EVLA Nova Project Observations of the Classical Nova V1723 Aquilae

TL;DR

This paper presents comprehensive radio observations of the classical nova V1723 Aql using EVLA, revealing complex behavior inconsistent with simple models and suggesting shock-related phenomena.

Contribution

First EVLA Nova Project paper providing detailed radio spectra and light curves, highlighting complex nova ejecta behavior beyond traditional models.

Findings

Radio spectra are partially optically thin at all times.

Flux rises faster than linear expansion models predict.

X-ray data indicates the presence of shocks.

Abstract

We present radio light curves and spectra of the classical nova V1723 Aql obtained with the Expanded Very Large Array (EVLA). This is the first paper to showcase results from the EVLA Nova Project, which comprises a team of observers and theorists utilizing the greatly enhanced sensitivity and frequency coverage of EVLA radio observations, along with observations at other wavelengths, to reach a deeper understanding of the energetics, morphology, and temporal characteristics of nova explosions. Our observations of V1723 Aql span 1-37 GHz in frequency, and we report on data from 14-175 days following the time of the nova explosion. The broad frequency coverage and frequent monitoring show that the radio behavior of V1723 Aql does not follow the classic Hubble-flow model of homologous spherically expanding thermal ejecta. The spectra are always at least partially optically thin, and the flux rises on faster timescales than can be reproduced with linear expansion. Therefore, any description of the underlying physical processes must go beyond this simple picture. The unusual spectral properties and light curve evolution might be explained by multiple emitting regions or shocked material. Indeed, X-ray observations from Swift reveal that shocks are likely present.