Two recent kHz outer heliospheric radio emissions seen at Voyager 1-What are the interplanetary events that trigger them and where are these events when the radio emissions start?

TL;DR

This study links recent outer heliospheric kHz radio emissions detected by Voyager 1 to intense solar events that generate large pressure waves reaching the termination shock, proposing a new origin paradigm distinct from previous models.

Contribution

It introduces a new paradigm connecting large pressure waves from solar events to kHz emissions, emphasizing their arrival at the termination shock rather than the heliopause.

Findings

Two recent kHz emissions linked to intense solar events.

Pressure waves reaching 6-8 times the average solar wind pressure.

Proposes pressure wave arrival at the termination shock as the emission trigger.

Abstract

We have examined instigating events at the Sun that may be responsible for two of the most recent outer heliospheric kHz emissions detected by the University of Iowa plasma wave detector on Voyager 1 starting at 2004.64 and 2006.39, respectively. These interplanetary events have been followed outward from the Sun using plasma and cosmic ray data from Ulysses and Voyagers 1 and 2. For both intervals of kHz emissions, events originating near the Sun that turn out to be the most intense events in this 11-year solar cycle as observed by the plasma and cosmic ray variations in the outer heliosphere, reach V1 and V2 which are near the heliospheric termination shock at almost the same time that the two kHz radio emissions turn-on. These two events which originate near the Sun about 2003.89 (the 2003 Halloween event) and at 2005.71, are also unusual in that they develop solar wind ram pressure waves in the outer heliosphere with maximum pressures ~6-8 times the average solar wind pressure when they reach the heliospheric termination shock. We believe that this study suggests a possible new paradigm for the origin of these latest kHz emissions. This new paradigm is different from the current one describing earlier kHz events. It is related to the strength of these pressure waves in the outer heliosphere and involves the arrival of these large pressure waves at the heliospheric termination shock rather than the arrival of a shock at the heliopause as is the current paradigm.