FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W4246656875> ?p ?o ?g. }

• W4246656875 endingPage "611" @default.
• W4246656875 startingPage "611" @default.
• W4246656875 abstract "view Abstract Citations (143) References (82) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Soft X-Ray Properties of a Complete Sample of Optically Selected Quasars. I. First Results Laor, Ari ; Fiore, Fabrizio ; Elvis, Martin ; Wilkes, Belinda J. ; McDowell, Jonathan C. Abstract We present the results of ROSAT PSPC observations of 10 quasars. These objects are part of our ROSAT program to observe a complete sample of optically selected quasars. This sample includes all 23 quasars from the bright quasar survey with a redshift z <= 0.400 and a Galactic H I column density N_HI_^Gal^ < 1.9 x 10^20^ cm^-2^. These selection criteria, combined with the high sensitivity and improved energy resolution of the PSPC, allow us to determine the soft (~0.2-2 keV) X-ray spectra of quasars with about an order of magnitude higher precision compared with earlier soft X-ray observations. The following main results are obtained: Strong correlations are suggested between the soft X-ray spectral slope α_x_ and the following emission line parameters: HβFWHM, L_[O III}_, and the Fe II/Hβ flux ratio. These correlations imply the following: (1) The quasar's environment is likely to be optically thin down to ~0.2 keV. (2) In most objects α_x_ varies by less than ~10% on timescales shorter than a few years. (3)α_x_ might be a useful absolute luminosity indicator in quasars. (4) The Galactic He I and H I column densities are well correlated. Most spectra are well characterized by a simple power law, with no evidence for either significant absorption excess or emission excess at low energies, to within ~30%. We find <α_x_> = - 1.50+/-0.40, which is consistent with other ROSAT observations of quasars. However, this average is significantly steeper than suggested by earlier soft X-ray observations of the Einstein IPC. The 0.3 keV flux in our sample can be predicted to better than a factor of 2 once the 1.69 micron flux is given. This implies that the X-ray variability power spectra of quasars flattens out between f~10^-5^ and f ~ 10^-8^ Hz. A steep α_x_ is mostly associated with a weak hard X-ray component, relative to the near-IR and optical emission, rather than a strong soft excess, and the scatter in the normalized 0.3 keV flux is significantly smaller than the scatter in the normalized 2 keV flux. This argues against either thin or thick accretion disks as the origin of the soft X-ray emission. Further possible implications of the results found here are briefly discussed. Publication: The Astrophysical Journal Pub Date: November 1994 DOI: 10.1086/174841 Bibcode: 1994ApJ...435..611L Keywords: Galactic Radiation; Quasars; X Ray Astronomy; X Ray Spectra; Flux Density; Red Shift; Rosat Mission; Stellar Luminosity; Astronomy; ACCRETION; ACCRETION DISKS; ISM: ABUNDANCES; GALAXIES: QUASARS: GENERAL; X-RAYS: GALAXIES full text sources ADS | data products SIMBAD (23) NED (23) HEASARC (1) Related Materials (1) Part 2: 1997ApJ...477...93L" @default.
• W4246656875 created "2022-05-12" @default.
• W4246656875 creator A5002705377 @default.
• W4246656875 creator A5022459860 @default.
• W4246656875 creator A5044482994 @default.
• W4246656875 creator A5051825718 @default.
• W4246656875 creator A5088633481 @default.
• W4246656875 date "1994-11-01" @default.
• W4246656875 modified "2023-10-17" @default.
• W4246656875 title "The soft x-ray properties of a complete sample of optically selected quasars. 1: First results" @default.
• W4246656875 doi "https://doi.org/10.1086/174841" @default.
• W4246656875 hasPublicationYear "1994" @default.
• W4246656875 type Work @default.
• W4246656875 citedByCount "92" @default.
• W4246656875 countsByYear W42466568752012 @default.
• W4246656875 countsByYear W42466568752013 @default.
• W4246656875 countsByYear W42466568752014 @default.
• W4246656875 countsByYear W42466568752015 @default.
• W4246656875 countsByYear W42466568752016 @default.
• W4246656875 countsByYear W42466568752017 @default.
• W4246656875 countsByYear W42466568752018 @default.
• W4246656875 countsByYear W42466568752020 @default.
• W4246656875 countsByYear W42466568752022 @default.
• W4246656875 countsByYear W42466568752023 @default.
• W4246656875 crossrefType "journal-article" @default.
• W4246656875 hasAuthorship W4246656875A5002705377 @default.
• W4246656875 hasAuthorship W4246656875A5022459860 @default.
• W4246656875 hasAuthorship W4246656875A5044482994 @default.
• W4246656875 hasAuthorship W4246656875A5051825718 @default.
• W4246656875 hasAuthorship W4246656875A5088633481 @default.
• W4246656875 hasBestOaLocation W42466568751 @default.
• W4246656875 hasConcept C121332964 @default.
• W4246656875 hasConcept C12287442 @default.
• W4246656875 hasConcept C1276947 @default.
• W4246656875 hasConcept C135041427 @default.
• W4246656875 hasConcept C33024259 @default.
• W4246656875 hasConcept C43481613 @default.
• W4246656875 hasConcept C44870925 @default.
• W4246656875 hasConcept C4839761 @default.
• W4246656875 hasConcept C75776270 @default.
• W4246656875 hasConcept C98444146 @default.
• W4246656875 hasConceptScore W4246656875C121332964 @default.
• W4246656875 hasConceptScore W4246656875C12287442 @default.
• W4246656875 hasConceptScore W4246656875C1276947 @default.
• W4246656875 hasConceptScore W4246656875C135041427 @default.
• W4246656875 hasConceptScore W4246656875C33024259 @default.
• W4246656875 hasConceptScore W4246656875C43481613 @default.
• W4246656875 hasConceptScore W4246656875C44870925 @default.
• W4246656875 hasConceptScore W4246656875C4839761 @default.
• W4246656875 hasConceptScore W4246656875C75776270 @default.
• W4246656875 hasConceptScore W4246656875C98444146 @default.
• W4246656875 hasLocation W42466568751 @default.
• W4246656875 hasLocation W42466568752 @default.
• W4246656875 hasLocation W42466568753 @default.
• W4246656875 hasOpenAccess W4246656875 @default.
• W4246656875 hasPrimaryLocation W42466568751 @default.
• W4246656875 hasRelatedWork W1997076624 @default.
• W4246656875 hasRelatedWork W1997425891 @default.
• W4246656875 hasRelatedWork W2005283866 @default.
• W4246656875 hasRelatedWork W2054450735 @default.
• W4246656875 hasRelatedWork W2187560648 @default.
• W4246656875 hasRelatedWork W2979312616 @default.
• W4246656875 hasRelatedWork W3122217315 @default.
• W4246656875 hasRelatedWork W3124963366 @default.
• W4246656875 hasRelatedWork W3185934485 @default.
• W4246656875 hasRelatedWork W2127550666 @default.
• W4246656875 hasVolume "435" @default.
• W4246656875 isParatext "false" @default.
• W4246656875 isRetracted "false" @default.
• W4246656875 workType "article" @default.