SIMBAD references

We report the discovery of thermal X-ray emission from the youngest Galactic supernova remnant G1.9+0.3, from a 237 ks Chandra observation. We detect strong Kα lines of Si, S, Ar, Ca, and Fe. In addition, we detect a 4.1 keV line with 99.971% confidence which we attribute to ⁴⁴Sc, produced by electron capture from ⁴⁴Ti. Combining the data with our earlier Chandra observation allows us to detect the line in two regions independently. For a remnant age of 100 yr, our measured total line strength indicates synthesis of (1-7)x10^–5 M_☉ of ⁴⁴Ti, in the range predicted for both Type Ia and core-collapse supernovae (SNe), but somewhat smaller than the 2 x 10^–4 M_☉ reported for Cas A. The line spectrum indicates supersolar abundances. The Fe emission has a width of about 28,000 km/s, consistent with an age of ∼100 yr and with the inferred mean shock velocity of 14,000 km/s deduced assuming a distance of 8.5 kpc. Most thermal emission comes from regions of lower X-ray but higher radio surface brightness. Deeper observations should allow more detailed spatial mapping of ⁴⁴Sc, with significant implications for models of nucleosynthesis in Type Ia SNe.