#Quasar spectra archive

Properties, emission line properties, and the Eddington ratio (e.g., Ulrich et al. With various physical parameters such as time-lag, rest-frame wavelength, luminosity, radio Numerous studies have shown that the optical/UV continuum variability of quasars correlates 2008 LSST Science Collaborations 2009)Ĭombining high photometric accuracy, large survey areas, sufficiently long time baselines,Īnd a high number of observation epochs holds the promise of significant progress. The advent of modern variability surveys (e.g., Ivezić et al. Physical mechanisms behind these fluctuations are still poorly known, though it has longīeen understood that the observed flux variations of AGNs hold keys to the structure of the From the onset of the study of quasars, which are the most luminousĪGNs, variability is known to be a diagnostic property and has been successfully used as aĬriterion for selecting quasar candidates in a number of studies. The variation in flux density over time is one of the key characteristics of active Key words: galaxies: active / quasars: general / quasars: emission lines Line emission and may be indicative of high Eddington ratios in these unusual quasars. This trend is the opposite of that expected from the dilution effect of variability due to Spectra and weak emission lines tend to have less variability than conventional quasars. Finally, we find that quasars with unusual Of more than 8000 quasars, confirm the previous findings by Wilhite and collaborators forģ15 quasars with repeated SDSS spectroscopy. ~10% of that of the underlying continuum. (i.e., is bluer when brighter) and (b) the variability of the emission line flux is only fluctuation of the quasar continuum flux follows a power law Weįind that the observed variability ratio-redshift relations are described well assuming While variability isĪlmost always stronger in the bluer passband than in the redder, the variability ratioĭepends on whether strong emission lines contribute to either one band or the other. Redshift resemble the corresponding colour index-redshift relations. Luminosity, wavelength, and redshift, where the latter can be fully explained as aĬonsequence of the former two dependencies. We also confirm that anti-correlations exist with Time-lag the best power-law fit of the sample-averaged structure function has a slope We confirm the well-known dependence of variability on Monte Carlo simulations of variable quasar spectra. Interpretation of these relations is provided by comparing with the results of simple Ratios for adjacent SDSS filter bands as a function of redshift. Timescales for all quasars (about 1 to 2 yr in the rest-frame). The structureįunctions are used to create a variability indicator that is related to the same intrinsic The quasarĬatalogue was matched with the Light Motion Curve Catalogue for SDSS Stripe 82 andįirst-order structure functions were computed from the lightcurves. Survey (SDSS) to create a sample of over 9000 quasars in the Stripe 82.

#Quasar spectra archive

We exploited the spectral archive of the Sloan Digital Sky Here, we present a newĪpproach to analysing the dependence of quasar variability on rest-frame wavelengths. Variability on timescale, rest-frame wavelength, and luminosity. Variability of quasars is hampered by the combined effects of the dependence of

The study of the ensemble properties of the UV/optical broadband de Hoon 3Īstrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482Īims. Astronomical objects: linking to databases.Including author names using non-Roman alphabets.Suggested resources for more tips on language editing in the sciences Punctuation and style concerns regarding equations, figures, tables, and footnotes