X-ray Measurements of $^{44}$Ti in Four Supernova Remnants

TL;DR

This study searches for X-ray fluorescence from $^{44}$Ti decay in four young supernova remnants using archival XMM-Newton data, finding tentative signals consistent with prior gamma-ray observations.

Contribution

It provides the first systematic X-ray search for $^{44}$Ti in multiple supernova remnants, complementing gamma-ray measurements and constraining $^{44}$Ti mass estimates.

Findings

All remnants show modest signals consistent with previous gamma-ray data.

No definitive X-ray detection of $^{44}$Ti was achieved.

Results support existing gamma-ray-based $^{44}$Ti mass estimates.

Abstract

We present the results of a search for scandium K$_\alpha$ X-ray fluorescence resulting from $^{44}$Ti electron capture decay in four young supernova remnants. We analyzed archival XMM-Newton data from Tycho's SNR, Kepler's SNR, Cassiopeia A, and SN 1987A. We fit the X-ray spectra in regions of interest with up to four components, thermal and power-law, as needed to fit the spectrum, and add a gaussian to test for extra Sc emission. While all require the line with modest confidence, none represent definitive detections on their own, and all are consistent with previous gamma-ray detections or limits on the $^{44}$Ti mass.