The Experts below are selected from a list of 216 Experts worldwide ranked by ideXlab platform
Hiroya Yamaguchi - One of the best experts on this subject based on the ideXlab platform.
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a Chandrasekhar mass progenitor for the type ia supernova remnant 3c 397 from the enhanced abundances of nickel and manganese
The Astrophysical Journal, 2015Co-Authors: Hiroya Yamaguchi, Carles Badenes, Adam R Foster, E Bravo, Brian J Williams, Keiichi Maeda, Masayoshi NobukawaAbstract:Despite decades of intense efforts, many fundamental aspects of Type Ia supernovae (SNe Ia) remain elusive. One of the major open questions is whether the mass of an exploding white dwarf (WD) is close to the Chandrasekhar Limit. Here, we report the detection of strong K-shell emission from stable Fe-peak elements in the Suzaku X-ray spectrum of the Type Ia supernova remnant (SNR) 3C 397. The high Ni/Fe and Mn/Fe mass ratios (0.11–0.24 and 0.018–0.033, respectively) in the hot plasma component that dominates the K-shell emission lines indicate a degree of neutronization in the supernova ejecta that can only be achieved by electron capture in the dense cores of exploding WDs with a near-Chandrasekhar mass. This suggests a single-degenerate origin for 3C 397, since Chandrasekhar mass progenitors are expected naturally if the WD accretes mass slowly from a companion. Together with other results supporting the double-degenerate scenario, our work adds to the mounting evidence that both progenitor channels make a significant contribution to the SN Ia rate in star-forming galaxies.
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a Chandrasekhar mass progenitor for the type ia supernova remnant 3c 397 from the enhanced abundances of nickel and manganese
arXiv: High Energy Astrophysical Phenomena, 2015Co-Authors: Hiroya Yamaguchi, Carles Badenes, Adam R Foster, E Bravo, Brian J Williams, Keiichi Maeda, Masayoshi NobukawaAbstract:Despite decades of intense efforts, many fundamental aspects of Type Ia supernova (SNe Ia) remain elusive. One of the major open questions is whether the mass of the exploding white dwarf (WD) is close to the Chandrasekhar Limit. Here we report the detection of strong K-shell emission from stable Fe-peak elements in the Suzaku X-ray spectrum of the Type Ia supernova remnant (SNR) 3C 397. The high Ni/Fe and Mn/Fe mass ratios (0.11-0.24 and 0.018-0.033, respectively) in the hot plasma component that dominates the K-shell emission lines indicate a degree of neutronization in the SN ejecta which can only be achieved by electron captures in the dense cores of exploding WDs with a near-Chandrasekhar mass. This suggests a single-degenerate origin for 3C 397, since Chandrasekhar mass progenitors are expected naturally if the WD accretes mass slowly from a companion. Together with other results supporting the double-degenerate scenario, our work adds to the mounting evidence that both progenitor channels make a significant contribution to the SN Ia rate in star-forming galaxies.
Keiichi Maeda - One of the best experts on this subject based on the ideXlab platform.
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a Chandrasekhar mass progenitor for the type ia supernova remnant 3c 397 from the enhanced abundances of nickel and manganese
The Astrophysical Journal, 2015Co-Authors: Hiroya Yamaguchi, Carles Badenes, Adam R Foster, E Bravo, Brian J Williams, Keiichi Maeda, Masayoshi NobukawaAbstract:Despite decades of intense efforts, many fundamental aspects of Type Ia supernovae (SNe Ia) remain elusive. One of the major open questions is whether the mass of an exploding white dwarf (WD) is close to the Chandrasekhar Limit. Here, we report the detection of strong K-shell emission from stable Fe-peak elements in the Suzaku X-ray spectrum of the Type Ia supernova remnant (SNR) 3C 397. The high Ni/Fe and Mn/Fe mass ratios (0.11–0.24 and 0.018–0.033, respectively) in the hot plasma component that dominates the K-shell emission lines indicate a degree of neutronization in the supernova ejecta that can only be achieved by electron capture in the dense cores of exploding WDs with a near-Chandrasekhar mass. This suggests a single-degenerate origin for 3C 397, since Chandrasekhar mass progenitors are expected naturally if the WD accretes mass slowly from a companion. Together with other results supporting the double-degenerate scenario, our work adds to the mounting evidence that both progenitor channels make a significant contribution to the SN Ia rate in star-forming galaxies.
