Recent Posts

Below you will see a visualisation of the maneuvers that the Swift spacecraft performed in the course of its tiling observations in response to GW170817. This campaign was comprised of 744 individual pointings that covered 92% of the galaxy-convolved gravitational wave error region. Swift is the only spacecraft that can perform this type of fast-response tiling, and will remain so for the foreseeable future. The video shows a skymap. The large and small red circles are the sun and moon constraints on the sky, respectively.

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On August 17, 2017 the first object ever detected with both gravitational waves and light was found, now known as AT 2017gfo. The initial LIGO/Virgo and Fermi GBM alerts sent astronomers all over the world dashing to their telescopes to try and localize the electromagnetic counterpart in the relatively small (compared to past events) but still quite large localization region. The counterpart was independently found in the first night of searching by several different teams, though the Swope Supernova Survey were the first to report it.

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This post is about a very tricky math puzzle, and really has very little to do with aliens or presidents. This puzzle made the rounds stumping people at Reed College in 2014, and was created by my friend Steve Silverman (who seems to have an unlimited supply of unique puzzles of his own design). All credit for cleverness and ingenuity goes to him. This post was written because there were several people who did not believe that this puzzle had a real, unique, solution or else that there was some wordplay involved rather than mathematics.

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The first one-and-a-half lines of Genesis go as follows: …בראשית ברא אלהים את השמים ואת הארץ. והארץ היתה תהו ובהו וחשך על־פני תהום In the Hebrew text above, the phrase ‘Tohu va-vohu’ is in bold, the 3rd and 4th words of the second sentence (right-to-left). These lines are commonly translated as: “In the beginning, God created the Heavens and the Earth. And the Earth was Tohu va-vohu and darkness was on the face of the deep…”

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Selected Talks

July 10: Invited seminar at Columbia University on joint gamma-ray/GW sub-threshold searches with Swift/BAT.

June 6: Invited colloquium at the Albert Einstein institute in Hanover, on The search for UV and gamma-ray transient counterparts to gravitational wave events.
April 25: Invited talk at the Enabling Multi-messenger Astrophysics in the Big Data Era Workshop .
January 8: Talk at the American Astronomical Society #233 titled 'Swift in the gravitational wave era: results from O2 and optimization for the future.'


Dec 2: Poster and sparkler talk at the Gravitational Wave Physics and Astronomy Workshop titled 'Chasing the LIGO lobes across the sky: Increasing the GW/GRB yield with Swift/BAT biasing.'
May 16: Talk at the FRIB Neutron Star Merger summer school titled 'Swift's sGRB legacy and new capabilities for the multi-messenger era.'
May 11: Talk at the Swift X-ray Telescope Team Meeting at the Open University, UK titled 'Searching for the 3.5 keV line in M31 and ultra-faint dwarfs with Swift'.

November 7: Lunch talk to the Astro department at Penn State on Swift's hunt for EM counterparts to gravitational-wave events.
November 5: Talk at the Mid-Atlantic APS titled Searching for the radiative decay of sterile neutrino dark matter with Swift XRT.
October 30: Lay-talk to a public audience at Astronomy on Tap: State College titled 'Hearing and Seeing the Universe: Hunting for EM counterparts to gravitational-waves with Swift.' Video.
October 19: Talk titled Swift as a follow-up engine for GW triggers: Improving for O3 at the IAU Symposium Gravitational Wave Astrophysics: Early Results from GW Searches and Electromagnetic Counterparts in Baton Rouge, Louisiana.
October 14: Talk titled 'The absence of (true) bound states for the single-particle Dirac equation on the Kerr black hole' at the 27th Midwest Relativity Meeting in Ann Arbor, Michigan.