3,863 research outputs found
Spectropolarimetry of Core-Collapse Supernovae
We briefly review the young field of spectropolarimetry of core-collapse
supernovae (SNe). Spectropolarimetry provides the only direct known probe of
early-time supernova (SN) geometry. The fundamental result is that asphericity
is a ubiquitous feature of young core-collapse SNe. However, the nature and
degree of the asphericity vary considerably. The best predictor of
core-collapse SN polarization seems to be the mass of the hydrogen envelope
that is intact at the time of the explosion: those SNe that arise from
progenitors with large, intact envelopes (e.g., Type II-plateau) have very low
polarization, while those that result from progenitors that have lost part (SN
IIb, SN IIn) or all (SN Ib) of their hydrogen (or even helium; SN Ic) layers
prior to the explosion tend to show substantial polarization. Thus, the deeper
we probe into core-collapse events, the greater the asphericity seems to be,
suggesting a fundamentally asymmetric explosion with the asymmetry damped by
the addition of envelope material.Comment: Invited review at Supernovae as Cosmological Lighthouses, 16-19 June,
Padua, IT. 6 page
Localized shocks
We study products of precursors of spatially local operators,
, where .
Using chaotic spin-chain numerics and gauge/gravity duality, we show that a
single precursor fills a spatial region that grows linearly in . In a
lattice system, products of such operators can be represented using tensor
networks. In gauge/gravity duality, they are related to Einstein-Rosen bridges
supported by localized shock waves. We find a geometrical correspondence
between these two descriptions, generalizing earlier work in the spatially
homogeneous case.Comment: 23 pages plus appendices, 12 figures. v2: minor error in Appendix B
corrected. v3: figure added to the introduction comparing the butterfly
effect cone with the standard light con
A Spectropolarimetric Comparison of the Type II-Plateau Supernovae SN 2008bk and SN 2004dj
The Type II-Plateau supernova (SN II-P) SN 2004dj was the first SN II-P for which
spectropolarimetry
data were obtained with fine temporal sampling before, during, and after its fall off of the
photometric plateau – the point that marks the transition from the photospheric to the nebular phase in
SNe II-P. Unpolarized during the plateau, SN 2004dj showed a dramatic spike in polarization during the
descent off of the plateau, and then exhibited a smooth polarization decline over the next two
hundred days. This behavior was interpreted by Leonard et al. (2006) as evidence for a strongly
non-spherical explosion mechanism that had imprinted asphericity only in the innermost ejecta. In this brief
report, we compare nine similarly well-sampled epochs of spectropolarimetry of the Type II-P SN
2008bk to those of SN 2004dj. In contrast to SN 2004dj, SN 2008bk became polarized well before the end
of the plateau and also retained a nearly constant level of polarization through the early nebular
phase. Curiously, although the onset and persistence of polarization differ between the
two objects, the detailed spectropolarimetric characteristics at the epochs of recorded maximum
polarization for the two objects are extremely similar, feature by feature. We briefly interpret the
data in light of non-Local-Thermodynamic Equilibrium, time-dependent radiative-transfer simulations
specifically crafted for SN II-P ejecta
“Chastisement of Beauty”: A Mode of the Religious Sublime in Dickinson’s Poetry
Emily Dickinson shared with other Romantic poets, American and European, the intuition that the age of reason had run its course and had failed to bring the hoped-for illumination and order. In the new century, as the focus turned toward self, the feelings of the individual tended to replace authority and schema in the measure of truth and beauty. From the beginning, Dickinson\u27s poetry reflects the poet\u27s awareness that emotional sensations occur in various dimensions within the consciousness, so that joy and grief, for example, or exultation and fear, may combine in single complex reactions. The most intense emotions, in fact. are frequently the most paradoxical. The combination of emotional opposites would become characteristic in Dickinson\u27s poetry, and it is in fact the indivisible unity of terror and ecstasy which constituted what Dickinson considered the most intense emotion of all, what she called awe
Probing the Geometry of Supernovae with Spectropolarimetry
We present results from a spectropolarimetric survey of young supernovae
completed at the Keck Observatory, including at least one example from each of
the major supernova types: Ia (1997dt), Ib (1998T, 1997dq), Ib/c-pec (1997ef),
IIn (1997eg), and II-P (1997ds). All objects show evidence for intrinsic
polarization, suggesting that asphericity may be a common feature in young
supernova atmospheres.Comment: 4 pages, 2 figures. To appear in the Proceedings of the 10th Annual
October Astrophysics Conference in Maryland: Cosmic Explosion
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