Quasar microlensing

Schmidt, R. W.; Wambsganß, J.

doi:10.1007/s10714-010-0956-x

Cited by 55 publications

(56 citation statements)

References 91 publications

(107 reference statements)

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“…Microlenses typically magnify regions of the source on scales similar to or smaller than a few micro-arcsecs, the size of their angular Einstein radius R E (Wambsganss 1998(Wambsganss , 2006Schmidt & Wambsganss 2010). Hence, the quasar continuum region (accretion disc) and the broad line region are likely to be microlensed.…”

Section: Introductionmentioning

confidence: 99%

Microlensing of the broad line region in 17 lensed quasars

Sluse

Hutsemékers

Courbin

et al. 2012

A&A

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137

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When an image of a strongly lensed quasar is microlensed, the different components of its spectrum are expected to be differentially magnified owing to the different sizes of the corresponding emitting region. Chromatic changes are expected to be observed in the continuum while the emission lines should be deformed as a function of the size, geometry and kinematics of the regions from which they originate. Microlensing of the emission lines has been reported only in a handful of systems so far. In this paper we search for microlensing deformations of the optical spectra of pairs of images in 17 lensed quasars with bolometric luminosities between 10 44.7−47.4 erg/s and black hole masses 10 7.6−9.8 M . This sample is composed of 13 pairs of previously unpublished spectra and four pairs of spectra from literature. Our analysis is based on a simple spectral decomposition technique which allows us to isolate the microlensed fraction of the flux independently of a detailed modeling of the quasar emission lines. Using this technique, we detect microlensing of the continuum in 85% of the systems. Among them, 80% show microlensing of the broad emission lines. Focusing on the most common emission lines in our spectra (C iii] and Mg ii) we detect microlensing of either the blue or the red wing, or of both wings with the same amplitude. This observation implies that the broad line region is not in general spherically symmetric. In addition, the frequent detection of microlensing of the blue and red wings independently but not simultaneously with a different amplitude, does not support existing microlensing simulations of a biconical outflow. Our analysis also provides the intrinsic flux ratio between the lensed images and the magnitude of the microlensing affecting the continuum. These two quantities are particularly relevant for the determination of the fraction of matter in clumpy form in galaxies and for the detection of dark matter substructures via the identification of flux ratio anomalies.

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Section: Introductionmentioning

confidence: 99%

Microlensing of the broad line region in 17 lensed quasars

Sluse

Hutsemékers

Courbin

et al. 2012

A&A

Self Cite

137

184

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“…Broad Fe Kα line is observed in a large number of Seyfert galaxies and quasars, starting from the initial ASCA discovery of the line in MCG 15-6-30 galaxy spectrum (Tanaka et al 1995).…”

Section: Discussionmentioning

confidence: 99%

“…Radiatively efficient accretion onto supermassive black holes in quasars and Seyfert galaxies is conventionally assumed to proceed through an accretion disk which rotates at nearly Keplerian velocities in the equatorial plane around a black hole (Shakura & Sunyaev 1973;Novikov & Thorne 1974). Photons emitted by the matter moving along the circular orbits are gravitationally redshifted and also red / blue shifted by the Doppler effect.…”

Section: Relativistically Broadened Lines From the Black Hole Accretimentioning

confidence: 99%

“…month (12) The time variability effect of the microlensing is now observed in a range of the strongly lensed quasars, via the measurement of the difference in the lightcurves of the multiple images of the lensed sources (Chang & Refsdal 1979;Schmidt & Wambsganss 2010;Dai et al 2010;Chartas et al 2012;MacLeod et al 2015). Measurements of the strength of the microlensing effect leads to the estimates of the sizes of the regions of visible (Kochanek 2004;Eigenbrod et al 2008), and Xray (Dai et al 2010;Chartas et al 2012;MacLeod et al 2015) emission in the lensed quasars.…”

Section: Qualitative Picturementioning

confidence: 99%

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Test of relativistic gravity using microlensing of relativistically broadened lines in gravitationally lensed quasars

Neronov

Vovk

2016

Phys. Rev. D

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Aims. We show that observation of the time-dependent effect of microlensing of relativistically broadened emission lines (such as e.g. the Fe Kα line in X-rays) in strongly lensed quasars could provide data on celestial mechanics of circular orbits in the direct vicinity of the horizon of supermassive black holes. Methods. This information can be extracted from the observation of evolution of red / blue edge of the magnified line just before and just after the period of crossing of the innermost stable circular orbit by the microlensing caustic. The functional form of this evolution is insensitive to numerous astrophysical parameters of the accreting black hole and of the microlensing caustics network system (as opposed to the evolution the full line spectrum). Results. Measurement of the temporal evolution of the red / blue edge could provide a precision measurement of the radial dependence of the gravitational redshift and of velocity of the circular orbits, down to the innermost stable circular orbit. These measurements could be used to discriminate between the General Relativity and alternative models of the relativistic gravity in which the dynamics of photons and massive bodies orbiting the gravitating centre is different from that of the geodesics in the Schwarzschild or Kerr space-times.

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“…Following the fading transients over several years will be crucial to establish the preamplification flux, and so remove the degeneracy in light curve fitting, and find the distribution of amplification factors. We also need to model the light curves using galaxy simulations -in the analysis presented for this conference paper we have used a simple single-star model, whereas even at small impact parameter the effect of many overlapping stars will be significant (see Schmidt and Wambsganss 2010).…”

Section: Future Prospectsmentioning

confidence: 99%

Bright PanSTARRS Nuclear Transients – what are they?

Lawrence

Gezari

Elvis

et al. 2012

EPJ Web of Conferences

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Abstract. We present an initial analysis of 49 bright transients occurring in the nuclei of galaxies with no previous known Active Galactic Nucleus (AGN). They have been discovered as part of the PanSTARRs 3π survey, and followed up with the Liverpool Telescope. Based on colours, light curve shape, and a small number with optical spectra, these transients seem to fall into three groups. Red/fast transients are nuclear supernovae of various types. Some bright nuclear transients are blue and decay on a timescale of a few months; these may be candidates for tidal disruption events. However most of the events we have found are blue and are either still rising or decaying slowly, on a timescale of years; the few spectra we have show AGN at z ∼ 1. We argue that these transients are background AGN microlensed by stars in foreground galaxies by a factor 10-100. Monitoring such events gives us very promising prospects for measuring the structure of AGN and so testing current theories.

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Quasar microlensing

Cited by 55 publications

References 91 publications

Microlensing of the broad line region in 17 lensed quasars

Microlensing of the broad line region in 17 lensed quasars

Test of relativistic gravity using microlensing of relativistically broadened lines in gravitationally lensed quasars

Bright PanSTARRS Nuclear Transients – what are they?

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