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a Chandrasekhar mass progenitor for the type ia supernova remnant 3c 397 from the enhanced abundances of nickel and manganese
arXiv: High Energy Astrophysical Phenomena, 2015Co-Authors: Hiroya Yamaguchi, Carles Badenes, Adam R Foster, E Bravo, Brian J Williams, Keiichi Maeda, Masayoshi NobukawaAbstract:Despite decades of intense efforts, many fundamental aspects of Type Ia supernova (SNe Ia) remain elusive. One of the major open questions is whether the mass of the exploding white dwarf (WD) is close to the Chandrasekhar Limit. Here we report the detection of strong K-shell emission from stable Fe-peak elements in the Suzaku X-ray spectrum of the Type Ia supernova remnant (SNR) 3C 397. The high Ni/Fe and Mn/Fe mass ratios (0.11-0.24 and 0.018-0.033, respectively) in the hot plasma component that dominates the K-shell emission lines indicate a degree of neutronization in the SN ejecta which can only be achieved by electron captures in the dense cores of exploding WDs with a near-Chandrasekhar mass. This suggests a single-degenerate origin for 3C 397, since Chandrasekhar mass progenitors are expected naturally if the WD accretes mass slowly from a companion. Together with other results supporting the double-degenerate scenario, our work adds to the mounting evidence that both progenitor channels make a significant contribution to the SN Ia rate in star-forming galaxies.
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the impact of type ia supernova explosions on helium companions in the Chandrasekhar mass explosion scenario
The Astrophysical Journal, 2013Co-Authors: Z W Liu, Keiichi Maeda, Ivo R Seitenzahl, R Pakmor, W Hillebrandt, M Kromer, F K Ropke, P V F Edelmann, S Taubenberger, Bo WangAbstract:In the version of the single-degenerate scenario of Type Ia supernovae (SNe Ia) studied here, a carbon-oxygen white dwarf explodes close to the Chandrasekhar Limit after accreting material from a non-degenerate helium (He) companion star. In the present study, we employ the STELLAR GADGET code to perform three-dimensional hydrodynamical simulations of the interaction of the SN Ia ejecta with the He companion star taking into account its orbital motion and spin. It is found that only 2%-5% of the initial companion mass is stripped off from the outer layers of He companion stars due to the supernova (SN) impact. The dependence of the unbound mass (or the kick velocity) on the orbital separation can be fitted to a good approximation by a power law for a given companion model. After the SN impact, the outer layers of a He donor star are significantly enriched with heavy elements from the low-expansion-velocity tail of SN Ia ejecta. The total mass of accumulated SN-ejecta material on the companion surface reaches about greater than or similar to 10(-3)M(circle dot) for different companion models. This enrichment with heavy elements provides a potential way to observationally identify the surviving companion star in SN remnants. Finally, by artificially adjusting the explosion energy of the W7 explosion model, we find that the total accumulation of SN ejecta on the companion surface is also dependent on the explosion energy with a power-law relation to a good approximation.
Masayoshi Nobukawa - One of the best experts on this subject based on the ideXlab platform.
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a Chandrasekhar mass progenitor for the type ia supernova remnant 3c 397 from the enhanced abundances of nickel and manganese
The Astrophysical Journal, 2015Co-Authors: Hiroya Yamaguchi, Carles Badenes, Adam R Foster, E Bravo, Brian J Williams, Keiichi Maeda, Masayoshi NobukawaAbstract:Despite decades of intense efforts, many fundamental aspects of Type Ia supernovae (SNe Ia) remain elusive. One of the major open questions is whether the mass of an exploding white dwarf (WD) is close to the Chandrasekhar Limit. Here, we report the detection of strong K-shell emission from stable Fe-peak elements in the Suzaku X-ray spectrum of the Type Ia supernova remnant (SNR) 3C 397. The high Ni/Fe and Mn/Fe mass ratios (0.11–0.24 and 0.018–0.033, respectively) in the hot plasma component that dominates the K-shell emission lines indicate a degree of neutronization in the supernova ejecta that can only be achieved by electron capture in the dense cores of exploding WDs with a near-Chandrasekhar mass. This suggests a single-degenerate origin for 3C 397, since Chandrasekhar mass progenitors are expected naturally if the WD accretes mass slowly from a companion. Together with other results supporting the double-degenerate scenario, our work adds to the mounting evidence that both progenitor channels make a significant contribution to the SN Ia rate in star-forming galaxies.
