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1. chinaXiv:201612.00090 [pdf]

Development of a pulsar-based timescale

G. Hobbs; W. Coles; R. N. Manchester; M. J. Keith,1 R. M. Shannon; D. Chen; M. Bailes,4 N. D. R. Bhat; S. Burke-Spolaor; D. Champion; A. Chaudhary; A. Hotan; J. Khoo,1 J. Kocz; Y. Levin; S.Oslowski; B. Preisig; V. Ravi; J. E. Reynolds; J. Sarkissian; W. van Straten; J. P. W. Verbiest; D. Yardley
Subjects: Geosciences >> Space Physics

Using observations of pulsars from the Parkes Pulsar Timing Array (PPTA) project we develop the first pulsar-based timescale that has a precision comparable to the uncertainties in international atomic timescales. Our ensemble of pulsars provides an Ensemble Pulsar Scale (EPS) analogous to the free atomic timescale 碋chelle Atomique Libre (EAL). The EPS can be used to detect fluctuations in atomic timescales and therefore can lead to a new realisation of Terrestrial Time, TT(PPTA11). We successfully follow features known to affect the frequency of the International Atomic Timescale (TAI) and we find marginally significant differences between TT(PPTA11) and TT(BIPM11). We discuss the various phenomena that lead to a correlated signal in the pulsar timing residuals and therefore limit the stability of the pulsar timescale.

submitted time 2016-12-22 Hits363Downloads195 Comment 0

2. chinaXiv:201612.00018 [pdf]

Development of a pulsar-based timescale

G. Hobbs; W. Coles; R. N. Manchester; M. J. Keith,1 R. M. Shannon; D. Chen; M. Bailes,4 N. D. R. Bhat; S. Burke-Spolaor; D. Champion; A. Chaudhary; A. Hotan; J. Khoo,1 J. Kocz; Y. Levin; S.Oslowski; B. Preisig; V. Ravi; J. E. Reynolds; J. Sarkissian; W. van Straten; J. P. W. Verbiest; D. Yardley
Subjects: Geosciences >> Space Physics

Using observations of pulsars from the Parkes Pulsar Timing Array (PPTA) project we develop the first pulsar-based timescale that has a precision comparable to the uncertainties in international atomic timescales. Our ensemble of pulsars provides an Ensemble Pulsar Scale (EPS) analogous to the free atomic timescale 碋chelle Atomique Libre (EAL). The EPS can be used to detect fluctuations in atomic timescales and therefore can lead to a new realisation of Terrestrial Time, TT(PPTA11). We successfully follow features known to affect the frequency of the International Atomic Timescale (TAI) and we find marginally significant differences between TT(PPTA11) and TT(BIPM11). We discuss the various phenomena that lead to a correlated signal in the pulsar timing residuals and therefore limit the stability of the pulsar timescale.

submitted time 2016-12-01 Hits391Downloads233 Comment 0

3. chinaXiv:201609.01022 [pdf]

Versatile Directional Searches for Gravitational Waves with Pulsar Timing Arrays

D. R. Madison(1; 2); X.-J. Zhu(3; 4); G. Hobbs; W. Coles; R. M. Shannon(4; 6); J. Wang; C. Tiburzi(8; 9; 10; 11); R. N. Manchester; M. Bailes; N. D. R. Bhat; S. Burke-Spolaor; S.Dai; J. Dempsey; M. Keith
Subjects: Physics >> Nuclear Physics

By regularly monitoring the most stable millisecond pulsars over many years, pulsar timing arrays (PTAs) are positioned to detect and study correlations in the timing behaviour of those pulsars. Gravitational waves (GWs) from supermassive black hole binaries (SMBHBs) are an exciting potentially detectable source of such correlations. We describe a straight-forward technique by which a PTA can be "phased-up" to form time series of the two polarisation modes of GWs coming from a particular direction of the sky. Our technique requires no assumptions regarding the time-domain behaviour of a GW signal. This method has already been used to place stringent bounds on GWs from individual SMBHBs in circular orbits. Here, we describe the methodology and demonstrate the versatility of the technique in searches for a wide variety of GW signals including bursts with unmodeled waveforms. Using the first six years of data from the Parkes Pulsar Timing Array, we conduct an all-sky search for a detectable excess of GW power from any direction. For the lines of sight to several nearby massive galaxy clusters, we carry out a more detailed search for GW bursts with memory, which are distinct signatures of SMBHB mergers. In all cases, we find that the data are consistent with noise.

submitted time 2016-09-14 Hits365Downloads190 Comment 0

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