Search Results for author: Hendrik Hildebrandt

Found 12 papers, 7 papers with code

Magnification bias in galaxy surveys with complex sample selection functions

1 code implementation13 Jan 2021 Maximilian von Wietersheim-Kramsta, Benjamin Joachimi, Jan Luca van den Busch, Catherine Heymans, Hendrik Hildebrandt, Marika Asgari, Tilman Tröster, Angus H. Wright

For BOSS-like lenses, we forecast a contribution of the magnification bias to the GGL signal between the multipole moments, $\ell$, of 100 and 4600 with a cumulative signal-to-noise ratio between 0. 1 and 1. 1 for sources from the Kilo-Degree Survey (KiDS), between 0. 4 and 2. 0 for sources from the Hyper Suprime-Cam survey (HSC), and between 0. 3 and 2. 8 for ESA Euclid-like source samples.

Cosmology and Nongalactic Astrophysics

Organised Randoms: Learning and correcting for systematic galaxy clustering patterns in KiDS using self-organising maps

no code implementations15 Dec 2020 Harry Johnston, Angus H. Wright, Benjamin Joachimi, Maciej Bilicki, Nora Elisa Chisari, Andrej Dvornik, Thomas Erben, Benjamin Giblin, Catherine Heymans, Hendrik Hildebrandt, Henk Hoekstra, Shahab Joudaki, Mohammadjavad Vakili

We then create `organised' randoms, i. e. random galaxy catalogues with spatially variable number densities, mimicking the learnt systematic density modes in the data.

Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies

Cosmic Shear Cosmology Beyond 2-Point Statistics: A Combined Peak Count and Correlation Function Analysis of DES-Y1

no code implementations4 Dec 2020 Joachim Harnois-Déraps, Nicolas Martinet, Tiago Castro, Klaus Dolag, Benjamin Giblin, Catherine Heymans, Hendrik Hildebrandt, Qianli Xia

With mock DES-Y1 data we calibrate the impact of photometric redshift and shear calibration uncertainty on the peak-count, marginalising over these uncertainties in our cosmological analysis.

Cosmology and Nongalactic Astrophysics

Clustering of red and blue galaxies around high-redshift 3C radio sources as seen by the Hubble Space Telescope

no code implementations13 Oct 2020 Zohreh Ghaffari, Martin Haas, Marco Chiaberge, S. P. Willner, Rolf Chini, Hendrik Hildebrandt, Michael West, Roberto de Propris

To properly understand the evolution of high-redshift galaxy clusters, both passive and star-forming galaxies have to be considered.

Astrophysics of Galaxies

KiDS+VIKING-450: Improved cosmological parameter constraints from redshift calibration with self-organising maps

no code implementations8 May 2020 Angus H. Wright, Hendrik Hildebrandt, Jan Luca van den Busch, Catherine Heymans, Benjamin Joachimi, Arun Kannawadi, Konrad Kuijken

We present updated cosmological constraints for the KiDS+VIKING-450 cosmic shear dataset (KV450), estimated using redshift distributions and photometric samples defined using self organising maps (SOMs).

Cosmology and Nongalactic Astrophysics

Photometric Redshift Calibration with Self Organising Maps

no code implementations20 Sep 2019 Angus H. Wright, Hendrik Hildebrandt, Jan Luca van den Busch, Catherine Heymans

We demonstrate that the previous direct redshift calibration method applied to the full cosmic shear sample is accurate to $| \Delta \langle z \rangle | < 0. 025$.

Cosmology and Nongalactic Astrophysics Instrumentation and Methods for Astrophysics

Weak-lensing shear measurement with machine learning: teaching artificial neural networks about feature noise

1 code implementation5 Jul 2018 Malte Tewes, Thibault Kuntzer, Reiko Nakajima, Frédéric Courbin, Hendrik Hildebrandt, Tim Schrabback

A challenging peculiarity of this ML application is the combination of the noisiness of the input features and the requirements on the accuracy of the inverse regression.

Cosmology and Nongalactic Astrophysics Machine Learning

KiDS-450 + 2dFLenS: Cosmological parameter constraints from weak gravitational lensing tomography and overlapping redshift-space galaxy clustering

1 code implementation20 Jul 2017 Shahab Joudaki, Chris Blake, Andrew Johnson, Alexandra Amon, Marika Asgari, Ami Choi, Thomas Erben, Karl Glazebrook, Joachim Harnois-Deraps, Catherine Heymans, Hendrik Hildebrandt, Henk Hoekstra, Dominik Klaes, Konrad Kuijken, Chris Lidman, Alexander Mead, Lance Miller, David Parkinson, Gregory B. Poole, Peter Schneider, Massimo Viola, Christian Wolf

The complementarity of our observables allows for constraints on modified gravity degrees of freedom that are not simultaneously bounded with either probe alone, and up to a factor of three improvement in the $S_8$ constraint in the extended cosmology compared to KiDS alone.

Cosmology and Nongalactic Astrophysics

CFHTLenS revisited: assessing concordance with Planck including astrophysical systematics

1 code implementation21 Jan 2016 Shahab Joudaki, Chris Blake, Catherine Heymans, Ami Choi, Joachim Harnois-Deraps, Hendrik Hildebrandt, Benjamin Joachimi, Andrew Johnson, Alexander Mead, David Parkinson, Massimo Viola, Ludovic van Waerbeke

When the systematic uncertainties are considered independently, the intrinsic alignment amplitude is the only degree of freedom that is substantially preferred by the data.

Cosmology and Nongalactic Astrophysics

CFHTLenS: A Weak Lensing Shear Analysis of the 3D-Matched-Filter Galaxy Clusters

1 code implementation11 Sep 2014 Jes Ford, Ludovic van Waerbeke, Martha Milkeraitis, Clotilde Laigle, Hendrik Hildebrandt, Thomas Erben, Catherine Heymans, Henk Hoekstra, Thomas Kitching, Yannick Mellier, Lance Miller, Ami Choi, Jean Coupon, Liping Fu, Michael J. Hudson, Konrad Kuijken, Naomi Robertson, Barnaby Rowe, Tim Schrabback, Malin Velander

We present the cluster mass-richness scaling relation calibrated by a weak lensing analysis of >18000 galaxy cluster candidates in the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS).

Cosmology and Nongalactic Astrophysics

Cluster Magnification & the Mass-Richness Relation in CFHTLenS

1 code implementation8 Oct 2013 Jes Ford, Hendrik Hildebrandt, Ludovic van Waerbeke, Thomas Erben, Clotilde Laigle, Martha Milkeraitis, Christopher Morrison

Gravitational lensing magnification is measured with a significance of 9. 7 sigma on a large sample of galaxy clusters in the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS).

Cosmology and Nongalactic Astrophysics

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