Publications by Karina Alexandra Rojas Olate

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

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

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

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

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

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, Martin Raoul Robert Millon, Hung-Hsu Chan, 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, Sun Hee Kim, Vivien François Bonvin, Martin Raoul Robert Millon, Eric Gérard Guy Paic, Hung-Hsu Chan, 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

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

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

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

The STRong lensing Insights into the Dark Energy Survey (STRIDES) 2016 follow-up campaign - I. Overview and classification of candidates selected by two techniques

Eduardo Sanchez, Georges Meylan, Frédéric Courbin, Joo Yeon Kim, Craig Matthew Smith, Riccardo Agnello, Augusto Martins Lima, Hung-Hsu Chan, Karina Alexandra Rojas Olate, Cameron Alexander Campbell Lemon, Adriano Agnello

The primary goals of the STRong lensing Insights into the Dark Energy Survey (STRIDES) collaboration are to measure the dark energy equation of state parameter and the free streaming length of dark matter. To this aim, STRIDES is discovering strongly lense ...

OXFORD UNIV PRESS2018

COSMOGRAIL XVII. Time delays for the quadruply imaged quasar PG 1115+080

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

We present time-delay estimates for the quadruply imaged quasar PG 1115+080. Our results are based on almost daily observations for seven months at the ESO MPIA 2.2m telescope at La Silla Observatory, reaching a signal-to-noise ratio of about 1000 per quas ...

EDP SCIENCES S A2018

Constraining the microlensing effect on time delays with a new time-delay prediction model in H-0 measurements

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

Time-delay strong lensing provides a unique way to directly measure the Hubble constant (H-0). The precision of the H-0 measurement depends on the uncertainties in the time-delay measurements, the mass distribution of the main deflector(s), and the mass di ...

OXFORD UNIV PRESS2018

Karina Alexandra Rojas Olate

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

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

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

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

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

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

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

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

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

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

The STRong lensing Insights into the Dark Energy Survey (STRIDES) 2016 follow-up campaign - I. Overview and classification of candidates selected by two techniques

COSMOGRAIL XVII. Time delays for the quadruply imaged quasar PG 1115+080

Constraining the microlensing effect on time delays with a new time-delay prediction model in H-0 measurements

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses

DES meets Gaia: discovery of strongly lensed quasars from a multiplet search

Extreme magnification of an individual star at redshift 1.5 by a galaxy-cluster lens