We present X-ray source catalogs for the ≈7 Ms exposure of the Chandra Deep Field-South (CDF-S), which covers a total area of 484.2arcmin 2 . Utilizing WAVDETECT for initial source detection and ACIS Extract for photometric extraction and significance assessment, we create a main source catalog containing 1008 sources that are detected in up to three X-ray bands: 0.5-7.0keV, 0.5-2.0keV, and 2-7keV. A supplementary source catalog is also provided,including 47 lower-significance sources that have bright (  K 23 s ) near-infrared counterparts. We identify multiwavelength counterparts for 992 (98.4%) of the main-catalog sources, and we collect redshifts for 986 of these sources, including 653 spectroscopic redshifts and 333 photometric redshifts. Based on the X-ray and multiwavelength properties, we identify 711 active galactic nuclei (AGNs) from the main-catalog sources. Compared to the previous ≈4 Ms CDF-S catalogs, 291 of the main-catalog sources are new detections. We have achieved unprecedented X-ray sensitivity with average flux limits over the central ≈1 arcmin 2 region of ≈1.9×10 −17 , 6.4×10 −18 , and 2.7×10 −17 ergcm −2 s −1 in the three X-ray bands, respectively. We provide cumulative number-count measurements observing, for the first time, that normal galaxies start to dominate the X-ray source population at the faintest 0.5-2.0keV flux levels. The highest X-ray source density reaches ≈50,500 deg −2 , and 47%±4% of these sources are AGNs (≈23,900 deg −2 ).

We investigate the population of high-redshift (3 z < 6) AGN selected in the two deepest X-ray surveys, the 7 Ms Chandra Deep Field-South and 2 Ms Chandra Deep Field-North. Their outstanding sensitivity and spectral characterization of faint sources allow us to focus on the sub-L * regime (logL X 44), poorly sampled by previous works using shallower data, and the obscured population. Taking fully into account the individual photometric-redshift probability distribution functions, the final sample consists of ≈ 102 X-ray selected AGN at 3 z < 6. The fraction of AGN obscured by column densities logN H > 23 is ∼ 0.6 − 0.8, once incompleteness effects are taken into account, with no strong dependence on redshift or luminosity. We derived the high-redshift AGN number counts down to F 0.5−2 keV = 7 × 10 −18 erg cm −2 s −1 , extending previous results to fainter fluxes, especially at z > 4. We put the tightest constraints to date on the low-luminosity end of AGN luminosity function at high redshift. The space-density, in particular, declines at z > 3 at all luminosities, with only a marginally steeper slope for low-luminosity AGN. By comparing the evolution of the AGN and galaxy densities, we suggest that such a decline at high luminosities is mainly driven by the underlying galaxy population, while at low luminosities there are hints of an intrinsic evolution of the parameters driving nuclear activity. Also, the black-hole accretion rate density and star-formation rate density, which are usually found to evolve similarly at z 3, appear to diverge at higher redshifts.

Neutron star-neutron star mergers are known to be associated with short gammaray bursts 1-4 . If the neutron star equation of state is sufficiently stiff, at least some of such mergers will leave behind a supramassive or even a stable neutron star that spins rapidly with a strong magnetic field (i.e., a magnetar) 5-8 . Such a magnetar signature may have been observed as the X-ray plateau following a good fraction (up to 50%) of short gamma-ray bursts 9, 10 , and it has been expected that one may observe short gamma-ray burst-less X-ray transients powered by double neutron star mergers 11, 12 . A fast X-ray transient (CDF-S XT1) was recently found to be associated with a faint host galaxy whose redshift is unknown 13 . Its X-ray and host-galaxy properties allow several possible explanations including a short gamma-ray burst seen off axis, a low-luminosity gamma-ray burst at high redshift, or a tidal disruption event involving an intermediate mass black hole and a white dwarf 13 . Here we report a second X-ray transient, CDF-S XT2, that is associated with a galaxy at redshift z = 0.738 14 .The light curve is fully consistent with being powered by a millisecond magnetar. More intriguingly, CDF-S XT2 lies in the outskirts of its star-forming host galaxy with a moderate offset from the galaxy center, as short bursts often do 15,16 . The estimated event rate density of similar X-ray transients, when corrected to the local value, is consistent with the double neutron star merger rate density inferred from the detection of GW170817 1 .Upon the completion of the deepest X-ray survey to date, the 7 Ms Chandra Deep Field-

Previous studies suggest that the growth of supermassive black holes (SMBHs) may be fundamentally related to host-galaxy stellar mass (M ). To investigate this SMBH growth-M relation in detail, we calculate long-term SMBH accretion rate as a function of M and redshift [BHAR(M , z)] over ranges of log(M /M ) = 9.5-12 and z = 0.4-4. Our BHAR(M , z) is constrained by high-quality survey data (GOODS-South, GOODS-North, and COSMOS), and by the stellar mass function and the X-ray luminosity function. At a given M , BHAR is higher at high redshift. This redshift dependence is stronger in more massive systems (for log(M /M ) ≈ 11.5, BHAR is three decades higher at z = 4 than at z = 0.5), possibly due to AGN feedback. Our results indicate that the ratio between BHAR and average star formation rate (SFR) rises toward high M at a given redshift. This BHAR/SFR dependence on M does not support the scenario that SMBH and galaxy growth are in lockstep. We calculate SMBH mass history [M BH (z)] based on our BHAR(M , z) and the M (z) from the literature, and find that the M BH -M relation has weak redshift evolution since z ≈ 2. The M BH /M ratio is higher toward massive galaxies: it rises from ≈ 1/5000 at log M 10.5 to ≈ 1/500 at log M 11.2. Our predicted M BH /M ratio at high M is similar to that observed in local giant ellipticals, suggesting that SMBH growth from mergers is unlikely to dominate over growth from accretion.

We present an investigation into the first 500 Myr of galaxy evolution from the Cosmic Evolution Early Release Science (CEERS) survey. CEERS, one of 13 JWST ERS programs, targets galaxy formation from z ∼ 0.5 to >10 using several imaging and spectroscopic modes. We make use of the first epoch of CEERS NIRCam imaging, spanning 35.5 arcmin2, to search for candidate galaxies at z > 9. Following a detailed data reduction process implementing several custom steps to produce high-quality reduced images, we perform multiband photometry across seven NIRCam broad- and medium-band (and six Hubble broadband) filters focusing on robust colors and accurate total fluxes. We measure photometric redshifts and devise a robust set of selection criteria to identify a sample of 26 galaxy candidates at z ∼ 9–16. These objects are compact with a median half-light radius of ∼0.5 kpc. We present an early estimate of the z ∼ 11 rest-frame ultraviolet (UV) luminosity function, finding that the number density of galaxies at M UV ∼ −20 appears to evolve very little from z ∼ 9 to 11. We also find that the abundance (surface density [arcmin−2]) of our candidates exceeds nearly all theoretical predictions. We explore potential implications, including that at z > 10, star formation may be dominated by top-heavy initial mass functions, which would result in an increased ratio of UV light per unit halo mass, though a complete lack of dust attenuation and/or changing star formation physics may also play a role. While spectroscopic confirmation of these sources is urgently required, our results suggest that the deeper views to come with JWST should yield prolific samples of ultrahigh-redshift galaxies with which to further explore these conclusions.