We present the results obtained from a detailed X-ray timing and spectral analysis of Seyfert 2 galaxy NGC 6300 by using observations with the {\it Suzaku}, {\it Chandra} and {\it NuSTAR} observatories between 2007 and 2016. We calculate variance, rms fractional variability of the source in different energy bands and find variabilities in various energy bands. Spectral properties of the source are studied by using various phenomenological and physical models. The properties of the Compton clouds, reflection, Fe K$α$ line emission and soft X-ray excess are studied in detail. Several physical parameters of the source are extracted and investigated to establish the presence/absence of any correlation between them. We also investigate the nature of the circumnuclear `torus' and find that the torus is not uniform, rather clumpy. The observed changes in the line-of-sight column density can be explained in terms of transiting clouds. The iron line emitting region is found to be different in the different epoch of observations. We also observe that the torus and the nucleus independently evolve over the years.
We report a clumpy elongated feature found with deep Chandra ACIS high-resolution imaging of the Fe Kα line emission in the nuclear region of the Compton Thick Active Galactic Nucleus (CT AGN) galaxy NGC 5643. This feature extends for ~65 pc N-S. No corresponding feature is seen in the 3.0-6.0 keV continuum. The Fe Kα feature is spatially consistent with the N-S elongation found in the CO(2-1) high resolution imaging with ALMA (Alonso-Herrero et al 2018), but slightly more extended than the rotating molecular disk of r=26 pc indicated by the kinematics of the CO(2-1) line. The Chandra detectio…
The inner-most region of the Seyfert galaxy NGC 2992 has long been suspected to be the location of intense AGN-host galaxy interaction, but photon pile-up in previous high-resolution observations hampered the study of soft X-ray excess and the interaction near its nucleus. We present an X-ray imaging spectroscopic analysis of the circumnuclear ($1^{\prime\prime}$--$3^{\prime\prime}$) region of NGC 2992 using the zeroth-order image of a 135 ks grating observation obtained with Chandra, which captured the nucleus in a historically low flux state. Extended soft X-ray emission is detected in the c…
We present the results of the latest NuSTAR monitoring campaign of the Compton-thick Seyfert 2 galaxy NGC 1068, composed of four $\sim$50 ks observations performed between July 2017 and February 2018 to search for flux and spectral variability on timescales from 1 to 6 months. We detect one unveiling and one eclipsing event with timescales less than 27 and 91 days, respectively, ascribed to Compton-thick material with $N_H=(1.8\pm0.8)\times10^{24}$ cm$^{-2}$ and $N_H\geq(2.4\pm0.5)\times10^{24}$ cm$^{-2}$ moving across our line of sight. This gas is likely located in the innermost part of the …
The shape of the ambient circumnuclear medium (ACM) density profile can probe the history of accretion onto the central supermassive black hole in galaxies and the circumnuclear environment. However, due to the limitation of the instrument resolution, the density profiles of the ACM for most of galaxies remain largely unknown. In this work, we propose a novel method to measure the ACM density profile of active galactic nucleus (AGN) by the equilibrium between the radiation pressure on the warm absorbers (WAs, a type of AGN outflows) and the drag pressure from the ACM. We study the correlation …
We present the Chandra imaging and spectral analysis of NGC 4968, a nearby (z = 0.00986) Seyfert 2 galaxy. We discover extended ($\sim$1 kpc) X-ray emission in the soft band (0.5 - 2 keV) that is neither coincident with the narrow line region nor the extended radio emission. Based on spectral modeling, it is linked to on-going star formation ($\sim$2.6-4 M$_{\sun}$ yr$^{-1}$). The soft emission at circumnuclear scales (inner $\sim$400 pc) originates from hot gas, with kT $\sim$ 0.7 keV, while the most extended thermal emission is cooler (kT $\sim$ 0.3 keV). We refine previous measurements of t…
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 21…
Active Galactic Nuclei (AGN) show excess X-ray emission above 10 keV compared with extrapolation of spectra from lower energies. Risaliti et al. have recently attempted to model the hard X-ray excess in the type 1.8 AGN NGC 1365, concluding that the hard excess most likely arises from Compton-scattered reflection of X-rays from an inner accretion disk close to the black hole. Their analysis disfavored a model in which the hard excess arises from a high column density of circumnuclear gas partially covering a primary X-ray source, despite such components being required in the NGC 1365 data belo…
