Reply to a comment on `Understanding the gamma-ray emission from the globular cluster 47 Tuc: evidence for dark matter?'

TL;DR

This paper defends previous findings that gamma-ray emission from 47 Tuc is best explained by a combination of millisecond pulsars and dark matter, addressing critiques and emphasizing the significance of the dark matter component.

Contribution

The authors respond to critiques by reaffirming the evidence for a dark matter component in gamma-ray emission from 47 Tuc, highlighting the importance of their spectral analysis and implications for future radio studies.

Findings

Evidence supports a dual source model of MSPs and dark matter in 47 Tuc

Tension exists between different MSP spectral fits when uncertainties are considered

The dark matter component remains a significant factor in gamma-ray emission interpretation

Abstract

Analysing 9 years of Fermi-LAT observations, we recently studied the spectral properties of the prominent globular cluster 47 Tuc (Brown et al. 2018). In particular, we investigated several models to explain the observed gamma-ray emission, ranging from millisecond pulsars (MSP) to Dark Matter (DM), with the motivation for the latter model driven by recent evidence that 47 Tuc harbours an intermediate-mass black hole (IMBH). This investigation found evidence that the observed gamma-ray emission from 47 Tuc is due to two source populations of MSPs and DM. In Bartels \& Edwards (2018), the authors comment that this evidence is an artifact of the MSP spectra used in (Brown et al. 2019). Here we reply to this comment and argue that the authors of Bartels \& Edwards (2018) (i) do not give due consideration to a very important implication of their result and (ii) there is tension between our MSP fit and their MSP fit when taking uncertainties into consideration. As such, we still conclude there is evidence for a DM component which motivates a deeper radio study of the prominent globular cluster 47 Tuc.