# Can Dust Injected by SNe Explain the NIR-MIR Excess in Young Massive Stellar Clusters?

## TL;DR

This paper proposes a model where dust from supernovae, surviving in young massive star clusters, explains the observed near- to mid-infrared excess by considering dust grain production, fragmentation, heating, and destruction processes.

## Contribution

It introduces a physically-motivated model linking supernova dust production and destruction to the NIR-MIR excess in young star clusters, incorporating grain size effects and cluster environment conditions.

## Key findings

- Small grains can produce high-temperature emission explaining NIR-MIR excess.
- The excess persists longer if grain incorporation into the medium is slow.
- Model successfully explains observations in M33 star clusters.

## Abstract

We present a physically-motivated model involving the different processes affecting supernova dust grains as they are incorporated into the thermalized medium within young massive star clusters. The model is used to explain the near- to mid-infrared (NIR-MIR) excess found in such clusters and usually modeled as a blackbody with temperature $\sim (400-1000)$ K. In our approach, dust grains are efficiently produced in the clumpy ejecta of core-collapse supernovae, fragmented into small pieces ($\lesssim 0.05$ $\mu$m) as they are incorporated into the hot and dense ISM, heated via frequent collisions with electrons and the absorption of energetic photons. Grains with small sizes can more easily acquire the high temperatures ($\sim 1000$ K) required to produce a NIR-MIR excess with respect to the emission of foreground PAHs and starlight. However, the extreme conditions inside young massive clusters make difficult for these small grains to have a persistent manifestation at NIR-MIR wavelengths as they are destroyed by efficient thermal sputtering. Nevertheless, the chances for a persistent manifestation are increased by taking into account that small grains become increasingly transparent to their impinging ions as their size decreases. For an individual SN event, we find that the NIR-MIR excess last longer if the time required to incorporate all the grains into the thermalized medium is also longer, and in some cases, comparable to the characteristic interval between supernova explosions. Our models, can successfully explain the near-infrared excesses found in the star clusters observed in M33 (Rela\~no et al. 2016) assuming a low heating efficiency and mass-loading. In this scenario, the presence of the NIR-MIR excess is an indication of efficient dust production in SNe and its subsequent destruction