S. Osłowski
A5003985421- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Geophysics and Gravity Measurements
- Gamma-ray bursts and supernovae
- Advanced Frequency and Time Standards
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- GNSS positioning and interference
- Cosmology and Gravitation Theories
- Stellar, planetary, and galactic studies
- Geophysics and Sensor Technology
- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Medical Imaging Techniques and Applications
- High-pressure geophysics and materials
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Seismic Waves and Analysis
- Statistical and numerical algorithms
- Solar and Space Plasma Dynamics
- Adaptive optics and wavefront sensing
- Particle Accelerators and Free-Electron Lasers
- Scientific Research and Discoveries
- Ionosphere and magnetosphere dynamics
- Inertial Sensor and Navigation
Manly Hospital
2021-2024
Swinburne University of Technology
2012-2022
Bielefeld University
2014-2020
Max Planck Institute for Radio Astronomy
2014-2020
ARC Centre of Excellence for Gravitational Wave Discovery
2018-2020
Australian Research Council
2018-2020
Max Planck Society
2015
Australia Telescope National Facility
2010-2014
Commonwealth Scientific and Industrial Research Organisation
2009-2014
Astronomy and Space
2011-2014
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...
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.
We present new limits on an isotropic stochastic gravitational-wave background (GWB) using a six pulsar dataset spanning 18 yr of observations from the 2015 European Pulsar Timing Array data release. Performing Bayesian analysis, we fit simultaneously for intrinsic noise parameters each pulsar, along with common correlated signals including clock, and Solar System ephemeris errors, obtaining robust 95$\%$ upper limit dimensionless strain amplitude $A$ $A<3.0\times 10^{-15}$ at reference...
A "pulsar timing array" (PTA), in which observations of a large sample pulsars spread across the celestial sphere are combined, allows investigation "global" phenomena such as background gravitational waves or instabilities atomic timescales that produce correlated residuals array. The Parkes Pulsar Timing Array (PPTA) is an implementation PTA concept based on with 64-m radio telescope. 20 millisecond being observed at three radio-frequency bands, 50cm (~700 MHz), 20cm (~1400 MHz) and 10cm...
Placing bounds on gravitational wave detection Gravitational waves are expected to be generated by the interaction of massive bodies in black-hole binary systems. As distort spacetime, it should possible verify their existence as they interfere with pulses emitted millisecond pulsars. However, after monitoring 24 pulsars Parkes radio telescope for 12 years, Shannon et al. found no detectable variation pulsar records. This nondetection result indicates that a new strategy is needed. Science ,...
The highly stable spin of neutron stars can be exploited for a variety (astro)physical investigations. In particular, arrays pulsars with rotational periods the order milliseconds used to detect correlated signals such as those caused by gravitational waves. Three ‘pulsar timing arrays’ (PTAs) have been set up around world over past decades and collectively form ‘International’ PTA (IPTA). this paper, we describe first joint analysis data from three regional PTAs, i.e. IPTA set. We available...
We report on the high-precision timing of 42 radio millisecond pulsars (MSPs) observed by European Pulsar Timing Array (EPTA). This EPTA Data Release 1.0 extends up to mid-2014 and baselines range from 7-18 years. It forms basis for stochastic gravitational-wave background, anisotropic continuous-wave limits recently presented elsewhere. The Bayesian analysis performed with TempoNest yields detection several new parameters: seven parallaxes, nine proper motions and, in case six binary...
Pinpointing a single fast radio burst Fast bursts (FRBs) are flashes of emission from distant astronomical sources. Two FRBs known to have repeated, but most last just few milliseconds and never seen again. Most telescopes that sensitive poor angular resolutions, so the FRB host galaxies remain unknown. Bannister et al. used dedicated observing mode on interferometer detect localize nonrepeating 180924, then followed up with optical telescope observations (see Perspective by Petroff). They...
We present timing models for 20 millisecond pulsars in the Parkes Pulsar Timing Array. The precision of parameter measurements these has been improved over earlier results by using longer data sets and modelling non-stationary noise. describe a new noise procedure demonstrate its effectiveness simulated data. Our methodology includes addition annual dispersion measure (DM) variations to some pulsars. first significant parallax PSRs J1024−0719, J1045−4509, J1600−3053, J1603−7202, J1730−2304,...
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...
We have searched for continuous gravitational wave (CGW) signals produced by individually resolvable, circular supermassive black hole binaries (SMBHBs) in the latest EPTA dataset, which consists of ultra-precise timing data on 41 millisecond pulsars. develop frequentist and Bayesian detection algorithms to search both monochromatic frequency-evolving systems. None adopted show evidence presence such a CGW signal, indicating that are best described pulsar radiometer noise only. Depending...
The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in new era multi-messenger astronomy. In this paper, we present event GW170817 and its SSS17a/DLT17ck (IAU label AT2017gfo) 14 Australian telescopes partner observatories as part Australian-based Australian-led research programs. We report early- late-time multi-wavelength observations, including optical imaging spectroscopy,...
Quantum fluctuations of the gravitational field in early Universe, amplified by inflation, produce a primordial gravitational-wave background across broad frequency band. We derive constraints on spectrum this radiation, and hence theories combining experiments that cover 29 orders magnitude frequency. These include Planck observations cosmic microwave temperature polarization power spectra lensing, together with baryon acoustic oscillations big bang nucleosynthesis measurements, as well new...
Abstract We describe system verification tests and early science results from the pulsar processor (PTUSE) developed for newly commissioned 64-dish SARAO MeerKAT radio telescope in South Africa. is a high-gain ( ${\sim}2.8\,\mbox{K Jy}^{-1}$ ) low-system temperature ${\sim}18\,\mbox{K at }20\,\mbox{cm}$ array that currently operates 580–1 670 MHz can produce tied-array beams suitable observations. This paper presents MeerTime Large Survey Project commissioning with PTUSE. Highlights include...
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 ×...
Signals from radio pulsars show a wavelength-dependent delay due to dispersion in the interstellar plasma. At typical observing wavelength, this can vary by tens of microseconds on five-year time scales, far excess signals interest pulsar timing arrays, such as that induced gravitational-wave background. Measurement these variations is not only crucial for detection signals, but also provides an unparallelled measurement turbulent plasma at au scales. In paper we demonstrate without...
Using observations of pulsars from the Parkes Pulsar Timing Array (PPTA) project we develop first pulsar-based timescale that has a precision comparable to uncertainties in international atomic timescales.Our ensemble provides an Ensemble Scale (EPS) analogous free Échelle Atomique Libre (EAL).The EPS can be used detect fluctuations timescales and therefore lead new realisation Terrestrial Time, TT(PPTA11).We successfully follow features known affect frequency International Atomic Timescale...
The formation and growth processes of supermassive black holes (SMBHs) are not well constrained. SMBH population models, however, provide specific predictions for the properties gravitational-wave background (GWB) from binary SMBHs in merging galaxies throughout Universe. Using observations Parkes Pulsar Timing Array, we constrain fractional GWB energy density with 95% confidence to be ${\Omega}_{GW}(H_0/73 {\rm km} s}^{-1} Mpc}^{-1})^2 < 1.3 \times 10^{-9}$ at a frequency 2.8 nHz, which is...
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...
We present high signal-to-noise ratio, multifrequency polarization pulse profiles for 24 millisecond pulsars that are being observed as part of the Parkes Pulsar Timing Array project. The in three bands, centred close to 730, 1400 and 3100 MHz, using a dual-band 10 cm/50 cm receiver central beam 20-cm multibeam receiver. Observations spanning approximately six years have been carefully calibrated summed produce S/N profiles. This allows us study individual profile components particular how...