Publications by Chris Lintott
ICARUS 271 (2016) 30-48
Extended X-ray emission in the IC 2497 - Hanny's Voorwerp system: Energy injection in the gas around a fading AGN
Monthly Notices of the Royal Astronomical Society 457 (2016) 3629-3636
© 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.We present deep Chandra X-ray observations of the core of IC 2497, the galaxy associated with Hanny's Voorwerp and hosting a fading AGN.We find extended soft X-ray emission from hot gas around the low intrinsic luminosity (unobscured) AGN (Lbol ~ 1042-1044 erg s-1). The temperature structure in the hot gas suggests the presence of a bubble or cavity around the fading AGN (Ebub ~ 1054-1055 erg). A possible scenario is that this bubble is inflated by the fading AGN, which after changing accretion state is now in a kinetic mode. Other possibilities are that the bubble has been inflated by the past luminous quasar (Lbol ~ 1046 erg s-1), or that the temperature gradient is an indication of a shock front from a superwind driven by the AGN. We discuss the possible scenarios and the implications for the AGN-host galaxy interaction, as well as an analogy between AGN and X-ray binaries lifecycles.We conclude that the AGN could inject mechanical energy into the host galaxy at the end of its lifecycle, and thus provide a source for mechanical feedback, in a similar way as observed for X-ray binaries.
Journal of Science Communication 15 (2016)
We investigate the development of scientific content knowledge of volunteers participating in online citizen science projects in the Zooniverse (www.zooniverse.org). We use econometric methods to test how measures of project participation relate to success in a science quiz, controlling for factors known to correlate with scientific knowledge. Citizen scientists believe they are learning about both the content and processes of science through their participation. We don't directly test the latter, but we find evidence to support the former - that more actively engaged participants perform better in a project-specific science knowledge quiz, even after controlling for their general science knowledge. We interpret this as evidence of learning of science content inspired by participation in online citizen science.
PLANET HUNTERS. X. SEARCHING for NEARBY NEIGHBORS of 75 PLANET and ECLIPSING BINARY CANDIDATES from the K2 KEPLER EXTENDED MISSION
Astronomical Journal 151 (2016)
© 2016. The American Astronomical Society. All rights reserved..We present high-resolution observations of a sample of 75 K2 targets from Campaigns 1-3 using speckle interferometry on the Southern Astrophysical Research (SOAR) telescope and adaptive optics imaging at the Keck II telescope. The median SOAR I-band and Keck Ks-band detection limits at were mag and mag, respectively. This sample includes 37 stars likely to host planets, 32 targets likely to be eclipsing binaries (EBs), and 6 other targets previously labeled as likely planetary false positives. We find nine likely physically bound companion stars within of three candidate transiting exoplanet host stars and six likely EBs. Six of the nine detected companions are new discoveries. One of these new discoveries, EPIC 206061524, is associated with a planet candidate. Among the EB candidates, companions were only found near the shortest period ones ( days), which is in line with previous results showing high multiplicity near short-period binary stars. This high-resolution data, including both the detected companions and the limits on potential unseen companions, will be useful in future planet vetting and stellar multiplicity rate studies for planets and binaries.
The milky way project and atlasgal: The distribution and physical properties of cold clumps near infrared bubbles
Astrophysical Journal 825 (2016)
© 2016. The American Astronomical Society. All rights reserved.We present a statistical study of the distribution and physical properties of cold, dense material in and around the inner Galactic Plane near-infrared bubbles as cataloged by the Milky Way Project citizen scientists. Using data from the Atacama Pathfinder Experiment (APEX) Telescope Large Area Survey of the Galaxy 870 μm survey, we show that 48 ± 2% of all cold clumps in the studied survey region (|l| ≤ 65°, |b| ≤ 1°) are found in close proximity to a bubble, and 25 ± 2% appear directly projected toward a bubble rim. A two-point correlation analysis confirms the strong correlation of massive cold clumps with expanding bubbles. It shows an overdensity of clumps along bubble rims that grows with increasing bubble size, which shows how interstellar medium material is reordered on large scales by bubble expansion around regions of massive star formation. The highest column density clumps appear to be resistent to the expansion, remaining overdense toward the bubbles' interior rather than being swept up by the expanding edge. Spectroscopic observations in ammonia show that cold dust clumps near bubbles appear to be denser, hotter, and more turbulent than those in the field, offering circumstantial evidence that bubble-associated clumps are more likely to be forming stars. These observed differences in physical conditions persist beyond the region of the bubble rims.
