Deep view of the Large Magellanic Cloud with 6 years of Fermi-LAT observations

Abstract

The nearby Large Magellanic Cloud (LMC) provides a rare opportunity of a spatially resolved view of an external star-forming galaxy in gamma-rays. The LMC was detected at 0.1-100GeV as an extended source with CGRO/EGRET and using early observations with the Fermi-LAT. The emission was found to correlate with massive star-forming regions and to be particularly bright towards 30 Doradus. Studies of the origin and transport of cosmic rays (CRs) in the Milky Way are frequently hampered by line-of-sight confusion and poor distance determination. The LMC offers a complementary way to address these questions by revealing whether and how the gamma-ray emission is connected to specific objects, populations of objects, and structures in the galaxy. We revisited the gamma-ray emission from the LMC using about 73 months of Fermi-LAT P7REP data in the 0.2-100GeV range. We developed a complete spatial and spectral model of the LMC emission, for which we tested several approaches: a simple geometrical description, template-fitting, and a physically driven model for CR-induced interstellar emission. In addition to identifying PSR J0540-6919 through its pulsations, we find two hard sources positionally coincident with plerion N 157B and supernova remnant N 132D, which were also detected at TeV energies with H.E.S.S. We detect an additional soft source that is currently unidentified. Extended emission dominates the total flux from the LMC. It consists of an extended component of about the size of the galaxy and additional emission from 3 to 4 regions with degree-scale sizes. If it is interpreted as CRs interacting with interstellar gas, the large-scale emission implies a large-scale population of ~1-100GeV CRs with a density of ~30% of the local Galactic value. On top of that, the 3 to 4 small-scale emission regions would correspond to enhancements of the CR density by factors 2 to 6 or higher (Abridged).

Accepted for publication in A&A; 17 pages and 23 figures; corresponding author: Pierrick MARTIN. Revised version after language editing and update of a plot in Fig. 4

References in corpus (13)

• The ATNF Pulsar Catalogue
• The spectrum of isotropic diffuse gamma-ray emission between 100 MeV and 820 GeV
• An eclipsing binary distance to the Large Magellanic Cloud accurate to 2 per cent
• The exceptionally powerful TeV gamma-ray emitters in the Large Magellanic Cloud
• Fermi Large Area Telescope observations of Local Group galaxies: Detection of M31 and search for M33
• CHANDRA ACIS Spectroscopy of N157B -- A Young Composite Supernova Remnant in a Superbubble
• No Evidence for Significant Age Spreads in Young Massive LMC Clusters
• Ejecta, Dust, and Synchrotron Radiation in B0540-69.3: A More Crab-Like Remnant than the Crab
• Search for Gamma-ray Emission from Dark Matter Annihilation in the Large Magellanic Cloud with the Fermi Large Area Telescope
• X-Ray Emitting Ejecta of Supernova Remnant N132D
• Expected gamma-ray emission of supernova remnant SN 1987A
• The Fermi-LAT model of interstellar emission for standard point source analysis
• Spitzer observations of the N157B supernova remnant and its surroundings

Cited by in corpus (56)

