Superluminous supernovae(SLSNe)and luminous supernovae(LSNe)exhibit extreme luminosities,which require additional energy supply mechanisms such as central engines or circumstellar interaction.In the centralengine scen...Superluminous supernovae(SLSNe)and luminous supernovae(LSNe)exhibit extreme luminosities,which require additional energy supply mechanisms such as central engines or circumstellar interaction.In the centralengine scenario,jets inject energy into the polar ejecta,modifying its evolution and shaping the explosion geometry.This study investigates the polarization signatures of jet-driven bipolar explosions in SLSNe/LSNe,where the asymmetric ejecta structure and differential photospheric evolution imprint distinct observational features.We develop a two-component ejecta model,consisting of fast-expanding polar ejecta(powered by jets)and slower equatorial ejecta.We find that polarization exhibits complex temporal evolution,where the ejecta geometry and flux asymmetry between the two regions jointly produce a double-peaked feature.In addition,the line opacity in the polar region further enhances the wavelength dependence of the polarization.Spectropolarimetric observations,particularly during early phases,can constrain the geometry and energy sources of SLSNe/LSNe,advancing our understanding of their explosion mechanisms.展开更多
The nature of progenitors of Type Ia supernovae(SNe Ia)and their explosion mechanism remains unclear.It has been suggested that SNe Ia may have resulted from thermonuclear explosions of hybrid carbon-oxygen-neon white...The nature of progenitors of Type Ia supernovae(SNe Ia)and their explosion mechanism remains unclear.It has been suggested that SNe Ia may have resulted from thermonuclear explosions of hybrid carbon-oxygen-neon white dwarfs(CONe WDs)when they grow in mass to approach the Chandrasekhar mass limit by accreting matter from a binary main-sequence(MS)companion.In this work,we combine the results of detailed binary evolution calculations with population synthesis models to investigate the rates and delay times of SNe Ia in the CONe WD+MS channel at a low metallicity environment of Z=0.0001.For a constant star formation rate of 5M_(⊙)yr^(−1),our calculations predict that the SN Ia rates in the CONe WD+MS channel at low metallicity of Z=0.0001 is about 0.11−3.89×10^(−4) yr^(−1).In addition,delay times in this channel cover a wide range of 0.05−2.5 Gyr.We further compare our results to those given by a previous study for the CONe WD+MS channel with a higher metallicity of Z=0.02 to explore the influence of metallicity on the results.We find that these two metallicity environments give a slight difference in rates and delay times of SNe Ia from the CONe WD+MS channel,although SNe Ia produced at a low metallicity environment of Z=0.0001 have relatively longer delay times.展开更多
We use a simple dynamical scheme to simulate the ejecta of type Ⅰa supernova(SN Ia) scenarios with two exploding white dwarfs(WDs) and find that the velocity distribution of the ejecta has difficulties accounting for...We use a simple dynamical scheme to simulate the ejecta of type Ⅰa supernova(SN Ia) scenarios with two exploding white dwarfs(WDs) and find that the velocity distribution of the ejecta has difficulties accounting for bimodal emission line profiles with a large separation between the two emission peaks.The essence of the dynamical code is in including the fact that the ejecta does not leave the system instantaneously.We find that the final separation velocity between the centers of masses of the two WDs' ejecta is ≃80% of the pre-explosion WDs' orbital velocity,i.e.,we find separation velocities of 4200-5400 km s^(-1) for two WDs of masses M_(1)=M_(2)=0.94 M⊙.The lower separation velocities we find challenge scenarios with two exploding WDs to explain bimodal emission line profiles with observed velocity separations of up to ≃7000 km s^(-1).Only the mass in the ejecta of one WD with an explosion velocity lower than the separation velocity contributes to one peak of the bimodal profile;this is the inner ejecta.We find the inner ejecta to be only≲15% of the ejecta mass in energetic explosions.Less energetic explosions yield higher inner mass but lower separation velocities.We encourage searching for alternative explanations of bimodal line profiles.展开更多
I further study the manner by which a pair of opposite jets shape the“keyhole”morphological structure of the core-collapse supernova(CCSN)SN 1997A,now the CCSN remnant(CCSNR)1987A.By doing so,I strengthen the claim ...I further study the manner by which a pair of opposite jets shape the“keyhole”morphological structure of the core-collapse supernova(CCSN)SN 1997A,now the CCSN remnant(CCSNR)1987A.By doing so,I strengthen the claim that the jittering-jet explosion mechanism accounts for most,likely all,CCSNe.The“keyhole”structure comprises a northern low-intensity zone closed with a bright rim on its front and an elongated low-intensity nozzle in the south.This rim-nozzle asymmetry is observed in some cooling flow clusters and planetary nebulae that are observed to be shaped by jets.I build a toy model that uses the planar jittering jets pattern,where consecutive pairs of jets tend to jitter in a common plane,implying that the accreted gas onto the newly born neutron star at the late explosion phase flows perpendicular to that plane.This allows for a long-lived jet-launching episode.This long-lasting jet-launching episode launches more mass into the jets that can inflate larger pairs of ears or bubbles,forming the main jets'axis of the CCSNR that is not necessarily related to a possible pre-collapse core rotation.I discuss the relation of the main jets'axis to the neutron star's natal kick velocity.展开更多
