Gamma-rays from millisecond pulsar population within the central stellar cluster in the Galactic Center

TL;DR

This paper suggests that millisecond pulsars in the dense stellar cluster at the Galactic Center can explain observed GeV and TeV gamma-ray emissions through cumulative effects and inverse Compton scattering of accelerated leptons.

Contribution

It introduces a model linking the millisecond pulsar population in the central cluster to gamma-ray emissions observed from the Galactic Center, including TeV energies.

Findings

The gamma-ray emission can be explained by MSPs in the central cluster.

Leptons accelerated by MSPs produce TeV gamma-rays via inverse Compton scattering.

Approximately 1,000 MSPs are needed in the cluster for the model to match observations.

Abstract

It was proposed that the central dense stellar cluster in the Galactic Center, containing the mass of $\sim$4 times larger than that of the central black hole, had been formed as a result of a merging of several massive globular clusters. These globular clusters are expected to provide a large number of millisecond pulsars (MSPs) within the central parsec of the Galactic Center. We propose that the GeV $\gamma$-ray emission observed from the Galactic Center is in fact a cumulative effect of the emission from several globular clusters captured by the Galactic Center black hole. Moreover, the millisecond pulsars in globular clusters accelerate leptons in their wind zones to energies of the order of a few tens of TeV injecting them into the dense infrared and optical radiation region present within the central parsec. We calculate the expected TeV $\gamma$-ray emission produced by these leptons by the Inverse Compton Scattering process in the soft radiation field. It is shown that this emission can be responsible for the multi-TeV $\gamma$-rays observed by the Cherenkov telescopes from the Galactic Center for reasonable densities of the soft radiation, diffusion models for the propagation of leptons, their injection parameters (fluxes and spectral proprieties). If the energy conversion efficiency from the pulsars to the relativistic leptons is of the order of 10%, then about a thousand of MSPs have to be present in the central cluster in the Galactic Center.