Anne M. Archibald
A5030889135- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Geophysics and Gravity Measurements
- Radio Astronomy Observations and Technology
- High-pressure geophysics and materials
- Astrophysics and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Stellar, planetary, and galactic studies
- Advanced Frequency and Time Standards
- Particle Accelerators and Free-Electron Lasers
- Superconducting Materials and Applications
- Mechanics and Biomechanics Studies
- GNSS positioning and interference
- Relativity and Gravitational Theory
- Particle accelerators and beam dynamics
- Geophysics and Sensor Technology
- Seismic Waves and Analysis
- Seismology and Earthquake Studies
- Geological and Geophysical Studies
- Black Holes and Theoretical Physics
- Atomic and Subatomic Physics Research
- Astronomy and Astrophysical Research
- Hippo pathway signaling and YAP/TAZ
- Scientific Research and Discoveries
Newcastle University
2021-2024
University of Amsterdam
2016-2024
University of Alberta
2024
Campbell Collaboration
2023
Netherlands Institute for Radio Astronomy
2013-2021
University of Washington
2019
Anton Proksch Institut
2018
Roslin Institute
2018
The Netherlands Cancer Institute
2018
Cornell University
2018
Abstract The Astropy Project supports and fosters the development of open-source openly developed Python packages that provide commonly needed functionality to astronomical community. A key element is core package astropy , which serves as foundation for more specialized projects packages. In this article, we summarize features in recent major release, version 5.0, updates on Project. We then discuss supporting a broader ecosystem interoperable packages, including connections with several...
Abstract We report multiple lines of evidence for a stochastic signal that is correlated among 67 pulsars from the 15 yr pulsar timing data set collected by North American Nanohertz Observatory Gravitational Waves. The correlations follow Hellings–Downs pattern expected gravitational-wave background. presence such background with power-law spectrum favored over model only independent noises Bayes factor in excess 10 14 , and this same an uncorrelated common factors 200–1000, depending on...
The International Pulsar Timing Array project combines observations of pulsars from both northern and southern hemisphere observatories with the main aim detecting ultra-low frequency (∼ 10−9–10−8 Hz) gravitational waves. Here we introduce project, review methods used to search for waves emitted coalescing supermassive binary black-hole systems in centres merging galaxies discuss status project.
Radio pulsars with millisecond spin periods are thought to have been spun up by transfer of matter and angular momentum from a low-mass companion star during an X-ray-emitting phase. The the neutron stars in several such X-ray binary (LMXB) systems shown be regime, but no radio pulsations detected. Here we report on detection follow-up observations nearby pulsar (MSP) circular orbit optically identified star. Optical indicate that accretion disk was present this system within last decade....
Abstract The 15 yr pulsar timing data set collected by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) shows positive evidence presence of a low-frequency gravitational-wave (GW) background. In this paper, we investigate potential cosmological interpretations signal, specifically cosmic inflation, scalar-induced GWs, first-order phase transitions, strings, and domain walls. We find that, with exception stable strings field theory origin, all these models can...
Millisecond radio pulsars acquire their rapid rotation rates through mass and angular momentum transfer in a low-mass X-ray binary system. Recent studies of PSR J1824−2452I J1023+0038 have observationally demonstrated this link, they also shown that such systems can repeatedly transition back-and-forth between the millisecond pulsar states. This suggests fraction are not newly born but rather suspended back-and-forth, state-switching phase, perhaps for gigayears. XSS J12270−4859 has been...
The NANOGrav 15-year data set shows evidence for the presence of a low-frequency gravitational-wave background (GWB). While many physical processes can source such gravitational waves, here we analyze signal as coming from population supermassive black hole (SMBH) binaries distributed throughout Universe. We show that astrophysically motivated models SMBH binary populations are able to reproduce both amplitude and shape observed spectrum. multiple model variations GWB spectrum at our current...
Abstract We present observations and timing analyses of 68 millisecond pulsars (MSPs) comprising the 15 yr data set North American Nanohertz Observatory for Gravitational Waves (NANOGrav). NANOGrav is a pulsar array (PTA) experiment that sensitive to low-frequency gravitational waves (GWs). This NANOGrav’s fifth public release, including both “narrowband” “wideband” time-of-arrival (TOA) measurements corresponding models. have added 21 MSPs extended our baselines by 3 yr, now spanning nearly...
