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A Bressan - One of the best experts on this subject based on the ideXlab platform.
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the Mass Spectrum of compact remnants from the parsec stellar evolution tracks
Monthly Notices of the Royal Astronomical Society, 2015Co-Authors: Mario Spera, M Mapelli, A BressanAbstract:The Mass Spectrum of stellar-Mass black holes (BHs) is highly uncertain. Dynamical Mass measurements are available only for few ( 10) BHs in X-ray binaries, while theoretical models strongly depend on the hydrodynamics of supernova (SN) explosions and on the evolution of Massive stars. In this paper, we present and discuss the Mass Spectrum of compact remnants that we obtained with SEVN, a new public populationsynthesis code, which couples the PARSEC stellar evolution tracks with up-to-date recipes for SN explosion (depending on the Carbon-Oxygen Mass of the progenitor, on the compactness of the stellar core at pre-SN stage, and on a recent two-parameter criterion based on the dimensionless entropy per nucleon at pre-SN stage). SEVN can be used both as a stand-alone code and in combination with direct-summation N-body codes (Starlab, HiGPUs). The PARSEC stellar evolution tracks currently implemented in SEVN predict signicantly larger values of the Carbon-Oxygen core Mass with respect to previous models. For most of the SN recipes we adopt, this implies substantially larger BH Masses at low metallicity (6 2 10 3 ), than other populationsynthesis codes. The maximum BH Mass found with SEVN is 25, 60 and 130 M at metallicity Z = 2 10 2 , 2 10 3 and 2 10 4 , respectively. Mass loss by stellar winds plays a major role in determining the Mass of BHs for very Massive stars (> 90 M ), while the remnant Mass Spectrum depends mostly on the adopted SN recipe for lower progenitor Masses. We discuss the implications of our results for the transition between NS and BH Mass, and for the expected number of Massive BHs (with Mass > 25 M ) as a function of metallicity.
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the Mass Spectrum of compact remnants from the parsec stellar evolution tracks
arXiv: Solar and Stellar Astrophysics, 2015Co-Authors: Mario Spera, M Mapelli, A BressanAbstract:The Mass Spectrum of stellar-Mass black holes (BHs) is highly uncertain. Dynamical Mass measurements are available only for few ($\sim{}10$) BHs in X-ray binaries, while theoretical models strongly depend on the hydrodynamics of supernova (SN) explosions and on the evolution of Massive stars. In this paper, we present and discuss the Mass Spectrum of compact remnants that we obtained with SEVN, a new public population-synthesis code, which couples the PARSEC stellar evolution tracks with up-to-date recipes for SN explosion (depending on the Carbon-Oxygen Mass of the progenitor, on the compactness of the stellar core at pre-SN stage, and on a recent two-parameter criterion based on the dimensionless entropy per nucleon at pre-SN stage). SEVN can be used both as a stand-alone code and in combination with direct-summation N-body codes (Starlab, HiGPUs). The PARSEC stellar evolution tracks currently implemented in SEVN predict significantly larger values of the Carbon-Oxygen core Mass with respect to previous models. For most of the SN recipes we adopt, this implies substantially larger BH Masses at low metallicity ($\leq{}2\times{}10^{-3}$), than other population-synthesis codes. The maximum BH Mass found with SEVN is $\sim{}$25, 60 and 130 M$_{\odot}$ at metallicity $Z =2 \times{} 10^{-2}$ , $2 \times{}10^{-3}$ and $2\times{} 10^{-4}$ , respectively. Mass loss by stellar winds plays a major role in determining the Mass of BHs for very Massive stars ($\geq{}90$ M$_\odot{}$), while the remnant Mass Spectrum depends mostly on the adopted SN recipe for lower progenitor Masses. We discuss the implications of our results for the transition between NS and BH Mass, and for the expected number of Massive BHs (with Mass $>25$ M$_\odot{}$) as a function of metallicity.
Alan G Marshall - One of the best experts on this subject based on the ideXlab platform.
