Multiple emission components in the Cygnus cocoon detected from Fermi-LAT observations

Abstract

Star-forming regions may play an important role in the life cycle of Galactic cosmic rays. Gamma-ray observations of Cygnus X have revealed the presence of an excess of hard-spectrum gamma-ray emission, possibly related to a cocoon of freshly accelerated particles. Based on ~13 years of observations with the Fermi-Large Area Telescope (LAT), we performed an improved spectro-morphological characterisation of the residual emission including the cocoon. The best-fit model for the cocoon includes two main emission components: an extended component FCES G78.74+1.56, described by a 2D Gaussian of extension $r_{68}=4.4^{\circ }\pm 0.1^{\circ }{}_{-0.1^{\circ }}^{+0.1^{\circ }}$, and a central component FCES G80.00+0.50, traced by the distribution of ionised gas within the borders of the photo-dissociation regions. The two have significantly different spectra. An additional extended emission component FCES G78.83+3.57, located on the edge of the central cavities in Cygnus X and with a spectrum compatible with that of FCES G80.00+0.50, is likely related to the cocoon. For the two main components, spectra and radial-azimuthal profiles of the emission can be accounted for in a diffusion-loss framework involving one single population of non-thermal particles. Particles span the full extent of FCES G78.74+1.56 as a result of diffusion from a central source, and give rise to source FCES G80.00+0.50 by interacting with ionised gas in the innermost region. For this simple diffusion-loss model, viable setups can be very different in terms of energetics, transport conditions, and timescales involved, and both hadronic and leptonic scenarios are possible. The solutions range from long-lasting particle acceleration, possibly in prominent star clusters such as Cyg OB2 and NGC 6910, to a more recent and short-lived release of particles within the last 10-100 kyr, likely from a supernova remnant. (Abridged)

arXiv commentPublished in A&A. Fixed typos in metadata. The main results are available in machine-readable format at https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/671/A47

References in corpus (67)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• The Large Area Telescope on the Fermi Gamma-ray Space Telescope Mission
• The ATNF Pulsar Catalogue
• The Milky Way in Molecular Clouds: A New Complete CO Survey
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• A Hipparcos census of the nearby OB associations
• A new calibration of stellar parameters of Galactic O stars
• Fermi-LAT Observations of the Diffuse Gamma-Ray Emission: Implications for Cosmic Rays and the Interstellar Medium
• Statistics: Handle with Care, Detecting Multiple Model Components with the Likelihood Ratio Test
• Incremental Fermi Large Area Telescope Fourth Source Catalog
• Painting a portrait of the Galactic disc with its stellar clusters
• Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth
• Development of the Model of Galactic Interstellar Emission for Standard Point-Source Analysis of Fermi Large Area Telescope Data
• Constraints on cosmic-ray propagation models from a global Bayesian analysis
• CMasher: Scientific colormaps for making accessible, informative and 'cmashing' plots
• A Census of High-Energy Observations of Galactic Supernova Remnants
• Science with e-ASTROGAM (A space mission for MeV-GeV gamma-ray astrophysics)
• Evidence for a fundamental stellar upper mass limit from clustered star formation
• Precise Gamma-Ray Timing and Radio Observations of 17 Fermi Gamma-Ray Pulsars
• The origin of Galactic cosmic rays: challenges to the standard paradigm
• Eight gamma-ray pulsars discovered in blind frequency searches of Fermi LAT data
• A radiation transfer model for the Milky-Way: I. Radiation fields and application to High Energy Astrophysics
• The exceptionally powerful TeV gamma-ray emitters in the Large Magellanic Cloud
• Galactic cosmic rays after the AMS-02 observations
• Particle acceleration in winds of star clusters
• Nuclear enhancement factor in calculation of Galactic diffuse gamma-rays: A new estimate with DPMJET-3
• HAWC observations of the acceleration of very-high-energy cosmic rays in the Cygnus Cocoon
• The Massive Star Forming Region Cygnus OB2. II. Integrated Stellar Properties and the Star Formation History
• Efficiently Cooled Stellar Wind Bubbles in Turbulent Clouds I. Fractal Theory and Application to Star-Forming Clouds
• Imprints of Cosmic Rays in Multifrequency Observations of the Interstellar Emission
• Cosmic-ray transport from AMS-02 B/C data: benchmark models and interpretation
• Identification of the TeV Gamma-ray Source ARGO J2031+4157 with the Cygnus Cocoon
• Fermi-LAT improved Pass~8 event selection
• A lower bound on intergalactic magnetic fields from time variability of 1ES 0229+200 from MAGIC and Fermi/LAT observations
• Particle Transport within the Pulsar Wind Nebula HESS J1825-137
• The Outer Disk of the Milky Way Seen in 21-cm Absorption
• On the shape of the spectrum of cosmic-rays accelerated inside superbubbles
• High-energy particles and radiation in star-forming regions
• Multiwavelength monitoring and X-ray brightening of Be X-ray binary PSR J2032+4127/MT91 213 on its approach to periastron
• Cosmic rays, gas and dust in nearby anticentre clouds : I -- CO-to-H2 conversion factors and dust opacities
• Cosmic ray production in superbubbles
• Gamma-rays from halos around stars and the Sun
• The cosmic-ray and gas content of the Cygnus region as measured in gamma rays by the Fermi Large Area Telescope
• The Origin of Galactic Cosmic Rays as Revealed by their Composition
• Evolutionary Models for 43 Galactic Supernova Remnants with Distances and X-ray Spectra
• Non-linear diffusion of cosmic rays escaping from supernova remnants - II. Hot ionized media
• Gamma rays as probes of cosmic-ray propagation and interactions in galaxies
• Energy dependent morphology of the pulsar wind nebula HESS J1825-137 with Fermi-LAT
• Fermi-LAT Observations of High- and Intermediate-Velocity Clouds: Tracing Cosmic Rays in the Halo of the Milky Way
• X-ray and Radio Observations of the gamma Cygni Supernova Remnant G78.2+2.1
• Dynamics and Energy Loss in Superbubbles
• Identification of plasma modes in Galactic turbulence with synchrotron polarization
• Spectroscopic characterization of the known O-star population in Cygnus OB2. Evidence of multiple star-forming bursts
• Constraining cosmic ray acceleration in young star clusters using multi-wavelength observations
• Are pulsar halos rare ?
• Unveiling the physical conditions in NGC 6910
• A new method to perform data/model comparison in Fermi-LAT analysis
• Gamma-Ray Puzzles in Cygnus X: Implications for High-Energy Neutrinos
• Morphology of Gamma-Ray Halos around Middle-Aged Pulsars: Influence of the Pulsar Proper Motion
• Filamentary structures of ionized gas in Cygnus X
• Gamma-ray emission from middle-aged supernova remnants interacting with molecular clouds: the challenge for current models
• Multiple accelerated particle populations in the Cygnus Loop with Fermi-LAT
• Suzaku Observation of the Fermi Cygnus Cocoon: Search for a Signature of Young Cosmic-Ray Electrons
• A HaloSat Analysis of the Cygnus Superbubble
• MHD decomposition explains diffuse $\gamma$-ray emission in Cygnus X

Cited by in corpus (5)

• Contribution of young massive star clusters to Galactic diffuse $\gamma$-ray emission
• Limits on Leptonic TeV Emission from the Cygnus Cocoon with Swift-XRT
• Suppressed diffusion and gamma-ray emission from the Cygnus bubble
• The Cosmic-ray Knee as a Local Signature of Nearby PeVatrons
• Deciphering the gamma-ray emission in the Cygnus region