A 5.5-year robotic optical monitoring of Q0957+561: substructure in a non-local cD galaxy

Shalyapin, V. N.; Goicoechea, L. J.; Gil-Merino, R.

doi:10.1051/0004-6361/201118316

Cited by 14 publications

(29 citation statements)

References 39 publications

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“…4, we can also clearly see the well-known quasi-constancy of the residuals of the B image between 1996 and 2006. In more recent years, higher variability took place (Hainline et al 2012;Shalyapin et al 2012;Gil-Merino et al 2018) and the new results support the claim of Hainline et al (2012) that a microlensing event occurred during these years. The duration of this microlensing event (starting in 2009 and lasting at least until 2015) is still unclear and further future monitoring to map the full extent of the event will be needed.…”

Section: Intrinsic Variability and Microlensingsupporting

confidence: 81%

Revealing the structure of the lensed quasar Q 0957+561

Fian

Mediavilla

Jiménez-Vicente

et al. 2021

A&A

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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 evaluate the impact of uncertainties on our recently developed method (controlled by the distance between the modeled and the experimental magnitude difference histograms between two lensed images), and thus to test the robustness of microlensing-based disk-size estimates. Methods. We analyzed the well-sampled 21-year GLENDAMA optical light curves of the double-lensed quasar and studied the intrinsic and extrinsic continuum variations. Using accurate measurements for the time delay between the images A and B, we modeled and removed the intrinsic quasar variability, and from the statistics of microlensing magnifications we used a Bayesian method to derive the size of the region emitting the continuum at λrest = 2558 Å. Results. Analysis of the Q 0957+561 R-band light curves show a slow but systematic increase in the brightness of the B relative to the A component during the past ten years. The relatively low strength of the magnitude differences between the images indicates that the quasar has an unusually big optical accretion disk of half-light radius: R1/2 = 17.6±6.1 √(M/0.3 M⊙) lt-days.

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Section: Intrinsic Variability and Microlensingsupporting

confidence: 81%

Revealing the structure of the lensed quasar Q 0957+561

Fian

Mediavilla

Jiménez-Vicente

et al. 2021

A&A

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“…The lens has a measured time delay (e.g. Shalyapin et al 2012). They however also find a three-day lag between the g-and r-bands, a disagreement at the 2σ-level.…”

Section: The Individual Lensesmentioning

confidence: 97%

Light versus dark in strong-lens galaxies: dark matter haloes that are rounder than their stars

Bruderer

Read

Coles

et al. 2015

Mon. Not. R. Astron. Soc.

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We measure the projected density profile, shape and alignment of the stellar and dark matter mass distribution in 11 strong-lens galaxies. We find that the projected dark matter density profile -under the assumption of a Chabrier stellar initial mass function -shows significant variation from galaxy to galaxy. Those with an outermost image beyond ∼ 10 kpc are very well fit by a projected NFW profile; those with images within 10 kpc appear to be more concentrated than NFW, as expected if their dark haloes contract due to baryonic cooling. We find that over several half-light radii, the dark matter haloes of these lenses are rounder than their stellar mass distributions. While the haloes are never more elliptical than e dm = 0.2, their stars can extend to e * > 0.2. Galaxies with high dark matter ellipticity and weak external shear show strong alignment between light and dark; those with strong shear (γ 0.1) can be highly misaligned. This is reassuring since isolated misaligned galaxies are expected to be unstable. Our results provide a new constraint on galaxy formation models. For a given cosmology, these must explain the origin of both very round dark matter haloes and misaligned strong-lens systems.

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“…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).…”

Section: Data Collection: Light Curvesmentioning

confidence: 99%

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

Belete

Martins

Leão

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Knowledge about how the nonlinear behaviour of the intrinsic signal from lensed background sources changes on its path to the observer provides much information, particularly about the matter distribution in lensing galaxies and the physical properties of the current universe, in general. Here, we analyse the multifractal (nonlinear) behaviour of the optical observations of A and B images of Q0957+561 in the r and g bands. AIMS: To verify the presence, or absence, of extrinsic variations in the observed signals of the quasar images and investigate whether extrinsic variations affect the multifractal behaviour of their intrinsic signals. METHOD: We apply a wavelet transform modulus maxima-based multifractality analysis approach. RESULTS: We detect strong multifractal (nonlinear) signatures in the light curves of the quasar images. The degree of multifractality for both images in the r band changes over time in a non-monotonic way, possibly indicating the presence of extrinsic variabilities in the light curves of the images, i.e., the signals of the quasar images are a combination of both intrinsic and extrinsic signals. Additionally, in the r band, in periods of quiescent microlensing activity, we find that the degree of multifractality (nonlinearity) of image A is stronger than that of B, while B has a larger multifractal strength in recent epochs (from day 5564 to day 7527) when it appears to be affected by microlensing. Finally, comparing the optical bands in a period of quiescent microlensing activity, we find that the degree of multifractality is stronger in the r band for both quasar images. In the absence of microlensing, the observed excesses of nonlinearity are most likely generated when the broad-line region (BLR) reprocesses the radiation from the compact sources.

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A 5.5-year robotic optical monitoring of Q0957+561: substructure in a non-local cD galaxy

Cited by 14 publications

References 39 publications

Revealing the structure of the lensed quasar Q 0957+561

Revealing the structure of the lensed quasar Q 0957+561

Light versus dark in strong-lens galaxies: dark matter haloes that are rounder than their stars

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

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