We describe an ongoing search for pulsars and dispersed pulses of radio emission, such as those from rotating transients (RRATs) fast bursts, at 350 MHz using the Green Bank Telescope. With Ultimate Pulsar Processing Instrument, we record 100 bandwidth divided into 4096 channels every 81.92 μs. This survey will cover entire sky visible to Telescope (δ > −40°, or 82% sky) outside Galactic Plane be sensitive enough detect slow low dispersion measure (<30 pc cm−3) millisecond (MSPs) with a 0.08...
We present radio and γ-ray observations, which, along with concurrent X-ray reveal that the binary millisecond pulsar (MSP)/low-mass transition system PSR J1023+0038 has undergone a transformation in state. Whereas until recently harbored bright pulsar, pulsations at frequencies between 300 to 5000 MHz have now become undetectable. Concurrent this disappearance, flux of quintupled. conclude that, though is currently not detectable, mechanism still active wind, as well newly formed accretion...
We report the first detections of repeating fast radio burst source FRB 121102 above 5.2 GHz. Observations were performed using 4$-$8 GHz receiver Robert C. Byrd Green Bank Telescope with Breakthrough Listen digital backend. present spectral, temporal and polarization properties 21 bursts detected within 60 minutes a total 6-hour observations. These observations comprise highest density yet reported in literature, 18 being 30 minutes. A few clearly show sub-structures distinct spectral...
Abstract FRB 121102 is the only known repeating fast radio burst source. Here we analyze a wide-frequency-range (1–8 GHz) sample of high signal-to-noise, coherently dedispersed bursts detected using Arecibo and Green Bank telescopes. These reveal complex time–frequency structures that include subbursts with finite bandwidths. The frequency-dependent structure complicates determination dispersion measure (DM); argue it appropriate to use DM metric maximizes frequency-averaged pulse structure,...
Pulsar timing arrays (PTAs) are galactic-scale gravitational wave detectors. Each individual arm, composed of a millisecond pulsar, radio telescope, and kiloparsecs-long path, differs in its properties but, aggregate, can be used to extract low-frequency (GW) signals. We present noise sensitivity analysis accompany the NANOGrav 15-year data release associated papers, along with an in-depth introduction PTA models. As first step our analysis, we characterize each pulsar set three types white...
Abstract Evidence for a low-frequency stochastic gravitational-wave background has recently been reported based on analyses of pulsar timing array data. The most likely source such is population supermassive black hole binaries, the loudest which may be individually detected in these data sets. Here we present search individual binaries NANOGrav 15 yr set. We introduce several new techniques, enhance efficiency and modeling accuracy analysis. uncovered weak evidence two candidate signals,...
Abstract The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has reported evidence the presence of an isotropic nanohertz gravitational-wave background (GWB) in its 15 yr data set. However, if GWB is produced by a population inspiraling supermassive black hole binary (SMBHB) systems, then predicted to be anisotropic, depending on distribution these systems local Universe and statistical properties SMBHB population. In this work, we search anisotropy using multiple...
Abstract The Australian, Chinese, European, Indian, and North American pulsar timing array (PTA) collaborations recently reported, at varying levels, evidence for the presence of a nanohertz gravitational-wave background (GWB). Given that each PTA made different choices in modeling their data, we perform comparison GWB individual noise parameters across results reported from PTAs constitute International Pulsar Timing Array (IPTA). We show despite making choices, there is no significant...
Abstract The NANOGrav 15 yr data provide compelling evidence for a stochastic gravitational-wave (GW) background at nanohertz frequencies. simplest model-independent approach to characterizing the frequency spectrum of this signal consists simple power-law fit involving two parameters: an amplitude A and spectral index γ . In Letter, we consider next logical step beyond minimal model, allowing running (i.e., logarithmic dependence) index, <mml:math...
PSR J1023+0038 is an exceptional system for understanding how slowly rotating neutron stars are spun up to millisecond rotational periods through accretion from a companion star. Observed as radio pulsar 2007–2013, optical data showed that the had disk in 2000/2001. Starting at end of 2013 June, has become undetectable, suggesting return previous accretion-disk state, where more closely resembles X-ray binary. In this Letter we report first targeted observations ever performed active phase...