Publications de Karina Alexandra Rojas Olate

The impact of human expert visual inspection on the discovery of strong gravitational lenses

Frédéric Courbin, Benjamin Yvan Alexandre Clement, Eric Gérard Guy Paic, Hung-Hsu Chan, Martin Raoul Robert Millon, Karina Alexandra Rojas Olate, Rémy Elie Joseph, Elodie Marie Charlène Savary, Yue Pan

We investigate the ability of human 'expert' classifiers to identify strong gravitational lens candidates in Dark Energy Survey like imaging. We recruited a total of 55 people that completed more than 25 per cent of the project. During the classification t ...

OXFORD UNIV PRESS2023

Discovery of strongly lensed quasars in the Ultraviolet Near Infrared Optical Northern Survey (UNIONS)

Benjamin Yvan Alexandre Clement, Eric Gérard Guy Paic, Hung-Hsu Chan, Martin Raoul Robert Millon, Karina Alexandra Rojas Olate, Cameron Alexander Campbell Lemon, Georgios Vernardos, Elodie Marie Charlène Savary

We report the discovery of five new doubly imaged lensed quasars from the first 2500 square degrees of the ongoing Canada-France Imaging Survey (CFIS), which is a component of the Ultraviolet Near Infrared Optical Northern Survey. The systems are preselect ...

EDP SCIENCES S A2022

Search of strong lens systems in the Dark Energy Survey using convolutional neural networks

Frédéric Courbin, Benjamin Yvan Alexandre Clement, Hung-Hsu Chan, Aymeric Alexandre Galan, Karina Alexandra Rojas Olate, Cameron Alexander Campbell Lemon, Georgios Vernardos, Elodie Marie Charlène Savary

We present our search for strong lens, galaxy-scale systems in the first data release of the Dark Energy Survey (DES), based on a color-selected parent sample of 18 745 029 luminous red galaxies (LRGs). We used a convolutional neural network (CNN) to grade ...

EDP SCIENCES S A2022

Strong lensing in UNIONS: Toward a pipeline from discovery to modeling

Frédéric Courbin, Benjamin Yvan Alexandre Clement, Hung-Hsu Chan, Karina Alexandra Rojas Olate, Cameron Alexander Campbell Lemon, Georgios Vernardos, Elodie Marie Charlène Savary

We present a search for galaxy-scale strong gravitational lenses in the initial 2500 square degrees of the Canada-France Imaging Survey (CFIS). We designed a convolutional neural network (CNN) committee that we applied to a selection of 2 344 002 r-band im ...

EDP SCIENCES S A2022

Measuring accretion disk sizes of lensed quasars with microlensing time delay in multi-band light curves

Frédéric Courbin, Vivien François Bonvin, Hung-Hsu Chan, Martin Raoul Robert Millon, Karina Alexandra Rojas Olate

Time-delay cosmography in strongly lensed quasars offers an independent way of measuring the Hubble constant, H-0. However, it has been proposed that the combination of microlensing and source-size effects, also known as microlensing time delay, can potent ...

EDP SCIENCES S A2021

Revealing the structure of the lensed quasar Q 0957+561 I. Accretion disk size

Karina Alexandra Rojas Olate

Aims. We aim to use signatures of microlensing induced by stars in the foreground lens galaxy to infer the size of the accretion disk in the gravitationally lensed quasar Q 0957 +561. The long-term photometric monitoring of this system (which so far has pr ...

2021

TDCOSMO II. Six new time delays in lensed quasars from high-cadence monitoring at the MPIA 2.2m telescope

Frédéric Courbin, Vivien François Bonvin, Eric Gérard Guy Paic, Sun Hee Kim, Hung-Hsu Chan, Martin Raoul Robert Millon, Karina Alexandra Rojas Olate, Cameron Alexander Campbell Lemon, Adriano Agnello

We present six new time-delay measurements obtained from Rc-band monitoring data acquired at the Max Planck Institute for Astrophysics (MPIA) 2.2m telescope at La Silla observatory between October 2016 and February 2020. The lensed quasars HE0047 1756, WG0 ...

EDP SCIENCES S A2020

HOLISMOKES: II. Identifying galaxy-scale strong gravitational lenses in Pan-STARRS using convolutional neural networks

Karina Alexandra Rojas Olate, Cameron Alexander Campbell Lemon, Elodie Marie Charlène Savary

We present a systematic search for wide-separation (with Einstein radius theta(E)greater than or similar to 1.5 ''), galaxy-scale strong lenses in the 30 000 deg(2) of the Pan-STARRS 3 pi survey on the Northern sky. With long time delays of a few days to w ...

2020

Microlensing Analysis for the Gravitational Lens Systems SDSS0924+0219, Q1355-2257, and SDSS1029+2623

Karina Alexandra Rojas Olate

We use spectroscopic observations of the gravitationally lensed systems SDSS0924+0219(BC), Q1355-2257(AB), and SDSS1029+2623(BC) to analyze microlensing and dust extinction in the observed components. We detect chromatic microlensing effects in the continu ...

2020

COSMOGRAIL XVIII. time delays of the quadruply lensed quasar WFI2033-4723

Frédéric Courbin, Georges Meylan, Malte Tewes, Sun Hee Kim, Vivien François Bonvin, Hung-Hsu Chan, Martin Raoul Robert Millon, Karina Alexandra Rojas Olate

We present new measurements of the time delays of WFI2033-4723. The data sets used in this work include 14 years of data taken at the 1.2 m Leonhard Euler Swiss telescope, 13 years of data from the SMARTS 1.3 m telescope at Las Campanas Observatory and a s ...

2019