Start year
1988
Organizational Unit
Organizing institutions
Related grants:
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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UV surface brightness of galaxies from the local universe to z ~ 5The Tolman test for surface brightness (SB) dimming was originally proposed as a test for the expansion of the universe. The test, which is independent of the details of the assumed cosmology, is based on comparisons of the SB of identical objects at different cosmological distances. Claims have been made that the Tolman test provides compellingLerner, E. J. et al.
Advertised on:
52014 -
The extent of the Mg II absorbing circumgalactic medium of quasarsWe investigate the extent and the properties of the Mg II cool, low-density absorbing gas located in the halo and in the circumgalactic environment of quasars, using a sample of 31 projected quasar pairs with impact parameter pd 200 kpc in the redshift range 0.5 ≲ z ≲ 1.6. In the transverse direction, we detect 18 Mg II absorbers associated withFarina, E. P. et al.
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62014 -
Photometric Decomposition of Mergers in Disk GalaxiesSeveral observational studies and numerical simulations suggest that mergers must contribute to the evolution of galaxies; however, the role that they play is not yet fully understood. In this paper we study a sample of 52 double nucleus disk galaxies that are considered as candidates for a minor merger event. The luminosity of each of the nucleiMezcua, M. et al.
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32014 -
The Average Size and Temperature Profile of Quasar Accretion DisksWe use multi-wavelength microlensing measurements of a sample of 10 image pairs from 8 lensed quasars to study the structure of their accretion disks. By using spectroscopy or narrowband photometry, we have been able to remove contamination from the weakly microlensed broad emission lines, extinction, and any uncertainties in the large-scale macroMediavilla, E. et al.
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32014 -
Long-term Monitoring, Time Delay, and Microlensing in the Gravitational Lens System Q0142-100We present 12 yr of monitoring of the gravitational lens Q0142-100 from the Teide Observatory. The data, taken from 1999 to 2010, comprise 105 observing nights with the IAC80 Telescope. The application of the δ2 method to the dataset leads to a value for the time delay between both components of the system of 72 ± 22 days (68% confidence level)Muñoz, J. A. et al.
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122013 -
Microlensing of Quasar Ultraviolet Iron EmissionWe measure the differential microlensing of the UV Fe II and Fe III emission line blends between 14 quasar image pairs in 13 gravitational lenses. We find that the UV iron emission is strongly microlensed in four cases with amplitudes comparable to that of the continuum. Statistically modeling the magnifications, we infer a typical size of r_s\simGuerras, E. et al.
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122013 -
Reclassification of the nearest quasar pair candidate: SDSS J15244+3032-RXS J15244+3032We present optical spectroscopy of the nearest quasar pair listed in the 13th edition of the Véron-Cetty & Véron catalogue, i.e. the two quasars SDSS J15244+3032 and RXS J15244+3032 (redshift z≈0.27, angular separation Δ θ≈7″, and line-of-sight velocity difference ΔV≈1900 km/s). This system would be an optimal candidate to investigate the mutualFarina, E. P. et al.
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52013 -
Microlensing of Quasar Broad Emission Lines: Constraints on Broad Line Region SizeWe measure the differential microlensing of the broad emission lines between 18 quasar image pairs in 16 gravitational lenses. We find that the broad emission lines are in general weakly microlensed. The results show, at a modest level of confidence (1.8σ), that high ionization lines such as C IV are more strongly microlensed than low ionizationFalco, E. et al.
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22013 -
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.
Advertised on:
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
