Results 71 to 80 of about 20,094 (246)

C IV Broad Absorption Line Variability in QSO Spectra from SDSS Surveys

Frontiers in Astronomy and Space Sciences, 2017
Broad absorption lines (BALs) in the spectra of quasi-stellar objects (QSOs) are thought to arise from outflowing winds along our line of sight; winds, in turn, are thought to originate from the accretion disk, in the very surroundings of the central ...
Demetra De Cicco, William N. Brandt, William N. Brandt, William N. Brandt, Catherine J. Grier, Maurizio Paolillo, Maurizio Paolillo, Maurizio Paolillo   +7 more
doaj   +1 more source

What are recent observations telling us in light of improved tests of distance duality relation?

Physics Letters B, 2023
As an exact result required by the Etherington reciprocity theorem, the cosmic distance duality relation (CDDR), η(z)=DL(z)(1+z)−2/DA(z)=1 plays an essential part in modern cosmology.
Tonghua Liu, Shuo Cao, Shuai Ma, Yuting Liu, Chenfa Zheng, Jieci Wang   +5 more
doaj   +1 more source

QSO Search by Slitless Spectroscopy [PDF]

Symposium - International Astronomical Union, 1986
Sandage and I have obtained “grism” plates that redundantly cover one square degree fields centered on ten Selected Areas. We used a grating-prism in the converging beam of the Mayall 4-meter telescope prime focus to photograph 1580 A·mm−1 slitless spectra to a limit of about B = 21.5 (cf. Hoag and Smith 1977).
openaire   +1 more source

Advancements in Q‐learning meta‐heuristic optimization algorithms: A survey

WIREs Data Mining and Knowledge Discovery, Volume 14, Issue 6, November/December 2024.
Future research directions include exploring diverse meta—heuristic integrations, investigating transfer learning strategies, and advancing techniques for state space reduction. Abstract This paper reviews the integration of Q‐learning with meta‐heuristic algorithms (QLMA) over the last 20 years, highlighting its success in solving complex optimization
Yang Yang, Yuchao Gao, Zhe Ding, Jinran Wu, Shaotong Zhang, Feifei Han, Xuelan Qiu, Shangce Gao, You‐Gan Wang   +8 more
wiley   +1 more source

Gaia science alerts and the observing facilities of the Serbian-Bulgarian mini-network telescopes [PDF]

Serbian Astronomical Journal, 2014
The astrometric European Space Agency (ESA) Gaia mission was launched in December 19, 2013. One of the tasks of the Gaia mission is production of an astrometric catalog of over one billion stars and more than 500000 extragalactic sources.
Damljanović G., Vince O., Boeva S.
doaj   +1 more source

FeII/MgII Emission Line Ratios of QSOs. II. z>6 Objects

, 2004
Near-infrared spectra of four QSOs located at $z>6$ are obtained with the OH-airglow suppressor mounted on the Subaru telescope. The FeII/MgII emission-line ratios of these QSOs are examined by the same fitting algorithm as in our previous study of $z6 ...
Fumihide Iwamuro, Iwamuro F., Kentaro Motohara, Mamoru Doi, Masahiko Kimura, Motohara K., Shigeru Eto, Toshinori Maihara, Yuzuru Yoshii   +8 more
core   +1 more source

Herschel-ATLAS: the far-infrared properties and star-formation rates of broad absorption line quasi-stellar objects [PDF]

, 2012
We have used data from the Herschel-ATLAS at 250, 350 and 500 \mu m to determine the far-infrared (FIR) properties of 50 Broad Absorption Line Quasars (BAL QSOs).
A. Cava, A. Cooray, A. Dariush, Antonucci, Arav, Best, Best, Bonfield, Booth, Bower, Brotherton, Béthermin, C. Hoyos, Carilli, Churchill, Cirasuolo, Cowie, Croton, D. J. B. Smith, D. L. Clements, Dai, De Lucia, DiPompeo, DiPompeo, E. Ibar, E. Valiante, Eales, Elvis, Elvis, Farrah, Farrah, Farrah, G. De Zotti, Gabel, Gallagher, Gallagher, Gallagher, Gibson, Gibson, Granato, Green, Griffin, Hall, Hamann, Hamann, Hardcastle, Hatziminaoglou, Hewett, Ho, Ibar, J. A. Stevens, J. M. Cao Orjales, K. Coppin, Kennicutt, L. Dunne, Lazarova, Leitherer, Lewis, M. Baes, M. J. Hardcastle, M. J. Jarvis, M. J. Page, Mann, McCarthy, Murray, Murray, Ogle, Omont, Page, Page, Pascale, Peacock, Pilbratt, Poglitsch, Priddey, Priddey, R. Auld, R. Hopwood, R. J. Ivison, Rawlings, Reichard, Reichard, Rigby, S. Dye, S. Eales, S. Maddox, Sanders, Scannapieco, Scaringi, Schneider, Schneider, Sijacki, Smith, Smith, Sprayberry, Springel, Streblyanska, Tolea, Trump, Urrutia, Voit, Weymann, Willott   +102 more
core   +4 more sources

Pending Problems in QSOs

International Journal of Astronomy and Astrophysics, 2011
REVIEW, 15 pages, accepted to be published in Intl. J. Astr. Astrophys (previously it had been accepted by Invertis J. Sci. Techn.
openaire   +3 more sources

QSO Absorption Lines

, 2021
The absorption lines found in the spectra of distant quasars provide a unique method of probing the physical conditions in the universe at early epochs. This thesis describes a study of the Lyman alpha forest absorption systems seen in the spectra of high redshift QSOs.
openaire   +1 more source

Effects of essential caregiver policies on COVID‐19 and non‐COVID‐19 deaths in nursing homes

Health Economics, Volume 33, Issue 10, Page 2321-2341, October 2024.
Abstract Federal authorities banned nursing home visitation in the early days of the coronavirus disease 2019 (COVID‐19) pandemic. However, there was growing concern that physical isolation may have unintended harms on nursing home residents. Thus, nursing homes and policymakers faced a tradeoff between minimizing COVID‐19 outbreaks and limiting the ...
Mingyu Qi, Nadia Ghazali, R. Tamara Konetzka   +2 more
wiley   +1 more source