Linda Tenhu: The optical-NIR spectrum of the pulsar and PWN in SNR 054

Thursday 15 Jun 2023, 13:00 → 14:00 Europe/Stockholm

Albano 3: 6228 - Mega (22 seats) (Albano Building 3)

The supernova remnant SNR 0540-69.3, twin of the Crab Nebula, offers an excellent opportunity to study the continuum emission from a young pulsar and pulsar-wind nebula (PWN). We make use of the observations taken with the VLT instruments MUSE and X-shooter in the wavelength range 3000–25,000 Å, which provide the possibility to study spatial variations of the optical spectra along with the first near-infrared (NIR) spectrum of the source. We model the optical spectra with a power law model and find clear spatial variations (including a torus-jet structure) in the spectral index across the PWN. Generally, we find spectral hardening toward the outer parts, which could be due to particle re-acceleration by the PWN shock at the inner edge of the ejecta or alternatively time variability of the pulsar wind. The full optical-NIR spectrum of the PWN is best described by a broken PL confirming that several (possibly synchrotron cooling) breaks are needed to model the full spectral energy distribution of the PWN, suggesting the presence of more than one particle population. Finally, we subtract the PWN contribution from the pulsar spectrum in MUSE and find that the spectrum is best described with a broken-PL model with positive spectral indices, in contrast to the Crab pulsar that has a negative spectral index and no break in the optical. This might imply that differences in the PWNe propagate to the pulsar spectra.