Enhanced proton parallel temperature inside patches of switchbacks in the inner heliosphere. (arXiv:2010.10379v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Woodham_L/0/1/0/all/0/1">L. D. Woodham</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Horbury_T/0/1/0/all/0/1">T. S. Horbury</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Matteini_L/0/1/0/all/0/1">L. Matteini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Woolley_T/0/1/0/all/0/1">T. Woolley</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Laker_R/0/1/0/all/0/1">R. Laker</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bale_S/0/1/0/all/0/1">S. D. Bale</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nicolaou_G/0/1/0/all/0/1">G. Nicolaou</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stawarz_J/0/1/0/all/0/1">J. E. Stawarz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stansby_D/0/1/0/all/0/1">D. Stansby</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hietala_H/0/1/0/all/0/1">H. Hietala</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Larson_D/0/1/0/all/0/1">D. E. Larson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Livi_R/0/1/0/all/0/1">R. Livi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Verniero_J/0/1/0/all/0/1">J. L. Verniero</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McManus_M/0/1/0/all/0/1">M. McManus</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kasper_J/0/1/0/all/0/1">J. C. Kasper</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Korreck_K/0/1/0/all/0/1">K. E. Korreck</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Raouafi_N/0/1/0/all/0/1">N. Raouafi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Moncuquet_M/0/1/0/all/0/1">M. Moncuquet</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pulupa_M/0/1/0/all/0/1">M. P. Pulupa</a>
Switchbacks are discrete angular deflections in the solar wind magnetic field
that have been observed throughout the heliosphere. Recent observations by
Parker Solar Probe (PSP) have revealed the presence of patches of switchbacks
on the scale of hours to days, separated by ‘quieter’ radial fields. We aim to
further diagnose the origin of these patches using measurements of proton
temperature anisotropy that can illuminate possible links to formation
processes in the solar corona. We fitted 3D bi-Maxwellian functions to the core
of proton velocity distributions measured by the SPAN-Ai instrument onboard PSP
to obtain the proton parallel, $T_{p,|}$, and perpendicular, $T_{p,perp}$,
temperature. We show that the presence of patches is highlighted by a
transverse deflection in the flow and magnetic field away from the radial
direction. These deflections are correlated with enhancements in $T_{p,|}$,
while $T_{p,perp}$ remains relatively constant. Patches sometimes exhibit
small proton and electron density enhancements. We interpret that patches are
not simply a group of switchbacks, but rather switchbacks are embedded within a
larger-scale structure identified by enhanced $T_{p,|}$ that is distinct from
the surrounding solar wind. We suggest that these observations are consistent
with formation by reconnection-associated mechanisms in the corona.
Switchbacks are discrete angular deflections in the solar wind magnetic field
that have been observed throughout the heliosphere. Recent observations by
Parker Solar Probe (PSP) have revealed the presence of patches of switchbacks
on the scale of hours to days, separated by ‘quieter’ radial fields. We aim to
further diagnose the origin of these patches using measurements of proton
temperature anisotropy that can illuminate possible links to formation
processes in the solar corona. We fitted 3D bi-Maxwellian functions to the core
of proton velocity distributions measured by the SPAN-Ai instrument onboard PSP
to obtain the proton parallel, $T_{p,|}$, and perpendicular, $T_{p,perp}$,
temperature. We show that the presence of patches is highlighted by a
transverse deflection in the flow and magnetic field away from the radial
direction. These deflections are correlated with enhancements in $T_{p,|}$,
while $T_{p,perp}$ remains relatively constant. Patches sometimes exhibit
small proton and electron density enhancements. We interpret that patches are
not simply a group of switchbacks, but rather switchbacks are embedded within a
larger-scale structure identified by enhanced $T_{p,|}$ that is distinct from
the surrounding solar wind. We suggest that these observations are consistent
with formation by reconnection-associated mechanisms in the corona.
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