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A search for close binary systems in the SALT survey of hydrogen-deficient stars using TESS
Dorsch, M.; Jeffery, C. S.; Snowdon, E. J. +1 more
The TESS periodograms of the SALT survey catalogue of hydrogen-deficient stars were searched for evidence of short-period variability. Periodic light-curve variations were identified in 16 stars out of 153 catalogue objects, of which 10 were false positives. From the remaining 6 identified variables, Ton S 415 is a known close binary system and th…
CDN-Net: Faint Celestial Target Detection Based on Densely Nested Hierarchical Network
Chen, Guo; Xue, Bindang; Li, Xinyang +2 more
The detection of celestial objects in ground-based wide-field optical telescope images serves as the foundational step for subsequent celestial analysis tasks. Existing methods for astronomical target detection have not addressed the challenges posed by a high dynamic range, faintness of targets, and an inaccurate supervision map. This paper prese…
A simplified approach for reproducing fully relativistic spectra in X-ray binary systems: Application to Cygnus X-1
Papavasileiou, Th. V.; Kosmas, O.; Kosmas, T. S.
Context. General relativistic effects are strong near the black hole of an X-ray binary and significantly impact the total energy released in the innermost accretion disk's region. The simple pseudo-Newtonian solution in the standard disk model cannot replenish for effects such as light-bending, gravitational redshift, and Doppler boost. These can…
JADES: The diverse population of infant black holes at 4 < z < 11: Merging, tiny, poor, but mighty
Charlot, Stéphane; Chevallard, Jacopo; Carniani, Stefano +25 more
Spectroscopy with the James Webb Space Telescope has opened the possibility of identifying moderate-luminosity active galactic nuclei (AGNs) in the early Universe, at and beyond the epoch of re-ionisation, complementing previous surveys of much more luminous (and much rarer) quasars. We present 12 new AGNs at 4 < z < 7 in the JADES survey (i…
Little Red Dots: An Abundant Population of Faint Active Galactic Nuclei at z ∼ 5 Revealed by the EIGER and FRESCO JWST Surveys
Maseda, Michael V.; van Dokkum, Pieter; Chisholm, John +25 more
Characterizing the prevalence and properties of faint active galactic nuclei (AGNs) in the early Universe is key for understanding the formation of supermassive black holes (SMBHs) and determining their role in cosmic reionization. We perform a spectroscopic search for broad Hα emitters at z ≈ 4–6 using deep JWST/NIRCam imaging and wide field slit…
A small and vigorous black hole in the early Universe
Charlot, Stéphane; Chevallard, Jacopo; Maseda, Michael V. +36 more
Several theories have been proposed to describe the formation of black hole seeds in the early Universe and to explain the emergence of very massive black holes observed in the first thousand million years after the Big Bang1-3. Models consider different seeding and accretion scenarios4-7, which require the detection and char…
The Early Data Release of the Dark Energy Spectroscopic Instrument
Alexander, D. M.; Juneau, S.; Kim, S. +267 more
The Dark Energy Spectroscopic Instrument (DESI) completed its 5 month Survey Validation in 2021 May. Spectra of stellar and extragalactic targets from Survey Validation constitute the first major data sample from the DESI survey. This paper describes the public release of those spectra, the catalogs of derived properties, and the intermediate data…
UNCOVER Spectroscopy Confirms the Surprising Ubiquity of Active Galactic Nuclei in Red Sources at z > 5
Papovich, Casey; Maseda, Michael V.; Glazebrook, Karl +33 more
The James Webb Space Telescope is revealing a new population of dust-reddened broad-line active galactic nuclei (AGN) at redshifts z ≳ 5. Here we present deep NIRSpec/Prism spectroscopy from the Cycle 1 Treasury program Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization (UNCOVER) of 15 AGN candidates selected to be compact,…
The SRG/eROSITA all-sky survey. First X-ray catalogues and data release of the western Galactic hemisphere
Zhang, X.; Haberl, F.; Burwitz, V. +142 more
The eROSITA telescope array aboard the Spektrum Roentgen Gamma (SRG) satellite began surveying the sky in December 2019, with the aim of producing all-sky X-ray source lists and sky maps of an unprecedented depth. Here we present catalogues of both point-like and extended sources using the data acquired in the first six months of survey operations…
Evidence for heavy-seed origin of early supermassive black holes from a z ≈ 10 X-ray quasar
Churazov, Eugene; Goulding, Andy D.; Jones, Christine +9 more
Observations of quasars reveal that many supermassive black holes (BHs) were in place less than 700 Myr after the Big Bang. However, the origin of the first BHs remains a mystery. Seeds of the first BHs are postulated to be either light (that is, 10‑100 M⊙), remnants of the first stars, or heavy (that is, 10‑105 M⊙…