General
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
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
-
First black hole mass estimation for the quadruple lensed system WGD2038-4008
Context. The quadruple lensed system WGD2038-4008 (zs = 0.777 ± 0.001) has recently been discovered with the help of new techniques and observations. Black hole masses have been estimated for lensed quasars, but they have mostly been calculated for one broad emission line of one image. However, the images could be affected by microlensing, which
Melo, A. et al.Advertised on:
122021Bibcode -
Revealing the structure of the lensed quasar Q 0957+561. I. Accretion disk size
Aims: We aim to use signatures of microlensing induced by stars in the foreground lens galaxy to infer the size of the accretion disk in the gravitationally lensed quasar Q 0957+561. The long-term photometric monitoring of this system (which so far has provided the longest available light curves of a gravitational lens system) permits us to
Fian, C. et al.Advertised on:
102021Bibcode -
Microlensing of the broad emission lines in 27 gravitationally lensed quasars. Broad line region structure and kinematics
Aims: We aim to study the structure and kinematics of the broad line region (BLR) of a sample of 27 gravitationally lensed quasars with up to five different epochs of observation. This sample is composed of ∼100 spectra from the literature plus 22 unpublished spectra of 11 systems. Methods: We measure the magnitude differences in the broad emission
Fian, C. et al.Advertised on:
92021Bibcode -
Testing Einsteins Equivalence Principle and Its Cosmological Evolution from Quasar Gravitational Redshifts
We propose and apply a new test of Einsteins equivalence principle (EEP) based on the gravitational redshift induced by the central supermassive black hole of quasars in the surrounding accretion disk. Specifically, we compare the observed gravitational redshift of the Fe III 2039-2113 emission line blend in quasars with the predicted values in a
Mediavilla, E. et al.Advertised on:
62021Bibcode -
The spectra of IceCube neutrino candidate sources - I. Optical spectroscopy of blazars
There is mounting evidence that ultra-energetic neutrinos of astrophysical origin may be associated with blazars. Here, we investigate a unique sample of 47 blazars, ∼20 of which could be new neutrino sources. In particular, we focus on 17 objects of yet unknown redshift, for which we present optical spectroscopy secured at the Gran Telescopio
Paiano, Simona et al.Advertised on:
72021Bibcode -
Low-redshift quasars in the SDSS Stripe 82 - II. Associated companion galaxies and signature of star formation
We present optical spectroscopy of the close companions of 22 low-redshift (z < 0.5) quasars (QSO) selected from a larger sample of QSO in the SDSS Stripe82 region for which both the host galaxy and the large-scale environments have been investigated in our previous work. The new observations extend the number of QSO studied in our previous paper
Stone, M. B. et al.Advertised on:
22021Bibcode -
The Impact of the Mass Spectrum of Lenses in Quasar Microlensing Studies. Constraints on a Mixed Population of Primordial Black Holes and Stars
We show that quasar microlensing magnification statistics induced by a population of point microlenses distributed according to a mass spectrum can be very well approximated by that of a single-mass, monochromatic, population. When the spatial resolution (physically defined by the source size) is small compared with the Einstein radius, the mass of
Esteban-Gutiérrez, A. et al.Advertised on:
122020Bibcode -
The circum-galactic medium of quasars: transverse and line-of-sight absorptions
Quasar projected pairs (QPPs) can be used for investigating the circumgalactic medium of quasars through the study of intervening absorption lines in the spectrum of the background quasar (QSOB) that are at the same redshift of the foreground quasar (QSOF). Here we report on optical spectroscopy, gathered at Gran Telescopio Canarias, of 14 QPPs. In
Sandrinelli, A. et al.Advertised on:
112020Bibcode -
Optical spectroscopy of BL Lac objects: TeV candidates
We investigate the spectroscopic optical properties of gamma-ray sources detected with high significance above 50 GeV in the Third Catalog of Hard Fermi-LAT Sources and that are good candidates as TeV emitters. We focus on the 91 sources that are labelled by the Fermi team as BL Lac (BLL) objects or blazar candidates of uncertain type (BCUs), are
Paiano, Simona et al.Advertised on:
62020Bibcode -
A Second-order Moment of Microlensing Variability as a Novel Tool to Constrain Source Emission Size or Discrete Lens Demographics in Extragalactic Research
We define a second-order moment of the observational differential microlensing curves that can be used to impose constraints on physical properties of lensed quasars. We show that this quantity is sensitive both to variations in the source size and the deflector mass. We formulize a methodology to recover the source size from the observational
Guerras, Eduardo et al.Advertised on:
62020Bibcode -
