scholarly journals Gravitational Lensing of Supernova Neutrino Bursts

Universe ◽  
2021 ◽  
Vol 7 (9) ◽  
pp. 335
Author(s):  
John M. LoSecco
Keyword(s):  
Gravitational Lensing ◽  
Gravitational Lens ◽  
Supernova Neutrino

Supernova neutrino bursts have been observed from extragalactic distances. This note addresses the question of how gravitational lensing could distort the information in the burst. We apply the gravitational lens hypothesis to try to understand the time and brightness structure of the SN1987A neutrino observations. Estimates of a possible lensing mass and alignment are made. These estimates suggest a path to verification.

scholarly journals Quantifying the structure of strong gravitational lens potentials with uncertainty-aware deep neural networks

2020 ◽  
Vol 499 (4) ◽  
pp. 5641-5652
Author(s):  
Georgios Vernardos ◽  
Grigorios Tsagkatakis ◽  
Yannis Pantazis
Keyword(s):  
Confidence Intervals ◽  
Galaxy Evolution ◽  
Gravitational Lensing ◽  
Probability Distributions ◽  
Mass Density ◽  
Ground Truth ◽  
Gaussian Random Fields ◽  
Training Data ◽  
Gravitational Lens ◽  
Data Set

ABSTRACT Gravitational lensing is a powerful tool for constraining substructure in the mass distribution of galaxies, be it from the presence of dark matter sub-haloes or due to physical mechanisms affecting the baryons throughout galaxy evolution. Such substructure is hard to model and is either ignored by traditional, smooth modelling, approaches, or treated as well-localized massive perturbers. In this work, we propose a deep learning approach to quantify the statistical properties of such perturbations directly from images, where only the extended lensed source features within a mask are considered, without the need of any lens modelling. Our training data consist of mock lensed images assuming perturbing Gaussian Random Fields permeating the smooth overall lens potential, and, for the first time, using images of real galaxies as the lensed source. We employ a novel deep neural network that can handle arbitrary uncertainty intervals associated with the training data set labels as input, provides probability distributions as output, and adopts a composite loss function. The method succeeds not only in accurately estimating the actual parameter values, but also reduces the predicted confidence intervals by 10 per cent in an unsupervised manner, i.e. without having access to the actual ground truth values. Our results are invariant to the inherent degeneracy between mass perturbations in the lens and complex brightness profiles for the source. Hence, we can quantitatively and robustly quantify the smoothness of the mass density of thousands of lenses, including confidence intervals, and provide a consistent ranking for follow-up science.

scholarly journals When Darwin Met Einstein: Gravitational Lens Inversion with Genetic Algorithms

2005 ◽  
Vol 22 (2) ◽  
pp. 128-135 ◽  
Author(s):  
Brendon J. Brewer ◽  
Geraint F. Lewis
Keyword(s):  
Genetic Algorithms ◽  
Gravitational Lensing ◽  
Surface Brightness ◽  
Initial Study ◽  
Brightness Distribution ◽  
Gravitational Lens ◽  
Atmospheric Effects ◽  
Lens Model ◽  
New Approach ◽  
Genetic Algorithm Approach

AbstractGravitational lensing can magnify a distant source, revealing structural detail which is normally unresolvable. Recovering this detail through an inversion of the influence of gravitational lensing, however, requires optimisation of not only lens parameters, but also of the surface brightness distribution of the source. This paper outlines a new approach to this inversion, utilising genetic algorithms to reconstruct the source profile. In this initial study, the effects of image degradation due to instrumental and atmospheric effects are neglected and it is assumed that the lens model is accurately known, but the genetic algorithm approach can be incorporated into more general optimisation techniques, allowing the optimisation of both the parameters for a lensing model and the surface brightness of the source.

scholarly journals Inner dark matter distribution of the Cosmic Horseshoe (J1148+1930) with gravitational lensing and dynamics

2019 ◽  
Vol 631 ◽  
pp. A40 ◽  
Author(s):  
S. Schuldt ◽  
G. Chirivì ◽  
S. H. Suyu ◽  
A. Yıldırım ◽  
A. Sonnenfeld ◽  
...  
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Gravitational Lens ◽  
Wide Field ◽  
Lens System ◽  
Matter Distribution ◽  
Mass Model ◽  
Luminous Matter ◽  
Dark Matter Distribution ◽  
Light Components

