A Central Compact Object in Kes 79: The hypercritical regime and neutrino expectation

TL;DR

This paper uses magnetohydrodynamical simulations to explore hypercritical accretion onto magnetized proto-neutron stars in Kes 79, explaining the properties of its central compact object and predicting neutrino signals.

Contribution

It demonstrates that magnetic field submergence during hypercritical accretion can account for the characteristics of Kes 79's central compact object, using detailed 2D simulations including neutrino effects.

Findings

Estimated 733±364 neutrinos detectable by Hyper-Kamiokande

Magnetic field submergence explains absence of pulsar wind nebula

Simulations support hypercritical accretion as key process

Abstract

We present magnetohydrodynamical simulations of a strong accretion onto magnetized proto-neutron stars for the Kesteven 79 (Kes 79) scenario. The supernova remnant Kes 79, observed with the Chandra ACIS-I instrument during approximately 8.3 h, is located in the constellation Aquila at a distance of 7.1 kpc in the galactic plane. It is a galactic and a very young object with an estimate age of 6 kyr. The Chandra image has revealed, for the first time, a point-like source at the center of the remnant. The Kes 79 compact remnant belongs to a special class of objects, the so-called Central Compact Objects, which exhibits no evidence for a surrounding pulsar wind nebula. In this work we show that the submergence of the magnetic field during the hypercritical phase can explain such behavior for Kes 79 and others CCOs. The simulations of such regime were carried out with the adaptive-mesh-refinement code FLASH in two spatial dimensions, including radiative loss by neutrinos and an adequate equation of state for such regime. From the simulations, we estimate that the number of thermal neutrinos expected on the Hyper-Kamiokande Experiment is 733$\pm$364. In addition, we compute the flavor ratio on Earth for a progenitor model.