2017/12/06 by Hitomi Collaboration, Felix Aharonian, Hiroki Akamatsu +234 · 17 citations
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Cassiopeia A #Ejecta #Emission spectrum #Galaxy #Gamma-ray bursts and supernovae #Interstellar medium #Ion #Ionization #Large Magellanic Cloud #Line (geometry) #Physics #Redshift #Spectral line #Spectral resolution #Supernova #Supernova remnant #astro-ph.HE
paper · pdf · doi:10.1093/pasj/psx151
published in Publications of the Astronomical Society of Japan 70(2) (Oxford University Press) · 18 pages, 15 figures, 1 table. Accepted for publication by PASJ
arxiv created 2017/12/06 · openalex publication_date 2017/12/11 · openalex created_date 2017/12/22 · arxiv updated 2018/04/25 · openalex updated_date 2026/08/06
Abstract We present Hitomi observations of N 132 D, 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−1 compared to the local LMC interstellar medium (ISM), with a 90% credible interval of 50–1500 km s−1 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 blueshifted 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.