We present a detailed analysis of the inner mass structure of the Cosmic Horseshoe (J1148+1930) strong gravitational lens system observed with the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3). In addition to the spectacular Einstein ring, this systems shows a radial arc. We obtained the redshift of the radial arc counterimage zs, r = 1.961 ± 0.001 from Gemini observations. To disentangle the dark and luminous matter, we considered three different profiles for the dark matter (DM) distribution: a power law profile, the Navarro, Frenk, and White (NFW) profile, and a generalized version of the NFW profile. For the luminous matter distribution, we based the model on the observed light distribution that is fitted with three components: a point mass for the central light component resembling an active galactic nucleus, and the remaining two extended light components scaled by a constant mass-to-light ratio (M/L). To constrain the model further, we included published velocity dispersion measurements of the lens galaxy and performed a self-consistent lensing and axisymmetric Jeans dynamical modeling. Our model fits well to the observations including the radial arc, independent of the DM profile. Depending on the DM profile, we get a DM fraction between 60% and 70%. With our composite mass model we find that the radial arc helps to constrain the inner DM distribution of the Cosmic Horseshoe independently of the DM profile.

scholarly journals PKS 1117+146: Gravitational Lens or Micro lobes

1996 ◽  
Vol 175 ◽  
pp. 118-119
Author(s):  
M. Bondi ◽  
M. Garrett ◽  
L. Gurvits
Keyword(s):  
Gravitational Lensing ◽  
Hot Spot ◽  
Low Frequency ◽  
Gravitational Lens ◽  
Central Component ◽  
Radio Sources ◽  
Double Structure ◽  
Global Arrays ◽  
Low Frequency Variability ◽  
First Time

PKS 1117+146 is a high power radio source (L327MHz=5.4 × 1026 W/Hz) identified with a galaxy of 20.1 red magnitude at z=0.362 (de Vries et al. 1995). At this redshift 1 mas ≃ 2.9 pc (H0 = 100 km/s–1Mpc–1). Based on the properties of the radio spectra, PKS 1117+146 is classified as a GigaHertz Peaked Spectrum source (GPS) (Stanghellini et al. 1990). The GPS are powerful but physically small (sub-galactic sizes) radio sources with turnovers in their radio spectra at v ≃ 1 GHz. They are supposed to be isotropically emitting radio sources confined by exceptional dense circumnuclear gas (O'Dea et al. 1991) or still relatively young (Fanti et al. 1990). PKS 1117+146 is also a low frequency variable (LFV) with no sign of variability at v > 1 GHz (Padrielli et al. 1987, Mitchell et al. 1994). The low frequency variability is caused by propagation effects in the interstellar medium of our Galaxy (Mantovani et al. 1990, Spangler et al. 1993). PKS 1117+146 was observed with VLBI global arrays at 608 MHz (Padrielli et al. 1991), at 327 MHz (Altschuler et al. 1995), and at 1667 MHz (Bondi et al. 1996). All the maps are in agreement showing a compact double structure with components separated by about 70 mas. Flux densities and separation of the two components derived from VLBI and MERLIN (see below) maps are listed in Table 1. The flux ratios of the two components from the VLBI observations are very similar, and the spectral index is relatively flat (α ≃ 0.3–0.4), even if the strong low frequency variability can introduce uncertainties. The similarity of the VLBI morphology and spectral properties of the two components suggested that 1117+146 could be a possible gravitational lens candidate prompting for higher frequency observations. We observed PKS 1117+146 with MERLIN at 22 GHz in March 1993. MERLIN observations reveal for the first time a weak central component with a total flux density of about 20 mJy (Fig.1). From Table 1 we can note that the P.A. between the components is constant at all the frequencies while the separation between the peak flux densities significantly increases at higher frequencies. This is the expected behaviour if the 2 components are 2 lobes with hot-spot at the outer edges. The MERLIN map at 22 GHz seems to rule out the possibility that the morphology of PKS 1117+146 is caused by gravitational lensing.

