28th Texas Symposium on Relativistic Astrophysics

Session

12 - Gravitational lensing

Lensing

17 Dec 2015, 14:00

International Conference Centre Geneva

Conveners

12 - Gravitational lensing

• Ludovic Van Waerbeke (University of British Columbia)

12 - Gravitational lensing

• Ludovic Van Waerbeke (University of British Columbia)

64. How the observational quantities of strong gravitational lens effect depend on BH's mass and spin

Hiromi Saida (Daido University)

17/12/2015, 14:00

Talk

According to the general relativity (GR), the black hole (BH) is characterized by three parameters: mass $M$, spin angular momentum $J$ and electric charge $Q$. In real cases, the charge is expected to be zero, $Q=0$. Then, the "BH observation" may be understood as the measurement of $M$ and $J$ through a direct observation of GR phenomena, for example the strong gravitational lens effect....

483. The future for strong gravitational lensing

R. Benton Metcalf (Univerity of Bologna)

17/12/2015, 14:21

Talk

The Euclid mission is expected to discover perhaps two orders of magnitude more strong gravitational lenses than are known today. These will be quasar-galaxy, galaxy-galaxy and galaxy-cluster lenses. I will discuss what is required to find and process such a large number of lenses. I will then describe what can be learned from these lenses with respect to the dark matter...

356. Search for lensed QSOs in the OGLE survey

Dr Zuzanna Kostrzewa-Rutkowska

17/12/2015, 14:42

Talk

We present the results of our search for gravitationally lensed quasars in the OGLE survey. We show candidates from a 650 square degrees area behind the Magellanic Clouds System. The study of strong lensing time delays serves as a powerful probe in cosmology. The OGLE database provides long time light curves, allowing for a cost-effective way to accurately derive time delays and therefore...

324. Weak lensing mass map in DECaLS DR1 survey

Dr Huanyuan Shan (EPFL)

17/12/2015, 15:03

Talk

We present the largest weak lensing mass map covering ~3000 square degrees of the DECaLS DR1 Survey. A good agreement can be found between optical and dark matter maps. Comparing with the mass maps from CFHT Stripe 82 Survey (CS82), the similar high signal-to-noise ratio peaks can be found, which means the systematics of the maps are well controlled. We found ~50,000 WL peaks with SNR higher...

407. CMB lensing - galaxy cross-correlations

Mr Yuuki Omori (McGill University)

17/12/2015, 15:24

Talk

Large scale structure in the universe causes gravitational lensing of the cosmic microwave background (CMB), which has now been well-measured by several CMB experiments. By cross-correlating CMB lensing with tracers of large scale structure (like galaxies), it is possible to obtain new constraints on cosmology and a better understanding of possible systematic errors in cosmological...

67. Where are the baryons?

Dr Dominique Eckert (University of Geneva)

17/12/2015, 16:15

Talk

In the local Universe, about half of the total baryon content of the Universe is still escaping our census. Understanding the state and distribution of these missing baryons is a major question for our knowledge of galaxy evolution and cosmology. Numerical simulations predict that the missing baryons should be in the form of a very diffuse, warm-hot (T~1e5-1e7 K) state, which would remain...

311. A direct measurement of tomographic lensing power spectra from CFHTLenS

Fabian Köhlinger

17/12/2015, 16:35

Talk

We measure the weak gravitational lensing shear power spectra and their cross-power in two photometric redshift bins from the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS). The measurements are performed directly in multipole space in terms of adjustable band powers. For the extraction of the band powers from the data we have implemented and extended a quadratic estimator, a maximum...

217. Gravitational microlensing as a probe for dark matter

Vitalii Sliusar (Astronomical Observatory of Taras Shevchenko National University of Kyiv, Ukraine)

17/12/2015, 16:55

Talk

We study effects due to a possible presence of putative dark matter mini-halos (DM clumps) in the light curves of source images of the extragalactic gravitational lens systems. The extended clumps are described by means of a simplified model of the lens mapping. Every microlens consists of a central point mass surrounded by a concentric extended mini-halo; this is characterized by the ratio q...

328. Test of relativistic gravity using the microlensing of broad iron line in quasars

Ievgen Vovk

17/12/2015, 17:15

Talk

We show that observation of the time-dependent effect of microlensing of relativistically broadened emission lines (such as e.g. the Fe Kalpha line in X-rays) in strongly lensed quasars could provide data on celestial mechanics of circular orbits in the direct vicinity of the horizon of supermassive black holes. This information can be extracted from the observation of evolution of red / blue...

119. Gravitational lensing flexion measurements in the Hubble Frontier Fields

Mr Markus Rexroth (EPFL - EPF Lausanne)

17/12/2015, 17:35

Poster

Flexion is the second order weak gravitational lensing effect which is responsible for the arclike appearance of lensed sources. Its strong signal in the intermediate regime and the orthogonality to the weak lensing shear field make flexion an ideal complement to today's gravitational lensing measurements. Furthermore, its high sensitivity to local density peaks makes it a great tool for...

44. Effects of the second-order vector mode on weak lensing signals

Mr Shohei Saga (Naogya university)

17/12/2015, 17:38

Poster

Vector mode of cosmological perturbation theory imprints characteristic signals on the weak lensing signals such as curl- and B-modes which are never imprinted by the scalar mode. However, the vector mode is neglected in the standard first-order cosmological perturbation theory since it only has a decaying mode. This situation changes if the cosmological perturbation theory is expanded up to...

344. Black Holes, Neutron Stars and White Dwarf Candidates from Microlensing with OGLE-III

Dr Zuzanna Kostrzewa-Rutkowska (Warsaw University Astronomical Observatory)

17/12/2015, 17:41

Poster

Most stellar remnants so far have been found in binary systems where they interact with matter from their companion. Isolated neutron stars and black holes are hard to find as they do not emit light, yet they are predicted to be present in our Galaxy in vast numbers. We explored the OGLE-III database of 150 million objects observed in years 2001-2009 and found 59 microlensing events...

101. How to use geodetic VLBI to measure relativistic light deflection from extragalactic objects

Oleg Titov

17/12/2015, 17:44

Poster

The Sun's gravitational field deflects the apparent positions of close objects in accordance with the formulae of general relativity. Optical astrometry is used to test the prediction, but only with the stars close to the Sun and only during total Solar eclipses. Nowadays, more advanced technique, geodetic Very Long Baseline Interferometry (VLBI) is applied for testing of general relativity...