One of the six extended X-ray sources found in the Chandra DeepField North is centred on HDF130, which has recently been shown to be a massive galaxy at z=1.99 with a compact radio nucleus. The X-ray source has a roughly double-lobed structure with each lobe about 41 arcsec long, or 345 kpc at the redshift of HDF130. We have analyzed the 2 Ms X-ray image and spectrum of the source and find that it is well fit by a power-law continuum of photon index 2.65 and has a 2--10 keV luminosity of 5.4x10^{43}ergps (if at z=1.99). Any further extended emission within a radius of 60 arcsec has a luminosity less than half this value, which is contrary to what is expected from a cluster of galaxies. The source is best explained as an inverse Compton ghost of a giant radio source, which is no longer being powered, and for which Compton losses have downgraded the energetic electrons, γ> 10^4, required for high-frequency radio emission. The lower energy electrons, γ~1000, produce X-rays by inverse Compton scattering on the Cosmic Microwave Background. Depending on the magnetic field strength, some low frequency radio emission may remain. Further inverse Compton ghosts may exist in the Chandra deep fields.
我们提出了最亮源（f_{2-10 keV} >10^{-15} $ cgs) in the Chandra Deep Field North. Our sample consists of 222 sources; for the vast majority (171) either a spectroscopic or a photometric redshift is available. Our goal is to discover the Compton-thick AGN in a direct way i.e. through their X-ray spectra. Compton-thick AGN give away their presence in X-rays either directly through the absorption turnover redshifted in the Chandra passband, or through a flat, reflection-dominated, spectrum. The above selection criteria yield 10 Compton-thick AGN candidates of which the nine are reflection dominated. The IR…
The AKARI North Ecliptic Pole (NEP) survey consists of two survey projects: NEP-Deep (0.5 sq.deg) and NEP-Wide (5.4 sq.deg), providing with tens of thousands of galaxies. A continuous filter coverage in the mid-infrared wavelengths (7, 9, 11, 15, 18 and 24 $μ$m) is unique to diagnose the contributions from dusty star-formation activity and AGNs. Here we present current status focused on the newly obtained optical images and near-future prospects with a new X-ray telescope. Hyper Suprime-Cam on Subaru telescope is a gigantic optical camera with huge Field of View (FoV). Thanks to the wide FoV, …
Investigating the radio emission in the Perseus cluster with LOFAR sub-80 MHz LBA
INAF – Istituto di Radioastromia（意大利国家天体物理研究所射电天文学研究所）；Leiden Observatory, Leiden University（莱顿大学莱顿天文台）；Université Laval（拉瓦尔大学）；Dunlap Institute for Astronomy and Astrophysics, University of Toronto（多伦多大学邓普天文学与天体物理学研究所）；Università di Bologna（博洛尼亚大学）
We present our analysis of the LyC emission and escape fraction of 111 spectroscopically verified galaxies with and without AGN from $2.26<z<4.3$. We extended our ERS sample from Smith et al. (2018; arXiv:1602.01555) with 64 galaxies in the GOODS North and South fields using WFC3/UVIS F225W, F275W, and F336W mosaics we independently drizzled using the HDUV, CANDELS, and UVUDF data. Among the 17 AGN from the 111 galaxies, one provided a LyC detection in F275W at $m_{AB}=23.19$ mag (S/N $\simeq$ 133) and $GALEX$ NUV at $m_{AB}=23.77$ mag (S/N $\simeq$ 13). We simultaneously fit $SDSS$ and $Chand…
The colliding cluster, CIZA J2242.8+5301, displays a spectacular, almost 2 Mpc long shock front with a radio based Mach number M ~ 5, that is puzzlingly large compared with the X-ray estimate of M ~ 2.5. The extent to which the X-ray temperature jump is diluted by cooler unshocked gas projected through the cluster currently lacks quantification. Thus, here we apply our self-consistent N-body/hydro-dynamical code (based on FLASH) to model this binary cluster encounter. We can account for the location of the shock front and also the elongated X-ray emission by tidal stretching of the gas and dar…
