Periodic Reporting for period 2 - MessMapp (Mapping Highly-Energetic Messengers throughout the Universe)
Periodo di rendicontazione: 2022-12-01 al 2024-01-31
MessMapp tackles the challenge of mapping highly-energetic messengers originated in our Universe. This encompasses the characterization of various cosmic messengers, in primis neutrinos, gamma rays, and cosmic rays. These messengers originate from extreme astrophysical phenomena, possibly in the farthest corners of our Universe, but their sources and propagation mechanisms remain largely poorly understood. The multi-messenger science initiative is focused on studying the connection between these astrophysical messengers and the most powerful cosmic accelerators—Active Galactic Nuclei (AGN) — by exploiting observational techniques and theorerical predictions.
Understanding the origins and properties of highly-energetic messengers in the Universe has broader implications for society beyond the realm of pure scientific curiosity. Firstly, it contributes to our understanding of the fundamental laws of physics and the nature of the Universe, enriching our knowledge about our cosmic environment. Secondly, it can provide insights into extreme physical phenomena that are not currently feasible to investigate using human-made physics accelerators on Earth.
The overarching objectives of the MessMapp project are twofold:
A) To develop cutting-edge observational techniques capable of detecting and characterizing the sources of highly-energetic neutrinos, and unraveling their possible connection to gamma rays, and cosmic rays. B) To utilize these advanced methodologies to address key scientific questions regarding the origins, propagation, and astrophysical implications of cosmic messengers.
Understanding the origins and properties of highly-energetic messengers in the Universe has broader implications for society beyond the realm of pure scientific curiosity. Firstly, it contributes to our understanding of the fundamental laws of physics and the nature of the Universe, enriching our knowledge about our cosmic environment. Secondly, it can provide insights into extreme physical phenomena that are not currently feasible to investigate using human-made physics accelerators on Earth.
The overarching objectives of the MessMapp project are twofold:
A) To develop cutting-edge observational techniques capable of detecting and characterizing the sources of highly-energetic neutrinos, and unraveling their possible connection to gamma rays, and cosmic rays. B) To utilize these advanced methodologies to address key scientific questions regarding the origins, propagation, and astrophysical implications of cosmic messengers.
In the following, article citations are numbered following their order in the Publications section.
The initial development phase of the MessMapp project has led to several major achievement and progress in the astrophysics field. It has pinpointed a subset of sources, belonging to the blazar population, as highly likely IceCube neutrino emitter [3,4]. The statistical confidence for the association has been corroborated to a higher level in the second phase of the project [Buson in prep.].
The project expanded toward studying the physical properties of this subsample of sources [9,13,14,17]. In parallel, we are continuing our effort in developing pipelines for the analysis of neutrino data [12], and theoretical modelling. A major milestone was reached with the publication of a first study tackling the theoretical angle [11], and the public release of the corresponding numerical modeling code AM3 [10]. In this way, the scientific community can reproduce and test theoretical results from the MessMapp project.
AM3 is a documented open-source software (https://am3.readthedocs.io/en/latest/(si apre in una nuova finestra)) that solves the coupled integro-differential equations describing the temporal evolution of the spectral densities of particles interacting in astrophysical environments. The software has been extensively used to simulate the multiwavelength and neutrino emission from AGN (including blazars), gamma-ray bursts, and tidal disruption events. The open-source and publicly availability of the AM3 code, developed with support from the ERC project MessMapp, offers an important benefit to the broader astrophysical community. It is the only public code available for conducting leptonic and lepto-hadronic modeling of a variety of astrophysical objects.
Several cutting-edge findings have been published in refereed Journals of the field. These include papers on the multiwavelength properties of the neutrino-emitter blazars, theoretical modeling, and companion papers tackling broader scientific questions. As anticipated in the design of the MessMapp project, the project has deliver a large bulk of high-quality, new astrophysical information in addition to those needed to achieve its aims. These have promoted impactful results in complementary fields [5,7,18,19].
A notable example are publications which expand the research into the gravitational waves field [18,19]. These studies report the largest systematic search of periodic emission in the gamma-ray lightcurves of 350 blazars. Using twelve years of Fermi-LAT data, they pinpointed a sample of 24 blazars displaying evidence of periodic emissions. Blazars display variable emission across the entire electromagnetic spectrum, ranging in time from minutes to years. This variability is generally interpreted as stochastic and unpredictable processes. However, periodic signals could be caused by, e.g. a helical jet or a precessing jet due to the presence of a supermassive black hole binary. Following these works, results may be interpreted in the framework of supermassive black hole binaries. Such binary systems are expected to originate gravitational waves, and therefore are primary targets for current and future generation of gravitational wave detectors (e.g. Pulsar Timing Array, Laser Interferometer Space Antenna, Einstein Telescope).
In addition to efforts by the PI, PostDocs, and PhD students of the team, bachelor's and master's students are regularly contributing to MessMapp studies under the PI's supervision. This not only advances the research but also nurtures the younger generation, inspiring them and providing valuable opportunities to grow both on the personal and scientific level.
The initial development phase of the MessMapp project has led to several major achievement and progress in the astrophysics field. It has pinpointed a subset of sources, belonging to the blazar population, as highly likely IceCube neutrino emitter [3,4]. The statistical confidence for the association has been corroborated to a higher level in the second phase of the project [Buson in prep.].
