Gravitationally lensed quasars in<i>Gaia</i>– III. 22 new lensed quasars from<i>Gaia</i>data release 2

Lemon, C.; Auger, Matthew W.; McMahon, R. G.

doi:10.1093/mnras/sty3366

Cited by 96 publications

(97 citation statements)

References 65 publications

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“…Achieving the goal of obtaining a 1% or better measurement of H 0 with time-delay cosmography requires a significantly larger sample of lensed quasars with high-quality data than has been analyzed to date. Many new lensed quasars have been discovered (e.g., Lin et al 2017;Schechter et al 2017;Agnello et al 2018;Ostrovski et al 2018;Williams et al 2018;Rusu et al 2019b;Lemon et al 2019) using state-of-the-art lens-finding techniques applied to current large sky surveys (e.g. Joseph et al 2014;Agnello 2017;Petrillo et al 2017;Ostrovski et al 2017;Lanusse et al 2018;Spiniello et al 2018;Treu et al 2018;Avestruz et al 2019), and more are expected to be found with the Large Synoptic Survey Telescope (Oguri & Marshall 2010).…”

Section: Distance Measurement From Time-delay Cosmographymentioning

confidence: 99%

A SHARP view of H0LiCOW: H0 from three time-delay gravitational lens systems with adaptive optics imaging

Chen

Fassnacht

Suyu

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present the measurement of the Hubble Constant, H 0 , with three strong gravitational lens systems. We describe a blind analysis of both PG 1115+080 and HE 0435−1223 as well as an extension of our previous analysis of RXJ 1131−1231. For each lens, we combine new adaptive optics (AO) imaging from the Keck Telescope, obtained as part of the SHARP AO effort, with Hubble Space Telescope (HST ) imaging, velocity dispersion measurements, and a description of the line-of-sight mass distribution to build an accurate and precise lens mass model. This mass model is then combined with the COSMOGRAIL measured time delays in these systems to determine H 0 . We do both an AO-only and an AO+HST analysis of the systems and find that AO and HST results are consistent. After unblinding, the AO-only analysis gives H 0 = 82.8 +9.4 −8.3 km s −1 Mpc −1 for PG 1115+080, H 0 = 70.1 +5.3 −4.5 km s −1 Mpc −1 for HE 0435−1223, and H 0 = 77.0 +4.0 −4.6 km s −1 Mpc −1 for RXJ 1131−1231. The joint AOonly result for the three lenses is H 0 = 75.6 +3.2 −3.3 km s −1 Mpc −1 . The joint result of the AO+HST analysis for the three lenses is H 0 = 76.8 +2.6−2.6 km s −1 Mpc −1 . All of the above results assume a flat Λ cold dark matter cosmology with a uniform prior on Ω m in [0.05, 0.5] and H 0 in [0, 150] km s −1 Mpc −1 . This work is a collaboration of the SHARP and H0LiCOW teams, and shows that AO data can be used as the high-resolution imaging component in lens-based measurements of H 0 . The full time-delay cosmography results from a total of six strongly lensed systems are presented in a companion paper.

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Section: Distance Measurement From Time-delay Cosmographymentioning

confidence: 99%

A SHARP view of H0LiCOW: H0 from three time-delay gravitational lens systems with adaptive optics imaging

Chen

Fassnacht

Suyu

et al. 2019

Monthly Notices of the Royal Astronomical Society

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204

167

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“…Considering that radio/X-ray observations are less affected by dust obscuration compared to optical, the lower-than-average recovery rates for the MORX sample may indicate that our RF classifier is less efficient in selecting obscured AGNs. It is also possible that the MORX sample has a higher contribution from host galaxy emission which would result in redder G − W 1 and bluer W 1 − W 2 colours compared to AGNs in the training set (e.g., Ostrovski et al 2017;Lemon et al 2019). To determine the number of new AGN candidates in our catalogues, we cross-match the C75 and R85 catalogues with the known AGN compilation using an aggressive matching radius of 5 .…”

Section: Comparisons With Other Agn Cataloguesmentioning

confidence: 99%

“…Lastly, we examine how many known strongly-lensed quasars are recovered in our AGN catalogues. To date there are 204 known strongly-lensed quasar systems according to the Gravitationally Lensed Quasar Database 4 (Lemon et al 2019). In total, 333 lensed quasar images in 168 known systems are in the Gaia-unWISE sample, of which 126 lensed quasar images in 104 systems have large enough PRF values to be included in the C75 catalogue.…”