Monthly Notices of the Royal Astronomical Society 459 (2016) 720-745
© 2016 The Authors.The dynamical history of most merging galaxies is not well understood. Correlations between galaxy interaction and star formation have been found in previous studies, but require the context of the physical history of merging systems for full insight into the processes that lead to enhanced star formation. We present the results of simulations that reconstruct the orbit trajectories and disturbed morphologies of pairs of interacting galaxies. With the use of a restricted three-body simulation code and the help of citizen scientists, we sample 105 points in parameter space for each system. We demonstrate a successful recreation of the morphologies of 62 pairs of interacting galaxies through the review of more than 3 million simulations. We examine the level of convergence and uniqueness of the dynamical properties of each system. These simulations represent the largest collection of models of interacting galaxies to date, providing a valuable resource for the investigation of mergers. This paper presents the simulation parameters generated by the project. They are now publicly available in electronic format at http://data.galaxyzoo.org/mergers.html. Though our best-fitting model parameters are not an exact match to previously published models, our method for determining uncertainty measurements will aid future comparisons between models. The dynamical clocks from our models agree with previous results of the time since the onset of star formation from starburst models in interacting systems and suggest that tidally induced star formation is triggered very soon after closest approach.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 457 (2016) 3988-4004
ANNUAL REVIEW OF ASTRONOMY AND ASTROPHYSICS, VOL 53 53 (2015) 247-278
ASTRONOMICAL JOURNAL 149 (2015) ARTN 155
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 447 (2015) 506-516
Journal of Surgical Research 187 (2014) 65-71
Background Validated methods of objective assessments of surgical skills are resource intensive. We sought to test a web-based grading tool using crowdsourcing called Crowd-Sourced Assessment of Technical Skill. Materials and methods Institutional Review Board approval was granted to test the accuracy of Amazon.com's Mechanical Turk and Facebook crowdworkers compared with experienced surgical faculty grading a recorded dry-laboratory robotic surgical suturing performance using three performance domains from a validated assessment tool. Assessor free-text comments describing their rating rationale were used to explore a relationship between the language used by the crowd and grading accuracy. Results Of a total possible global performance score of 3-15, 10 experienced surgeons graded the suturing video at a mean score of 12.11 (95% confidence interval [CI], 11.11-13.11). Mechanical Turk and Facebook graders rated the video at mean scores of 12.21 (95% CI, 11.98-12.43) and 12.06 (95% CI, 11.57-12.55), respectively. It took 24 h to obtain responses from 501 Mechanical Turk subjects, whereas it took 24 d for 10 faculty surgeons to complete the 3-min survey. Facebook subjects (110) responded within 25 d. Language analysis indicated that crowdworkers who used negation words (i.e., "but," "although," and so forth) scored the performance more equivalently to experienced surgeons than crowdworkers who did not (P < 0.00001). Conclusions For a robotic suturing performance, we have shown that surgery-naive crowdworkers can rapidly assess skill equivalent to experienced faculty surgeons using Crowd-Sourced Assessment of Technical Skill. It remains to be seen whether crowds can discriminate different levels of skill and can accurately assess human surgery performances. © 2014 Elsevier Inc. All rights reserved.
