XMMSL1 J060636.2-694933: An XMM-Newton Slew discovery and Swift/Magellan follow up of a new Classical Nova in the LMC

TL;DR

This paper reports the discovery and follow-up observations of a new classical nova in the LMC, identified through XMM-Newton slew data and confirmed with multi-wavelength observations, highlighting the effectiveness of slew data in finding transients.

Contribution

The study demonstrates the successful identification and classification of a new classical nova using XMM-Newton slew data combined with Swift, Magellan, and archival data, showcasing a novel approach for transient discovery.

Findings

The nova was in a super-soft X-ray state during decline.

The optical spectrum classified it as an Ao auroral phase nova.

Archival data indicated it was a very fast nova at onset.

Abstract

In order to discover new X-ray transients, the data taken by XMM-Newton as it slews between targets are being processed and cross-correlated with other X-ray observations. A bright source, XMMSL1 J060636.2-694933, was detected on 18 July 2006 at a position where no previous X-ray source had been seen. The XMM-Newton slew data, plus follow-up dedicated XMM-Newton and Swift observations, plus optical data acquired with the Magellan Clay telescope, and archival All-Sky Automated Survey (ASAS) data were used to classify the new object, and to investigate its properties. No XMM-Newton slew X-ray counts are detected above 1 keV and the source is seen to be over five hundred times brighter than the ROSAT All-Sky Survey upper limit at that position. The line-rich optical spectrum acquired with the Magellan telescope allows the object to be classified as an Ao auroral phase nova, and the soft X-ray spectrum indicates that the nova was in a super-soft source state in the X-ray decline seen in the follow-up X-ray observations. The archival ASAS data suggests that the nova at onset (Oct 2005) was a 'very fast' nova, and an estimate of its distance is consistent with the nova being situated within the LMC. With the discovery presented here of a new classical nova in the LMC, it is clear that XMM-Newton slew data are continuing to offer a powerful opportunity to find new X-ray transient objects.