Search results for "Gravitational microlensing"
showing 10 items of 42 documents
Integral field spectroscopy of the gravitational lens HE1104-1805
2004
We present integral field spectroscopy of the double imaged quasar HE1104-1805 taken with the optical fiber system INTEGRAL-WYFFOS at theWHT telescope. From the spectra of the two components we have measured the continuum and line emission ratios, finding an offset between them that can be related to microlensing. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
A Fast and Very Accurate Approach to the Computation of Microlensing Magnification Patterns Based on Inverse Polygon Mapping
2006
A new method of calculating microlensing magnification patterns is proposed that is based on the properties of the backward gravitational lens mapping of a lattice of polygonal cells defined at the image plane. To a first-order approximation, the local linearity of the transformation allows us to compute the contribution of each image-plane cell to the magnification by apportioning the area of the inverse image of the cell (transformed cell) among the source-plane pixels covered by it. Numerical studies in the κ = 0.1-0.8 range of mass surface densities demonstrate that this method (provided with an exact algorithm for distributing the area of the transformed cells among the source-plane pi…
A Study of the Correlation between the Amplification of the Fe Kα Line and the X‐Ray Continuum of Quasars due to Microlensing
2006
The observed enhancement of the Fe Kα line in three gravitationally lensed QSOs (MG J0414+0534, QSO 2237+0305, and H1413+117) is interpreted in terms of microlensing, even when equivalent X-ray continuum amplification is not observed. In order to interpret these observations, first we studied the effects of microlensing on quasar spectra produced by a straight fold caustic crossing over a standard relativistic accretion disk. The disk emission was analyzed using the ray-tracing method, considering Schwarzschild and Kerr metrics. When the emission is separated into two regions (an inner disk corresponding to the Fe Kα line and an outer annulus corresponding to the continuum, or vice versa), …
Measuring Microlensing using Spectra of Multiply Lensed Quasars
2012
We report on a program of spectroscopic observations of gravitationally-lensed QSOs with multiple images. We seek to establish whether microlensing is occurring in each QSO image using only single-epoch observations. We calculate flux ratios for the cores of emission lines in image pairs to set a baseline for no microlensing. The offset of the continuum flux ratios relative to this baseline yields the microlensing magnification free from extinction, as extinction affects the continuum and the lines equally. When we find chromatic microlensing, we attempt to constrain the size of the QSO accretion disk. SDSSJ1004+4112 and HE1104-1805 show chromatic microlensing with amplitudes $0.2< |\Delta …
Recurrence of the blue wing enhancements in the high ionization lines of SDSS 1004+4112 A
2006
We present integral field spectroscopic observations of the quadruple-lensed QSO SDSS 1004+4112 taken with the fiber system INTEGRAL at the William Herschel Telescope on 2004 January 19. In 2003 May, a blueward enhancement in the high-ionization lines of SDSS 1004+4112A was detected, and then it faded. Our observations are the first to note a second event of similar characteristics less than 1 year after. Although initially attributed to microlensing, the resemblance among the spectra of both events and the absence of microlensing-induced changes in the continuum of component A are puzzling. The lack of a convincing explanation under the microlensing or intrinsic variability hypotheses make…
The structure of the accretion disk in the lensed quasar SBS 0909+532
2011
We derive the size and temperature profile of the accretion disk of the lensed quasar SBS 0909+532 by measuring the wavelength dependence (chromaticity) of the microlensing magnification produced by the stars in the lens galaxy. After correcting for extinction using the flux ratios of 14 emission lines, we observe a marked change in the B-A flux ratio with wavelength, varying from -0.67 ± 0.05 mag at (rest frame) ∼1460 Åto -0.24 ± 0.07 mag at ∼6560 Å. For λ ≳ 7000 both effects, extinction and microlensing, look minimal. Simulations indicate that image B rather than A is strongly microlensed. If we model the change in disk size from 1460 Å to 6560 Å using a Gaussian source (I exp(-R 2/2r 2 s…
Systematic Redshift of the Fe III UV Lines in Quasars. Measuring Supermassive Black Hole Masses under the Gravitational Redshift Hypothesis
2018
We find that the Fe III$\lambda\lambda$2039-2113 spectral feature in quasars appears systematically redshifted by amounts accountable under the hypothesis of gravitational redshift induced by the central supermassive black hole. Our analysis of 27 composite spectra from the BOSS survey indicates that the redshift and the broadening of the lines in the Fe III$\lambda\lambda$2039-2113 blend roughly follow the expected correlation in the weak limit of Schwarzschild geometry for virialized kinematics. Assuming that the Fe III UV redshift provides a measure of $M_{BH}\over R$ (${\Delta \lambda\over \lambda}\simeq{3\over2}{G\over c^2} {M_{BH}\over R}$) and using different estimates of the emittin…
Size of the accretion disk in the gravitationally lensed quasar SDSS J1004+4112 from the statistics of microlensing magnifications
2016
We present eight monitoring seasons of the four brightest images of the gravitational lens SDSS J1004+4112 observed between December 2003 and October 2010. Using measured time delays for the images A, B and C and the model predicted time delay for image D we have removed the intrinsic quasar variability, finding microlensing events of about 0.5 and 0.7 mag of amplitude in the images C and D. From the statistics of microlensing amplitudes in images A, C, and D, we have inferred the half-light radius (at {\lambda} rest = 2407 {\AA}) for the accretion disk using two different methods, $R_{1/2}=8.7^{+18.5}_{-5.5} \sqrt{M/0.3 M_\odot}$ (histograms product) and $R_{1/2} = 4.2^{+3.2}_{-2.2} \sqrt{…
Microlensing of the broad emission lines in 27 gravitationally lensed quasars. Broad line region structure and kinematics
2021
We thank the anonymous referee for the helpful comments and the constructive remarks on this manuscript. C.F. acknowledges the financial support the Tel Aviv University and University of Haifa through a DFG grant HA3555-14/1. E.M. and J.A.M are supported by the Spanish MINECO with the grants AYA2016- 79104-C3-1-P and AYA2016-79104-C3-3-P. J.A.M. is also supported from the Generalitat Valenciana project of excellence Prometeo/2020/085. J.J.V. is supported by the project AYA2017-84897-P financed by the Spanish Ministerio de Economia y Competividad and by the Fondo Europeo de Desarrollo Regional (FEDER), and by project FQM-108 financed by Junta de Andalucia. V.M. acknowledges partial support f…
Flux and color variations of the quadruply imaged quasar HE 0435-1223
2011
aims: We present VRi photometric observations of the quadruply imaged quasar HE 0435-1223, carried out with the Danish 1.54m telescope at the La Silla Observatory. Our aim was to monitor and study the magnitudes and colors of each lensed component as a function of time. methods: We monitored the object during two seasons (2008 and 2009) in the VRi spectral bands, and reduced the data with two independent techniques: difference imaging and PSF (Point Spread Function) fitting.results: Between these two seasons, our results show an evident decrease in flux by ~0.2-0.4 magnitudes of the four lensed components in the three filters. We also found a significant increase (~0.05-0.015) in their V-R …