Section: Comparisons With Other Agn Cataloguesmentioning

confidence: 99%

“…From imaging data, we find that those un-recovered lensed quasar images are usually close to the lensing galaxies or 4 https://www.ast.cam.ac.uk/ioa/research/lensedquasars/ clustered within small separations. They have lower PRF values because 1) their W 1 − W 2 and G − W 1 colours are contaminated by the nearby lensing galaxies (e.g., Lemon et al 2019); 2) their proper motions and parallaxes are inaccurately inferred, perhaps due to Gaia mis-assigning nearby images at each epoch; 3) they generally have CNT4 > 1, which makes them less similar to AGNs in our training set where more than 99% of AGNs have CNT4 = 1. We note that finding highly-clustered AGNs on small scales ( 10 ) in the presence of nearby, bright galaxies is essentially a different task from building a large and clean sample of AGNs, and a separate classifier/approach might be needed.…”

Section: Comparisons With Other Agn Cataloguesmentioning

confidence: 99%

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Catalogues of active galactic nuclei from Gaia and unWISE data

Shu

Koposov

Evans

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present two catalogues of active galactic nucleus (AGN) candidates selected from the latest data of two all-sky surveys -Data Release 2 (DR2) of the Gaia mission and the unWISE catalogue of the Wide-field Infrared Survey Explorer (WISE ). We train a random forest classifier to predict the probability of each source in the Gaia-unWISE joint sample being an AGN, P RF , based on Gaia astrometric and photometric measurements and unWISE photometry. The two catalogues, which we designate C75 and R85, are constructed by applying different P RF threshold cuts to achieve an overall completeness of 75% (≈90% at Gaia G ≤ 20 mag) and reliability of 85% respectively. The C75 (R85) catalogue contains 2, 734,464 (2,182,193) AGN candidates across the effective 36,000 deg 2 sky, of which ≈0.91 (0.52) million are new discoveries. Photometric redshifts of the AGN candidates are derived by a random forest regressor using Gaia and WISE magnitudes and colours. The estimated overall photometric redshift accuracy is 0.11. Cross-matching the AGN candidates with a sample of known bright cluster galaxies, we identify a high-probability strongly-lensed AGN candidate system, SDSS J1326+4806, with a large image separation of 21. 06. All the AGN candidates in our catalogues will have ∼5-year long light curves from Gaia by the end of the mission, and thus will be a great resource for AGN variability studies. Our AGN catalogues will also be helpful in AGN target selections for future spectroscopic surveys, especially ones in the southern hemisphere. The C75 catalogue can be downloaded at https://www.ast.cam.ac.uk/~ypshu/AGN_Catalogues.html

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“…A large number of gravitationally lensed distant galaxies have also been discovered by deep imaging of central regions of massive clusters of galaxies [30][31][32]. Recently, more strong lens systems are being found in various surveys such as Gaia [33][34][35], Dark Energy Survey [36][37][38][39], Kilo-Degree Survey [40], Pan-STARRS1 [41], and Subaru Hyper Suprime-Cam survey [42,43].…”

Section: Introductionmentioning

confidence: 99%

Strong gravitational lensing of explosive transients

2019

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Recent rapid progress in time domain surveys makes it possible to detect various types of explosive transients in the Universe in large numbers, some of which will be gravitationally lensed into multiple images. Although a large number of strongly lensed distant galaxies and quasars have already been discovered, strong lensing of explosive transients opens up new applications, including improved measurements of cosmological parameters, powerful probes of small scale structure of the Universe, and new observational tests of dark matter scenarios, thanks to their rapidly evolving light curves as well as their compact sizes. In particular, the compactness of these transient events indicates that the wave optics effect plays an important role in some cases, which can lead to totally new applications of these lensing events. Recently we have witnessed first discoveries of strongly lensed supernovae, and strong lensing events of other types of explosive transients such as gamma-ray bursts, fast radio bursts, and gravitational waves from compact binary mergers are expected to be observed soon. In this review article, we summarize the current state of research on strong gravitational lensing of explosive transients and discuss future prospects.

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Gravitationally lensed quasars inGaia– III. 22 new lensed quasars fromGaiadata release 2

Cited by 96 publications

References 65 publications

A SHARP view of H0LiCOW: H0 from three time-delay gravitational lens systems with adaptive optics imaging

A SHARP view of H0LiCOW: H0 from three time-delay gravitational lens systems with adaptive optics imaging

Catalogues of active galactic nuclei from Gaia and unWISE data

Strong gravitational lensing of explosive transients

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