• Fermi Large Area Telescope Fourth Source Catalog
• 3FHL: The Third Catalog of Hard Fermi-LAT Sources
• The e-ASTROGAM mission (exploring the extreme Universe with gamma rays in the MeV-GeV range)
• The origin of Galactic cosmic rays: challenges to the standard paradigm
• Search for Spatial Extension in High-Latitude Sources Detected by the Fermi Large Area Telescope
• The $\gamma$-ray Emission of Star-Forming Galaxies
• Observations of M31 and M33 with the Fermi Large Area Telescope: a galactic center excess in Andromeda?
• The Hunt for Pevatrons: The Case of Supernova Remnants
• A Luminous Gamma-ray Binary in the Large Magellanic Cloud
• Cosmic Ray Transport, Energy Loss, and Influence in the Multiphase Interstellar Medium
• The EMU view of the Large Magellanic Cloud: Troubles for sub-TeV WIMPs
• Cosmic rays and non-thermal emission in simulated galaxies. II. $\gamma$-ray maps, spectra and the far infrared-$\gamma$-ray relation
• Search for 511 keV Emission in Satellite Galaxies of the Milky Way with INTEGRAL/SPI
• Gamma rays as probes of cosmic-ray propagation and interactions in galaxies
• The 30-Year Search for the Compact Object in SN 1987A
• Star-Forming Galaxies Significantly Contribute to the Isotropic Gamma-Ray Background
• Search for Gamma-ray Emission from Dark Matter Annihilation in the Small Magellanic Cloud with the Fermi Large Area Telescope
• Discovery of Molecular and Atomic Clouds Associated with the Magellanic Superbubble 30 Doradus C
• The gamma-ray / infrared luminosity correlation of star-forming galaxies
• Three-Dimensional Kinematic Reconstruction of the Optically-Emitting, High-Velocity, Oxygen-Rich Ejecta of Supernova Remnant N132D
• Thermal Pressures in the Interstellar Medium of the Magellanic Clouds
• ALMA CO Observations of Gamma-Ray Supernova Remnant N132D in the Large Magellanic Cloud: Possible Evidence for Shocked Molecular Clouds Illuminated by Cosmic-Ray Protons
• Theoretical predictions for dark matter detection in dwarf irregular galaxies with gamma rays
• Evidence of AGN activity in the gamma-ray emission from two starburst galaxies
• GeV $\gamma$-ray emission from M33 and Arp~299
• Hitomi Observations of the LMC SNR N132D: Highly Redshifted X-ray Emission from Iron Ejecta
• Spatially Resolved Chandra Spectroscopy of the Large Magellanic Cloud Supernova Remnant N132D
• Breaking the Radio - Gamma-Ray Connection in Arp 220
• The orbital parameters of the gamma-ray binary LMC P3
• Sensitivity of the Cherenkov Telescope Array to TeV photon emission from the Large Magellanic Cloud
• Plasma Diagnostics of the Supernova Remnant N132D Using Deep XMM-Newton Observations with the Reflection Grating Spectrometer
• Detection of variable VHE gamma-ray emission from the extra-galactic gamma-ray binary LMC P3
• Search for gamma-ray line features from Milky Way satellites with Fermi-LAT Pass 8 data
• LMC N132D: A mature supernova remnant with a power-law gamma-ray spectrum extending beyond 8 TeV
• Very-high-energy $\gamma$-ray emission from young massive star clusters in the Large Magellanic Cloud
• Local Volume HI Survey: the far-infrared radio correlation
• Searching for GeV gamma-ray emission from the bulge of M31
• Search for the Gamma-ray Emission from M33 with Fermi LAT
• Supernova origin of cosmic rays from a gamma-ray signal in the Constellation III region of the Large Magellanic Cloud
• Minimum Spanning Tree cluster analysis of the LMC region above 10 GeV: detection of the SNRs N 49B and N 63A
• Evidence of a spectral break in the gamma-ray emission of the disk component of Large Magellanic Cloud: a hadronic origin?
• Identification of blazar candidates behind Small and Large Magellanic Clouds
• HST Proper Motion Measurements of Supernova Remnant N132D: Center of Expansion and Age
• Fermi-LAT Gamma-ray Emission Discovered from the Composite Supernova Remnant B0453-685 in the Large Magellanic Cloud
• CONGRuENTS (COsmic-ray, Neutrino, Gamma-ray and Radio Non-Thermal Spectra). I. A predictive model for galactic non-thermal emission
• Discovery of GeV gamma-ray emission from the LMC B0443-6657 with the Fermi Large Area Telescope
• GeV emission of gamma-ray binary with pulsar scenario
• High energy gamma-ray detection of supernova remnants in the Large Magellanic Cloud
• Linking gamma-ray spectra of supernova remnants to the cosmic ray injection properties in the aftermath of supernovae
• How do the dynamics of the Milky Way -- Large Magellanic Cloud system affect gamma-ray constraints on particle dark matter?
• Search for $\gamma$-ray emission from SNRs in the Large Magellanic Cloud: a new cluster analysis at energies above 4 GeV
• Nonthermal processes and particle acceleration in supernova remnants
• Diffuse non-thermal emission in the disks of the Magellanic Clouds
• A MINOT-based Study of Gamma-ray emission from SPT-CL J2012-5649/Abell 3667
• Gamma-ray emission toward supergiant shells in the Large Magellanic Cloud
• The orbital dynamics of the LMC and SMC about the Milky Way