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resolution of 11 000 compositionally distinct components in a single electrospray ionization fourier transform ion cyclotron resonance Mass Spectrum of crude oil
Analytical Chemistry, 2002Co-Authors: Christine A Hughey, And Ryan P Rodgers, Alan G MarshallAbstract:Mass spectrometry is well-suited for complex mixture analysis, because unlike other types of spectroscopy, the number of Mass spectral peaks per analyte is of order one. Here, we extend significantly the upper limit for the number of chemically distinct components resolved and identified in a single step. Specifically, electrospray selectively ionizes only the basic compounds (i.e., a small fraction of the entire chemical composition) in a sample of South American crude oil. Nevertheless, their positive ion Fourier transform ion cyclotron resonance Mass Spectrum (average Mass resolving power of ∼350 000 from 225 to 1000 Da) contains more than 11 100 resolved peaks, of which >75% may be assigned to a unique elemental composition (CcHhOoNnSs). Mass scale expansion and graphical representations reveal increased heteroatom diversity, aromatic rings, and alkyl substitution with increased Mass. These results set a new standard and illustrate the potential of high-resolution Mass spectrometry for analysis of com...
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kendrick Mass defect Spectrum a compact visual analysis for ultrahigh resolution broadband Mass spectra
Analytical Chemistry, 2001Co-Authors: Christine A Hughey, Christopher L Hendrickson, And Ryan P Rodgers, Alan G Marshall, Kuangnan QianAbstract:At currently achievable Fourier transform ion cyclotron resonance broadband Mass spectrometry resolving power (m/Δm50% > 350 000 for 200 < m/z < 1000), it would be necessary to spread out a conventional Mass Spectrum over ∼200 m in order to provide visual resolution of the most closely resolved peaks. Fortunately, there are natural gaps in a typical Mass Spectrum, spaced 1 Da apart, because virtually no commonly encountered elemental compositions yield Masses at those values. Thus, it is possible to break a broadband Mass Spectrum into 1-Da segments, rotate each segment by 90°, scale each segment according to its Mass defect (i.e., difference between exact and nominal Mass), and then compress the spacing between the segments to yield a compact display. For hydrocarbon systems, conversion from IUPAC Mass to “Kendrick” Mass (i.e., multiplying each Mass by 14.00000/14.01565) further simplifies the display by rectilinearizing the peak patterns. The resulting display preserves not only the “coarse” spacings (e...
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reading chemical fine print resolution and identification of 3000 nitrogen containing aromatic compounds from a single electrospray ionization fourier transform ion cyclotron resonance Mass Spectrum of heavy petroleum crude oil
Energy & Fuels, 2001Co-Authors: Kuangnan Qian, Christopher L Hendrickson, Ryan P Rodgers, Mark R Emmett, Alan G MarshallAbstract:Extra heavy petroleum crude oil (50% of the mixture boils at >566 °C) has been analyzed directly, without prior fractionation, by a high-field (9.4 T) Fourier transform ion cyclotron resonance Mass spectrometer coupled to an external micro-electrospray ion source. At an average Mass resolving power, (m/Δm50% ≈ 50 000), a single wideband (250−1250 Da) Mass Spectrum exhibited ∼5000 resolved peaks with an average Mass of 617 Da (e.g., up to 7−10 resolved peaks at each nominal Mass). Their elemental compositions were positively identified by accurate Mass measurement with an average deviation of less than 1 mDa from each assigned elemental composition. The number of elemental compositions at each nominal Mass, the number of sulfur/oxygen atoms in a molecule, and aromaticity each increase with increasing Mass. On the basis of elemental composition alone, we resolve more than 3000 distinct chemical formulas (excluding 13C isotopic species). Of the 3000 unique elemental compositions, we identify 12 major heteroa...
M El S Naschie - One of the best experts on this subject based on the ideXlab platform.
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a review of e infinity theory and the Mass Spectrum of high energy particle physics
Chaos Solitons & Fractals, 2004Co-Authors: M El S NaschieAbstract:The essay outlines the basic conceptual framework of a new space–time theory with application to high energy particle physics. Both achievements and limitations are discussed with direct reference to the Mass Spectrum problem.
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the vak of vacuum fluctuation spontaneous self organization and complexity theory interpretation of high energy particle physics and the Mass Spectrum
Chaos Solitons & Fractals, 2003Co-Authors: M El S NaschieAbstract:The paper is a rather informal introduction to the concepts and results of the E-infinity Cantorian theory of quantum physics. The fundamental tools of complexity theory and non-linear dynamics (Hausdorff dimensions, fat fractals, etc.) are used to give what we think to be a new interpretation of high energy physics and to determine the corresponding Mass-Spectrum. Particular attention is paid to the role played by the VAK, KAM theorem, Arnold diffusion, Newhaus sinks and knot theory in determining the stability of an elementary ‘‘particle-wave’’ which emerges in self-organizatory manner out of sizzling vacuum fluctuation. 2003 Elsevier Science Ltd. All rights reserved.