Journal of Surgical Research (2013)
Background: Validated methods of objective assessments of surgical skills are resource intensive. We sought to test a web-based grading tool using crowdsourcing called Crowd-Sourced Assessment of Technical Skill. Materials and methods: Institutional Review Board approval was granted to test the accuracy of Amazon.com's Mechanical Turk and Facebook crowdworkers compared with experienced surgical faculty grading a recorded dry-laboratory robotic surgical suturing performance using three performance domains from a validated assessment tool. Assessor free-text comments describing their rating rationale were used to explore a relationship between the language used by the crowd and grading accuracy. Results: Of a total possible global performance score of 3-15, 10 experienced surgeons graded the suturing video at a mean score of 12.11 (95% confidence interval [CI], 11.11-13.11). Mechanical Turk and Facebook graders rated the video at mean scores of 12.21 (95% CI, 11.98-12.43) and 12.06 (95% CI, 11.57-12.55), respectively. It took 24 h to obtain responses from 501 Mechanical Turk subjects, whereas it took 24 d for 10 faculty surgeons to complete the 3-min survey. Facebook subjects (110) responded within 25 d. Language analysis indicated that crowdworkers who used negation words (i.e., "but," "although," and so forth) scored the performance more equivalently to experienced surgeons than crowdworkers who did not (P < 0.00001). Conclusions: For a robotic suturing performance, we have shown that surgery-naive crowdworkers can rapidly assess skill equivalent to experienced faculty surgeons using Crowd-Sourced Assessment of Technical Skill. It remains to be seen whether crowds can discriminate different levels of skill and can accurately assess human surgery performances. © 2013 Elsevier Inc. All rights reserved.
PLANET HUNTERS. VII. DISCOVERY OF A NEW LOW-MASS, LOW-DENSITY PLANET (PH3 C) ORBITING KEPLER-289 WITH MASS MEASUREMENTS OF TWO ADDITIONAL PLANETS (PH3 B AND D)
ASTROPHYSICAL JOURNAL 795 (2014) ARTN 167
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 445 (2014) 3466-3474
The ultraviolet attenuation law in backlit spiral galaxies Based in part on observations made with the NASA Galaxy Evolution Explorer. GALEX is operated for NASA by the California Institute of Technology under NASA contract NAS5-98034.
Astronomical Journal 147 (2014)
The effective extinction law (attenuation behavior) in galaxies in the emitted ultraviolet (UV) regime is well known only for actively star-forming objects and combines effects of the grain properties, fine structure in the dust distribution, and relative distributions of stars and dust. We use Galaxy Evolution Explorer, XMM Optical Monitor, and Hubble Space Telescope (HST) data to explore the UV attenuation in the outer parts of spiral disks which are backlit by other UV-bright galaxies, starting with the candidate list of pairs provided by Galaxy Zoo participants. New optical images help to constrain the geometry and structure of the target galaxies. Our analysis incorporates galaxy symmetry, using non-overlapping regions of each galaxy to derive error estimates on the attenuation measurements. The entire sample has an attenuation law across the optical and UV that is close to the Calzetti et al. form; the UV slope for the overall sample is substantially shallower than found by Wild et al., which is a reasonable match to the more distant galaxies in our sample but not to the weighted combination including NGC 2207. The nearby, bright spiral NGC 2207 alone gives an accuracy almost equal to the rest of our sample, and its outer arms have a very low level of foreground starlight. Thus, this widespread, fairly "gray" law can be produced from the distribution of dust alone, without a necessary contribution from differential escape of stars from dense clouds. Our results indicate that the extrapolation needed to compare attenuation between backlit galaxies at moderate redshifts from HST data, and local systems from Sloan Digital Sky Survey and similar data, is mild enough to allow the use of galaxy overlaps to trace the cosmic history of dust in galaxies. For NGC 2207, HST data in the near-UV F336W band show that the covering factor of clouds with small optical attenuation becomes a dominant factor farther into the UV, which opens the possibility that widespread diffuse dust dominates over dust in star-forming regions deep into the UV. Comparison with published radiative-transfer models indicates that the role of dust clumping dominates over differences in grain populations at this coarse spatial resolution. © 2014. The American Astronomical Society. All rights reserved.
