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Type Ia supernovae are thermonuclear explosions of white dwarf stars in close binary systems. They play an important role as cosmological distance indicators and have led to the discovery of the accelerated expansion of the Universe. Among the most important unsolved questions about supernovae are how the explosion actually proceeds and whether accretion occurs from a companion or by the merging of two white dwarfs. Tycho Brahe's supernova of 1572 (SN 1572) is thought to be one of the best candidates for a type Ia supernova in the Milky Way. The proximity of the SN 1572 remnant has allowed detailed studies, such as the possible identification of the binary companion, and provides a unique opportunity to test theories of the explosion mechanism and the nature of the progenitor. The determination of the hitherto unknown spectroscopic type of this supernova is crucial in relating these results to the diverse population of type Ia supernovae. Here we report an optical spectrum of Tycho's supernova near maximum brightness, obtained from a scattered-light echo more than four centuries after the direct light from the explosion swept past the Earth. We find that SN 1572 belongs to the majority class of normal type Ia supernovae.
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http://dx.doi.org/10.1038/nature07608 | DOI Listing |
Adv Exp Med Biol
July 2025
Lady Davis Institute for Medical Research, Jewish General Hospital and Department of Medicine, McGill University, Montreal, QC, Canada.
Iron is a highly abundant element, essential for life on earth and integral to various biological processes. It originated from stellar nucleosynthesis, particularly in supernovae type Ia, which produced iron used in planetary formation. Life's emergence on earth, about 3.
View Article and Find Full Text PDFPhys Rev Lett
May 2025
Leiden University, Institute Lorentz, PO Box 9506, Leiden 2300 RA, The Netherlands.
The cosmic microwave background (CMB) and baryon acoustic oscillations (BAO) are two of the most robust observations in cosmology. The recent BAO measurements from the DESI collaboration have presented, for the first time, inconsistency between BAO and CMB within the standard cosmological model ΛCDM, indicating a preference for dynamical dark energy over a cosmological constant. We analyze the theoretical implication of the DESI BAO observation for dark energy and gravity employing a nonparametric reconstruction approach for both the dark energy equation of state w_{DE}(a) and the effective field theory coefficients.
View Article and Find Full Text PDFPhilos Trans A Math Phys Eng Sci
May 2025
School of Physical Sciences, The Open University, Milton Keynes MK76AA, UK.
Like many areas of astrophysics and cosmology, the Vera C. Rubin Observatory will be transformational for almost all the applications of strong lensing, thanks to the dramatic increase in the number of known strong lenses by two orders of magnitude or more and the readily available time-domain data for the lenses with transient sources. In this article, we provide an overview of the forecasted number of discovered lenses of different types and describe the primary science cases these large lens samples will enable.
View Article and Find Full Text PDFPhys Rev Lett
March 2025
University of Waterloo, University of Waterloo, Waterloo Centre for Astrophysics, Waterloo, Ontario N2L 3G1, Canada and Department of Physics and Astronomy, Waterloo, Ontario N2L 3G1, Canada.
We introduce a new method for measuring the Hubble parameter from low-redshift large-scale observations that is independent of the comoving sound horizon. The method uses the baryon-to-photon ratio determined by the primordial deuterium abundance, together with big bang nucleosynthesis calculations and the present-day cosmic microwave background (CMB) temperature, to determine the physical baryon density Ω_{b}h^{2}. The baryon fraction Ω_{b}/Ω_{m} is measured using the relative amplitude of the baryonic signature in galaxy clustering measured by the Baryon Oscillation Spectroscopic Survey, scaling the physical baryon density to the physical matter density.
View Article and Find Full Text PDFPhys Rev Lett
February 2025
Department of Physics, Chonnam National University, 77, Yongbong-ro, Buk-gu, Gwangju 61186, Korea.
We present the first measurement of the missing energy due to nuclear effects in monoenergetic, muon neutrino charged-current interactions on carbon, originating from K^{+}→μ^{+}ν_{μ} decay at rest (E_{ν_{μ}}=235.5 MeV), performed with the J-PARC Sterile Neutrino Search at the J-PARC Spallation Neutron Source liquid scintillator based experiment. Toward characterizing the neutrino interaction, ostensibly ν_{μ}n→μ^{-}p or ν_{μ}^{12}C→μ^{-}^{12}N, we define the missing energy as the energy transferred to the nucleus (ω) minus the kinetic energy of the outgoing proton(s), E_{m}≡ω-∑T_{p}, and relate this to visible energy in the detector, E_{m}=E_{ν_{μ}}(235.
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