ﻻ يوجد ملخص باللغة العربية
We present an imaging and spectral analysis of the nuclear region of the ULIRG merger Arp 220, using deep textit{Chandra}-ACIS observations summing up to (sim 300mbox{ ks}). Narrow-band imaging with sub-pixel resolution of the innermost nuclear region reveals two distinct Fe-K emitting sources, coincident with the infrared and radio nuclear clusters. These sources are separated by 1 ((sim 380) pc). The X-ray emission is extended and elongated in the eastern nucleus, like the disk emission observed in millimeter radio images, suggesting starburst dominance in this region. We estimate Fe-K equivalent width (gtrsim 1) keV for both sources, and observed 2-10 keV luminosities (sim 2times{10}^{40}mbox{ erg}mbox{ s}^{-1}) (W) and (sim 3 times {10}^{40}mbox{ erg}mbox{ s}^{-1}) (E). In the 6-7 keV band the emission from these regions is dominated by the 6.7 keV Fe textsc{xxv} line, suggesting contribution from collisionally ionized gas. The thermal energy content of this gas is consistent with kinetic energy injection in the interstellar medium by Type II SNe. However, nuclear winds from hidden AGN ((varvsim 2000 mbox{ km}mbox{ s}^{-1})) cannot be excluded. The (3sigma) upper limits on the neutral Fe-K(alpha) flux of the nuclear regions correspond to intrinsic AGN 2-10 keV luminosities (< 1times {10}^{42}mbox{ erg}mbox{ s}^{-1}) (W) and (< 0.4times {10}^{42}mbox{ erg}mbox{ s}^{-1}) (E). For typical AGN SEDs the bolometric luminosities are (< 3times {10}^{43}mbox{ erg}mbox{ s}^{-1}) (W) and (< 8times {10}^{43}mbox{ erg}mbox{ s}^{-1}) (E), and black hole masses (<1times{10}^5 M_{astrosun}) (W) and (< 5times{10}^5 M_{astrosun}) (E) for Eddington limited AGNs with a standard 10% efficiency.
Extragalactic cosmic ray populations are important diagnostic tools for tracking the distribution of energy in nuclei and for distinguishing between activity powered by star formation versus active galactic nuclei (AGNs). Here, we compare different d
We present a high spatial resolution optical and infrared study of the circumnuclear region in Arp 220, a late-stage galaxy merger. Narrowband imaging using HST/WFC3 has resolved the previously observed peak in H$alpha$+[NII] emission into a bubble-s
We present an analysis of the diffuse soft X-ray emission from the nuclear region of M51 combining both XMM-Newton RGS and Chandra data. Most of the RGS spectrum of M51 can be fitted with a thermal model with a temperature of $sim0.5$ keV except for
Recent analyses of the gamma-ray spectrum from the ultra-luminous infrared galaxy Arp 220 have revealed a discrepancy in the cosmic ray energy injection rates derived from the gamma-rays versus the radio emission. While the observed radio emission is
We present the first very-long-baseline interferometry (VLBI) detections of Zeeman splitting in another galaxy. We used Arecibo Observatory, the Green Bank Telescope, and the Very Long Baseline Array to perform dual-polarization observations of OH ma