Periodic Reporting for period 4 - Spiders (Fundamental Physics Using Black Widow, Redback and Transitional Pulsar Binaries)
Reporting period: 2021-10-01 to 2023-09-30
The Spiders ERC project aimed to revolutionise our understanding of neutron stars by using multi-wavelength observations and theoretical insights to explore high-energy physics. Neutron stars are extreme objects with compactness, rapid rotation, and immense magnetic fields, making them ideal laboratories for fundamental physics. Key questions addressed include the neutron star equation of state, their rapid rotation, and the impact of millisecond pulsars on their environments.
The project sought to eliminate biases in current research by conducting a comprehensive population analysis of "spider binaries," a class of neutron star systems with some of the most massive and fastest spinning neutron stars. This approach involved discovering new spider systems, utilising optical and gamma-ray surveys to aid radio searches, and characterising them using advanced binary optical light curve modelling.
Key achievements include:
1. Characterisation: Over 100 hours of optical telescope observations produced the largest sample of spider binaries' photometric light curves, revealing long-term variability and extreme systems like the second-fastest spinning millisecond pulsar.
2. Discovery: Innovative methods combining optical, gamma-ray, and radio surveys led to the discovery of new spider systems. Machine learning techniques showed promise in classifying optical light curves, and extensive optical surveys supported the discovery of new binaries.
3. Theoretical Understanding: Improved modelling of spider timing data, detection of gravitational quadrupole moments, and advancements in heat redistribution models enhanced the understanding of companion stars' internal structures and physical processes.
The project has set a new standard in studying neutron star systems, significantly advancing theoretical and observational astrophysics.
The project sought to eliminate biases in current research by conducting a comprehensive population analysis of "spider binaries," a class of neutron star systems with some of the most massive and fastest spinning neutron stars. This approach involved discovering new spider systems, utilising optical and gamma-ray surveys to aid radio searches, and characterising them using advanced binary optical light curve modelling.
Key achievements include:
1. Characterisation: Over 100 hours of optical telescope observations produced the largest sample of spider binaries' photometric light curves, revealing long-term variability and extreme systems like the second-fastest spinning millisecond pulsar.
2. Discovery: Innovative methods combining optical, gamma-ray, and radio surveys led to the discovery of new spider systems. Machine learning techniques showed promise in classifying optical light curves, and extensive optical surveys supported the discovery of new binaries.
3. Theoretical Understanding: Improved modelling of spider timing data, detection of gravitational quadrupole moments, and advancements in heat redistribution models enhanced the understanding of companion stars' internal structures and physical processes.
The project has set a new standard in studying neutron star systems, significantly advancing theoretical and observational astrophysics.
From its inception, the Spiders ERC project made substantial strides across three main areas: characterising the spider system population, discovering new spider systems, and advancing theoretical understanding of these systems.
1. Characterisation:
- Observations: Follow-up observations using world-class optical telescopes characterised spider binaries.
- Extreme Systems: Identified some of the most extreme pulsars, including the second-fastest spinning neutron star.
- Long-term Variability: Investigated long-term optical variability in spider binary light curves, linking these changes to the evolution between accreting X-ray binaries and radio pulsar binaries.
2. Discovery:
- Multi-wavelength Synergy: Developed a method using optical observations to constrain parameters for gamma-ray and radio pulsation searches, leading to the discovery of two new spider systems.
- Large Surveys: Expanded the method to a large radio survey as part of MeerKAT's TRAPUM project, leading to the discovery of over 40 new pulsars, including around 15 new spider systems. Conducted optical surveys using the Thai Robotic Telescope network, NTT with ULTRACAM, GOTO, and BlackGEM to provide input for radio surveys.
3. Theoretical Understanding:
- Modeling Improvements: Improved the modelling of spider timing data by incorporating tides and general relativity effects, predicting non-circular orbits and providing insights into the internal structure of companion stars.
- Gravitational Quadrupole Moment: Detected the gravitational quadrupole moment of companion stars in spider systems, allowing researchers to probe the internal distribution of matter within these stars and understand stellar evolution.
Key Work Packages and Results:
- High-Precision Physics and Equation of State: Obtained high-precision photometry and spectroscopy data, leading to several key publications. Although an overly massive neutron star remains unproven, measurements delineated the landscape of neutron star masses and contributed to significant methodological advancements.
- Innovative Searching and Monitoring: Conducted a large optical survey using the ULTRACAM instrument, discovering multiple new spider pulsars. Joined consortia like BlackGEM and GOTO, monitoring spider binaries for state transitions and contributing to publications beyond the project's initial scope.
- Impact on Spider Binaries' Environment: Research on evaporation mechanisms and binary evolution refined our understanding of these processes. Developed foundational models for heat redistribution in irradiated binaries, with limited but ongoing efforts to detect circumbinary dust emissions.
- Discovery of Gamma Ray Eclipses: Analysed Fermi gamma ray data, discovering gamma ray eclipses in several systems. These eclipses provide direct geometrical constraints on orbits and companion sizes, validating optical modeling measurements.
Overall, the Spiders ERC project achieved significant progress, with numerous publications and discoveries advancing our understanding of neutron stars. The project's innovative approaches and comprehensive analysis promise continued advancements in high energy physics and stellar evolution.
1. Characterisation:
- Observations: Follow-up observations using world-class optical telescopes characterised spider binaries.