scholarly journals Gravitational Lensing

1992 ◽  
Vol 9 ◽  
pp. 3-32 ◽  
Author(s):  
Sjur Refsdal ◽  
Jean Surdej
Keyword(s):  
Gravitational Lensing ◽  
Gravitational Lens ◽  
Medium Size ◽  
Gravitational Lenses ◽  
Optical Lens ◽  
Basic Principles ◽  
History Of ◽  
Photometric Monitoring ◽  
A Site ◽  
Near Future

AbstractAtmospheric lensing effects deform our view of distant objects; similarly, without any doubt, gravitational lensing perturbs our view of the distant Universe and affects our physical understanding of various classes of extragalactic objects. We summarize here part of the theoretical and observational evidences supporting these claims.After briefly reviewing the history of gravitational lenses, we recall the basic principles underlying the formation of gravitationally lensed images of distant cosmic sources. We describe a simple optical lens experiment, which was actually shown during the oral discourse, and which accounts for all types of presently known gravitational lens systems.The various optical and radio searches for new gravitational lens systems that are being carried out at major observatories are reviewed. State-of-the-art observations of selected gravitational lens systems, obtained with highly performing ground-based telescopes, are then presented. These include several examples of multiply imaged QSO images, radio rings and giant luminous arcs.Through the modeling of these enigmatic objects, we show how it is possible to weigh the mass of distant lensing galaxies as well as to probe the distribution of luminous and dark matter in the Universe. Among the astrophysical and cosmological interests of observing and studying gravitational lenses, we also discuss the possibility of deriving the value of the Hubble parameter Ho from the measurement of a time delay, and how to determine the size and structure of distant quasars via the observational study of micro-lensing effects.At the end of this paper, we conclude on how to possibly achieve major astro-physical and cosmological goals in the near future by dedicating, on a site with good atmospheric seeing conditions, a medium size (2-3 m) telescope to the photometric monitoring of the multiple images of known and suspected gravitational lens systems.

scholarly journals A Cusp—Counting Formula For Caustics Due To Multiplane Gravitational Lensing

1996 ◽  
Vol 173 ◽  
pp. 281-282
Author(s):  
A. O. Petters
Keyword(s):  
Light Source ◽  
Gravitational Lensing ◽  
Deflection Angle ◽  
Gravitational Lens ◽  
Source Plane ◽  
Lens System ◽  
Light Rays ◽  
Counting Formula

Consider a gravitational lens system with K planes. If light rays are traced back from the observer to the light source plane, then the points on the first lens plane where a light ray either terminates, or, passes through and terminates before reaching the light source plane, are “obstruction points.” More precisely, tracing rays back to the source plane induces a K-plane lensing map η : U ⊆ R2 → R2 of the form η(x1) = x1 −∑i=1k αi(xi(xi)). We then define an obstruction point of η to be a point a of U where limx1→a |αi(xi(x1))| = ∞ for some “deflection angle” αi.

Gravitational Lensing for Measuring Astrophysical Quantities

2005 ◽  
Vol 277-279 ◽  
pp. 783-788
Author(s):  
K. Chang
Keyword(s):  
Time Delay ◽  
Gravitational Lensing ◽  
Critical Curve ◽  
Gravitational Lens ◽  
Density Parameter ◽  
Cosmological Distance Scale ◽  
Compact Source ◽  
Cosmological Distance ◽  
Structure Density ◽  
Source Structure

Gravitational lensing (GL) provides the sudden changes in flux densities, when a compact source crosses a critical curve. Due to lensing, the image of the lensed object is split into at least two images, and merged together upon the source crossing the critical curve. Light paths of the images differ from one another’s, so results time delay to the observer. Asymmetric light curves and the time delay in lensing contain astrophysical information on the GL system: e.g. source structure, density distribution, and cosmological distance scale. The disalignment of GL system, b, is an important parameter in the GL analysis. We derive b as a function of density parameter of gravitational lens mass. We present an analytical formulation to determine cosmological distance scales, hence the Hubble parameter, and other properties of GL system. We also discuss degeneracies in the GL mapping.

