Nonhomologous end joining (NHEJ) plays a major role in double-strand break DNA repair, which involves a series of steps mediated by multiprotein complexes. A ring-shaped Ku70/Ku80 heterodimer forms first at broken DNA ends, DNA-dependent protein kinase catalytic subunit (DNA-PKcs) binds to mediate synapsis and nucleases process DNA overhangs. DNA ligase IV (LigIV) is recruited as a complex with...

The luminosity function (LF) of active galactic nuclei (AGN) probes the history supermassive black hole assembly and growth across cosmic time. To mitigate selection biases, we present a consistent analysis AGN LFs derived for both X-ray mid-infrared (MIR) selected in XMM-Large Scale Structure (XMM-LSS) field. There are 4268 used to construct MIR (IRLF) 3427 (XLF), providing largest census popu...

A major pathway for repair of DNA double-strand breaks is nonhomologous end-joining (NHEJ). In this issue of Cell, and report the discovery of a new NHEJ factor called Cernunnos-XLF. Both groups report that this protein is mutated in a rare inherited human syndrome characterized by severe immunodeficiency, developmental delay, and hypersensitivity to agents that cause DNA double-strand breaks.

We present a measure of the hard (2–8 keV) X-ray luminosity function (XLF) of Active Galactic Nuclei up to z ∼ 5. At high redshifts, the wide area coverage of the Chandra Multiwavength Project is crucial to detect rare and luminous (LX > 10 44 erg s) AGN. The inclusion of samples from deeper published surveys, such as the Chandra Deep Fields, allows us to span the lower LX range of the XLF. Our...

Almost all massive galaxies today are understood to contain supermassive black holes (SMBH) at their centers. SMBHs grew by accreting material from surroundings, emitting X-rays as they did so. X-ray Luminosity Functions (XLFs) of Active Galactic Nuclei (AGN) have been extensively studied in order understand the AGN population's cosmological properties and evolution. We present a new fixed rest...

ABSTRACT X-ray luminosity functions (XLFs) of active galactic nuclei (AGNs) trace the growth and evolution supermassive black hole populations across cosmic time. However, current XLF models are poorly constrained at redshifts z > 6, with a lack spectroscopic constraints these high redshifts. In this work, we place limits on bright-end = 5.7–6.4 using high-redshift AGN identified within ...

We propose that the shape of the upper-end X-ray luminosity function (XLF) observed in elliptical galaxies for point sources carries valuable information about the black-hole (BH) mass spectrum among old X-ray transients formed in the galaxies. Here we present the line of arguments and analysis that support this connection and the methodology for deriving the BH mass spectrum slope from the obs...

We present the results of ROSAT All–Sky Survey observations of Seyfert and IR–luminous galaxies from the Extended 12 μm Galaxy Sample and the optically–selected CfA Sample. Detections are available for 80% (44/55) of the Seyfert 1s and 34% (23/67) of the Seyfert 2s in the 12 μm sample, and for 76% (26/34) of the Seyfert 1s and 38% (6/16) of the Seyfert 2s in the CfA sample. Roughly half of the ...