Craig Russell
A5022260477- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Geophysics and Gravity Measurements
- Software-Defined Networks and 5G
- Cosmology and Gravitation Theories
- Internet Traffic Analysis and Secure E-voting
- Energy Efficiency and Management
- Network Traffic and Congestion Control
- Network Security and Intrusion Detection
- GNSS positioning and interference
- Gamma-ray bursts and supernovae
- Superconducting Materials and Applications
- Advanced Optical Network Technologies
- Astrophysics and Cosmic Phenomena
- Ionosphere and magnetosphere dynamics
- Dark Matter and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Advanced Frequency and Time Standards
- Global Energy and Sustainability Research
- Earthquake Detection and Analysis
- Computational Physics and Python Applications
- Terahertz technology and applications
- Seismic Waves and Analysis
- Wind Energy Research and Development
- Power Line Communications and Noise
Commonwealth Scientific and Industrial Research Organisation
2016-2025
Australia Telescope National Facility
2019-2023
University of Delaware
2023
UNSW Sydney
2021-2022
Services Australia
2017-2021
Data61
2016-2019
Astronomy and Space
2019
University of California, Los Angeles
2018
Oak Ridge National Laboratory
2015
Collaboration for Australian Weather and Climate Research
2012
Abstract Pulsar timing arrays aim to detect nanohertz-frequency gravitational waves (GWs). A background of GWs modulates pulsar arrival times and manifests as a stochastic process, common all pulsars, with signature spatial correlation. Here we describe search for an isotropic gravitational-wave (GWB) using observations 30 millisecond pulsars from the third data release Parkes Timing Array (PPTA), which spans 18 yr. Using current Bayesian inference techniques recover characterize...
We searched for an isotropic stochastic gravitational wave background in the second data release of International Pulsar Timing Array, a global collaboration synthesizing decadal-length pulsar-timing campaigns North America, Europe, and Australia. In our reference search power law strain spectrum form $h_c = A(f/1\,\mathrm{yr}^{-1})^{\alpha}$, we found strong evidence spectrally-similar low-frequency process amplitude $A 3.8^{+6.3}_{-2.5}\times10^{-15}$ spectral index $\alpha -0.5 \pm 0.5$,...
In this paper, we describe the International Pulsar Timing Array second data release, which includes recent pulsar timing obtained by three regional consortia: European Array, North American Nanohertz Observatory for Gravitational Waves, and Parkes Array. We analyse where possible combine high-precision 65 millisecond pulsars are regularly observed these groups. A basic noise analysis, including processes both correlated uncorrelated in time, provides models ephemerides pulsars. find that...
Abstract We present the third data release from Parkes Pulsar Timing Array (PPTA) project. The contains observations of 32 pulsars obtained using 64-m ‘Murriyang’ radio telescope. span is up to 18 yr with a typical cadence 3 weeks. This formed by combining an updated version our second $\sim$ more recent primarily ultra-wide-bandwidth receiver system that operates between 704 and 4032 MHz. provide calibrated pulse profiles, flux density dynamic spectra, times arrival, initial pulsar timing...
The noise in millisecond pulsar (MSP) timing data can include contributions from observing instruments, the interstellar medium, solar wind, system ephemeris errors, and pulsars themselves. environment must be accurately characterized order to form null hypothesis which signal models compared, including signature induced by nanohertz-frequency gravitational waves (GWs). Here we describe developed for each of MSPs Parkes Pulsar Timing Array (PPTA) third release, have been used as basis a...
ABSTRACT The International Pulsar Timing Array 2nd data release is the combination of sets from worldwide collaborations. In this study, we search for continuous waves: gravitational wave signals produced by individual supermassive black hole binaries in local universe. We consider on circular orbits and neglect evolution orbital frequency over observational span. find no evidence such set sky averaged 95 per cent upper limits their amplitude h95. most sensitive 10 nHz with h95 = 9.1 ×...
Abstract We describe 14 yr of public data from the Parkes Pulsar Timing Array (PPTA), an ongoing project that is producing precise measurements pulse times arrival 26 millisecond pulsars using 64-m radio telescope with a cadence approximately 3 weeks in three observing bands. A comprehensive description pulsar systems employed at since 2004 provided, including calibration methodology and analysis stability system components. attempt to provide full accounting reduction raw measured Stokes...
It is widely accepted that dark matter contributes about a quarter of the critical mass-energy density in our Universe. The nature currently unknown, with mass possible constituents spanning nearly one hundred orders magnitude. ultralight scalar field matter, consisting extremely light bosons m∼10−22 eV and often called “fuzzy” provides intriguing solutions to some challenges at sub-Galactic scales for standard cold model. As shown by Khmelnitsky Rubakov, such Galaxy would produce an...
A cosmological first-order phase transition is expected to produce a stochastic gravitational wave background. If the temperature on MeV scale, power spectrum of induced waves peaks around nanohertz frequencies, and can thus be probed with high-precision pulsar timing observations. We search for such background latest data set Parkes Pulsar Timing Array. find no evidence Hellings-Downs spatial correlation as Therefore, we present constraints model parameters. Our analysis shows that...
