The γ-Ray Emission of Star-forming Galaxies

Ajello, M.; Mauro, Mattia Di; Paliya, Vaidehi S.; Garrappa, S.

doi:10.3847/1538-4357/ab86a6

Cited by 120 publications

(224 citation statements)

References 91 publications

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“…We are also interested in determining the statistical significance of the relations. To that end, we apply the generalized Kendall rank correlation test and perform Monte Carlo (MC) simulations following a similar procedure as advanced previously in the literature for multiwavelength correlations of star-forming galaxies [15,16], and misaligned active galactic nuclei [17].…”

Section: Pos(icrc2021)617mentioning

confidence: 99%

Evidence for inverse Compton emission from globular clusters

Song¹,

Macías²,

Horiuchi³

et al. 2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

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Millisecond pulsars are very likely the main source of gamma-ray emission from globular clusters. However, the relative contributions of two separate emission processes-curvature radiation from millisecond pulsar magnetospheres vs. inverse Compton emission from relativistic pairs launched into the globular cluster environment by millisecond pulsars-have long been unclear. To address this, we search for evidence of inverse Compton emission in 8-year Fermi-LAT data from the directions of 157 Milky Way globular clusters. We find that the -ray luminosities of the globular clusters are correlated with their stellar encounter rates (6.4 ) and total radiation field energy density (3.8 ). We demonstrate that the gamma-ray emission of globular clusters can be resolved spectrally into two components: i) an exponentially cut-off power law and ii) a pure power law. The latter component-which we uncover at a significance of 8.2 -is most naturally interpreted as inverse Compton emission by cosmic-ray electrons and positrons injected by millisecond pulsars. The luminosity of this inverse Compton component suggests that the fraction of millisecond pulsar spin-down luminosity into relativistic leptons is similar to the fraction of the spin-down luminosity into prompt magnetospheric radiation.

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Section: Pos(icrc2021)617mentioning

confidence: 99%

Evidence for inverse Compton emission from globular clusters

Song¹,

Macías²,

Horiuchi³

et al. 2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

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“…Several nearby star-forming galaxies (SFGs) have been resolved in -rays [1], establishing such systems as a candidate source class for the extra-galactic -ray background (EGB). Their -ray emission is driven by an abundant reservoir of cosmic rays (CRs).…”

Section: Introductionmentioning

confidence: 99%

Assessing the signatures imprinted by star-forming galaxies in the cosmic gamma-ray background

Owen¹,

Lee²,

Kong³

2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

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In recent years, -ray emission has been detected from star-forming galaxies (SFGs) in the local universe, including M82, NGC 253, Arp 220 and M33. The bulk of this emission is thought to be of hadronic origin, arising from the interactions of cosmic rays (CRs) with the interstellar medium of their host galaxy. More distant SFGs would also presumably be bright in -rays, but these would not be resolved as point sources. Instead, they contribute -rays as unresolved sources to the extra-galactic -ray background (EGB). However, despite the wealth of high-quality all-sky EGB data from the Fermi-LAT -ray space telescope collected over more than a decade of operation, the exact contribution of SFGs to the EGB and the signatures their emission would imprint on the -ray sky remains unsettled. In this study, we model the -ray emission from SFG populations and demonstrate that such emission can be characterised by just a small number of key physically-motivated parameters. We further show that source populations would leave anisotropic signatures in the EGB, which could be used to yield information about the underlying properties, dynamics and evolution of SFGs rich in CRs over cosmic time.

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“…Additional γ-ray emission unaccompanied by neutrinos can occur via leptonic processes such as synchrotron radiation, ICS, γγ annihilation and Bethe-Heitler pair production [169] (p + γ −→ p + e + + e − ), which is expected to dominate in AGN cores [170]. Furthermore, we have considered relatively conservative conventional EGB contributions; several higher estimates exist in the literature [132,133,134,148]. In particular, we neglect the contribution from cosmogenic γ-ray production by UHECRs propagating through the intergalactic space, which could be significant at 10 GeV energies (see Figure 5 in [171]).…”

Section: Interpretations and Discussionmentioning

confidence: 99%

“…-All three EGB FG models (see Section 4.1), -Separate nuisance parameters for blazars and radio galaxies in the χ 2 definition, -Gaussian and log-normal pull terms in the χ 2 , -Updated conventional contributions from blazars [132], RGs [133] and SFGs [134], -Only the > 10 GeV part of the EGB, instead of the entire energy range.…”

Section: Final Remarksmentioning

confidence: 99%

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Cascaded Gamma-Ray Counterpart of the Icecube Neutrinos

GALVAO¹

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The γ-Ray Emission of Star-forming Galaxies

Cited by 120 publications

References 91 publications

Evidence for inverse Compton emission from globular clusters

Evidence for inverse Compton emission from globular clusters

Assessing the signatures imprinted by star-forming galaxies in the cosmic gamma-ray background

Cascaded Gamma-Ray Counterpart of the Icecube Neutrinos

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