Microlensing of a Ring Model for Quasar Structure

Schild, Rudolph E.; Vakulik, V. G.

doi:10.1086/376472

Cited by 20 publications

(41 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…16 and 17;2003, Figs. 2 and 3) feature such outflow structures. These Romanova et al simulations also feature an inner ringlike structure similar to the inner ring of the Schild & Vakulik (2003) empirical model. The Romanova et al models are nonrelativistic and therefore relevant to the nonrelativistic region where the Elvis structures that they feature form; thus the models are presumably relevant in Galactic black hole candidate objects and in quasars.…”

Section: Discussionmentioning

confidence: 64%

“…The multiple peaks are evidently produced when the central black hole's variability produces brightness enhancements at the several continuum-emitting regions, which are seen at different times (lags) by the terrestrial observer. A double-ring quasar model by Schild & Vakulik (2003) has reproduced all the complex microlensing phenomena observed to date and will be the basis for the further developments in this report. Note the potential for confusion in referring to the ''double-ring model.'…”

Section: Introductionmentioning

confidence: 68%

“…The Romanova et al models are nonrelativistic and therefore relevant to the nonrelativistic region where the Elvis structures that they feature form; thus the models are presumably relevant in Galactic black hole candidate objects and in quasars. General relativistic effects will predominate in the region of the inner ring of the Schild & Vakulik (2003) model, and the fully relativistic ''magnetic propeller'' models of Robertson & Leiter (2002 feature such an inner ring structure. Such models, when scaled up from stellar to quasar masses, imply that the quasar MECO (magnetic eternally collapsing object) operates in a low-hard spectral state.…”

Section: Discussionmentioning

confidence: 99%

“…This was already anticipated by Schild (1996) when he first computed the quasar size from the brightness fluctuations and noticed that the structure inferred from autocorrelation peaks was larger by a factor of 10; he concluded that ''the quasar's luminous source is structured , and consists of rings or clouds with a 10% filling factor.'' The further development of this conclusion has produced the Schild & Vakulik (2003) model that can reproduce all the microlensing phenomena observed to date.…”

Section: Comparison With Other Estimates Of Quasar Sizementioning

confidence: 90%

“…Autocorrelation calculations of the brightness records show a network of peaks on time lags of order 200 proper days, suggesting that the quasar's luminous structures are at size scales of 200 lt-days and that the source of this luminosity is probably scattering of the emitted continuum. Of course this seems to be contradicted by the observations of brightness fluctuations on 1 day timescales as mentioned above, but because the fluctuations have low amplitude it is possible that the quasar luminosity comes from several regions with size scales between 3 and 200 days (Schild & Vakulik 2003). It is then necessary to ask what the effect of microlensing would be on such a large luminous object.…”

Section: Introductionmentioning

confidence: 96%

See 4 more Smart Citations

Accretion Disk Structure and Orientation in the Lensed and Microlensed Q0957+561 Quasar

Schild¹

2005

Astron J

View full text Add to dashboard Cite

Because quasars are unresolved in optical imaging, their structures must currently be inferred. Gravitational microlensing offers the possibility of producing information about the luminous structure provided that the Einstein ring diameter of the microlensing particle is comparable to or smaller than the radiating quasar components. Particularly interesting is the case of multiple-image gravitational lenses, where differences in the brightness histories of the multiple images can reveal the presence of the microlensing particles and allow inferences about the quasar's structure. The long brightness history measured for the Q0957 quasar has been analyzed previously for information about the microlensing particles, and evidence for the existence of a cosmologically significant population of planetary-mass particles has been reported. The microlensing results have also directly determined the sizes of the ultraviolet light emitting surfaces in the quasar. Autocorrelation analysis of the same brightness record has produced evidence for complex structure in the quasar; if the quasar suddenly brightens today, it is probable that it will brighten again after 129, 190, 540, and 620 days. We interpret these lags as the result of luminous structure around the quasar, and in particular we interpret them in the context of the Elvis model of the quasar's structure. We find that the autocorrelation peaks imply that beyond the luminous inner edge of the accretion disk, the biconic structures of the Elvis model must lie at a radial distance of 2 ; 10 17 cm from the black hole, and 2 ; 10 16 cm above and below the plane of the accretion disk. The quasar is apparently inclined 55 to the line of sight. A second possible solution with lower inclination and larger structure is also indicated but statistically less probable.

show abstract

Section: Discussionmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 68%

Section: Discussionmentioning

confidence: 99%

Section: Comparison With Other Estimates Of Quasar Sizementioning

confidence: 90%

Section: Introductionmentioning

confidence: 96%

See 3 more Smart Citations

Accretion Disk Structure and Orientation in the Lensed and Microlensed Q0957+561 Quasar

Schild¹

2005

Astron J

View full text Add to dashboard Cite

show abstract

Super-Eddington accretion in the Q2237+0305 quasar?

