Results 1 to 10 of about 62,229 (199)

The Physical Properties of Low-redshift FeLoBAL Quasars. IV. Optical–Near-IR Spectral Energy Distributions and Near-IR Variability Properties

The Astrophysical Journal
We present the optical–near-infrared spectral energy distributions (SED) and near-infrared variability properties of 30 low-redshift iron low-ionization Broad Absorption Line quasars (FeLoBALQs) and matched samples of LoBALQs and unabsorbed quasars ...
Karen M. Leighly, Hyunseop Choi, Michael Eracleous, Donald M. Terndrup, Sarah C. Gallagher, Gordon T. Richards   +5 more
doaj   +1 more source

Black hole masses and enrichment of z ~ 6 SDSS quasars

, 2007
We present sensitive near-infrared spectroscopic observations for a sample of five z ~ 6 quasars. These are amongst the most distant, currently known quasars in the universe. The spectra have been obtained using ISAAC at the VLT and include the CIV, MgII
Aoki K., Chris Carilli, Dominik A. Riechers, Eddington A. S., Fabian Walter, Fan X., Hans‐Walter Rix, Jaron D. Kurk, Laura Pentericci, Linhua Jiang, Maselli A., Michael A. Strauss, Moorwood A., Ryan-Weber E. V., Stefan Wagner, Venemans B. P., Xiaohui Fan   +16 more
core   +1 more source

The host galaxies of low luminosity quasars at high redshift

, 2005
We present VLT/ISAAC near-infrared imaging of the host galaxies of 15 low luminosity quasars at 1 < z < 2. This work complements our studies to trace the cosmological evolution of the host galaxies of high luminosity quasars.
A. Treves, Bahcall, Barger, Bettoni, Bressan, de Vries, Dunlop, Falomo, Falomo, Ferrarese, Häring, J.K. Kotilainen, Kauffmann, Kauffmann, Kukula, M. Uslenghi, Madau, Marconi, Nolan, Pagani, Pentericci, R. Falomo, Veron-Cetty, Willott, Yu   +24 more
core   +1 more source

Machine Learning–based Search of High-redshift Quasars

The Astrophysical Journal Supplement Series
We present a machine learning search for high-redshift (5.0 < z < 6.5) quasars using the combined photometric data from the Dark Energy Spectroscopic Instrument (DESI) Imaging Legacy Surveys and the Wide-field Infrared Survey Explorer survey.
Guangping Ye, Huanian Zhang, Qingwen Wu
doaj   +1 more source

Quasar candidate selection and photometric redshift estimation based on SDSS and UKIDSS data

, 2010
We present a sample of 8498 quasars with both SDSS $ugriz$ optical and UKIDSS $YJHK$ near-IR photometric data. With this sample, we obtain the median colour-z relations based on 7400 quasars with magnitude uncertainties less than 0.1mag in all bands.
Abazajian, Ball, Boyle, Casali, Chiu, Croom, Croom, D'Abrusco, Fan, Fan, Fan, Hambly, Hewett, Ivezic, Ivezic, Kaiser, Lawrence, Maddox, Maddox, Richards, Richards, Richards, Richards, Richards, Schlegel, Schmidt, Schneider, Sesar, Smith, Su, Tyson, Warren, Weinstein, Wu, Xue-Bing Wu, York, Zhendong Jia   +36 more
core   +1 more source

Quest for a Coherent Definition of Weak-line Quasars and Its Physical Implications

The Astrophysical Journal
Weak-line quasars (WLQs) represent a subset of type 1 quasars distinguished by remarkably weak high-ionization broad emission lines, yet exhibiting normal optical/UV continua. This study establishes a physically motivated definition of WLQs using 371,091
Xiaoqiang Cheng, Jianfeng Wu, Qiaoya Wu
doaj   +1 more source

X-ray Spectral Survey of WGACAT Quasars, II: Optical and Radio Properties of Quasars with Low Energy X-ray Cut-offs

, 1997
We have selected quasars with X-ray colors suggestive of a low energy cut-off, from the ROSAT PSPC pointed archive. We examine the radio and optical properties of these 13 quasars.
Allen S. W., Baath L. B., Barthel P. D., Branson N. J. B. A., Browne I. W. A., Browne I. W. A., Brundage R. K., Fabbiano G., Fabrizio Fiore, Fugmann W., Giommi P., Hales S. E. G., Hamman F., Hook I. M., Jenkins C. J., Kuhr H., Marcha M. J. M., Martin Elvis, Mathur S., McMahon R., Morton D. C., Murphy D. W., O'Dea C. P., Owen F. N., Paolo Giommi, Paolo Padovani, Patnaik A. R., Pooley G. G., Quiniento Z. M., Reynolds C. S., Riley J. M., Roberts D. H., Robson I. E., Rottgering H. J. A., Rudy R. J., Saikia D. J., Steppe H., Stickel M., Stickel M., Stickel M., Tornikoski M., Ulrich M.-H., Wilkes B. J., Wright A. E.   +43 more
core   +1 more source

Star formation rate and dynamical mass of 10^8 solar mass black hole host galaxies at redshift 6

, 2015
We present ALMA observations of two moderate luminosity quasars at redshift 6. These quasars from the Canada-France High-z Quasar Survey (CFHQS) have black hole masses of ~10^8 M_solar.
Bergeron, Jacqueline, Omont, Alain, Willott, Chris J.   +2 more
core   +2 more sources

Extreme Variability Quasars in Their Various States. II. Spectral Variation Revealed with Multiepoch Spectra

The Astrophysical Journal
We previously built a sample of 14,012 extremely variable quasars (EVQs) based on Sloan Digital Sky Survey (SDSS) and Pan-STARRS1 photometric observations.
Wenke Ren, Junxian Wang, Zhenyi Cai, Xufan Hu   +3 more
doaj   +1 more source

Prospects for Observing High-redshift Radio-loud Quasars in the SKA Era: Paving the Way for 21 cm Forest Observations

The Astrophysical Journal
The 21 cm forest is a sensitive probe for the early heating process and small-scale structures during the epoch of reionization (EOR), to be realized with the upcoming Square Kilometre Array (SKA). Its detection relies on the availability of radio-bright
Qi Niu, Yichao Li, Yidong Xu, Hong Guo, Xin Zhang   +4 more
doaj   +1 more source