274 research outputs found
Effect of Supernovae on the Local Interstellar Material
A range of astronomical data indicates that ancient supernovae created the
galactic environment of the Sun and sculpted the physical properties of the
interstellar medium near the heliosphere. In this paper we review the
characteristics of the local interstellar medium that have been affected by
supernovae. The kinematics, magnetic field, elemental abundances, and
configuration of the nearest interstellar material support the view that the
Sun is at the edge of the Loop I superbubble, which has merged into the low
density Local Bubble. The energy source for the higher temperature X-ray
emitting plasma pervading the Local Bubble is uncertain. Winds from massive
stars and nearby supernovae, perhaps from the Sco-Cen Association, may have
contributed radioisotopes found in the geologic record and galactic cosmic ray
population. Nested supernova shells in the Orion and Sco-Cen regions suggest
spatially distinct sites of episodic star formation. The heliosphere properties
vary with the pressure of the surrounding interstellar cloud. A nearby
supernova would modify this pressure equilibrium and thereby severely disrupt
the heliosphere as well as the local interstellar medium.Comment: 30 pages, 7 figures. Author version, updated and modified (several
updated and new paragraphs, one new subsection), of an article that was
published in the Handbook of Supernovae, A.W. Alsabti, P. Murdin (eds.),
Springer, 201
Cosmic-ray acceleration and gamma-ray signals from radio supernovae
In this work the efficiency of particle acceleration at the forward shock
right after the SN outburst for the particular case of the well-known SN 1993J
is analyzed. Plasma instabilities driven by the energetic particles accelerated
at the shock front grow over intraday timescales and drive a fast amplification
of the magnetic field at the shock, that can explain the magnetic field
strengths deduced from the radio monitoring of the source. The maximum particle
energy is found to reach 1-10 PeV depending on the instability dominating the
amplification process. We derive the time dependent particle spectra and the
associated hadronic signatures of secondary particles arising from proton
proton interactions. We find that the Cherenkov Telescope Array (CTA) should
easily detect objects like SN 1993J in particular above 1 TeV, while current
generation of Cherenkov telescopes such as H.E.S.S. could only marginally
detect such events. The gamma-ray signal is found to be heavily absorbed by
pair production process during the first week after the outburst. We predict a
low neutrino flux above 10 TeV, implying a detectability horizon with a
KM3NeT-type telescope of 1 Mpc only. We finally discuss the essential
parameters that control the particle acceleration and gamma-ray emission in
other type of SNe.Comment: 7 pages, 3 figures (Note: conflict of .sty file version explains the
problems with journal title and the abstract, apologies for any
inconvenience). Appears as Nuclear Physics B Proceedings Supplement 2014
Proceedings of the workshop "Cosmic Ray Origin beyond the standard models",
San Vito (2014), ed. by O.Tibolla, L. Drur
Chandra Fails to Detect X-ray Emission from Type Ia SN 2018fhw/ASASSN-18tb
We report on Chandra X-ray observations of ASASSN-18tb/SN 2018fhw, a low
luminosity Type Ia supernova that showed a H line in its optical spectrum. No
X-ray emission was detected at the location of the SN. Upper limits to the
luminosity of up to 3 erg s are calculated, depending
on the assumed spectral model, temperature and column density. These are
compared to two Type Ia-CSM SNe, SN 2005gj and SN 2002ic, that have been
observed with Chandra in the past. The upper limits are lower than the X-ray
luminosity found for the Type Ia-CSM SN 2012ca, the only Type Ia SN to have
been detected in X-rays. Consideration of various scenarios for the H
line suggests that the density of the surrounding medium at the time of
H line detection could have been as high as 10 cm, but must
have decreased below 5 cm at the time of X-ray
observation. Continual X-ray observations of SNe which show a H line in their
spectrum are necessary in order to establish Type Ia SNe as an X-ray emitting
class.Comment: 9 pages, 1 figure, 3 tables. Accepted to MNRA
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