We study the extended nuclear emission of the starburst galaxy NGC 1365. A weak obscured AGN and a strong starburst both contribute to the observed X-ray, optical, infrared, and radio emission in the inner 2kpc. The X-ray emission is spatially resolved, allowing comparison with multiwavelength data that highlights the structures dominating the nuclear region: the AGN, the nuclear spiral, the circumnuclear starburst ring, and nuclear outflow. The ultrasoft X-ray emission below 0.5keV is spatially coincident with the conical outflow traced by higher excitation optical emission lines like [O III]…
NGC1275 is the Brightest Cluster Galaxy (BCG) in the Perseus cluster and hosts the active galactic nucleus (AGN) that is heating the central 100\,kpc of the intracluster medium (ICM) atmosphere via a regulated feedback loop. Here we use a deep 490ks Cycle-19 Chandra High-Energy Transmission Grating (HETG) observation of NGC1275 to study the anatomy of this AGN. The X-ray continuum is adequately described by an unabsorbed power-law with photon index $Γ\approx 1.9$, creating strong tension with the detected column of molecular gas seen via HCN and HCO$^+$ line absorption against the parsec-scale…
JWST reveals how black holes are fed: kiloparsec-scale multiphase filaments feed sub-kiloparsec circumnuclear disks
Université de Montréal（蒙特利尔大学）；University of Michigan（密歇根大学）；Princeton University（普林斯顿大学）；Michigan State University（密歇根州立大学）；Institut Trottier de recherche sur les exoplanètes（特鲁瓦耶系外行星研究所）；Universidad Nacional Autónoma de México（墨西哥国立自治大学）；University of Portsmouth（朴茨茅斯大学）
Recent blazar detections by HESS, MAGIC, and VERITAS suggest that very-high-energy (VHE, E > 100 GeV) gamma-rays may be produced in most, if not all, types of blazars, including those that possess intense circumnuclear radiation fields. In this paper, we investigate the interaction of nuclear VHE gamma-rays with the circumnuclear radiation fields through gamma-gamma absorption and pair production, and the subsequent Compton-supported pair cascades. We have developed a Monte-Carlo code to follow the spatial development of the cascade in full 3-dimensional geometry, and calculate the radiative o…
NGC 5905 is one of the few galaxies with no prior evidence for an AGN in which an X-ray flare, due to the tidal disruption of a star by the massive black hole in the center of the galaxy, was detected by the RASS in 1990-91. Here we present analysis of late-time follow-up observations of NGC 5905 using Chandra, Spitzer VLA 3 GHz and 8 GHz archival data and GMRT 1.28 GHz radio observations. The X-ray image shows no compact source that could be associated with an AGN. Instead, the emission is extended -- likely due to nuclear star formation and the total measured X-ray luminosity is comparable t…
Obscuration of the innermost parts of active galactic nuclei (AGN) is observed in the majority of the population both in the nearby universe and at high redshift. However, the nature of the structures causing obscuration, especially in low-luminosity AGN, is poorly understood at present. We present a novel approach to multi-epoch broadband X-ray spectroscopy, anchored in the long-term average spectrum in the hard X-ray band, applied to the nearby, X-ray bright AGN in the galaxy NGC 1052. From spectral features due to X-ray reprocessing in the circumnuclear material, based on a simple, uniform-…
Five archived X-ray observations of NGC 4051, taken using the NuSTAR observatory, have been analysed, revealing lags between flux variations in bands covering a wide range of X-ray photon energy. In all pairs of bands compared, the harder band consistently lags the softer band by at least 1000s, at temporal frequencies ~5E-5 Hz. In addition, soft-band lags up to 400s are measured at frequencies ~2E-4 Hz. Light echos from an excess of soft band emission in the inner accretion disk cannot explain the lags in these data, as they are seen in cross-correlations with energy bands where the softer ba…
We present a wide field study of the Globular Clusters/Low Mass X-ray Binaries connection in the cD elliptical NGC1399, combining HST/ACS and Chandra high resolution data. We find evidence that LMXB formation likelihood is influenced by GCs structural parameters, in addition to the well known effects of mass and metallicity, independently from galactocentric distance.
