Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userSuzaku Observation of HCG 62: Temperature, Abundance, and Extended Hard X-ray Emission Profiles
114
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We present results of 120 ks observation of a compact group of galaxies HCG~62 ($z=0.0145$) with Suzaku XIS and HXD-PIN@. The XIS spectra for four annular regions were fitted with two temperature {it vapec} model with variable abundance, combined with the foreground Galactic component. The Galactic component was constrained to have a common surface brightness among the four annuli, and two temperature {it apec} model was preferred to single temperature model. We confirmed the multi-temperature nature of the intra-group medium reported with Chandra and XMM-Newton, with a doughnut-like high temperature ring at radii 3.3--6.5$$ in a hardness image. We found Mg, Si, S, and Fe abundances to be fairly robust. We examined the possible ``high-abundance arc at $sim 2$ southwest from the center, however Suzaku data did not confirm it. We suspect that it is a misidentification of an excess hot component in this region as the Fe line. Careful background study showed no positive detection of the extended hard X-rays previously reported with ASCA, in 5--12 keV with XIS and 12--40 keV with HXD-PIN, although our upper limit did not exclude the ASCA result. There is an indication that the X-ray intensity in $r<3.3$ region is $70pm 19$% higher than the nominal CXB level (5--12 keV), and Chandra and Suzaku data suggest that most of this excess could be due to concentration of hard X-ray sources with an average photon index of $Gamma=1.38pm 0.06$. Cumulative mass of O, Fe and Mg in the group gas and the metal mass-to-light ratio were derived and compared with those in other groups. Possible role of AGN or galaxy mergers in this group is also discussed.
rate research
Read More
We carried out observations of the central and 20 east offset regions of the cluster of galaxies Abell 1060 with Suzaku. Spatially resolved X-ray spectral analysis has revealed temperature and abundance profiles of Abell 1060 out to 27 ~ 380; /h_70 kpc, which corresponded to ~ 0.25; r_180. Temperature decrease of the intra cluster medium from 3.4 keV at the center to 2.2 keV in the outskirt region are clearly observed. Abundances of Si, S and Fe also decrease by more than 50% from the center to the outer, while Mg shows fairly constant abundance distribution at ~ 0.7 solar within r < 17. O shows lower abundance of ~ 0.3 solar in the central region (r~ 6), and indicates a similar feature with Mg, however it is sensitive to the estimated contribution of the Galactic components of kT_1 ~ 0.15 keV and kT_2 ~ 0.7 keV in the outer annuli (r ~ 13). Systematic effects due to the point spread function tails, contamination on the XIS filters, instrumental background, cosmic and/or Galactic X-ray background, and the assumed solar abundance tables are carefully examined. Results on temperature and abundances of Si, S, and Fe are consistent with those derived by XMM-Newton at r < 13. Formation and metal enrichment process of the cluster are discussed based on the present results.
We observed a group of galaxies, HCG 57, with ASCA. Regardless that their member galaxies are dominated by spiral galaxies, we detected extended thermal X-ray emission that is attributed to hot gas with a temperature of $1.04pm0.10$ keV. This is the second clear detection of thermal X-ray emission from a spiral-dominant group of galaxies after HCG 92. The luminosity of the thermal emission is about $5times10^{41}$ erg s$^{-1}$ in the 0.5--10 keV band, which is higher than that of HCG 92, but relatively less luminous among groups of galaxies. The X-ray emission is extended over several member galaxies, and is thus associated with the group rather than an individual galaxy. The metal abundance cannot be well constrained with a lower limit of 0.08 solar. The gas-to-stellar mass ratio is $sim0.3$. Although this is relatively low among groups, the hot gas is also a significant component even in the spiral-dominant group. We suggest that the X-ray faintness of spiral-dominant groups is due to the low surface brightness and somewhat low gas mass, at least in the case of HCG 57.
We present the results of Suzaku observation of the radio halo cluster Abell 2319. The metal abundance in the central cool region is found to be higher than the surrounding region, which was not resolved in the former studies. We confirm that the line-of-sight velocities of the intracluster medium in the observed region are consistent with those of the member galaxies of entire A2319 and A2319A subgroup for the first time, though any velocity difference within the region is not detected. On the other hand, we do not find any signs of gas motion relevant to A2319B subgroup. Hard X-ray emission from the cluster is clearly detected, but its spectrum is likely thermal. Assuming a simple single temperature model for the thermal component, we find that the upper limit of the non-thermal inverse Compton component becomes $2.6 times 10^{-11}$ erg s$^{-1}$ cm$^{-2}$ in the 10-40 keV band, which means that the lower limit of the magnetic field is 0.19 $mu$G with the radio spectral index 0.92. Although the results slightly depend on the detailed spectral modeling, it is robust that the upper limit of the power-law component flux and lower limit of the magnetic field strength become $sim 3 times 10^{-11}$ erg s$^{-1}$ cm$^{-2}$ and $sim 0.2 mu$G, respectively. Considering the lack of a significant amount of very hot ($sim 20$ keV) gas and the strong bulk flow motion, it is more likely that the relativistic non-thermal electrons responsible for the radio halo are accelerated through the intracluster turbulence rather than the shocks.
The recent Chandra discovery of extended $sim$kpc-scale hard ($>$ 3 keV) X-ray emission in nearby Compton-thick (CT) active galactic nuclei (AGN) opens a new window to improving AGN torus modeling and investigating how the central super massive black hole interacts with and impacts the host galaxy. Since there are only a handful of detections so far, we need to establish a statistical sample to determine the ubiquity of the extended hard X-ray emission in CT AGN, and quantify the amount and extent of this component. In this paper, we present the spatial analysis results of a pilot Chandra imaging survey of 7 nearby ($0.006 < z < 0.013$) CT AGN selected from the Swift-BAT spectroscopic AGN survey. We find that five out of the seven CT AGN show extended emission in the 3-7 keV band detected at $>$ 3$sigma$ above the Chandra PSF with $sim$12% to 22% of the total emission in the extended components. ESO 137-G034 and NGC 3281 display biconical ionization structures with extended hard X-ray emission reaching kpc-scales ($sim$ 1.9 kpc and 3.5 kpc in diameter). The other three show extended hard X-ray emission above the PSF out to at least $sim$360 pc in radius. We find a trend that a minimum 3-7 keV count rate of 0.01 cts/s and total excess fraction $>$20% is required to detect a prominent extended hard X-ray component. Given that this extended hard X-ray component appears to be relatively common in this uniformly selected CT AGN sample, we further discuss the implications for torus modeling and AGN feedback.
The Hard X-ray Detector (HXD) on board Suzaku covers a wide energy range from 10 keV to 600 keV by combination of silicon PIN diodes and GSO scintillators. The HXD is designed to achieve an extremely low in-orbit back ground based on a combination of new techniques, including the concept of well-type active shield counter. With an effective area of 142 cm^2 at 20 keV and 273 cm2 at 150 keV, the background level at the sea level reached ~1x10^{-5} cts s^{-1} cm^{-2} keV^{-1} at 30 keV for the PI N diodes, and ~2x10^{-5} cts s^{-1} cm^{-2} keV^{-1} at 100 keV, and ~7x10^{-6} cts s^{-1} cm^{-2} keV^{-1} at 200 keV for the phoswich counter. Tight active shielding of the HXD results in a large array of guard counters surrounding the main detector parts. These anti-coincidence counters, made of ~4 cm thick BGO crystals, have a large effective area for sub-MeV to MeV gamma-rays. They work as an excellent gamma-ray burst monitor with limited angular resolution (~5 degree). The on-board signal-processing system and the data transmitted to the ground are also described.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
