Results 141 to 150 of about 110,927 (295)

Quasar Microlensing Variability Studies Favor Shallow Accretion Disk Temperature Profiles [PDF]

, 2020
Matthew A. Cornachione, Christopher W. Morgan, Matthew A. Cornachione, Christopher W. Morgan   +3 more
openalex   +1 more source

Impact of extended source‐to‐surface distances and respiratory motion on the precision of electron beam therapy

Journal of Applied Clinical Medical Physics, Volume 26, Issue 10, October 2025.
Abstract Purpose In electron beam therapy targeting superficial thoracic and abdominal lesions, the source‐to‐surface distance (SSD) varies due to patient respiration. This study aimed to investigate the percentage depth dose (PDD) and off‐center ratio (OCR) of 6, 9, and 12 MeV electron beams at extended SSDs; and to assess the variations in dose ...
Takaaki Ito, Hiroyuki Kosaka, Yuya Yanagi, Yusuke Sakai, Hajime Monzen   +4 more
wiley   +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

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

The WISSH quasars project

Astronomy & Astrophysics, 2018
Winds accelerated by active galactic nuclei (AGNs) are invoked in the most successful models of galaxy evolution to explain the observed physical and evolutionary properties of massive galaxies.
G. Vietri, E. Piconcelli, M. Bischetti, F. Duras, S. Martocchia, A. Bongiorno, A. Marconi, L. Zappacosta, S. Bisogni, G. Bruni, M. Brusa, A. Comastri, G. Cresci, C. Feruglio, E. Giallongo, F. La Franca, V. Mainieri, F. Mannucci, F. Ricci, E. Sani, V. Testa, F. Tombesi, C. Vignali, F. Fiore   +23 more
semanticscholar   +1 more source

The Jets in Micro-Quasars and Quasars: A Comparison [PDF]

Highlights of Astronomy, 2005
AbstractThe discovery of relativistic jets in radio emitting X-ray binaries in our own galaxy has led to the term ‘microquasar’ being coined for these objects. In this paper the properties of microquasars are compared with those of quasars and radio galaxies, with the aim of trying to see how the similarities and differences can inform us about the ...
openaire   +1 more source

RESOLVING THE OPTICAL EMISSION LINES OF Lyα BLOB “B1” ATz= 2.38: ANOTHER HIDDEN QUASAR [PDF]

, 2013
Roderik Overzier, N. P. H. Nesvadba, Mark Dijkstra, N. A. Hatch, M. D. Lehnert, M. Villar-Martı́n, R. J. Wilman, A. Zirm   +7 more
openalex   +1 more source

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