Unidentified Galactic High-Energy Sources as Ancient Pulsar Wind Nebulae in the light of new high energy observations and the new code

TL;DR

This paper explores how ancient pulsar wind nebulae can remain bright in gamma rays long after the pulsar's death, explaining unidentified gamma-ray sources and offering new modeling insights.

Contribution

It introduces a new modeling code to analyze the evolution of PWNe and their gamma-ray emission, providing a novel framework for understanding high-energy astrophysical sources.

Findings

PWNe can remain gamma-ray bright for 10^5 - 10^6 years after pulsar death

The magnetic field in the progenitor star's wind cavity influences PWN evolution

New code confirms the potential of PWNe to explain dark gamma-ray sources

Abstract

In a Pulsar Wind Nebula (PWN), the lifetime of inverse Compton (IC) emitting electrons exceeds the lifetime of its progenitor pulsar (as well as its shell-type remnant), but it also exceeds the age of those that emit via synchrotron radiation. Therefore, during its evolution, the PWN can remain bright in IC so that its GeV-TeV gamma-ray flux remains high for timescales much larger (for 10^5 - 10^6 yrs) than the pulsar lifetime and the X-ray PWN lifetime. In this scenario, the magnetic field in the cavity induced by the wind of the progenitor star plays a crucial role. This scenario is in line with the discovery of several unidentified or "dark" sources in the TeV gamma-ray band without X-ray counterparts; and it is also finding confirmation in the recent discoveries at GeV gamma rays. Moreover, these consequences could be also important for reinterpreting the detection of starburst galaxies in the TeV gamma-ray band when considering a leptonic origin of the gamma-ray signal. Both theoretical aspects and their observational proofs will be discussed, as well as the first results of our new modeling code.