The gamma ray burst – supernova connection

An artist’s impression of a superluminous supernova and an
associated gamma-ray burst being driven by a rapidly
spinning neutron star. A new model proposes that a slight
misalignment between the spin and magnetic axes of the
neutron star can power both the superluminous supernova and
the gamma-ray burst phenomena. Credit: ESO

A “core-collapse” supernova occurs when the iron core of a
massive star collapses under the force of gravity and then
rebounds, generating pressure waves and shocks that propagate
outward. A superluminous supernovae is a rare class of core
collapse supernovae whose luminosity, equal to 10-1000
billion suns, is too high to be powered by the usual process
that drives supernovae, the radioactive decay of nickel
(there is not enough nickel present to do it). The source of
the energetics has been hotly contested, with suggestions
including shocks from the ejected material or pulsating
instabilities interacting with surrounding material. The most
favored model, however, is the sustained injection of energy
from a source like a spinning compact remnant: a neutron star
or an accreting black hole.

Long-duration gamma-ray bursts are those that last for a few
seconds up to several minutes, unlike the more common gamma-ray
bursts that last for under a few seconds. The long-duration
bursts are suspected of being sustained by the rotational
energy of a spinning compact object left behind from a
supernova. Superluminous seem to be associated with these kinds
of long-duration bursts, lending support to the idea that they
too are powered by a spinning remnant.

CfA astronomer Matt Nicholl and four colleagues have proposed a
unifying model for and long-duration
gamma-ray bursts in which a spinning neutron star has a slight
misalignment between its spin axis and its magnetic axis. The
consequence is that substantial fractions of the spinning power
are supplied both to the supernova and to a jet of particles
moving at speeds close to the speed of light that enabled the
long burst. Moreover, the scientists are able to predict the
radio emission and thermal wind effects, and to address some of
the transient effects that appear in these dramatic events.

Explore further:

Scientists dedicate the birth of a new black hole to Stephen
Hawking

More information: Ben Margalit et al. The GRB–SLSN
connection: misaligned magnetars, weak jet emergence, and
observational signatures, Monthly Notices of the Royal
Astronomical Society
(2018). DOI:
10.1093/mnras/sty013


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