Astrophysical Applications of Gravitational Micro-Lensing

Kayser, R.; Refsdal, S.; Stabell, R.; Grieger, B.

doi:10.1007/978-94-009-3853-3_91

Cited by 235 publications

(335 citation statements)

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“…We model the light curve using inverse ray shooting (Kayser et al 1986;Schneider & Weiss 1988;Wambsganss 1997) when the source is close to a caustic, and multipole approximations (Pejcha & Heyrovský 2009;Gould 2008) otherwise. We initially consider an (s, q, α) grid of starting points for Markov Chain Monte Carlo (MCMC) searches, with the remaining parameters starting at values consistent with a point-lens model.…”

Section: Ground-based Modelmentioning

confidence: 99%

OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

Ryu¹,

Yee²,

Udalski³

et al. 2017

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We report the discovery of OGLE-2016-BLG-1190Lb, which is likely to be the first Spitzer microlensing planet in the Galactic bulge/bar, an assignation that can be confirmed by two epochs of high-resolution imaging of the combined source-lens baseline object. The planet's mass, M p =13.4±0.9 M J , places it right at the deuteriumburning limit, i.e., the conventional boundary between "planets" and "brown dwarfs." Its existence raises the question of whether such objects are really "planets" (formed within the disks of their hosts) or "failed stars" (lowmass objects formed by gas fragmentation). This question may ultimately be addressed by comparing disk and bulge/bar planets, which is a goal of the Spitzer microlens program. The host is a G dwarf, M host =0.89±0.07 M e , and the planet has a semimajor axis a∼2.0 au. We use Kepler K2 Campaign 9 microlensing data to break the lens-mass degeneracy that generically impacts parallax solutions from Earth-Spitzer observations alone, which is the first successful application of this approach. The microlensing data, derived primarily from near-continuous, ultradense survey observations from OGLE, MOA, and three KMTNet telescopes, contain more orbital information than for any previous microlensing planet, but not quite enough to accurately specify the full orbit. However, these data do permit the first rigorous test of microlensing orbital-motion measurements, which are typically derived from data taken over <1% of an orbital period.

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Section: Ground-based Modelmentioning

confidence: 99%

OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

Ryu¹,

Yee²,

Udalski³

et al. 2017

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“…Magnification bias is calculated based on the magnification of the first light-curve point (the sum of magnifications for a multiply imaged source). The effective transverse source plane velocity was computed from the two transverse velocity components for each of the source, lens, and observer (Kayser, Refsdal, & Stabell 1986). We assume each component to be Gaussian-distributed with a dispersion of 400 km s À1 .…”

Section: Quasar Flux Variability Due To Microlensingmentioning

confidence: 99%

Gravitational Lensing of the Sloan Digital Sky Survey High‐Redshift Quasars

Wyithe

Loeb

2002

ApJ

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We predict the effects of gravitational lensing on the color-selected flux-limited samples of z s $ 4:3 and z s e5:8 quasars, recently published by the Sloan Digital Sky Survey (SDSS). Our main findings are the following: (1) The lensing probability should be 1-2 orders of magnitude higher than for conventional surveys. The expected fraction of multiply imaged quasars is highly sensitive to redshift and the uncertain slope of the bright end of the luminosity function, h . For h ¼ 2:58 (3.43) we find that at z s $ 4:3 and i Ã < 20:0 the fraction is $4% (13%), while at z s $ 6 and z Ã < 20:2 the fraction is $7% (30%). (2) The distribution of magnifications is heavily skewed; sources having the redshift and luminosity of the SDSS z s e5:8 quasars acquire median magnifications of medðl obs Þ $ 1:1 1:3 and mean magnifications of hl obs i $ 5 50. Estimates of the quasar luminosity density at high redshift must therefore filter out gravitationally lensed sources. (3) The flux in the Gunn-Peterson trough of the highest redshift (z s ¼ 6:28) quasar is known to be f < 3 Â 10 À19 ergs s À1 cm À2 Å À1 . Should this quasar be multiply imaged, we estimate a 40% chance that light from the lens galaxy would have contaminated the same part of the quasar spectrum with a higher flux. Hence, spectroscopic studies of the epoch of reionization need to account for the possibility that a lens galaxy, which boosts the quasar flux, also contaminates the Gunn-Peterson trough. (4) Microlensing by stars should result in $ 1 3 of multiply imaged quasars in the z s e5:8 catalog varying by more than 0.5 mag over the next decade. The median emission-line equivalent width of multiply imaged quasars would be lowered by $20% with respect to the intrinsic value because of differential magnification of the continuum and emission-line regions.

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“…Soon after the discovery of the first gravitationally lensed quasar, it has been realised that microlensing (ML) produced by compact objects in the lensing galaxy towards a multiply imaged quasar could be used as an astrophysical tool to probe the inner parsecs of distant quasars (Chang & Refsdal 1979;Kayser et al 1986;Paczynski 1986;Grieger et al 1988). Microlenses typically magnify regions of the source on scales similar to or smaller than a few micro-arcsecs, the size of their angular Einstein radius R E (Wambsganss 1998(Wambsganss , 2006Schmidt & Wambsganss 2010).…”

Section: Introductionmentioning

confidence: 99%

Microlensing of the broad line region in 17 lensed quasars

Sluse

Hutsemékers

Courbin

et al. 2012

A&A

137

184

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When an image of a strongly lensed quasar is microlensed, the different components of its spectrum are expected to be differentially magnified owing to the different sizes of the corresponding emitting region. Chromatic changes are expected to be observed in the continuum while the emission lines should be deformed as a function of the size, geometry and kinematics of the regions from which they originate. Microlensing of the emission lines has been reported only in a handful of systems so far. In this paper we search for microlensing deformations of the optical spectra of pairs of images in 17 lensed quasars with bolometric luminosities between 10 44.7−47.4 erg/s and black hole masses 10 7.6−9.8 M . This sample is composed of 13 pairs of previously unpublished spectra and four pairs of spectra from literature. Our analysis is based on a simple spectral decomposition technique which allows us to isolate the microlensed fraction of the flux independently of a detailed modeling of the quasar emission lines. Using this technique, we detect microlensing of the continuum in 85% of the systems. Among them, 80% show microlensing of the broad emission lines. Focusing on the most common emission lines in our spectra (C iii] and Mg ii) we detect microlensing of either the blue or the red wing, or of both wings with the same amplitude. This observation implies that the broad line region is not in general spherically symmetric. In addition, the frequent detection of microlensing of the blue and red wings independently but not simultaneously with a different amplitude, does not support existing microlensing simulations of a biconical outflow. Our analysis also provides the intrinsic flux ratio between the lensed images and the magnitude of the microlensing affecting the continuum. These two quantities are particularly relevant for the determination of the fraction of matter in clumpy form in galaxies and for the detection of dark matter substructures via the identification of flux ratio anomalies.

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Astrophysical Applications of Gravitational Micro-Lensing

Cited by 235 publications

References 1 publication

OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

Gravitational Lensing of the Sloan Digital Sky Survey High‐Redshift Quasars

Microlensing of the broad line region in 17 lensed quasars

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