Individual Estimates of the Virial Factor in 10 Quasars: Implications on the Kinematics of the Broad-line Region
Assuming a gravitational origin for the Fe iiiλλ2039-2113 redshift and using microlensing based estimates of the size of the region emitting this feature, we obtain individual measurements of the virial factor, f, in 10 quasars. The average values for the Balmer lines, $\langle {f}_{{\rm{H}}\beta }\rangle =0.43\pm 0.20$ and $\langle {f}_{{\rm{H}}
Mediavilla, E. et al.Advertised on:
62020Bibcode -
Visible and near-infrared observations of interstellar comet 2I/Borisov with the 10.4-m GTC and the 3.6-m TNG telescopes
In this work, we present the results of an observational study of 2I/Borisov carried out with the 10.4-m Gran Telescopio Canarias (GTC) and the 3.6-m Telescopio Nazionale Galileo (TNG), both telescopes located at the Roque de Los Muchachos Observatory, in the island of La Palma (Spain). The study includes images in the visible and near-infrared, as
de León, J. et al.Advertised on:
42020Bibcode -
Microlensing Analysis for the Gravitational Lens Systems SDSS0924+0219, Q1355-2257, and SDSS1029+2623
We use spectroscopic observations of the gravitationally lensed systems SDSS0924+0219(BC), Q1355-2257(AB), and SDSS1029+2623(BC) to analyze microlensing and dust extinction in the observed components. We detect chromatic microlensing effects in the continuum and microlensing in the broad emission line profiles of the systems SDSS0924+0219(BC) and
Rojas, K. et al.Advertised on:
22020Bibcode -
Spectroscopy and polarimetry of the gravitationally lensed quasar SDSS J1004+4112 with the 6m SAO RAS telescope
Context. We present new spectroscopic and polarimetric observations of the gravitational lens SDSS J1004+4112 taken with the 6 m telescope of the Special Astrophysical Observatory (Russia). Aims: In order to explain the variability that is observed only in the blue wing of the C IV emission line, corresponding to image A, we analyze the
Popović, L. Č. et al.Advertised on:
22020Bibcode -
The Initial Mass Function of Lens Galaxies from Quasar Microlensing
We present a new approach to studying the initial mass function (IMF) in external galaxies based on quasar microlensing observations. We use measurements of quasar microlensing magnifications in 24 lensed quasars to estimate the average mass of the stellar population in the lens galaxies without any a priori assumption on the shape of the IMF. The
Jiménez-Vicente, J. et al.Advertised on:
112019Bibcode -
Challenging a Newtonian prediction through Gaia wide binaries
Under Newtonian dynamics, the relative motion of the components of a binary star should follow a Keplerian scaling with separation. Once orientation effects and a distribution of ellipticities are accounted for, dynamical evolution can be modeled to include the effects of Galactic tides and stellar mass perturbers, over the lifetime of the solar
Hernandez, X. et al.Advertised on:
02019Bibcode -
Measuring Supermassive Black Hole Masses: Correlation between the Redshifts of the Fe III UV Lines and the Widths of Broad Emission Lines
We test the recently proposed black hole mass scaling relationship based on the redshift with respect to the quasar's rest frame of the Fe III λλ2039-2113 line blend. To this end, we fit this feature in the spectra of a well suited sample of quasars, observed with X-shooter at the Very Large Telescope, whose masses have been independently estimated
Mediavilla, E. et al.Advertised on:
82019Bibcode -
A New Einstein Cross Gravitational Lens of a Lyman-break Galaxy
We report the study of an “Einstein Cross” configuration first identified in a set of HST images by Cerny et al. Deep spectroscopic observations obtained at the Spanish 10.4 m Gran Telescopio Canarias telescope, allowed us to demonstrate the lens nature of the system, that consists of a Lyman-break galaxy (LBG), not a quasi-stellar object as is
Bettoni, D. et al.Advertised on:
32019Bibcode -
Optical Spectroscopic Survey of a Sample of Unidentified Fermi Objects: II
We report on optical spectroscopy obtained at the 10.4 m Gran Telescopio Canarias of 28 Fermi γ-ray sources that completes the study of a sample of 60 targets of unidentified objects for which the detection of an X-ray and/or radio source inside the 3FGL error box is available. The observations aim to characterize the nature and measure the
Paiano, Simona et al.Advertised on:
22019Bibcode -
Estimate of the Accretion Disk Size in the Gravitationally Lensed Quasar HE 0435–1223 Using Microlensing Magnification Statistics
We present a measurement of the accretion disk size of the quadruple lensed quasar HE 0435–1223 from well-sampled 13-year COSMOGRAIL optical light curves. Using accurate time delays for the images A, B, C, and D, we modeled and removed the intrinsic quasar variability, and found microlensing events of amplitude up to 0.6, 0.4, and 0.5 mag in the
Fian, C. et al.Advertised on:
122018Bibcode
Related talks
No related talks were found.Related conferences
No related conferences were found.News
-
ESPRESSO puts the physical constants to the testAdvertised on