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تسجيل مستخدم جديدExploration of Aspherical Ejecta Properties in Type Ia Supernova: Progenitor Dependence and Applications to Progenitor Classification
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Several explosions of thermonuclear supernovae (SNe Ia) have been found to exhibit deviations from spherical symmetry upon closer inspection. Examples are the gamma-ray lines from SN 2014J as measured by INTEGRAL/SPI, and morphology information from radioactive isotopes in older remnants such as Tycho. A systematic study on the effects of parameters such as ignition geometry and burning morphology in SNe Ia is still missing. We use a 2D hydrodynamics code with post-processing nucleosynthesis and simulate the double detonations in a sub-Chandrasekhar mass carbon-oxygen white dwarf starting from the nuclear runaway in the accumulated He envelope towards disruption of the white dwarf. We explore potential variety through four triggering scenarios that sample main asymmetry drivers. We further investigate their global effects on the aspherical structure of the ejecta based on individual elements. We apply the results to the well observed SN 2014J and other recently observed SN remnants in order to illustrate how these new observational data together with other observed quantities help to constrain the explosion and the progenitors of SNe Ia.
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It is generally believed that Type Ia supernovae are thermonuclear explosions of carbon-oxygen white dwarfs (WDs). However, there is currently no consensus regarding the events leading to the explosion. A binary WD (WD-WD) merger is a possible progen
itor of Type Ia supernovae. Space-based gravitational wave (GW) detectors with great sensitivity in the decihertz range like DECIGO can observe WD-WD mergers directly. Therefore, access to the deci-Hz band of GWs would enable multi-messenger observations of Type Ia supernovae to constrain their progenitor and explosion mechanism. In this paper, we consider the event rate of WD-WD mergers and minimum detection range to observe one WD-WD merger per year, using nearby galaxy catalog and the relation between the Ia supernova and the host galaxy. Furthermore, we calculate the DECIGOs ability to localize WD-WD mergers and to determine the masses of binary mergers. We estimate that if the deci-Hz GW observatory can detect the GW whose amplitude is $hsim10^{-20}[rm Hz^{-1/2}]$ at 0.1 Hz, 1000 times higher than the detection limit of DECIGO. In fact, DECIGO is expected to detect WD-WD ($1M_{odot}-1M_{odot}$) mergers within $z=0.115$,corresponding to the detection rate of $sim20000,rm yr^{-1}$, and identify the host galaxy of WD-WD mergers for $sim8000$ WD-WDs only by the GW detection.
The explosive origin of the young supernova remnant (SNR) 3C 397 (G41.1-0.3) is debated. Its elongated morphology and proximity to a molecular cloud are suggestive of a core-collapse (CC) SN origin, yet recent X-ray studies of heavy metals show chemi
cal yields and line centroid energies consistent with a Type Ia SN. In this paper, we analyze the full X-ray spectrum from 0.7-10 keV of 3C 397 observed with Suzaku and compare the line centroid energies, fluxes, and elemental abundances of intermediate-mass and heavy metals (Mg to Ni) to Type Ia and CC hydrodynamical model predictions. Based on the results, we conclude that 3C 397 likely arises from an energetic Type Ia explosion in a high-density ambient medium, and we show that the progenitor was a near Chandrasekhar mass white dwarf.
We report unique EVLA observations of SN 2011fe representing the most sensitive radio study of a Type Ia supernova to date. Our data place direct constraints on the density of the surrounding medium at radii ~10^15-10^16 cm, implying an upper limit o
n the mass loss rate from the progenitor system of Mdot <~ 6 x 10^-10 Msol/yr (assuming a wind speed of 100 km/s), or expansion into a uniform medium with density n_CSM <~ 6 cm^-3. Drawing from the observed properties of non-conservative mass transfer among accreting white dwarfs, we use these limits on the density of the immediate environs to exclude a phase space of possible progenitors systems for SN 2011fe. We rule out a symbiotic progenitor system and also a system characterized by high accretion rate onto the white dwarf that is expected to give rise to optically-thick accretion winds. Assuming that a small fraction, 1%, of the mass accreted is lost from the progenitor system, we also eliminate much of the potential progenitor parameter space for white dwarfs hosting recurrent novae or undergoing stable nuclear burning. Therefore, we rule out the most popular single degenerate progenitor models for SN 2011fe, leaving a limited phase space inhabited by some double degenerate systems and exotic progenitor scenarios.
We present an early-phase $g$-band light curve and visual-wavelength spectra of the normal Type Ia supernova (SN) 2013gy. The light curve is constructed by determining the appropriate S-corrections to transform KAIT natural-system $B$- and $V$-band p
hotometry and Carnegie Supernova Project natural-system $g$-band photometry to the Pan-STARRS1 $g$-band natural photometric system. A Markov Chain Monte Carlo calculation provides a best-fit single power-law function to the first ten epochs of photometry described by an exponent of $2.16^{+0.06}_{-0.06}$ and a time of first light of MJD 56629.4$^{+0.1}_{-0.1}$, which is $1.93^{+0.12}_{-0.13}$ days (i.e., $<48$~hr) before the discovery date (2013 December 4.84 UT) and $-19.10^{+0.12}_{-0.13}$ days before the time of $B$-band maximum (MJD 56648.5$pm0.1$). The estimate of the time of first light is consistent with the explosion time inferred from the evolution of the Si II $lambda$6355 Doppler velocity. Furthermore, discovery photometry and previous nondetection limits enable us to constrain the companion radius down to $R_c leq 4,R_{odot}$. In addition to our early-time constraints, we use a deep +235 day nebular-phase spectrum from Magellan/IMACS to place a stripped H-mass limit of $< 0.018,M_{odot}$. Combined, these limits effectively rule out H-rich nondegenerate companions.
We present Hubble Space Telescope observations and photometric measurements of the Type Ia supernova (SN Ia) SN 2013aa 1500 days after explosion. At this epoch, the luminosity is primarily dictated by the amounts of radioactive ${}^{57}textrm{Co}$ an
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