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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Spectroscopy of 10 γ-Ray BL Lac Objects at High RedshiftWe present optical spectra with high signal-to-noise ratio of 10 BL Lac objects detected at GeV energies by the Fermi satellite (3FGL catalog), which previous observations suggested are at relatively high redshift. The new observations, obtained at the 10 m Gran Telescopio Canarias, allowed us to find the redshift for J0814.5+2943 (z = 0.703), andPaiano, S. et al.
Advertised on:
82017 -
On the lensed blazar B0218+357We present an optical spectrum (λλ4000-10 500) of the lensed blazar B0218+357 secured at the 10 m GTC and aimed to investigate and clarify the properties of this intriguing system. We found that the emission line spectrum of the blazar is characterized by only one broad emission line that interpreted as Mg ii 2800 Å yields z = 0.95. In addition, weFalomo, R. et al.
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92017 -
On the Redshift of TeV BL Lac ObjectsWe report results of a spectroscopic campaign carried out at the 10 m Gran Telescopio Canarias for a sample of 22 BL Lac objects detected (or candidates) at TeV energies, aiming to determine or constrain their redshift. This is of fundamental importance for the interpretation of their emission models and for population studies and is also mandatoryPaiano, S. et al.
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32017 -
Limits on the Mass and Abundance of Primordial Black Holes from Quasar Gravitational MicrolensingThe idea that dark matter can be made of intermediate-mass primordial black holes (PBHs) in the 10 M ⊙ ≲ M ≲ 200 M ⊙ range has recently been reconsidered, particularly in the light of the detection of gravitational waves by the LIGO experiment. The existence of even a small fraction of dark matter in black holes should nevertheless result inMediavilla, E. et al.
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22017 -
Probing the Broad-line Region and the Accretion Disk in the Lensed Quasars HE 0435-1223, WFI 2033-4723, and HE 2149-2745 Using Gravitational MicrolensingWe use single-epoch spectroscopy of three gravitationally lensed quasars, HE 0435-1223, WFI 2033-4723, and HE 2149-2745, to study their inner structure (broad-line region [BLR] and continuum source). We detect microlensing-induced magnification in the wings of the broad emission lines of two of the systems (HE 0435-1223 and WFI 2033-4723). In theMotta, V. et al.
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22017 -
MONDian dynamical modelling of NGC 288 with β ≠ 0NGC 288 is a diffuse Galactic globular cluster; it is remarkable in that its low density results in internal accelerations being below the critical MOND a0 acceleration throughout. This makes it an ideal testing ground for MONDian gravity, as the details of the largely unknown transition function between the Newtonian and modified regimes becomeHernandez, X. et al.
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12017 -
What Is the Redshift of the Gamma-ray BL Lac Source S4 0954+65?High signal-to-noise ratio spectroscopic observations of the BL Lac object S4 0954+65 at the alleged redshift z = 0.367 are presented. This source was detected at gamma frequencies by the MAGIC (TeV) and FERMI (GeV) telescopes during a remarkable outburst that occurred in 2015 February, making the determination of its distance particularly relevantLandoni, M. et al.
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122015 -
Resolving the Innermost Region of the Accretion Disk of the Lensed Quasar Q2237+0305 through Gravitational MicrolensingWe study three high magnification microlensing events, generally recognized as probable caustic crossings, in the optical light curves of the multiply imaged quasar Q2237+0305. We model the light curve of each event as the convolution of a standard thin disk luminosity profile with a straight fold caustic. We also allow for a linear gradient thatMediavilla, E. et al.
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122015 -
Probing the Dark Matter Radial Profile in Lens Galaxies and the Size of X-Ray Emitting Region in Quasars with MicrolensingWe use X-ray and optical microlensing measurements to study the shape of the dark matter density profile in the lens galaxies and the size of the (soft) X-ray emission region. We show that single epoch X-ray microlensing is sensitive to the source size. Our results, in good agreement with previous estimates, show that the size of the X-ray emissionJiménez-Vicente, J. et al.
Advertised on:
62015 -
Dark Matter Mass Fraction in Lens Galaxies: New Estimates from MicrolensingWe present a joint estimate of the stellar/dark matter mass fraction in lens galaxies and the average size of the accretion disk of lensed quasars based on microlensing measurements of 27 quasar image pairs seen through 19 lens galaxies. The Bayesian estimate for the fraction of the surface mass density in the form of stars is α = 0.21 ± 0.14 nearJiménez-Vicente, J. et al.
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22015 -
Statistics of Microlensing Caustic Crossings in Q 2237+0305: Peculiar Velocity of the Lens Galaxy and Accretion Disk SizeWe use the statistics of caustic crossings induced by microlensing in the lens system Q 2237+0305 to study the lens galaxy peculiar velocity. We calculate the caustic crossing rates for a comprehensive family of stellar mass functions and find a dependence of the average number of caustic crossings with the effective transverse velocity and theMediavilla, E. et al.
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12015 -
Strong Chromatic Microlensing in HE0047–1756 and SDSS1155+6346We use spectra of the double-lensed quasars HE0047–1756 and SDSS1155+6346 to study their unresolved structure through the impact of microlensing. There is no significant evidence of microlensing in the emission line profiles except for the Lyα line of SDSS1155+6346, which shows strong differences in the shapes for images A and B. However, theRojas, K. et al.
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122014 -
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.
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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
