at 909+/-4 Mpc (comoving distance in the standard model). The X-ray spectra of the source are well-fitted by an absorbed power-law model. By tying $N_mathrm{H}$ between the six available spectra, we found a variable index $Gamma$ running from ~2 in 2000-2001 years, to 1.4-1.6 in the 2005-2014 period. Alternatively, by tying $Gamma$, we found variable absorption columns of N_H ~ 0.34 x $10^{-22}$ cm$^{-2}$ in 2000-2001 years, and 0.54-0.75 x $10^{-22}$ cm$^{-2}$ in the 2005-2014 period. Although we cannot distinguish between an spectral or absorption origin, from the derived unabsorbed X-ray fluxes, we are able to assure the presence of long-term X-ray variability. Furthermore, the unabsorbed X-ray luminosities of 0.8-2 x 10$^{43}$ erg s$^{-1}$ derived in the X-ray band are in agreement with a weakly obscured Seyfert-2 AGN at $z approx 0.22$.
A large reverberation mapping study of the Seyfert 1 galaxy NGC 7469 has yielded emission-line lags for Hbeta 4861 and He II 4686 and a central black hole mass measurement of about 10 million solar masses, consistent with previous measurements. A very low level of variability during the monitoring campaign precluded meeting our original goal of recovering velocity-delay maps from the data, but with the new Hbeta measurement, NGC 7469 is no longer an outlier in the relationship between the size of the Hbeta-emitting broad-line region and the AGN luminosity. It was necessary to detrend the continuum and Hbeta and He II 4686 line light curves and those from archival UV data for different time-series analysis methods to yield consistent results.
AGN are a key ingredient for understanding galactic evolution. AGN-driven outflows are one of the manifestations of feedback. The AO mode for MUSE at the VLT permits to study the innermost tens of parsecs of nearby AGN in the optical. We present a detailed analysis of the ionised gas in the central regions of NGC 7130, an archetypical composite Seyfert and nuclear starburst galaxy. We achieve an angular resolution of 0.17$^{primeprime}$ (50 pc). We performed a multi-component analysis of the main ISM lines and identified nine kinematic components, six of which correspond to the outflow. The outflow is biconic and has velocities of a few $100,{rm km,s^{-1}}$ with respect to the disc. We decompose the approaching side of the outflow into a broad and a narrow component with typical velocity dispersions below and above $sim200,{rm km,s^{-1}}$, respectively. The blueshifted narrow component has substructure, in particular a collimated plume aligned with the radio jet, indicating that it may be jet-powered. The redshifted lobe is composed of two Narrow Components and a Broad Component. An additional redshifted component is seen outside the main outflow axis. Line ratio diagnostics indicate that the outflow gas in the main axis is AGN-powered whereas the off-axis component has LINER properties. The ionised gas mass outflow rate is $dot{M}=1.2pm0.7,M_{odot},{rm yr^{-1}}$ and the kinetic power is $dot{E}_{rm kin}=(2.7pm2.0)times10^{41},{rm erg,s^{-1}}$, which corresponds to $F_{rm kin}=0.12pm0.09%$ of the bolometric AGN power. The combination of high angular resolution integral field spectroscopy and a careful multi-component decomposition allows a uniquely detailed view of the outflow in NGC 7130, illustrating that AGN kinematics are more complex than traditionally derived from less sophisticated data and analyses. (abridged)
We derive a distance of $15.8pm0.4$ Mpc to the archetypical Seyfert 1 galaxy NGC 4151 based on the near-infrared Cepheid Period-Luminosity relation and new Hubble Space Telescope multiband imaging. This distance determination, based on measurements of 35 long-period ($P > 25$d) Cepheids, will support the absolute calibration of the supermassive black hole mass in this system, as well as studies of the dynamics of the feedback or feeding of its active galactic nucleus.