The project expanded toward studying the physical properties of this subsample of sources [9,13,14,17]. In parallel, we are continuing our effort in developing pipelines for the analysis of neutrino data [12], and theoretical modelling. A major milestone was reached with the publication of a first study tackling the theoretical angle [11], and the public release of the corresponding numerical modeling code AM3 [10]. In this way, the scientific community can reproduce and test theoretical results from the MessMapp project.
AM3 is a documented open-source software (https://am3.readthedocs.io/en/latest/(si apre in una nuova finestra)) that solves the coupled integro-differential equations describing the temporal evolution of the spectral densities of particles interacting in astrophysical environments. The software has been extensively used to simulate the multiwavelength and neutrino emission from AGN (including blazars), gamma-ray bursts, and tidal disruption events. The open-source and publicly availability of the AM3 code, developed with support from the ERC project MessMapp, offers an important benefit to the broader astrophysical community. It is the only public code available for conducting leptonic and lepto-hadronic modeling of a variety of astrophysical objects.
Several cutting-edge findings have been published in refereed Journals of the field. These include papers on the multiwavelength properties of the neutrino-emitter blazars, theoretical modeling, and companion papers tackling broader scientific questions. As anticipated in the design of the MessMapp project, the project has deliver a large bulk of high-quality, new astrophysical information in addition to those needed to achieve its aims. These have promoted impactful results in complementary fields [5,7,18,19].
A notable example are publications which expand the research into the gravitational waves field [18,19]. These studies report the largest systematic search of periodic emission in the gamma-ray lightcurves of 350 blazars. Using twelve years of Fermi-LAT data, they pinpointed a sample of 24 blazars displaying evidence of periodic emissions. Blazars display variable emission across the entire electromagnetic spectrum, ranging in time from minutes to years. This variability is generally interpreted as stochastic and unpredictable processes. However, periodic signals could be caused by, e.g. a helical jet or a precessing jet due to the presence of a supermassive black hole binary. Following these works, results may be interpreted in the framework of supermassive black hole binaries. Such binary systems are expected to originate gravitational waves, and therefore are primary targets for current and future generation of gravitational wave detectors (e.g. Pulsar Timing Array, Laser Interferometer Space Antenna, Einstein Telescope).
In addition to efforts by the PI, PostDocs, and PhD students of the team, bachelor's and master's students are regularly contributing to MessMapp studies under the PI's supervision. This not only advances the research but also nurtures the younger generation, inspiring them and providing valuable opportunities to grow both on the personal and scientific level.
Studying the blazars and astrophysical neutrinos link
Our works conducted a cross-correlation analysis to explore the potential connection between blazars and astrophysical neutrinos detected by IceCube. The studies identified a spatial correlation between high-energy neutrino events and the positions of blazars, particularly a subset of sources from 5th Roma Blazar Catalog. These findings suggest that blazars could be plausible sources of the astrophysical neutrinos, providing new insights into the potential role of blazars as contributors to the high-energy cosmic neutrino flux.
The ultimate goal of the program is to corroborate or rule out the blazar/neutrino association by addressing the question through complementary approaches, such as multi-messenger techniques and theoretical perspectives. Initial progress has been made in these areas, including optical spectroscopy (for the full set of candidate objects) and numerical modeling of the blazar spectral energy distribution (conducted on one object so far). These studies will be expanded to the larger sample, with the aim of achieving a statistically meaningful analysis.
A FAIR-principles oriented program
Among the basic principles of the scientific method is the importance of result reproducibility, though this is not always achieved in practice in the multi-messenger astrophysics and astroparticle fields. While the original MessMapp work plan did not include provisions for publicly releasing the team's internally developed codes, which are essential for deriving scientific findings of the project, we have chosen to make this extra effort. This decision was driven by our commitment to scientific integrity and aligned with the FAIR (Findable, Accessible, Interoperable, and Reusable) principles. As MessMapp progresses, we will strive to align with these principles, provided there are sufficient resources to support the additional workload. It will have broader implications for the field, enabling the community to fully benefit from the work supported by the ERC. A first example in this direction is provided in the previous section, in regards of the numerical modeling software “AM3”.
Our works conducted a cross-correlation analysis to explore the potential connection between blazars and astrophysical neutrinos detected by IceCube. The studies identified a spatial correlation between high-energy neutrino events and the positions of blazars, particularly a subset of sources from 5th Roma Blazar Catalog. These findings suggest that blazars could be plausible sources of the astrophysical neutrinos, providing new insights into the potential role of blazars as contributors to the high-energy cosmic neutrino flux.
The ultimate goal of the program is to corroborate or rule out the blazar/neutrino association by addressing the question through complementary approaches, such as multi-messenger techniques and theoretical perspectives. Initial progress has been made in these areas, including optical spectroscopy (for the full set of candidate objects) and numerical modeling of the blazar spectral energy distribution (conducted on one object so far). These studies will be expanded to the larger sample, with the aim of achieving a statistically meaningful analysis.
A FAIR-principles oriented program
Among the basic principles of the scientific method is the importance of result reproducibility, though this is not always achieved in practice in the multi-messenger astrophysics and astroparticle fields. While the original MessMapp work plan did not include provisions for publicly releasing the team's internally developed codes, which are essential for deriving scientific findings of the project, we have chosen to make this extra effort. This decision was driven by our commitment to scientific integrity and aligned with the FAIR (Findable, Accessible, Interoperable, and Reusable) principles. As MessMapp progresses, we will strive to align with these principles, provided there are sufficient resources to support the additional workload. It will have broader implications for the field, enabling the community to fully benefit from the work supported by the ERC. A first example in this direction is provided in the previous section, in regards of the numerical modeling software “AM3”.