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Register a new userX-ray spectra of sources in the 13H XMM-Newton / Chandra deep field
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We present the X-ray spectra of 86 optically-identified sources in the 13H XMM-Newton/Chandra deep field which have >70 X-ray counts. The sample consists of 50 broad line AGN, 25 narrow emission line galaxies, 6 absorption line galaxies, and 5 Galactic stars. The majority (42/50) of the broad line AGN have X-ray spectra which are consistent with a power law shape. They have a mean photon index of Gamma = 2.0 +- 0.1 and an intrinsic dispersion sigma = 0.4 +- 0.1. Five BLAGN show a deficit of soft X-rays, indicating absorption. Significant absorption is more common in the narrow emission line galaxies (13/25) and absorption line galaxies (2/6) than in the broad line AGN (5/50), but is not universal in any of these classes of object. The majority of the 20 absorbed sources have X-ray spectra consistent with a simple cold photoelectric absorber, but 6/20 require more complex models with either an additional component of soft X-ray emitting plasma, or an ionised absorber. Of the 16 galaxies which do not show evidence for X-ray absorption, only 2 objects are likely to be powered by star formation, and both have 2-10 keV X-ray luminosities of <= 10^40 cgs. The X-ray emission in the other 14 unabsorbed NELGs and galaxies is most likely powered by AGN, which are not detected in the optical because they are outshone by their luminous host galaxies. The Galactic stars show multi-temperature thermal spectra which peak between 0.5 and 1 keV. Star/AGN discrimination is possible for 4 of the 5 stars solely from their X-ray spectra.
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Discerning the exact nature of the faint (sub-mJy) radio population has been historically difficult due to the low luminosity of these sources at most wavelengths. Using deep observations from Chandra/XMM-Newton/Spitzer and ground based follow up we are able to disentangle the AGN and star-forming populations for the first time in a deep multi-frequency GMRT/VLA/MERLIN Survey. The many diagnostics include radio luminosity, morphology, radio to mid-IR flux density ratios, radio to optical flux density ratios and radio spectral indices. Further diagnostics, e.g. optical spectra X-ray spectra/hardness ratios, IR colours indicate the presence of the AGN {em independent} of whether the radio emission is powered by AGN or star-formation. We are able to examine the star-formation history of the universe up to z=2.5 in a unique way based on an unbiased star-formation rate indicator, radio luminosity. This work provides an alternative perspective on the distribution of star-formation by mass, ``downsizing and allows us to examine the prevalence of AGN in star-bursts.
(Abridged) We present the results of M31 globular cluster (GC) X-ray source survey, based on the data of XMM-Newton and Chandra observations covering ~6100 sq.arcmin of M31. We detected 43 X-ray sources coincident with globular cluster candidates from optical surveys. The estimated isotropic X-ray luminosities of GC sources lie between ~10e35 and ~10e39 erg/s in the 0.3 - 10 keV energy band. The spectral properties and variability of M31 GC X-ray sources are consistent with that derived for the LMXBs in the bulges of M31 and Milky Way. We found that ~80% of the M31 GC sources with multiple flux measurements available show significant variability on a time scales from days to years. The X-ray luminosity function of GC sources is found to be significantly different from that of the point sources in the bulge and disk of M31 and that of the Galactic GC X-ray sources. GC sources make dominant contribution to the bright source counts in the areas of M31 covered by the survey: ~40% of the total number of sources with luminosities above 10e37 ergs/s reside in GCs with fraction of GC sources rising to 67-90% for the luminosities above 10e38 ergs/s. The contribution of the GC sources to the total number of bright sources found in M31 is much higher than in the Milky Way galaxy, but surprisingly close to that of the early-type galaxies. The brightest M31 GC sources tend to reside at large galactocentric distances outside the central bulge. We found that globular clusters hosting bright X-ray sources are optically brighter and more metal rich than the rest of M31 globular clusters. The brightest sources with luminosities above ~10e38 ergs/s show tendency to reside in more metal poor clusters.
In this work we present the results of the survey carried out on one of the deepest X-ray fields observed by the XMM-Newton satellite. The 1.75 Ms Ultra Narrow Deep Field (XMM175UNDF) survey is made by 13 observations taken over 2 years with a total exposure time of 1.75 Ms (1.372 Ms after flare-filtered) in a field of $30 times 30 $ centered around the blazar 1ES 1553+113. We stacked the 13 observations reaching flux limits of $4.03 times 10^{-16} $, $1.3 times 10^{-15}$, and $9.8 times 10^{-16}, erg, s^{-1}, cm^{-2}$ in the soft $(0.2 - 2, mathrm{keV})$, hard $(2 - 12, mathrm{keV})$, and full $(0.2 - 12, mathrm{keV})$ bands, respectively. Using a conservative threshold of Maximum Likelihood significance of $ML geq 6$, corresponding to $3sigma$, we detected 301 point-sources for which we derived positions, fluxes in different bands, and hardness ratios. Thanks to an optical follow-up carried out using the 10.4m the Gran Telescopio Canarias (GTC) on the same field in the $ugriz$ bands, combined with WISE/2MASS IR data; we identified 244 optical/IR counterpart candidates for our X-ray sources and estimated their X-ray luminosities, redshift distribution, X-ray/optical $-$ X-ray/IR flux ratios, and absolute magnitudes. Finally, we divided this subsample in 40 non-active sources and 204 AGNs, of which 139 are classified as Seyfert galaxies and 41 as Quasars.
We present first results from an X-ray study of the Hubble Deep Field North (HDF-N) and its environs obtained using 166 ks of data collected by the Advanced CCD Imaging Spectrometer (ACIS) on board the Chandra X-ray Observatory. This is the deepest X-ray observation ever reported, and in the HDF-N itself we detect six X-ray sources down to a 0.5--8 keV flux limit of 4E-16 erg cm^-2 s^-1. Comparing these sources with objects seen in multiwavelength HDF-N studies shows positional coincidences with the extremely red object NICMOS J123651.74 +621221.4, an active galactic nucleus (AGN), three elliptical galaxies, and one nearby spiral galaxy. The X-ray emission from the ellipticals is consistent with that expected from a hot interstellar medium, and the spiral galaxy emission may arise from a `super-Eddington X-ray binary or ultraluminous supernova remnant. Four of the X-ray sources have been detected at radio wavelengths. We also place X-ray upper limits on AGN candidates found in the HDF-N, and we present the tightest constraints yet on X-ray emission from the SCUBA submillimeter source population. None of the 10 high-significance submillimeter sources reported in the HDF-N and its vicinity is detected with Chandra ACIS. These sources appear to be dominated by star formation or have AGN with Compton-thick tori and little circumnuclear X-ray scattering.
Our VLA observations of the XMM-Newton/Chandra 13hr deep survey field (see Page et al., this proceedings) result in one of the two deepest 1.4GHz radio maps ever made. Within the 15 radius field covered by the deep X-ray data (0.19 sq deg), a total of 556 radio sources are detected, down to a 4 sigma flux limit of 28uJy. Of the 214 Chandra sources, 55 have radio counterparts. The sub-arcsecond accuracy of the VLA and Chandra positions enable us to determine with high confidence the sources common to both surveys. Here we present the relationship between the X-ray and radio source populations at the faintest radio flux limits yet probed by such a study. We discuss how the X-ray/radio relationship differs as a function of optical morphology, ie between unresolved `stellar objects and well resolved galaxies. We then discuss the origin of the X-ray and radio emission, ie AGN, starburst or a mixture of both, in these two classes of object.
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