- Extreme Systems: Identified some of the most extreme pulsars, including the second-fastest spinning neutron star.
- Long-term Variability: Investigated long-term optical variability in spider binary light curves, linking these changes to the evolution between accreting X-ray binaries and radio pulsar binaries.
2. Discovery:
- Multi-wavelength Synergy: Developed a method using optical observations to constrain parameters for gamma-ray and radio pulsation searches, leading to the discovery of two new spider systems.
- Large Surveys: Expanded the method to a large radio survey as part of MeerKAT's TRAPUM project, leading to the discovery of over 40 new pulsars, including around 15 new spider systems. Conducted optical surveys using the Thai Robotic Telescope network, NTT with ULTRACAM, GOTO, and BlackGEM to provide input for radio surveys.
3. Theoretical Understanding:
- Modeling Improvements: Improved the modelling of spider timing data by incorporating tides and general relativity effects, predicting non-circular orbits and providing insights into the internal structure of companion stars.
- Gravitational Quadrupole Moment: Detected the gravitational quadrupole moment of companion stars in spider systems, allowing researchers to probe the internal distribution of matter within these stars and understand stellar evolution.
Key Work Packages and Results:
- High-Precision Physics and Equation of State: Obtained high-precision photometry and spectroscopy data, leading to several key publications. Although an overly massive neutron star remains unproven, measurements delineated the landscape of neutron star masses and contributed to significant methodological advancements.
- Innovative Searching and Monitoring: Conducted a large optical survey using the ULTRACAM instrument, discovering multiple new spider pulsars. Joined consortia like BlackGEM and GOTO, monitoring spider binaries for state transitions and contributing to publications beyond the project's initial scope.
- Impact on Spider Binaries' Environment: Research on evaporation mechanisms and binary evolution refined our understanding of these processes. Developed foundational models for heat redistribution in irradiated binaries, with limited but ongoing efforts to detect circumbinary dust emissions.
- Discovery of Gamma Ray Eclipses: Analysed Fermi gamma ray data, discovering gamma ray eclipses in several systems. These eclipses provide direct geometrical constraints on orbits and companion sizes, validating optical modeling measurements.
Overall, the Spiders ERC project achieved significant progress, with numerous publications and discoveries advancing our understanding of neutron stars. The project's innovative approaches and comprehensive analysis promise continued advancements in high energy physics and stellar evolution.
The Spiders ERC project pushed the boundaries of neutron star research, achieving progress beyond the state of the art in several key areas:
1. Comprehensive Population Analysis: Moving beyond the traditional selective study of individual neutron stars, the project developed a comprehensive population analysis of spider binaries. This approach minimised biases and provided a more accurate representation of neutron star properties.
2. Novel Observational Techniques: The project utilised cutting-edge optical telescopes and innovative observational techniques, significantly enhancing the discovery and characterisation of spider systems. The synergy of optical observations and the use of ancillary gamma ray data has proved extremely successful at uncovering new spider binaries in the latest radio surveys.
3. Enhanced Theoretical Models: By incorporating advanced physical components such as tides and general relativity into spider timing data models, the project provided new insights into the orbital dynamics and internal structure of companion stars. This modelling improvement had implications for all binary star systems.
Expected results/legacy beyond the end of the project include:
- Publication of a comprehensive database of spider binary physical parameters.
- Continued discovery of new spider systems, aided by refined observational multi-wavelength techniques.
- Further advancements in theoretical models, particularly in understanding the gravitational quadrupole moments and heat redistribution in spider binaries.
- Study of the irradiation mechanisms leading to an understanding of the underlying process responsible for the asymmetrical light curves.
- The optical light curve modelling software Icarus, developed by the PI and improved by the ERC team, has de facto being adopted as the standard tool for this type of work in the field.
The Spiders ERC project was poised to make significant contributions to our understanding of neutron stars, influencing both theoretical and observational astrophysics.
1. Comprehensive Population Analysis: Moving beyond the traditional selective study of individual neutron stars, the project developed a comprehensive population analysis of spider binaries. This approach minimised biases and provided a more accurate representation of neutron star properties.
2. Novel Observational Techniques: The project utilised cutting-edge optical telescopes and innovative observational techniques, significantly enhancing the discovery and characterisation of spider systems. The synergy of optical observations and the use of ancillary gamma ray data has proved extremely successful at uncovering new spider binaries in the latest radio surveys.
3. Enhanced Theoretical Models: By incorporating advanced physical components such as tides and general relativity into spider timing data models, the project provided new insights into the orbital dynamics and internal structure of companion stars. This modelling improvement had implications for all binary star systems.
Expected results/legacy beyond the end of the project include:
- Publication of a comprehensive database of spider binary physical parameters.
- Continued discovery of new spider systems, aided by refined observational multi-wavelength techniques.
- Further advancements in theoretical models, particularly in understanding the gravitational quadrupole moments and heat redistribution in spider binaries.
- Study of the irradiation mechanisms leading to an understanding of the underlying process responsible for the asymmetrical light curves.
- The optical light curve modelling software Icarus, developed by the PI and improved by the ERC team, has de facto being adopted as the standard tool for this type of work in the field.
The Spiders ERC project was poised to make significant contributions to our understanding of neutron stars, influencing both theoretical and observational astrophysics.