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vak vacuum fluctuation and the Mass Spectrum of high energy particle physics
Chaos Solitons & Fractals, 2003Co-Authors: M El S NaschieAbstract:Abstract We introduce a fundamental hypothesis identifying quantum vacuum fluctuation with the vague attractor of Kolmogorov, the so-called VAK. This Hamiltonian conterpart of a dissipative attractor is then modelled by e(∞), topology as a “limit set” of a wild dynamics generated by Mobius-like transformation of space. We proceed as follows: First we give an introduction to the e(∞) quantum spacetime theory from the point of view of nonlinear dynamics, complexity, string and KAM theory. Subsequently we give without proof several theorems and conjectures that we consider to be fundamental to the foundation of any general theory for high energy particles interaction. The final picture seems to be a synthesis between compactified Kleinian groups acting on an essentially nonlinear dynamics of a KAM system which enables us to give a very accurate estimation of the Mass Spectrum of the standard model and further still we are granted a glimpse into the physics of grand unification as well as quantum gravity. It is concluded that VAK in the infinite dimensions of e(∞) is a valid model for stable quantum states.
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complex vacuum fluctuation as a chaotic limit set of any kleinian group transformation and the Mass Spectrum of high energy particle physics via spontaneous self organization
Chaos Solitons & Fractals, 2003Co-Authors: M El S NaschieAbstract:Abstract First we give an introduction to the E (∞) quantum space-time theory from the point of view of nonlinear dynamics, complexity, string and KAM theory. Subsequently we give without proof several theorems that we consider to be fundamental to the foundation of any general theory for high energy particles interaction. The final picture seems to be a synthesis between compactified Kleinian groups acting on the essentially nonlinear dynamics of a KAM system, which enables us to give a very accurate estimation of the Mass Spectrum of the standard model, and further still we are granted a glimpse into the physics of grand unification as well as quantum gravity.
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on the exact Mass Spectrum of quarks
Chaos Solitons & Fractals, 2002Co-Authors: M El S NaschieAbstract:Abstract The present work proposes a general methodology for obtaining the exact E (∞) Mass Spectrum of current and constituent quarks. The theory is based upon a physical interpretation of four-dimensional fusion algebra, noncommutative geometry and related theories. All the so-obtained results were found to be in remarkable agreement with the generally accepted experimental and theoretical results found in the literature.
Mordecaimark Mac Low - One of the best experts on this subject based on the ideXlab platform.
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the stellar Mass Spectrum from non isothermal gravoturbulent fragmentation
Astronomy and Astrophysics, 2005Co-Authors: Ralf S Klessen, Richard B Larson, Mordecaimark Mac Low, Katharina JappsenAbstract:The thermodynamic state of star-forming gas determines its fragmentation behavior and thus plays a crucial role in determining the stellar initial Mass function (IMF). We address the issue by studying the effects of a piecewise polytropic equation of state (EOS) on the formation of stellar clusters in turbulent, self-gravitating molecular clouds using three-dimensional, smoothed particle hydrodynamics simulations. In these simulations stars form via a process we call gravoturbulent fragmentation, i.e., gravitational fragmentation of turbulent gas. To approximate the results of published predictions of the thermal behavior of collapsing clouds, we increase the polytropic exponent γ from 0.7 to 1.1 at a critical density n c , which we estimated to be $2.5\times10^5\,\mathrm{cm^{-3}}$. The change of thermodynamic state at n c selects a characteristic Mass scale for fragmentation M ch , which we relate to the peak of the observed IMF. A simple scaling argument based on the Jeans Mass $M_\mathrm{J}$ at the critical density $n_\mathrm{c}$ leads to $M_{\mathrm{ch}}\propto n_{\mathrm{c}}^{-0.95}$. We perform simulations with $4.3\times10^4\,\mathrm{cm^{-3}} < n_{\mathrm{c}} < 4.3\times10^7\,\mathrm{cm^{-3}}$ to test this scaling argument. Our simulations qualitatively support this hypothesis, but we find a weaker density dependence of $M_{\mathrm{ch}} \propto n_{\mathrm{c}}^{-0.5\pm0.1}$. We also investigate the influence of additional environmental parameters on the IMF. We consider variations in the turbulent driving scheme, and consistently find $M_{\mathrm{J}}$ is decreasing with increasing $n_{\mathrm{c}}$. Our investigation generally supports the idea that the distribution of stellar Masses depends mainly on the thermodynamic state of the star-forming gas. The thermodynamic state of interstellar gas is a result of the balance between heating and cooling processes, which in turn are determined by fundamental atomic and molecular physics and by chemical abundances. Given the abundances, the derivation of a characteristic stellar Mass can thus be based on universal quantities and constants.