Erratum: Planet hunters. V. A confirmed jupiter-size planet in the habitable zone and 42 planet candidates from the kepler archive data (ApJ (2013) 776 (10))
Astrophysical Journal 778 (2013)
Measuring the conceptual understandings of citizen scientists participating in zooniverse projects: A first approach
Astronomy Education Review 12 (2013)
The Zooniverse projects turn everyday people into "citizen scientists" who work online with real data to assist scientists in conducting research on a variety of topics related to galaxies, exoplanets, lunar craters, and solar flares, among others. This paper describes our initial study to assess the conceptual knowledge and reasoning abilities of citizen scientists participating in two Zooniverse projects: Galaxy Zoo and Moon Zoo. In order to measure their knowledge and abilities, we developed two new assessment instruments, the Zooniverse Astronomical Concept Survey (ZACS) and the Lunar Cratering Concept Inventory (LCCI). We found that citizen scientists with the highest level of participation in the Galaxy Zoo and Moon Zoo projects also have the highest average correct scores on the items of the ZACS and LCCI. However, the limited nature of the data provided by Zooniverse participants prevents us from being able to evaluate the statistical significance of this finding, and we make no claim about whether there is a causal relationship between one's participation in Galaxy Zoo or Moon Zoo and one's level of conceptual understanding or reasoning ability on the astrophysical topics assessed by the ZACS or the LCCI. Overall, both the ZACS and the LCCI provide Zooniverse's citizen scientists with items that offer a wide range of difficulties. Using the data from the small subset of participants who responded to all items of the ZACS, we found evidence suggesting the ZACS is a reliable instrument (α=0.78), although twenty-one of its forty items appear to have point biserials less than 0.3. The work reported here provides significant insight into the strengths and limitations of various methods for administering assessments to citizen scientists. Researchers who wish to study the knowledge and abilities of citizen scientists in the future should be sure to design their research methods to avoid the pitfalls identified by our initial findings. © 2013 The American Astronomical Society.
ASTRONOMY & GEOPHYSICS 54 (2013) 37-38
AAAI Workshop - Technical Report WS-13-18 (2013) 103-
The Zooniverse (zooniverse.org) began in 2007 with the launch of Galaxy Zoo, a project in which more than 175,000 people provided shape analyses of more than 1 million galaxy images sourced from the Sloan Digital Sky Survey. These galaxy 'classifications', some 60 million in total, have subsequently been used to produce more than 50 peer-reviewed publications based not only on the original research goals of the project but also because of serendipitous discoveries made by the volunteer community. Based upon the success of Galaxy Zoo the team have gone on to develop more than 25 web-based citizen science projects, all with a strong research focus in a range of subjects from astronomy to zoology where human-based analysis still exceeds that of machine intelligence. Over the past 6 years Zooniverse projects have collected more than 300 million data analyses from over 1 million volunteers providing fantastically rich datasets for not only the individuals working to produce research from their projects but also the machine learning and computer vision research communities. The Zooniverse platform has always been developed to be the 'simplest thing that works', implementing only the most rudimentary algorithms for functionality such as task allocation and user-performance metrics. These simplifications have been necessary to scale the Zooniverse so that the core team of developers and data scientists can remain small and the cost of running the computing infrastructure relatively modest. To date these simplifications have been acceptable for the data volumes and analysis tasks being addressed. This situation however is changing: next generation telescopes such as the Large Synoptic Sky Telescope (LSST) will produce data volumes dwarfing those previously analyzed. If citizen science is to have a part to play in analyzing these next-generation datasets then the Zooniverse will need to evolve into a smarter system capable for example of modeling the abilities of users and the complexities of the data being classified in real time. In this session we will outline the current architecture of the Zooniverse platform and introduce new functionality being developed that should be of interest to the HCOMP community. Our platform is evolving into a system capable of integrating human and machine intelligence in a live environment. Data APIs providing realtime access to 'event streams' from the Zooniverse infrastructure are currently being tested as well as API endpoints for making decisions about for example what piece of data to show next to a volunteer as well as when to retire a piece of data from the live system because a consensus has been reached.