arXiv subjects

Isabel Sander

Publications and source records attributed to Isabel Sander.

3 recordsLinked to original sources

arXiv2026

The Hand of God Revisited: Revealing the Shell Structure and Jet-Supernova Remnant Interaction in MSH 15-52

We present an X-ray analysis of the supernova remnant (SNR) MSH 15-52 associated with the young rotation-powered pulsar PSR B1509-58, using Chandra, XMM-Newton, and eROSITA, complemented by MeerKAT radio data. We report the discovery of the missing southern counterpart to the bright northern RCW 89 region and identify a foreground X-ray source that may be a previously unidentified SNR candidate. Imaging and spectroscopy with XMM-Newton and eROSITA reveal the shell properties of MSH 15-52 and suggest that both the southern and northern shell-like structures are consistent with shocked interstellar medium associated with the forward shock, while their low ionization timescales and possible hard power-law components indicate possible influence from particle injection or additional heating by the pulsar wind nebula (PWN) jets. New Chandra spectral maps of the southern jet reveal a region of hard non-thermal emission, with a photon index of approximately 1.6, suggesting interaction between the PWN and the reverse shock and possible re-acceleration of the pulsar outflow. Spatially resolved spectroscopy of the RCW 89 northern clumps reveals high-velocity, metal-rich ejecta with enhanced Ne and Mg abundances. Comparison with core-collapse nucleosynthesis models favors a massive progenitor with an initial mass of approximately 29 solar masses in one-dimensional yield models, while asymmetric explosion models show that lower-mass progenitors can also reproduce the observed abundance ratios. Our study supports a picture in which RCW 89 is part of a larger asymmetric SNR shell interacting with energetic pulsar jets, making the system a valuable laboratory for probing pulsar-PWN-SNR interaction.

astro-ph.HE↗

arXiv2026

The Salamander: A case study of the magnetic field and peculiar morphology of G309.8-2.6 through radio polarimetry

Studying the interaction between core-collapse supernova remnants (SNRs) and their surrounding environments is essential to understanding the mechanism for energy transfer to the interstellar medium (ISM) and the intrinsic physical properties of these remnants. In this paper, we focus on G309.8-2.6. Our new observations reveal that this object includes an SNR shell with a relic pulsar wind nebula (PWN) that extends well beyond the emission that has been previously observed in X-rays. We present new radio continuum and polarization images of G309.8-2.6 from the Evolutionary Map of the Universe (EMU) and Polarization Sky Survey of the Universe's Magnetism (POSSUM) surveys with the Australian Square Kilometre Array Pathfinder (ASKAP). The images reveal the complex and peculiar morphology of G309.8-2.6. The linear polarization displays an atypical S-shaped morphology and a highly ordered magnetic field. The rotation measure (RM) map shows a large-scale gradient or possible sign reversal, depending on the foreground RM. We reprocessed archival X-ray observations from Chandra and eROSITA, and retrieved archival H$α$ and infrared observations. We performed a joint analysis of the multiwavelength data and proposed scenarios to explain the unusual shape. Our results place new constraints on the magnetic field of G309.8-2.6, including its environment, and demonstrate the power of polarization observations in probing the properties of SNRs.

astro-ph.GA↗

arXiv2021

A Quick Look at the $3\,$GHz Radio Sky I. Source Statistics from the Very Large Array Sky Survey

The Very Large Array Sky Survey (VLASS) is observing the entire sky north of $-40^{\circ}$ in the S-band ($2<ν<4\,$GHz), with the highest angular resolution ($2''.5$) of any all-sky radio continuum survey to date. VLASS will cover its entire footprint over three distinct epochs, the first of which has now been observed in full. Based on Quick Look images from this first epoch, we have created a catalog of $1.9\times10^{6}$ reliably detected radio components. Due to the limitations of the Quick Look images, component flux densities are underestimated by $\sim 15\,\%$ at $S_{\text{peak}}>3\,$mJy/beam and are often unreliable for fainter components. We use this catalog to perform statistical analyses of the $ν\sim 3\,$GHz radio sky. Comparisons with the Faint Images of the Radio Sky at Twenty cm survey (FIRST) show the typical $1.4-3\,$GHz spectral index, $α$, to be $\sim-0.71$. The radio color-color distribution of point and extended components is explored by matching with FIRST and the LOFAR Two Meter Sky Survey. We present the VLASS source counts, $dN/dS$, which are found to be consistent with previous observations at $1.4$ and $3\,$GHz. Resolution improvements over FIRST result in excess power in the VLASS two-point correlation function at angular scales $\lesssim 7''$, and in $18\,\%$ of active galactic nuclei associated with a single FIRST component being split into multi-component sources by VLASS.

astro-ph.GA↗