Berdina

Tsvetkova

Shulga

2021

A&A

View full text Add to dashboard Cite

The interband time lags between the flux variations of the Q2237+0305 quasar have been determined from light curves in the Johnson-Cousins V, R, and I spectral bands. The values of the time lags for filter pairs R − V, I − R, and I − V are significantly higher than those predicted by the standard accretion disk model by Shakura and Sunyaev. To explain the discrepancy, the idea of a supercritical accretion regime in quasars considered in 1973 by Shakura and Sunyaev is applied. This regime has been shown by them to cause an extended scattering envelope around the accretion disk. The envelope efficiently scatters and re-emits the radiation from the accretion disk and thus increases the apparent disk size. We made use of analytical expressions for the envelope radius and temperature derived by Shakura and Sunyaev in their analysis of super-Eddington accretion and show that our results are consistent with the existence of such an envelope. The corresponding parameters of the accretion regime were calculated. They provide the radii of the envelope in the V, R, and I spectral bands consistent with the inter-band time lags determined in our work.

show abstract

Color effects associated with the 1999 microlensing brightness peaks in gravitationally lensed quasar Q2237+0305

Vakulik¹,

Schild

Dudinov³

et al. 2004

A&A

View full text Add to dashboard Cite

Abstract. We present photometry of the Q2237+0305 gravitational lens system in VRI spectral bands with the 1.5-m telescope of the high-altitude Maidanak observatory in 1995−2000. The time interval includes the epoch of the dramatic brightness peaks discovered previously in the A and C image components (Wozniak et al. 2000a,b). By good luck three nights of observation in 1999 were almost at the time of the strong brightness peak of image C, and approximately in the middle of the ascending slope of the brightness peak of image A. Having reached its brightness maximum at the very end of June 1999, the C component had changed its (V − I) color from 0.3 m to 0.12 m since August 1998, and from 0.56 m to 0.12 m since August 1997. It was the bluest component in the system in 1998 and 1999, but by October 2000 that was no longer the case. We do not know the color of the A component exactly at its brightness peak, but we do know that it became 0.47 m brighter in R and 0.15 m bluer in (V − R) between August 1998 and August 2000, about three months before the peak. More intensive monitoring of Q2237+0305 in July-October 2000, made on a nearly daily basis, did not reveal rapid (night-to-night and intranight) brightness variations of the components during this time period, exceeding the photometry error bars. Rather slow changes of magnitudes of the components were observed, in particular, nearly synchronous 0.08 m fading of B and C components, and 0.05 m brightening of D in the R band during July 23−October 7, 2000, while the B component had become the faintest in all filters by the end of this time period. The behavior of the colors of the components was analyzed on the basis of all our VRI observations, made in 1995−2000 on Maidanak. A qualitative tendency of the components to become bluer as their brightness increases, noted in our previous works, was confirmed quantitatively. A correlation between the color variations and variations of magnitudes of the components is demonstrated to be significant and reaches 0.75 for ∆(V − I) vs. ∆R, with a regression line slope of 0.33± 0.08 for these quantities. A plot of (V − I) vs. (V − R) shows the components settled in a cluster, stretchng along a line with a slope of 1.31 ± 0.14. Both slopes are noticeably less steep than those expected if a standard galactic interstellar reddening law were responsible for the differences between the colors of images and their variations over time. We attribute the brightness and color changes to microlensing of the quasar's structure, which we conclude to be more compact at shorter wavelengths, as predicted by most quasar models featuring an energizing central source.

show abstract

Microlensing of a Ring Model for Quasar Structure

Cited by 20 publications

References 22 publications

Accretion Disk Structure and Orientation in the Lensed and Microlensed Q0957+561 Quasar

Accretion Disk Structure and Orientation in the Lensed and Microlensed Q0957+561 Quasar

Super-Eddington accretion in the Q2237+0305 quasar?

Color effects associated with the 1999 microlensing brightness peaks in gravitationally lensed quasar Q2237+0305

Contact Info

Product

Resources

About