Start year
1988
Organizational Unit
Organizing institutions
Grants related:
General
Description
Introduction
Gravitational lenses are a powerful tool for Astrophysics and Cosmology. The goals of this project are: i) to obtain a robust determination of the Hubble constant from the time delay measured between the images of a lensed quasar; ii) to study the individual and statistical properties of dark matter condensations in lens galaxies from microlensing on the images of lensed quasars; iii) to study the unresolved structure of quasars (broad and narrow emission line and continuum emission regions) from induced variations by microlensing in the photometry of the lensed quasar images as well as in the profile of their emission lines; iv) to study the variation of dust extinction properties with redshift from the determination of extinction curves in lens galaxies; (v) to develop new numerical and statistical methods to study microlensing and (vi) to detect exoplanets through gravitational microlensing.
Members
Principal investigator
Evencio
Mediavilla Gradolph
Project staff
Miquel
Serra Ricart
Alejandro
Oscoz Abad
Dr.
E. Falco
Dr.
L. Popovic
Dr.
R. Gil-Merino
Dr.
C.S. Kochanek
Dr.
V. Motta
Dr.
P. Gómez
Dr.
T. Mediavilla
Dr.
O. Ariza
Dr.
C. González-Morcillo
Dr.
J. Jiménez
Dr.
Ricardo Scarpa
Results
- We have introduced a new method to measure the masses of the supermassive black holes of the quasars based on the gravitational redshift of the ultraviolet lines of the iron (UV Fe III). The calculated masses are in agreement with the estimates obtained using the virial theorem.
Scientific activity
Related publications
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The quasar MBH-Mhost relation through cosmic time - II. Evidence for evolution from z = 3 to the present ageWe study the dependence of the relation on the redshift up to z = 3 for a sample of 96 quasars, the host galaxy luminosities of which are known. Black hole masses were estimated assuming virial equilibrium in the broad-line regions, while the host galaxy masses were inferred from their luminosities. With these data, we are able to pin down theDecarli, R. et al.
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32010 -
The quasar MBH-Mhost relation through cosmic time - I. Data set and black hole massesWe study the relation as a function of cosmic time in a sample of 96 quasars from z = 3 to the present epoch. In this paper, we describe the sample, the data sources and the new spectroscopic observations. We then illustrate how we derive from single-epoch spectra, pointing out the uncertainties in the procedure. In a companion paper, we addressDecarli, R. et al.
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32010 -
Testing Newtonian gravity in the low acceleration regime with globular clusters: the case of ω Centauri revisitedContext. Stellar kinematics in the external regions of globular clusters can be used to probe the validity of Newton's law in the low acceleration regimes without the complication of non-baryonic dark matter. Indeed, in contrast to the case of galaxies, in globular clusters a systematic deviation of the velocity dispersion profile from the expectedScarpa, R. et al.
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112010 -
RXJ 0921+4529: A Binary Quasar or a Gravitational Lens?We report the new spectroscopic observations of the gravitational lens RXJ 021+4529 with the multi-mode focal reducer SCORPIO of the SAO RAS 6 m telescope. The new spectral observations were compared with the previously observed spectra of components A and B of RXJ 0921+4529, i.e., the same components observed in different epochs. We found aPopović, L. Č. et al.
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102010 -
New Developments on Inverse Polygon Mapping to Calculate Gravitational Lensing Magnification Maps: Optimized ComputationsWe derive an exact solution (in the form of a series expansion) to compute gravitational lensing magnification maps. It is based on the backward gravitational lens mapping of a partition of the image plane in polygonal cells (inverse polygon mapping, IPM), not including critical points (except perhaps at the cell boundaries). The zeroth-order termMediavilla, E. et al.
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112011 -
Measuring Microlensing Using Spectra of Multiply Lensed QuasarsWe 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 theMotta, V. et al.
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82012 -
Detection of Chromatic Microlensing in Q 2237 + 0305 AWe present narrowband images of the gravitational lens system Q 2237 + 0305 made with the Nordic Optical Telescope in eight different filters covering the wavelength interval 3510-8130 Å. Using point-spread function photometry fitting we have derived the difference in magnitude versus wavelength between the four images of Q 2237 + 0305. At λ = 4110Mosquera, A. M. et al.
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22009 -
Contribution of a disc component to single-peaked broad lines of active galactic nucleiWe study the disc emission component hidden in the single-peaked broad emission lines (BELs) of active galactic nuclei. We compare the observed broad lines from a sample of 90 Seyfert 1 spectra taken from the Sloan Digital Sky Survey with simulated line profiles. We consider a two-component broad line region model where an accretion disc and aBon, E. et al.
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122009 -
A Study of Gravitational Lens Chromaticity with the Hubble Space TelescopeWe report Hubble Space Telescope observations of six gravitational lenses with the Advanced Camera for Surveys. We measured the flux ratios between the lensed images in seven filters from 8140 Å to 2200 Å. In three of the systems, HE0512-3329, B1600+434, and H1413+117, we were able to construct UV extinction curves partially overlapping the 2175 ÅMuñoz, J. A. et al.
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122011 -
A Study of Gravitational Lens Chromaticity Using Ground-based Narrowband PhotometryWe present observations of wavelength-dependent flux ratios for four gravitational lens systems (SDSS J1650+4251, HE 0435-1223, FBQ 0951+2635, and Q 0142-100) obtained with the Nordic Optical Telescope. The use of narrowband photometry, as well as the excellent seeing conditions during the observations, allows us to study their chromatic behaviorMosquera, A. M. et al.
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22011 -
A Robust Determination of the Size of Quasar Accretion Disks Using Gravitational MicrolensingUsing microlensing measurements for a sample of 27 image pairs of 19 lensed quasars we determine a maximum likelihood estimate for the accretion disk size of an average quasar of rs = 4.0+2.4 - 3.1 lt-day at rest frame langλrang = 1736 Å for microlenses with a mean mass of langMrang = 0.3 M &sun;. This value, in good agreement with previous resultsJiménez-Vicente, J. et al.
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62012 -
Microlensing-based Estimate of the Mass Fraction in Compact Objects in Lens GalaxiesWe estimate the fraction of mass that is composed of compact objects in gravitational lens galaxies. This study is based on microlensing measurements (obtained from the literature) of a sample of 29 quasar image pairs seen through 20 lens galaxies. We determine the baseline for no microlensing magnification between two images from the ratios ofMediavilla, E. et al.
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122009 -
The Structure of the Accretion Disk in the Lensed Quasar SBS 0909+532We 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 fluxMediavilla, E. et al.
Advertised on:
32011
