A5071278495- Galaxies: Formation, Evolution, Phenomena
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Radio Astronomy Observations and Technology
- Advanced Statistical Methods and Models
- Astrophysics and Cosmic Phenomena
- Spectroscopy and Chemometric Analyses
Leiden University
2022-2024
University of Science and Technology of China
2021
Chinese Academy of Sciences
2021
Abstract The identification of bright quasars at z ≳ 6 enables detailed studies supermassive black holes, massive galaxies, structure formation, and the state intergalactic medium within first billion years after Big Bang. We present spectroscopic confirmation 55 redshifts 5.6 < 6.5 UV magnitudes −24.5 M 1450 −28.5 identified in optical Pan-STARRS1 near-IR VIKING surveys (48 7, respectively). Five these have independently been discovered other studies. quasar sample shows an extensive...
High redshift quasars ($z>5$) that also shine brightly at radio wavelengths are unique signposts of supermassive black hole activity in the early universe. However, bright sources $z\ge5$ extremely rare and therefore we have started a campaign to search for new high-$z$ by combining an optical dropout selection driven $g$, $r$, $z$ bands from Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys with low-frequency observations LOFAR Two-metre Sky Survey (LoTSS). Currently, LoTSS...
ABSTRACT We present the high-z quasar candidate archive (HzQCA), summarizing spectroscopic observations of 207 z ≳ 5 candidates using Keck/LRIS, Keck/MOSFIRE, and Keck/NIRES. identify 14 as ∼ 6 quasars, with 10 them newly reported here 63 brown dwarfs. In remaining sources, 79 are unlikely to be quasars; 2 sources inconclusive; others could not fully reduced or extracted. Based on classifications, we investigate distributions quasars contaminants in colour space photometry measurements from...
Abstract In this work, we train three decision-tree based ensemble machine learning algorithms (Random Forest Classifier, Adaptive Boosting and Gradient Decision Tree respectively) to study quasar selection in the variable source catalog SDSS Stripe 82. We build training test samples (both containing 1:1 of quasars stars) using spectroscopic confirmed sources DR14 (including 8330 3966 stars). find that when trained with variation parameters alone, all models can select similarly remarkably...
We present the high-$z$ quasar candidate archive (HzQCA), summarizing spectroscopic observations of 174 $z\gtrsim5$ candidates using Keck/LRIS, Keck/MOSFIRE, and Keck/NIRES. identify 7 as $z\sim 6$ quasars 3 them newly reported here, 51 brown dwarfs. In remaining sources, 74 are unlikely to be quasars; 2 sources inconclusive; others could not fully reduced or extracted. Based on classifications we investigate distributions contaminants in color space with photometry measurements from DELS...
High redshift quasars ($z>5$) that also shine brightly at radio wavelengths are unique signposts of supermassive black hole activity in the early universe. However, bright sources $z\ge5$ extremely rare and therefore we have started a campaign to search for new high-$z$ by combining an optical dropout selection driven $g$, $r$, $z$ bands from Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys with low-frequency observations LOFAR Two-metre Sky Survey (LoTSS). Currently,...
The identification of bright quasars at z>6 enables detailed studies supermassive black holes, massive galaxies, structure formation, and the state intergalactic medium within first billion years after Big Bang. We present spectroscopic confirmation 55 redshifts 5.6