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Malte Tewes

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Publications associées (33)

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses XI. Techniques for time delay measurement in presence of microlensing

Malte Tewes, Georges Meylan, Frédéric Courbin

Measuring time delays between the multiple images of gravitationally lensed quasars is now recognized as a competitive way to constrain the cosmological parameters, and it is complementary with other cosmological probes. This requires long and well sampled ...

Edp Sciences S A2013

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses XIV. Time delay of the doubly lensed quasar SDSS J1001+5027

Malte Tewes, Georges Meylan, Frédéric Courbin

This paper presents optical R-band light curves and the time delay of the doubly imaged gravitationally lensed quasar SDSS J1001+5027 at a redshift of 1.838. We have observed this target for more than six years, between March 2005 and July 2011, using the ...

Edp Sciences S A2013

The CORALIE survey for southern extrasolar planets XVII. New and updated long period and massive planets

Malte Tewes

Context. Since 1998, a planet-search program around main sequence stars within 50 pc in the southern hemisphere has been carried out with the CORALIE echelle spectrograph at La Silla Observatory. Aims. With an observing time span of more than 14 years, the ...

Edp Sciences S A2013

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses XII. Time delays of the doubly lensed quasars SDSS J1206+4332 and HS 2209+1914

Malte Tewes, Georges Meylan, Frédéric Courbin

Aims. Within the framework of the COSMOGRAIL collaboration we present 7- and 8.5-year-long light curves and time-delay estimates for two gravitationally lensed quasars: SDSS J1206+4332 and HS 2209+1914. Methods. We monitored these doubly lensed quasars in ...

Edp Sciences S A2013

Cosmology with Gravitational Lensing : Measuring Quasar Time Delays and Cosmic Shear

Malte Tewes

EPFL2013

Two Accurate Time-Delay Distances From Strong Lensing: Implications For Cosmology

Malte Tewes, Georges Meylan, Frédéric Courbin

Strong gravitational lenses with measured time delays between the multiple images and models of the lens mass distribution allow a one-step determination of the time-delay distance, and thus a measure of cosmological parameters. We present a blind analysis ...

American Astronomical Society2013

Image analysis for cosmology: results from the GREAT10 Galaxy Challenge

Nicolas Cantale, Malte Tewes, Frédéric Courbin, Marc Gentile, Guldariya Nurbaeva, Richard Massey

In this paper, we present results from the weak-lensing shape measurement GRavitational lEnsing Accuracy Testing 2010 (GREAT10) Galaxy Challenge. This marks an order of magnitude step change in the level of scrutiny employed in weak-lensing shape measureme ...

Blackwell Publishing Ltd, Oxford2012

Further Evidence That Quasar X-Ray Emitting Regions Are Compact: X-Ray And Optical Microlensing In The Lensed Quasar Q J0158-4325

Malte Tewes, Georges Meylan, Frédéric Courbin

We present four new seasons of optical monitoring data and six epochs of X-ray photometry for the doubly imaged lensed quasar Q J0158-4325. The high-amplitude, short-period microlensing variability for which this system is known has historically precluded ...

Iop Publishing Ltd2012

A fast empirical method for galaxy shape measurements in weak lensing surveys

Nicolas Cantale, Malte Tewes, Georges Meylan, Frédéric Courbin

We describe a simple and fast method to correct ellipticity measurements of galaxies from the distortion by the instrumental and atmospheric point spread function (PSF), in view of weak lensing shear measurements. The method performs a classification of ga ...

Edp Sciences S A2012

Three quasi-stellar objects acting as strong gravitational lenses

Malte Tewes, Georges Meylan, Frédéric Courbin, François Henri Ambroise Rérat

We report the discovery of three new cases of quasi-stellar objects (QSOs) acting as strong gravitational lenses on background emission line galaxies: SDSS J0827+5224 (z(QSO) = 0.293, z(s) = 0.412), SDSS J0919+2720 (z(QSO) = 0.209, z(s) = 0.558), SDSS J100 ...

2012

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses

Yves Revaz, Malte Tewes, Georges Meylan, Frédéric Courbin

We present accurate time delays for the quadruply imaged quasar HE 0435-1223. The delays were measured from 575 independent photometric points obtained in the R-band between January 2004 and March 2010. With seven years of data, we clearly show that quasar ...

2011

VLT adaptive optics search for luminous substructures in the lens galaxy towards SDSS J0924+0219

Nicolas Cantale, Malte Tewes, Georges Meylan, Frédéric Courbin

The anomalous flux ratios between quasar images are suspected of being caused by substructures in lens galaxies. We present new deep and high-resolution H and Ks imaging of the strongly lensed quasar SDSS J0924+0219 obtained using the ESO VLT with adaptive ...

2011

First case of strong gravitational lensing by a QSO: SDSS J0013+1523 at z=0.120

Malte Tewes, Georges Meylan, Frédéric Courbin, François Henri Ambroise Rérat

We present the first case of strong gravitational lensing by a QSO: SDSS J0013 + 1523 at z = 0.120. The discovery is the result of a systematic search for emission lines redshifted behind QSOs, among 22 298 spectra of the SDSS data release 7. Apart from th ...

2010

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