The Multi-Mission Maximum Likelihood framework (3ML)

Vianello, G.; Lauer, R.; Burgess, J. M.; Ayala, Hector Gutierrez; Fleischhack, Henrike; Harding, P.; Hui, Mingwei; Marinelli, Simona; Savchenko, V.; Zhou, H.

doi:10.22323/1.312.0130

Cited by 40 publications

(44 citation statements)

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“…www.sciencemag.org Materials and Methods Figs. S1, S2 References (36)(37)(38)(39)(40)(41) [Note: The numbers refer to any additional references cited only within the Supplementary Materials]…”

Section: Supplementary Materialsmentioning

confidence: 99%

Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth

Abeysekara

Albert

Alfaro

et al. 2017

Science

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The unexpectedly high flux of cosmic-ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report the detection, using the High-Altitude Water Cherenkov Observatory (HAWC), of extended tera-electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of accelerated leptons, but the measured tera-electron volt emission profile constrains the diffusion of particles away from these sources to be much slower than previously assumed. We demonstrate that the leptons emitted by these objects are therefore unlikely to be the origin of the excess positrons, which may have a more exotic origin.

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Section: Supplementary Materialsmentioning

confidence: 99%

Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth

Abeysekara

Albert

Alfaro

et al. 2017

Science

Self Cite

445

439

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“…These constants are allowed to vary in each spectral fit 21 . All spectral analysis and data reduction is performed within the 3ML framework 35 . Our radiative code is implemented in C++ and interfaced via Cython into astromodels 36 .…”

Section: Observations and Data Analysismentioning

confidence: 99%

Gamma-ray bursts as cool synchrotron sources

et al. 2019

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Gamma-ray bursts are the most energetic electromagnetic sources in the Universe. Their prompt gamma-ray radiation, lasting between a fraction of a second to several thousand seconds, corresponds to an energy release of 10 42 -10 47 J [1,2]. Fifty years after their discovery and several dedicated space-based instruments, the physical origin of this emission is still unknown. Synchrotron emission has been one of the early contenders 3,4 , but was criticized because spectral fits of empirical models (such as a smoothly-connected broken power law or a cut-off power law) suggest too hard a slope of the low-energy power law, violating the so-called synchrotron line-of-death 5,6 , reviving models of photospheric emission 7-9 . Fitting proper synchrotron spectra 10-12 (rather than heuristic functions) was first shown to work for individual GRBs 13,14 , though without tracking electron cooling. When the latter was taken into account, several GRB spectra could be fit successfully 10 . Here we show that idealized synchrotron emission, when properly incorporating time-dependent cooling of the electrons, is capable of fitting~95% of all time-resolved spectra of single-peaked GRBs as measured with Fermi/GBM. The comparison with spectral fit results based on previous empirical models demonstrates that the past exclusion of synchrotron radiation as an emission mechanism derived via the line-of-death was misleading. Our analysis probes the physics of these ultra-relativistic outflows and the microphysical processes which cause them to shine, and for the first time provides estimates of magnetic field strength and Lorentz factors of the emitting region directly from spectral fits. The parameter distributions that we find are grossly compatible with theoretical spectral 15-17 and outflow 18 predictions. The emission energetics remain challenging for all theoretical models. As synchrotron radiation alone can explain the observed emission, it is difficult to reconcile the time scales, efficiencies, and microphysics predicted by relativistic Fermi shock acceleration 19 and the fireball model 20 with the observations. Thus, our modeling of the Fermi/GBM observations provides evidence that GRBs are produced by moderately magnetized jets in which relativistic mini-jets emit optically-thin synchrotron radiation at large emission radii.We perform time-resolved spectral analysis of the prompt spectra of gamma-ray bursts (GRBs) detected with the Fermi Gamma-ray Burst Monitor (GBM). We select a subset of GRBs which exhibit a single contiguous, pulse-like structure which is justified by the assumption that the emission originates from a single dissipation episode 10 . In addition, we require that all GRBs have a measured redshift to ascertain their energetics. This results in a sample of 19 out of the 81 GRBs in the GBM time-resolved spectral catalog 21 . After background modeling, we employ the Bayesian blocks algorithm to create spectral datasets in optimised temporal bins for each of those GRBs, leading to a total of 162 bins, each with a P...

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“…Figure 3 compares the radial profile as a function of the distance from the pulsar from three morphological models. We then fit the gamma-ray emission around Geminga and PSR B0656+14 with the diffusion model defined in equation 4.5 and 4.6 using the Multi-Mission Maximum Likelihood framework [16], and calculate the diffusion coefficient of 100 TeV electrons based on the obtained diffusion angle from the likelihood fit.…”

Section: Diffusion Modelmentioning

confidence: 99%