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the stellar Mass Spectrum from non isothermal gravoturbulent fragmentation
arXiv: Astrophysics, 2004Co-Authors: Annekatharina Jappsen, Ralf S Klessen, Richard B Larson, Mordecaimark Mac LowAbstract:Identifying the processes that determine the initial Mass function of stars (IMF) is a fundamental problem in star formation theory. One of the major uncertainties is the exact chemical state of the star forming gas and its influence on the dynamical evolution. Most simulations of star forming clusters use an isothermal equation of state (EOS). However, theoretical predictions and observations suggest that the effective polytropic exponent gamma in the EOS varies with density. We address these issues and study the effect of a piecewise polytropic EOS on the formation of stellar clusters in turbulent, self-gravitating molecular clouds using three-dimensional, smoothed particle hydrodynamics simulations. To approximate the results of published predictions of the thermal behavior of collapsing clouds, we increase the polytropic exponent gamma from 0.7 to 1.1 at some chosen density n_c, which we vary. The change of thermodynamic state at n_c selects a characteristic Mass scale for fragmentation M_ch, which we relate to the peak of the observed IMF. Our investigation generally supports the idea that the distribution of stellar Masses depends mainly on the thermodynamic state of the star-forming gas. The thermodynamic state of interstellar gas is a result of the balance between heating and cooling processes, which in turn are determined by fundamental atomic and molecular physics and by chemical abundances. Given the abundances, the derivation of a characteristic stellar Mass can thus be based on universal quantities and constants.
Nozomu Tominaga - One of the best experts on this subject based on the ideXlab platform.
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the Mass Spectrum of the first stars
The Astrophysical Journal, 2014Co-Authors: Hajime Susa, K Hasegawa, Nozomu TominagaAbstract:We perform cosmological hydrodynamics simulations with non-equilibrium primordial chemistry to obtain 59 minihalos that host first stars. The obtained minihalos are used as initial conditions of local three dimensional radiation hydrodynamics simulations to investigate the formation of the first stars. We find two-thirds of the minihalos host multiple stars, while the rest of them have single stars. The Mass of the stars found in our simulations are in the range of 1M⊙ . M . 300M⊙, peaking at several×10M⊙. Most of the very Massive stars of & 140M⊙ are born as single stars, although not all of the single stars are very Massive. We also find a few stars of . 1M⊙ that are kicked by the gravitational three body interactions to the position distant from the center of Mass. The frequency that a star forming minihalo contains a binary system is ∼ 50%. We also investigate the abundance pattern of the stellar remnants by summing up the contributions from the first stars in the simulations. Consequently, the pattern is compatible with that of the low metallicity Damped Lyman−α systems or the Extremely Metal Poor (EMP) stars , if the Mass Spectrum obtained in our experiment is shifted to the low Mass side by 0.2 dex. If we consider the case that an EMP star is born in the remnant of the individual minihalo without mixing with others, the chemical signature of the pair instability supernova is more prominent, because most of them are born as single stars. Subject headings: early Universe—radiative transfer —first stars–metal poor stars
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the Mass Spectrum of the first stars
arXiv: Astrophysics of Galaxies, 2014Co-Authors: Hajime Susa, K Hasegawa, Nozomu TominagaAbstract:We perform cosmological hydrodynamics simulations with non-equilibrium primordial chemistry to obtain 59 minihalos that host first stars. The obtained minihalos are used as initial conditions of local three dimensional radiation hydrodynamics simulations to investigate the formation of the first stars. We find two-thirds of the minihalos host multiple stars, while the rest of them have single stars. The Mass of the stars found in our simulations are in the range of 1 Msun \la M \la 300 Msun, peaking at several x 10 Msun. Most of the very Massive stars of \ga 140 Msun are born as single stars, although not all of the single stars are very Massive. We also find a few stars of \la 1 Msun that are kicked by the gravitational three body interactions to the position distant from the center of Mass. The frequency that a star forming minihalo contains a binary system is \sim 50%. We also investigate the abundance pattern of the stellar remnants by summing up the contributions from the first stars in the simulations. Consequently, the pattern is compatible with that of the low metallicity Damped Lyman-alpha systems or the Extremely Metal Poor (EMP) stars, if the Mass Spectrum obtained in our experiment is shifted to the low Mass side by 0.2 dex. If we consider the case that an EMP star is born in the remnant of the individual minihalo without mixing with others, the chemical signature of the pair instability supernova is more prominent, because most of them are born as single stars.