Rapid Bayesian position reconstruction for gravitational-wave transients

Within the next few years, Advanced LIGO and Virgo should detect gravitational waves from binary neutron star and neutron star-black hole mergers. These sources are also predicted to power a broad array of electromagnetic transients. Because the electromagnetic signatures can be faint and fade rapidly, observing them hinges on rapidly inferring the sky location from the gravitational-wave observations. Markov chain Monte Carlo methods for gravitational-wave parameter estimation can take hours or more. We introduce BAYESTAR, a rapid, Bayesian, non-Markov chain Monte Carlo sky localization algorithm that takes just seconds to produce probability sky maps that are comparable in accuracy to the full analysis. Prompt localizations from BAYESTAR will make it possible to search electromagnetic counterparts of compact binary mergers.Comment: 23 pages, 12 figures, published in Phys. Rev.

The Needle in the Hundred-Square-Degree Haystack: from Fermi GRBs to LIGO Discoveries

Accurate localizations have driven and enriched our understanding of gamma-ray bursts. They could do the same for future gravitational-wave detections with LIGO and Virgo. We report the discovery of the optical afterglow of the gamma-ray burst (GRB) 130702A, identified upon searching 71 square degrees surrounding the Fermi Gamma-ray Burst Monitor (GBM) localization. Discovered and characterized by the intermediate Palomar Transient Factory (iPTF), iPTF13bxl is the first afterglow discovered solely based on a GBM localization. Real-time image subtraction, machine learning, human vetting, and rapid response multi-wavelength follow-up enabled us to quickly narrow a list of 27,004 optical transient candidates to a single afterglow-like source. The bright afterglow and emerging supernova offered an opportunity for extensive panchromatic follow-up. Furthermore, our discovery of iPTF13bxl represents an important step towards overcoming the challenges inherent in uncovering faint optical counterparts to comparably localized gravitational wave events in the Advanced LIGO and Virgo era

Outlook for detection of GW inspirals by GRB-triggered searches in the Advanced detector era

Short, hard gamma-ray bursts (GRBs) are believed to originate from the coalescence of two neutron stars (NSs) or a NS and a black hole (BH). If this scenario is correct, then short GRBs will be accompanied by the emission of strong gravitational waves (GWs), detectable by GW observatories such as LIGO, Virgo, KAGRA, and LIGO-India. As compared with blind, all-sky, all-time GW searches, externally triggered searches for GW counterparts to short GRBs have the advantages of both significantly reduced detection threshold due to known time and sky location and enhanced GW amplitude because of face-on orientation. Based on the distribution of signal-to-noise ratios in candidate compact binary coalescence events in the most recent joint LIGO-Virgo data, our analytic estimates, and our Monte Carlo simulations, we find an effective sensitive volume for GRB-triggered searches that is about 2 times greater than for an all-sky, all-time search. For NS-NS systems, a jet angle of 20 degrees, a gamma-ray satellite field of view of 10% of the sky, and priors with generally precessing spin, this doubles the number of NS-NS short-GRB and NS-BH short-GRB associations, to ~3-4% of all detections of NS-NSs and NS-BHs. We also investigate the power of tests for statistical excesses in lists of subthreshold events, and show that these are unlikely to reveal a subthreshold population until finding GW associations to short GRBs is already routine. Finally, we provide useful formulas for calculating the prior distribution of GW amplitudes from a compact binary coalescence, for a given GW detector network and given sky location.Comment: 14 pages, 4 figures, published in PRD; this version includes changes in final copyedited articl

Summary of Three Dissertation Recitals

In each of the three dissertation cello recitals, music from a different nation is featured. The first is music from France, the second from Germany and Austria, and the third from America. The repertoire chosen was meant to provide audiences with music receiving varying levels of notoriety and containing a wide range of compositional technique and style. Recital #1: Music from France - December 13th, 2020 in Stamps Auditorium Featuring: Narae Joo, piano This recital features well-known composers Gabriel Fauré and Claude Debussy, and other lesser known composers Arthur Honegger and Louis Vierne. Each of the works on this program presents a level of obscurity either for being rarely performed or for being reimagined from its original instrumentation: Sonatine for Clarinet or Cello and Piano, H. 42 by Arthur Honegger Cello Sonata No. 1, Op. 109 by Gabriel Fauré “Syrinx” by Claude Debussy arr. for Cello and Piano Cello Sonata, Op. 27 by Louis Vierne Recital #2: Music from Germany and Austria - February 21st, 2020 in Britton Recital Hall Featuring: Ji-Hyang Gwak, Narae Joo, Natalie Sherer, piano and Danielle Belen, violin The works on this concert are centered around the great Arnold Schoenberg. The pieces featured are by the composer himself, his students, people who lived in similar historical context to him, and his greatest influences. Many of the works are rethought for cello from their original vocal versions. Another goal of this particular program is to illustrate a more accessible side to the earlier writings of the Second Viennese School: “Waldesnacht” by Arnold Schoenberg arr. for Cello and Piano Zwei Lieder, Op. 14 by Arnold Schoenberg arr. for Cello and Piano Cello Sonata by Anton Webern Sieben Frühe Lieder by Alban Berg arr. for Cello and Piano Divertimento, Op. 37, No. 1 by Ernst Toch “O Tod” from Vier ernste Gesänge, Op. 121 by Johannes Brahms arr. for Cello and Piano Cello Sonata by Alexander Zemlinsky Recital #3: Music from America - March 20th, 2020 in Stamps Auditorium Featuring: Narae Joo, Michelle Papenfuss, piano The pieces performed on this recital were all written in America in the last seventy-five years. Each contains deep, powerful historical and/or personal significance to the composers that wrote them: Ricordanza (Soliloquy for Cello and Piano) by George Rochberg Abu Ghraib by John Harbison Three Pieces for Cello and Piano by Samuel Adler Sonata for Cello and Piano by Elliott CarterAMUMusic: PerformanceUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/155286/1/lrsinger_1.pd