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a Chandrasekhar mass progenitor for the type ia supernova remnant 3c 397 from the enhanced abundances of nickel and manganese
arXiv: High Energy Astrophysical Phenomena, 2015Co-Authors: Hiroya Yamaguchi, Carles Badenes, Adam R Foster, E Bravo, Brian J Williams, Keiichi Maeda, Masayoshi NobukawaAbstract:Despite decades of intense efforts, many fundamental aspects of Type Ia supernova (SNe Ia) remain elusive. One of the major open questions is whether the mass of the exploding white dwarf (WD) is close to the Chandrasekhar Limit. Here we report the detection of strong K-shell emission from stable Fe-peak elements in the Suzaku X-ray spectrum of the Type Ia supernova remnant (SNR) 3C 397. The high Ni/Fe and Mn/Fe mass ratios (0.11-0.24 and 0.018-0.033, respectively) in the hot plasma component that dominates the K-shell emission lines indicate a degree of neutronization in the SN ejecta which can only be achieved by electron captures in the dense cores of exploding WDs with a near-Chandrasekhar mass. This suggests a single-degenerate origin for 3C 397, since Chandrasekhar mass progenitors are expected naturally if the WD accretes mass slowly from a companion. Together with other results supporting the double-degenerate scenario, our work adds to the mounting evidence that both progenitor channels make a significant contribution to the SN Ia rate in star-forming galaxies.
Banibrata Mukhopadhyay - One of the best experts on this subject based on the ideXlab platform.
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modified virial theorem for highly magnetized white dwarfs
Monthly Notices of the Royal Astronomical Society, 2020Co-Authors: Banibrata Mukhopadhyay, Arnab Sarkar, Christopher A ToutAbstract:Generally the virial theorem provides a relation between various components of energy integrated over a system. This helps us to understand the underlying equilibrium. Based on the virial theorem we can estimate, for example, the maximum allowed magnetic field in a star. Recent studies have proposed the existence of highly magnetized white dwarfs (B-WDs), with masses significantly higher than the Chandrasekhar Limit. Surface magnetic fields of such white dwarfs could be more than |$10^{9}$| G with the central magnitude several orders higher. These white dwarfs could be significantly smaller in size than their ordinary counterparts (with surface fields restricted to about |$10^9$| G). In this paper, we reformulate the virial theorem for non-rotating B-WDs in which, unlike in previous formulations, the contribution of the magnetic pressure to the magnetohydrostatic balance cannot be neglected. Along with the new equation of magnetohydrostatic equilibrium, we approach the problem by invoking magnetic flux conservation and by varying the internal magnetic field with the matter density as a power law. Either of these choices is supported by previous independent work and neither violates any important physics. They are useful while there is no prior knowledge of field profile within a white dwarf. We then compute the modified gravitational, thermal, and magnetic energies and examine how the magnetic pressure influences the properties of such white dwarfs. Based on our results we predict important properties of these B-WDs, which turn out to be independent of our chosen field profiles.
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new mass Limit for white dwarfs super Chandrasekhar type ia supernova as a new standard candle
Physical Review Letters, 2013Co-Authors: Upasana Das, Banibrata MukhopadhyayAbstract:Type Ia supernovae, sparked off by exploding white dwarfs of mass close to the Chandrasekhar Limit, play the key role in understanding the expansion rate of the Universe. However, recent observations of several peculiar type Ia supernovae argue for its progenitor mass to be significantly super-Chandrasekhar. We show that strongly magnetized white dwarfs not only can violate the Chandrasekhar mass Limit significantly, but exhibit a different mass Limit. We establish from a foundational level that the generic mass Limit of white dwarfs is 2.58 solar mass. This explains the origin of overluminous peculiar type Ia supernovae. Our finding further argues for a possible second standard candle, which has many far reaching implications, including a possible reconsideration of the expansion history of the Universe. DOI: 10.1103/PhysRevLett.110.071102
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mass of highly magnetized white dwarfs exceeding the Chandrasekhar Limit an analytical view
Modern Physics Letters A, 2012Co-Authors: Aritra Kundu, Banibrata MukhopadhyayAbstract:In recent years a number of white dwarfs have been observed with very high surface magnetic fields. We can expect that the magnetic field in the core of these stars would be much higher (similar to 10(14) G). In this paper, we analytically study the effect of high magnetic field on relativistic cold electron, and hence its effect on the stability and the mass-radius relation of a magnetic white dwarf. In strong magnetic fields, the equation of state of the Fermi gas is modified and Landau quantization comes into play. For relatively very high magnetic fields (with respect to the average energy density of matter) the number of Landau levels is restricted to one or two. We analyze the equation of states for magnetized electron degenerate gas analytically and attempt to understand the conditions in which transitions from the zeroth Landau level to first Landau level occurs. We also find the effect of the strong magnetic field on the star collapsing to a white dwarf, and the mass-radius relation of the resulting star. We obtain an interesting theoretical result that it is possible to have white dwarfs with mass more than the mass set by Chandrasekhar Limit.
