R. N. Caballero
A5007990699- Pulsars and Gravitational Waves Research
- Geophysics and Gravity Measurements
- Radio Astronomy Observations and Technology
- Cosmology and Gravitation Theories
- Astrophysical Phenomena and Observations
- Advanced Frequency and Time Standards
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Superconducting Materials and Applications
- GNSS positioning and interference
- Dark Matter and Cosmic Phenomena
- Atmospheric Ozone and Climate
- Astro and Planetary Science
- Astrophysics and Cosmic Phenomena
- Molecular Spectroscopy and Structure
- Solar and Space Plasma Dynamics
- Seismic Waves and Analysis
- Embedded Systems Design Techniques
- Black Holes and Theoretical Physics
- Noncommutative and Quantum Gravity Theories
- Digital Filter Design and Implementation
- Particle physics theoretical and experimental studies
- Seismology and Earthquake Studies
Peking University
2019-2025
Kavli Institute for Theoretical Sciences
2019-2024
Hellenic Open University
2023-2024
Max Planck Institute for Radio Astronomy
2013-2019
Max Planck Society
2015
University of Amsterdam
2011
Observing and timing a group of millisecond pulsars (MSPs) with high rotational stability enables the direct detection gravitational waves (GWs). The GW signals can be identified from spatial correlations encoded in times-of-arrival widely spaced pulsar-pairs. Chinese Pulsar Timing Array (CPTA) is collaboration aiming at observations carried out using radio telescopes. This short article serves as `table contents' for forthcoming series papers related to CPTA Data Release 1 (CPTA DR1) which...
We present the results of search for an isotropic stochastic gravitational wave background (GWB) at nanohertz frequencies using second data release European Pulsar Timing Array (EPTA) 25 millisecond pulsars and a combination with first Indian (InPTA). analysed (i) full 24.7-year EPTA set, (ii) its 10.3-year subset based on modern observing systems, (iii) set InPTA ten commonly timed pulsars, (iv) data. These combinations allowed us to probe contributions instrumental noise interstellar...
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...
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...
We present results from the search for a stochastic gravitational-wave background (GWB) as predicted by theory of General Relativity using six radio millisecond pulsars Data Release 2 (DR2) European Pulsar Timing Array (EPTA) covering timespan up to 24 years. A GWB manifests itself long-term low-frequency signal common all pulsars, red (CRS), with characteristic Hellings-Downs (HD) spatial correlation. Our analysis is performed two independent pipelines, \eprise{} and \tn{}+\ftwo{}, which...
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...
Pulsar timing arrays offer a probe of the low-frequency gravitational wave spectrum (1 - 100 nanohertz), which is intimately connected to number markers that can uniquely trace formation and evolution Universe. We present dataset results analysis from second data release European Timing Array (EPTA). The contains high-precision pulsar 25 millisecond pulsars collected with five largest radio telescopes in Europe, as well Large for Pulsars. forms foundation search waves by EPTA, presented...
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 European Pulsar Timing Array (EPTA) and Indian (InPTA) collaborations have measured a low-frequency common signal in the combination of their second first data releases, respectively, with correlation properties gravitational wave background (GWB). Such may its origin number physical processes including cosmic population inspiralling supermassive black hole binaries (SMBHBs); inflation, phase transitions, strings, tensor mode generation by non-linear evolution scalar perturbations early...
The European Pulsar Timing Array (EPTA) and Indian (InPTA) collaborations have measured a low-frequency common signal in the combination of their second first data releases respectively, with correlation properties gravitational wave background (GWB). Such may its origin number physical processes including cosmic population inspiralling supermassive black hole binaries (SMBHBs); inflation, phase transitions, strings tensor mode generation by non-linear evolution scalar perturbations early...
Aims. The nanohertz gravitational wave background (GWB) is expected to be an aggregate signal of ensemble waves emitted predominantly by a large population coalescing supermassive black hole binaries in the centres merging galaxies. Pulsar timing arrays (PTAs), which are ensembles extremely stable pulsars at approximately kiloparsec distances precisely monitored for decades, most precise experiments capable detecting this background. However, subtle imprints that GWB induces on pulsar data...
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 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...
Pulsar Timing Array experiments probe the presence of possible scalar or pseudoscalar ultralight dark matter particles through decade-long timing an ensemble galactic millisecond radio pulsars. With second data release European Array, we focus on most robust scenario, in which interacts only gravitationally with ordinary baryonic matter. Our results show that masses 10^{-24.0} eV≲m≲10^{-23.3} eV cannot constitute 100% measured local density, but can have at density ρ≲0.3 GeV/cm^{3}.
We present the results of a search for continuous gravitational wave signals (CGWs) in second data release (DR2) European Pulsar Timing Array (EPTA) Collaboration. The most significant candidate event from this has frequency 4–5 nHz. Such signal could be generated by supermassive black hole binary (SMBHB) local Universe. follow-up analysis using both Bayesian and frequentist methods. gives Bayes factor 4 favour presence CGW over common uncorrelated noise process. In contrast, estimates...
The PSRIX backend is the primary pulsar timing instrument of Effelsberg 100-m radio telescope since early 2011. This new ROACH-based system enables bandwidths up to 500 MHz be recorded, significantly more than what was possible with its predecessor, Effelsberg-Berkeley Pulsar Processor (EBPP). We review first four years data for 33 pulsars collected as part monthly European Timing Array (EPTA) observations. describe automated analysis pipeline, CoastGuard, that we developed reduce these also...
Gravitational preferred frame effects are generally predicted by alternative theories that exhibit an isotropic violation of local Lorentz invariance gravity. They described three parameters in the parametrized post-Newtonian formalism. One their strong-field generalizations, , induces a precession pulsar's spin around its movement direction with respect to frame. We constrain using non-detection such characteristics pulse profile. In our analysis we use large number observations from 100 m...
We analyse the stochastic properties of 49 pulsars that comprise first International Pulsar Timing Array (IPTA) data release. use Bayesian methodology, performing model selection to determine optimal description signals present in each pulsar. In addition spin-noise and dispersion-measure (DM) variations, these models can include timing noise unique a single observing system, or frequency band. show improved radio-frequency coverage presence overlapping from different systems IPTA set...
Symmetries play an important role in modern theories of gravity. The strong equivalence principle (SEP) constitutes a collection gravitational symmetries which are all implemented by general relativity. Alternative theories, however, generally expected to violate some aspects SEP. We test three SEP using observed change rates the orbital period and eccentricity binary pulsar J1713+0747: 1. constant's constancy as part locational invariance gravitation; 2. post-Newtonian parameter...
We present the results of search for an isotropic stochastic gravitational wave background (GWB) at nanohertz frequencies using second data release European Pulsar Timing Array (EPTA) 25 millisecond pulsars and a combination with first Indian (InPTA). analysed (i) full 24.7-year EPTA set, (ii) its 10.3-year subset based on modern observing systems, (iii) set InPTA ten commonly timed pulsars, (iv) data. These combinations allowed us to probe contributions instrumental noise interstellar...
We present the results of a search for continuous gravitational wave signals (CGWs) in second data release (DR2) European Pulsar Timing Array (EPTA) collaboration. The most significant candidate event from this has frequency 4-5 nHz. Such signal could be generated by supermassive black hole binary (SMBHB) local Universe. follow-up analysis using both Bayesian and frequentist methods. gives Bayes factor 4 favor presence CGW over common uncorrelated noise process, while estimates p-value to...