ﻻ يوجد ملخص باللغة العربية
By using a large highly obscured ($N_{rm H} > 10^{23} rm cm^{-2}$) AGN sample (294 sources at $z sim 0-5$) selected from detailed X-ray spectral analyses in the deepest Chandra surveys, we explore distributions of these X-ray sources in various optical/IR/X-ray color-color diagrams and their host-galaxy properties, aiming at characterizing the nuclear obscuration environment and the triggering mechanism of highly obscured AGNs. We find that the refined IRAC color-color diagram fails to identify the majority of X-ray selected highly obscured AGNs, even for the most luminous sources with ${rm log},L_{rm X}, rm (erg s^{-1}) > 44$. Over 80% of our sources will not be selected as heavily obscured candidates using the flux ratio of $f_{rm 24 mu m}, /,f_R > 1000$ and $R - K > 4.5$ criteria, implying complex origins and conditions for the obscuring materials that are responsible for the heavy X-ray obscuration. The average star formation rate of highly obscured AGNs is similar to that of stellar mass- ($M_*$-) and $z$-controlled normal galaxies, while the lack of quiescent hosts is observed for the former. Partial correlation analyses imply that highly obscured AGN activity (traced by $L_{rm X}$) appears to be more fundamentally related to $M_*$, and no dependence of $N_{rm H}$ on either $M_*$ or SFR is detected. Morphology analyses reveal that 61% of our sources have a significant disk component, while only 27% of them exhibit irregular morphological signatures. These findings together point toward a scenario where secular processes (e.g., galactic-disk instabilities), instead of mergers, are most probable to be the leading mechanism that triggers accretion activities of X-ray-selected highly obscured AGNs.
We present a detailed X-ray spectral analysis of 1152 AGNs selected in the Chandra Deep Fields (CDFs), in order to identify highly obscured AGNs ($N_{rm H} > 10^{23} rm cm^{-2}$). By fitting spectra with physical models, 436 (38%) sources with $L_{rm
Understanding the nuclear growth and feedback processes in galaxies requires investigating their often obscured central regions. One way to do this is to use (sub)millimeter line emission from vibrationally excited HCN (HCN-vib). It has been suggeste
We examine the host morphologies of heavily obscured active galactic nuclei (AGN) at $zsim1$ to test whether obscured supermassive black hole growth at this epoch is preferentially linked to galaxy mergers. Our sample consists of 154 obscured AGN wit
Even in deep X-ray surveys, Compton-thick active galactic nuclei (CT AGNs, ${rm N_H} geqslant 1.5~times~10^{24}~{rm cm}^{-2}$) are difficult to be identified due to X-ray flux suppression and their complex spectral shape. However, the study of CT AGN
Spitzer/IRS has revealed many sources with very deep Si features at 9.7micron (tau>1). We set out to investigate whether a strong Si absorption feature is a good indicator for the presence of a heavily obscured AGN. We compile X-ray spectroscopic obs