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mass of highly magnetized white dwarfs exceeding the Chandrasekhar Limit an analytical view
arXiv: Solar and Stellar Astrophysics, 2012Co-Authors: Aritra Kundu, Banibrata MukhopadhyayAbstract:In recent years a number of white dwarfs has been observed with very high surface magnetic fields. We can expect that the magnetic field in the core of these stars would be much higher (~ 10^{14} G). In this paper, we analytically study the effect of high magnetic field on relativistic cold electron, and hence its effect on the stability and the mass-radius relation of a magnetic white dwarf. In strong magnetic fields, the equation of state of the Fermi gas is modified and Landau quantization comes into play. For relatively very high magnetic fields (with respect to the energy density of matter) the number of Landau levels is restricted to one or two. We analyse the equation of states for magnetized electron degenerate gas analytically and attempt to understand the conditions in which transitions from the zero-th Landau level to first Landau level occur. We also find the effect of the strong magnetic field on the star collapsing to a white dwarf, and the mass-radius relation of the resulting star. We obtain an interesting theoretical result that it is possible to have white dwarfs with mass more than the mass set by Chandrasekhar Limit.
Christopher A Tout - One of the best experts on this subject based on the ideXlab platform.
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modified virial theorem for highly magnetized white dwarfs
Monthly Notices of the Royal Astronomical Society, 2020Co-Authors: Banibrata Mukhopadhyay, Arnab Sarkar, Christopher A ToutAbstract:Generally the virial theorem provides a relation between various components of energy integrated over a system. This helps us to understand the underlying equilibrium. Based on the virial theorem we can estimate, for example, the maximum allowed magnetic field in a star. Recent studies have proposed the existence of highly magnetized white dwarfs (B-WDs), with masses significantly higher than the Chandrasekhar Limit. Surface magnetic fields of such white dwarfs could be more than |$10^{9}$| G with the central magnitude several orders higher. These white dwarfs could be significantly smaller in size than their ordinary counterparts (with surface fields restricted to about |$10^9$| G). In this paper, we reformulate the virial theorem for non-rotating B-WDs in which, unlike in previous formulations, the contribution of the magnetic pressure to the magnetohydrostatic balance cannot be neglected. Along with the new equation of magnetohydrostatic equilibrium, we approach the problem by invoking magnetic flux conservation and by varying the internal magnetic field with the matter density as a power law. Either of these choices is supported by previous independent work and neither violates any important physics. They are useful while there is no prior knowledge of field profile within a white dwarf. We then compute the modified gravitational, thermal, and magnetic energies and examine how the magnetic pressure influences the properties of such white dwarfs. Based on our results we predict important properties of these B-WDs, which turn out to be independent of our chosen field profiles.
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quasi stars giants and the schonberg Chandrasekhar Limit
Monthly Notices of the Royal Astronomical Society, 2012Co-Authors: Warrick H Ball, Christopher A Tout, Anna N żytkowAbstract:The Schonberg–Chandrasekhar (SC) Limit is a well-established result in the understanding of stellar evolution. It provides an estimate of the point at which an evolved isothermal core embedded in an extended envelope begins to contract. We investigate contours of constant fractional mass in terms of homology invariant variables U and V and find that the SC Limit exists because the isothermal core solution does not intersect all of the contours for an envelope with polytropic index 3. We find that this analysis also applies to similar Limits in the literature including the inner mass Limit for polytropic models of quasi-stars. Consequently, any core solution that does not intersect all of the fractional mass contours exhibits an associated Limit and we identify several relevant cases where this is so. We show that a composite polytrope is at a fractional core mass Limit when its core solution touches but does not cross the contour of the corresponding fractional core mass. We apply this test to realistic models of helium stars and find that stars typically expand when their cores are near a mass Limit. Furthermore, it appears that stars that evolve into giants have always first exceeded an SC-like Limit.
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quasi stars giants and the sch onberg Chandrasekhar Limit
arXiv: Solar and Stellar Astrophysics, 2012Co-Authors: Warrick H Ball, Christopher A Tout, Anna N żytkowAbstract:The Sch\"onberg-Chandrasekhar (SC) Limit is a well-established result in the understanding of stellar evolution. It provides an estimate of the point at which an evolved isothermal core embedded in an extended envelope begins to contract. We investigate contours of constant fractional mass in terms of homology invariant variables U and V and find that the SC Limit exists because the isothermal core solution does not intersect all the contours for an envelope with polytropic index 3. We find that this analysis also applies to similar Limits in the literature including the inner mass Limit for polytropic models of quasi-stars. Consequently, any core solution that does not intersect all the fractional mass contours exhibits an associated Limit and we identify several relevant cases where this is so. We show that a composite polytrope is at a fractional core mass Limit when its core solution touches but does not cross the contour of the corresponding fractional core mass. We apply this test to realistic models of helium stars and find that stars typically expand when their cores are near a mass Limit. Furthermore, it appears that stars that evolve into giants have always first exceeded an SC-like Limit.