The Nuclear Spectroscopic Telescope Array (NuSTAR) mission, launched on 2012 June 13, is the first focusing high-energy X-ray telescope in orbit. NuSTAR operates in the band from 3 to 79 keV, extending the sensitivity of focusing far beyond the ∼10 keV high-energy cutoff achieved by all previous X-ray satellites. The inherently low background associated with concentrating the X-ray light enables NuSTAR to probe the hard X-ray sky with a more than 100-fold improvement in sensitivity over the collimated or coded mask instruments that have operated in this bandpass. Using its unprecedented combination of sensitivity and spatial and spectral resolution, NuSTAR will pursue five primary scientific objectives: (1) probe obscured active galactic nucleus (AGN) activity out to the

We present new Chandra observations that complete a sample of seventeen (17) luminous infrared galaxies (LIRGs) with D < 60 Mpc and low Galactic column densities of N H < ∼ 5 × 10 20 cm −2 . The LIRGs in our sample have total infrared (8-1000µm) luminosities in the range of L IR ≈ (1-8) × 10 11 L ⊙ . The high-resolution imaging and X-ray spectral information from our Chandra observations allow us to measure separately X-ray contributions from active galactic nuclei (AGNs) and normal galaxy processes (e.g., X-ray binaries and hot gas). We utilized total infrared plus UV luminosities to estimate star-formation rates (SFRs) and K-band luminosities and optical colors to estimate stellar masses (M ⋆ ) for the sample. Under the assumption that the galaxy-wide 2-10 keV luminosity (L gal HX ) traces the combined emission from high mass X-ray binaries (HMXBs) and low mass X-ray binaries (LMXBs), and that the power output from these components are linearly correlated with SFR and M ⋆ , respectively, we constrain the relation L gal HX = αM ⋆ + βSFR. To achieve this, we construct a Chandra-based data set composed of our new LIRG sample combined with additional samples of less actively star-forming normal galaxies and more powerful LIRGs and ultraluminous infrared galaxies (ULIRGs) from the literature. Using these data, we measure best-fit values of α = (9.05 ± 0.37) × 10 28 ergs s −1 M −1 ⊙ and β = (1.62 ± 0.22) × 10 39 ergs s −1 (M ⊙ yr −1 ) −1 . This scaling provides a more physically meaningful estimate of L gal HX , with ≈0.1-0.2 dex less scatter, than a direct linear scaling with SFR. Our results suggest that HMXBs dominate the galaxy-wide X-ray emission for galaxies with SFR/M ⋆ > ∼ 5.9 × 10 −11 yr −1 , a factor of ≈2.9 times lower than previous estimates. We find that several of the most powerful LIRGs and ULIRGs, with SFR/M ⋆ > ∼ 10 −9 yr −1 , appear to be X-ray underluminous with respect to our best-fit relation. We argue that these galaxies are likely to contain X-ray binaries residing in compact star-forming regions that are buried under thick galactic columns large enough to attenuate emission in the 2-10 keV band (N H > ∼ 10 23 cm −2 ).

In this paper we assess the relationship of the population of Active Galactic Nuclei (AGN) selected by hard X-rays to the traditional population of AGN with strong optical emission lines. First, we study the emission-line properties of a new hard X-ray selected sample of 47 local AGN (classified optically as both Type 1 and Type 2 AGN). We find that the hard X-ray (3-20 keV) and [OIII]λ5007 optical emission-line luminosities are well-correlated over a range of about four orders-of-magnitude in luminosity (mean luminosity ratio 2.15 dex with a standard deviation of σ = 0.51 dex). Second, we study the hard X-ray properties of a sample of 55 local AGN selected from the literature on the basis of the flux in the [OIII] line. The correlation between the hard X-ray (2-10 keV) and [OIII] luminosity for the Type 1 AGN is consistent with what is seen in the hard X-ray selected sample. However, the Type 2 AGN have a much larger range in the luminosity ratio, and many are very weak in hard X-rays (as expected for heavily absorbed AGN). We then compare the hard X-ray (3-20 keV) and [OIII] luminosity functions of AGN in the local universe. These have similar faintend slopes with a luminosity ratio of 1.60 dex (0.55 dex smaller than the mean value for individual hard X-ray selected AGN). We conclude that at low redshift, selection by narrow optical emission-lines will recover most AGN selected by hard X-rays (with the exception of BL Lac objects). However, selection by hard X-rays misses a significant fraction of the local AGN population with strong emission lines.

Abstract. We report on the first deep X-ray survey with the XMM-Newton observatory during the performance verification phase. The field of the Lockman Hole, one of the best studied sky areas over a very wide range of wavelengths, has been observed. A total of ∼100 ksec good exposure time has been accumulated. Combining the images of the European Photon Imaging Camera (EPIC) detectors we reach a flux limit of 0.31, 1.4 and 2.4 10 −15 erg cm −2 s −1 , respectively in the 0.5-2, 2-10, and 5-10 keV band. Within an off-axis angle of 10 arcmin we detect 148, 112 and 61 sources, respectively. The log(N)-log(S) relation in the three bands is compared with previous results. In particular in the 5-10 keV band these observations present the deepest X-ray survey ever, about a factor 20 more sensitive than the previous BeppoSAX observations. Using X-ray spectral diagnostics and the set of previously known, spectroscopically identified ROSAT sources in the field, the new sources can be classified. XMM-Newton detects a significant number (∼40%) of X-ray sources with hard, probably intrinsically absorbed X-ray spectra, confirming a prediction of the population synthesis models for the X-ray background.

We present 0.5-2 keV, 2-8 keV, 4-8 keV, and 0.5-8 keV (hereafter, soft, hard, ultra-hard, and full bands, respectively) cumulative and differential number counts (log N-log S) measurements for the recently completed ≈4 Ms Chandra Deep Field-South (CDF-S) survey, the deepest X-ray survey to date. We implement a new Bayesian approach, which allows reliable calculation of number counts down to flux limits that are factors of ≈1.9-4.3 times fainter than the previously deepest number-counts investigations. In the soft band, the most sensitive bandpass in our analysis, the ≈4 Ms CDF-S reaches a maximum source density of ≈27,800 deg −2 . By virtue of the exquisite X-ray and multiwavelength data available in the CDF-S, we are able to measure the number counts from a variety of source populations (active galactic nuclei [AGNs], normal galaxies, and Galactic stars) and subpopulations (as a function of redshift, AGN absorption, luminosity, and galaxy morphology), and test models that describe their evolution. We find that AGNs still dominate the X-ray number counts down to the faintest flux levels for all bands and reach a limiting soft-band source density of ≈14,900 deg −2 , the highest reliable AGN source density measured at any wavelength. We find that the normal-galaxy counts rise rapidly near the flux limits, and at the limiting soft-band flux, reach source densities of ≈12,700 deg −2 and make up 46 ± 5% of the total number counts. The rapid rise of the galaxy counts toward faint fluxes, and significant normal-galaxy contributions to the overall number counts, indicate that normal galaxies will overtake AGNs just below the ≈4 Ms soft-band flux limit and will provide a numerically significant new X-ray source population in future surveys that reach below the ≈4 Ms sensitivity limit. We show that a future ≈10 Ms CDF-S would allow for a significant increase in X-ray detected sources, with many of the new sources being cosmologically distant (z > ∼ 0.6) normal galaxies.