New database for a sample of optically bright lensed quasars in the northern hemisphere

Abstract

In the framework of the Gravitational LENses and DArk MAtter (GLENDAMA) project, we present a database of nine gravitationally lensed quasars (GLQs) that have two or four images brighter than r = 20 mag and are located in the northern hemisphere. This new database consists of a rich variety of follow-up observations included in the GLENDAMA global archive, which is publicly available online and contains 6557 processed astronomical frames of the nine lens systems over the period 1999−2016. In addition to the GLQs, our archive also incorporates binary quasars, accretion-dominated radio-loud quasars, and other objects, where about 50% of the non-GLQs were observed as part of a campaign to identify GLQ candidates. Most observations of GLQs correspond to an ongoing long-term macro-programme with 2−10 m telescopes at the Roque de los Muchachos Observatory, and these data provide information on the distribution of dark matter at all scales. We outline some previous results from the database, and we additionally obtain new results for several GLQs that update the potential of the tool for astrophysical studies.

Revealing the non-linear behaviour of the lensed quasar Q0957+561

“…where J y stands for Jansky. For more information about the light curves used in this study, refer to Gil-Merino et al (2018), Shalyapin et al (2012), and Goicoechea et al (2008).…”

“…Though quasars, in general, are known by their extremely high luminosities, gravitationally lensed quasars (hereinafter GLQs) are brighter than their unlensed counterparts and produce different image components Agnello et al (2015). Study of GLQs provides significant information, mainly about background source quasar variability mechanisms and accretion disk structure (Jiménez-Vicente et al 2015;Pooley et al 2007), the mass distribution in lensing galaxies (Bate et al 2008) and, in general, information to constrain physical properties of the Universe (Gil-Merino et al 2018;Kostrzewa-Rutkowska et al 2018). It has been understood that the time delay caused by gravitational lensing is directly related to the current expansion rate of the Universe (the Hubble constant) and the mean surface mass density of E-mail: asnakew@fisica.ufrn.br the lensing galaxy (e.g., Kochanek & Schechter 2004;Refsdal 1964).…”

“…Though Shalyapin et al (2012) considered a dense cloud within the cD lensing galaxy along the line of sight to the image A as a possible cause for a 3 d lag between optical bands, this lag relies on standard cross-correlation techniques that could lead to biased results, so the true time delay ∆t B A is most likely achromatic (Gil-Merino et al 2018). Even though no microlensing effects have been detected in the light curves of the lensed quasar Q0957+561 over several decades, strong evidence for extrinsic variability was found in the initial and last years of monitoring, as reported in Pelt et al (1998) and Gil-Merino et al (2018). Here, we study the multifractal (nonlinear) behaviour of the optical observations of the lensed quasar Q0957+561 in the r and g bands separately.…”

Gravitational Lens System PS J0147+4630 (Andromeda’s Parachute): Main Lensing Galaxy and Optical Variability of the Quasar Images

“…The difference light curves for C and D include ∼0.1 mag fluctuations over timescales from 100 to 400 days. Some other quads show similar levels of microlensing activity (e.g., Fian et al 2018;Gil-Merino et al 2018). We remark that microlensing signals in the D image rely on time delays ∆t AD predicted by the Shajib et al's mass model and plausible values of H 0 .…”

Gravitationally Lensed Quasar SDSS J1442+4055: Redshifts of Lensing Galaxies, Time Delay, Microlensing Variability, and Intervening Metal System at z ∼ 2

“…This paper is dedicated to describe and deeply analyse follow-up observations of SDSS J1442+4055. In the framework of the Gravitational LENses and DArk MAtter (GLENDAMA) project (Gil-Merino et al 2018), in Section 2, we present a 2.7-year photometric monitoring with the 2.0 m Liverpool Telescope (LT) in the r band and associated light curves for both quasar images, as well as spectroscopic observations with the 10.4 m Gran Telescopio Canarias (GTC) and the LT. The high signal-to-noise ratio (SNR) spectroscopy over a wide wavelength interval with the GTC allows us to accurately identify the primary lensing galaxy G1, while we use the LT spectroscopic data of two bright secondary galaxies (G2 and another object in the field around the quasar) to measure their redshifts.…”