Hitomi Observations of the LMC SNR N132D: Highly Redshifted X-ray Emission from Iron Ejecta

Kavli Affiliate: Marshall W. Bautz

| First 5 Authors: Hitomi Collaboration, Felix Aharonian, Hiroki Akamatsu, Fumie Akimoto, Steven W. Allen

| Summary:

We present Hitomi observations of N132D, a young, X-ray bright, O-rich
core-collapse supernova remnant in the Large Magellanic Cloud (LMC). Despite a
very short observation of only 3.7 ks, the Soft X-ray Spectrometer (SXS) easily
detects the line complexes of highly ionized S K and Fe K with 16-17 counts in
each. The Fe feature is measured for the first time at high spectral
resolution. Based on the plausible assumption that the Fe K emission is
dominated by He-like ions, we find that the material responsible for this Fe
emission is highly redshifted at ~800 km/s compared to the local LMC
interstellar medium (ISM), with a 90% credible interval of 50-1500 km/s if a
weakly informative prior is placed on possible line broadening. This indicates
(1) that the Fe emission arises from the supernova ejecta, and (2) that these
ejecta are highly asymmetric, since no blue-shifted component is found. The S K
velocity is consistent with the local LMC ISM, and is likely from swept-up ISM
material. These results are consistent with spatial mapping that shows the
He-like Fe concentrated in the interior of the remnant and the S tracing the
outer shell. The results also show that even with a very small number of
counts, direct velocity measurements from Doppler-shifted lines detected in
extended objects like supernova remnants are now possible. Thanks to the very
low SXS background of ~1 event per spectral resolution element per 100 ks, such
results are obtainable during short pointed or slew observations with similar
instruments. This highlights the power of high-spectral-resolution imaging
observations, and demonstrates the new window that has been opened with Hitomi
and will be greatly widened with future missions such as the X-ray Astronomy
Recovery Mission (XARM) and Athena.

| Search Query: ArXiv Query: search_query=au:”Marshall W. Bautz”&id_list=&start=0&max_results=10

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