Pulsar timing array projects measure the pulse arrival times of millisecond pulsars for primary purpose detecting nanohertz-frequency gravitational waves. The measurements include contributions from a number astrophysical and instrumental processes, which can either be deterministic or stochastic. It is necessary to develop robust statistical physical models these noise processes because incorrect diminish sensitivity may cause spurious wave detection. Here we characterise 26 in second data...
ABSTRACT The main goal of pulsar timing array experiments is to detect correlated signals such as nanohertz-frequency gravitational waves. Pulsar data collected in dense monitoring campaigns can also be used study the stars themselves, their binary companions, and intervening ionized interstellar medium. Timing observations are extraordinarily sensitive changes path-length between Earth, enabling precise measurements positions, distances velocities, shapes orbits. Here we present a analysis...
Composed of ultralight bosons, fuzzy dark matter provides an intriguing solution to challenges that the standard cold model encounters on sub-galactic scales. The with mass $m\sim10^{-23} \rm{eV}$ will induce a periodic oscillation in gravitational potentials frequency nanohertz band, leading observable effects arrival times radio pulses from pulsars. Unlike scalar matter, pulsar timing signals induced by vector are dependent direction fields. In this work, we search for range $[2\times...
Abstract The observation of neutron stars enables the otherwise impossible study fundamental physical processes. timing binary radio pulsars is particularly powerful, as it precise characterization their (three-dimensional) positions and orbits. PSR J0437–4715 an important millisecond pulsar for array experiments also a primary target Neutron Star Interior Composition Explorer (NICER). main aim NICER mission to constrain star equation state by inferring compactness ( M p / R ) star. Direct...
Abstract Accurate estimates of long-term linear trends wind speed provide a useful indicator for circulation changes in the atmosphere and are invaluable planning financing sectors such as energy. Here large number observations over Australia reanalysis products analyzed to compute trends. After thorough quality control observations, it is found that 1975–2006 1989–2006 sensitive height station: they largely negative 2-m data but predominantly positive 10-m data. The mean relative trend at 2...
Improving energy efficiency of Internet equipment is becoming an increasingly important research topic, motivated by the need to reduce costs (and Carbon footprint) for Service Providers, as well increase power density achieve more switching capacity per-rack. While recent has profiled consumption commercial routing equipment, these profiles are coarse-grained (i.e., at granularity per line-card or port), and moreover such platforms inflexible experimentation with new energy-saving...
ABSTRACT We have constructed a new time-scale, TT(IPTA16), based on observations of radio pulsars presented in the first data release from International Pulsar Timing Array (IPTA). used two analysis techniques with independent estimates noise models for pulsar and different algorithms obtaining time-scale. The analyses agree within estimated uncertainties both TT(BIPM17), post-corrected time-scale produced by Bureau des Poids et Mesures (BIPM). show that methods could detect significant...
Pulsar timing array experiments have recently reported strong evidence for a common-spectrum stochastic process with strain spectral index consistent that expected of nanohertz-frequency gravitational-wave background, but negligible yet non-zero spatial correlations required definitive detection. However, it was pointed out by the Parkes Timing Array (PPTA) collaboration same models used in recent analyses resulted simulations where none is present. In this work, we introduce methodology to...
Pulsar timing array collaborations have recently reported evidence for a noise process with common spectrum among the millisecond pulsars in arrays. The spectral properties of this common-noise are consistent expectations an isotropic gravitational-wave background (GWB) from inspiralling supermassive black-hole binaries. However, recent simulation analyses based on Parkes Timing Array data indicate that such detection may arise spuriously. In paper, we use simulated pulsar datasets to...
Electron heating at Earth's quasiperpendicular bow shock has been surmised to be due the combined effects of a quasistatic electric potential and scattering through wave-particle interaction. Here we report observation electron distribution functions indicating new process occurring leading edge front. Incident solar wind electrons are accelerated parallel magnetic field toward downstream, reaching an electron-ion relative drift speed exceeding thermal speed. The bulk acceleration is...
Abstract A nanohertz-frequency stochastic gravitational-wave background can potentially be detected through the precise timing of an array millisecond pulsars. This produces low-frequency noise in pulse arrival times that would have a characteristic spectrum common to all pulsars and well-defined spatial correlation. Recently North American Nanohertz Observatory for Gravitational Waves collaboration (NANOGrav) found evidence common-spectrum component their 12.5 yr data set. Here we report on...
The nature of dark matter remains obscure in spite decades experimental efforts. mass candidates can span a wide range, and its coupling with the Standard Model sector uncertain. All these unknowns make detection extremely challenging. Ultralight matter, m∼10−22 eV, is proposed to reconcile disagreements between observations predictions from simulations small-scale structures cold paradigm while remaining consistent other observations. Because large de Broglie wavelength local occupation...
We present the third data release from Parkes Pulsar Timing Array (PPTA) project. The contains observations of 32 pulsars obtained using 64-m "Murriyang" radio telescope. span is up to 18 years with a typical cadence 3 weeks. This formed by combining an updated version our second $\sim 3$ more recent primarily ultra-wide-bandwidth receiver system that operates between 704 and 4032 MHz. provide calibrated pulse profiles, flux-density dynamic spectra, times arrival, initial pulsar timing...