GRAVITATIONAL LENS AMPLIFICATION OF GRAVITATIONAL RADIATION

2002 ◽  
Vol 11 (07) ◽  
pp. 1067-1074 ◽  
Author(s):  
ALEXANDER F. ZAKHAROV ◽  
YURI V. BARYSHEV
Keyword(s):  
Gravitational Wave ◽  
Gravitational Lensing ◽  
Gravitational Radiation ◽  
Gravitational Lens ◽  
Wave Form ◽  
Gravitational Lenses ◽  
Approximation Model ◽  
Radiation Sources ◽  
Wave Space ◽  
Stellar Masses

In a recent paper by Wang, Turner and Stebbins (1996) an influence of gravitational lensing on increasing an estimated rate of gravitational radiation sources was considered. We show that the authors used the geometrical optics approximation model for gravitational lensing and thus they gave overestimated rate of possible events for possible sources of gravitational radiation for the advanced LIGO detector. We show also that if we would use a more correct model of gravitational lensing, one could conclude that more strong influence on increasing rate of estimated events of gravitational radiation for advanced LIGO detector could give gravitational lenses of galactic masses but not gravitational lenses of stellar masses as Wang et al. concluced. Moreover, binary gravitational lenses could give essential distortion of gravitational wave form template, especially gravitational wave template of periodic sources and the effect could be significant for templates of quasi-periodic sources which could be detected by a future gravitational wave space detector like LISA.

scholarly journals A simple simulation technique for gravitational lenses

2011 ◽  
Vol 20 (2) ◽  
pp. 183-189
Author(s):  
CRISTIAN EDUARD RUSU ◽  
◽  
BETRIA SILVANA ROSSA ◽  
Keyword(s):  
Present Article ◽  
Gravitational Lensing ◽  
Weak Field ◽  
Simulation Technique ◽  
Gravitational Lens ◽  
Gravitational Lenses ◽  
Direct Simulation ◽  
Single Plane ◽  
Advantages And Disadvantages ◽  
Simple Simulation

The present article discusses the simulation of Gravitational Lensing with an algorithm developed in C++ and using the EasyBMP library. The algorithm numerically solves the general gravitational lens equation in the astrophysically significant weak field case, for any single-plane lens configuration. Examples of execution are considered, and a discussion is carried out on the advantages and disadvantages of the direct simulation technique employed.

scholarly journals Gravitational microlensing time delays at high optical depth: image parities and the temporal properties of fast radio bursts

2020 ◽  
Vol 497 (2) ◽  
pp. 1583-1589
Author(s):  
Geraint F Lewis
Keyword(s):  
Optical Depth ◽  
Gravitational Lensing ◽  
Time Delays ◽  
Saddle Points ◽  
Gravitational Lens ◽  
Depth Image ◽  
Short Time Scale ◽  
Solar Mass ◽  
Transient Sources ◽  
The Impact

ABSTRACT Due to differing gravitational potentials and path lengths, gravitational lensing induces time delays between multiple images of a source that, for solar mass objects, are of the order of ∼10−5 s. If an astrophysically compact source, such as a fast radio burst (FRB), is observed through a region with a high optical depth of such microlensing masses, this gravitational lensing time delay can be imprinted on short time-scale transient signals. In this paper, we consider the impact of the parity of the macroimage on the resultant microlensing time delays. It is found that this parity is directly imprinted on the microlensing signal, with macroimages formed at minima of the time arrival surface beginning with the most highly magnified microimages and then progressing to the fainter microimages. For macroimages at the maxima of the time arrival surface, this situation is reversed, with fainter images observed first and finishing with the brightest microimages. For macroimages at saddle points, the signal again begins with fainter images, followed by brighter images before again fading through the fainter microimages. The growing populations of cosmologically distant bursty transient sources will undoubtedly result in the discovery of strong lensed, multiply imaged FRBs, which will be susceptible to microlensing by compact masses. With the temporal resolution being offered by modern and future facilities, the detection of microlensing-induced time delays will reveal the parities of the gravitational lens macroimages, providing additional constraints on macrolensing mass models and improving the efficacy of these transient sources as cosmological probes.

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