The Needle in the Hundred-Square-Degree Haystack: from Fermi GRBs to LIGO Discoveries

Accurate localizations have driven and enriched our understanding of gamma-ray bursts. They could do the same for future gravitational-wave detections with LIGO and Virgo. We report the discovery of the optical afterglow of the gamma-ray burst (GRB) 130702A, identified upon searching 71 square degrees surrounding the Fermi Gamma-ray Burst Monitor (GBM) localization. Discovered and characterized by the intermediate Palomar Transient Factory (iPTF), iPTF13bxl is the first afterglow discovered solely based on a GBM localization. Real-time image subtraction, machine learning, human vetting, and rapid response multi-wavelength follow-up enabled us to quickly narrow a list of 27,004 optical transient candidates to a single afterglow-like source. The bright afterglow and emerging supernova offered an opportunity for extensive panchromatic follow-up. Furthermore, our discovery of iPTF13bxl represents an important step towards overcoming the challenges inherent in uncovering faint optical counterparts to comparably localized gravitational wave events in the Advanced LIGO and Virgo era

Planned search for LIGO-GBM coincidence in the first advanced LIGO data run

In the fall of 2015 the first scientific observing run (O1) of the advanced LIGO detectors will be conducted. Based on the recent commissioning progress at the LIGO Hanford and Livingston sites, the gravitational wave detector range for a neutron star binary inspiral is expected to be of order 60 Mpc. We describe here our planning for an O1 search for coincidence between a LIGO gravitational wave detection and a gamma-ray signal from the Fermi Gamma-ray Burst Monitor. Such a coincidence would constitute measurement of an electromagnetic counterpart to a gravitational wave signal, with significant corresponding scientific benefits, including revealing the central engine powering the gamma-ray burst, enhanced confidence in the event as a genuine astrophysical detection, and a determination of the relative speed of the photon and graviton.Comment: Submitted to Moriond Gravitation Conference Proceedings 201

Understanding health inequalities in multimorbidity and functional limitation of the ageing population in England

The thesis explored the social and life course factors behind the prevalence and risk of multimorbidity and functional limitation as well as their unequal distribution in the ageing population of England. Multimorbidity is the co-occurrence of two or more diseases within a person. Functional limitations are restrictions in performing fundamental physical and mental actions used in daily life. The thesis identified previously unmeasured inequality in the population with multimorbidity and functional limitation. People aged 50-54 years with the least household wealth had the same prevalence of complex multimorbidity as those 20 years older in the most affluent category and the prevalence of functional limitations comparable to those 30 years older in the top wealth group. Further analysis included a range of material, psychosocial and behavioural determinants into the analysis. Household wealth, sense of control over personal life, physical activity and loneliness were associated with the risk of multimorbidity and functional limitation. Finally, the thesis developed a pathway model of how childhood circumstances – social class, adverse experiences and health – affect the risk of multimorbidity and functional limitation in old age. The material, psychosocial and behavioural pathways acted as magnifiers of inequalities from the early life period

Childhood circumstances shape multimorbidity and functional limitation in the old age in England: a life course pathway model

The study presents a pathway model of the risk of multimorbidity and functional limitation from childhood to old age. Childhood circumstances, measured as parents’ social class, adverse experiences and child’s health, influenced multimorbidity and functional limitation at old age indirectly via material, psychosocial and behavioural pathways. These pathways acted as magnifiers of early inequalities: they enhanced the unequal impacts of the pre-existing differences between individuals in socio-economic position, psychological connections and health. The pathway effects measured at age 50-64 years were larger than the total effects of childhood social class, adverse experiences and child’s health. Thus pre-retirement appears to be an important period for the health of ageing adults in England. However, in people suffering from complex multimorbidity the total effect of the adverse experiences of abuse and family dysfunction in childhood surpassed the effect of adult psychosocial circumstances. This suggests an early-life sensitive period for this outcome. The strength of the paper is that childhood circumstances were approached from a broader angle than the usual focus on either the material conditions or extreme experiences of children. The framework is based on a complex mediation analysis with both parallel and serial mediators where the SEM framework with latent factors is an excellent tool to handle multiple regression relationships and measurement error.</p