The thin layer approximation applied to the expansion of a supernova remnant assumes that all the swept mass resides in a thin shell. The law of motion in the thin layer approximation is therefore found using the cons...The thin layer approximation applied to the expansion of a supernova remnant assumes that all the swept mass resides in a thin shell. The law of motion in the thin layer approximation is therefore found using the conservation of momentum. Here we instead introduce the conservation of energy in the framework of the thin layer approximation. The first case to be analysed is that of an interstellar medium with constant density and the second case is that of 7 profiles of decreasing density with respect to the centre of the explosion. The analytical and numerical results are applied to 4 supernova remnants: Tycho, Cas A, Cygnus loop, and SN 1006. The back reaction due to the radiative losses for the law of motion is evaluated in the case of constant density of the interstellar medium.展开更多
The Multi-channel Photometric Survey Telescope(Mephisto)is a real-time,three-color photometric system designed to capture the color evolution of stars and transients accurately.This telescope system can be crucial in ...The Multi-channel Photometric Survey Telescope(Mephisto)is a real-time,three-color photometric system designed to capture the color evolution of stars and transients accurately.This telescope system can be crucial in cosmological distance measurements of low-redshift(low-z,z■0.1)Type Ia supernovae(SNe Ia).To optimize the capabilities of this instrument,we perform a comprehensive simulation study before its official operation is scheduled to start.By considering the impact of atmospheric extinction,weather conditions,and the lunar phase at the observing site involving the instrumental features,we simulate light curves of SNe Ia obtained by Mephisto.The best strategy in the case of SN Ia cosmology is to take the image at an exposure time of 130 s with a cadence of 3 days.In this condition,Mephisto can obtain hundreds of high-quality SNe Ia to achieve a distance measurement better than 4.5%.Given the on-time spectral classification and monitoring of the Lijiang 2.4 m Telescope at the same observatory,Mephisto,in the whole operation,can significantly enrich the well-calibrated sample of supernovae at low-z and improve the calibration accuracy of high-z SNe Ia.展开更多
Here we extend the conservation of energy in the framework of the thin layer approximation to the asymmetrical case. Four types of interstellar mediums are analysed, in which the density follows an inverse square prof...Here we extend the conservation of energy in the framework of the thin layer approximation to the asymmetrical case. Four types of interstellar mediums are analysed, in which the density follows an inverse square profile, a power law profile, an exponential profile and a toroidal profile. An analytical solution for the radius as a function of time and the polar angle in spherical coordinates is derived in the case of the inverse square profile. The analytical and numerical results are applied to two supernova remnants: SN 1987A and SN 1006. The back reaction due to the radiative losses is evaluated in the case of the inverse square profile for the surrounding medium. Two models for the image formation are presented, which explain the triple ring visible in SN 1987A and the jet feature of SN 1006.展开更多
Here, using the Scale-Symmetric Theory (SST) we explain the cosmological tension and the origin of the largest cosmic structures. We show that a change in value of strong coupling constant for cold baryonic matter lea...Here, using the Scale-Symmetric Theory (SST) we explain the cosmological tension and the origin of the largest cosmic structures. We show that a change in value of strong coupling constant for cold baryonic matter leads to the disagreement in the galaxy clustering amplitude, quantified by the parameter S8. Within the same model we described the Hubble tension. We described also the mechanism that transforms the gravitational collapse into an explosion—it concerns the dynamics of virtual fields that lead to dark energy. Our calculations concern the Type Ia supernovae and the core-collapse supernovae. We calculated the quantized masses of the progenitors of supernovae, emitted total energy during explosion, and we calculated how much of the released energy was transferred to neutrinos. Value of the speed of sound in the strongly interacting matter measured at the LHC confirms that presented here model is correct. Our calculations show that the Universe is cyclic.展开更多
The light curves (LC) for Supernova (SN) can be modeled adopting the conversion of the flux of kinetic energy into radiation. This conversion requires an analytical or a numerical law of motion for the expanding radiu...The light curves (LC) for Supernova (SN) can be modeled adopting the conversion of the flux of kinetic energy into radiation. This conversion requires an analytical or a numerical law of motion for the expanding radius of the SN. In the framework of conservation of energy for the thin layer approximation, we present a classical trajectory based on a power law profile for the density, a relativistic trajectory based on the Navarro-Frenk-White profile for the density, and a relativistic trajectory based on a power law behaviour for the swept mass. A detailed simulation of the LC requires the evaluation of the optical depth as a function of time. We modeled the LC of SN 1993J in different astronomical bands, the LC of GRB 050814 and the LC GRB 060729 in the keV region. The time dependence of the magnetic field of equipartition is derived from the theoretical formula for the luminosity.展开更多
The theory of the conservation of energy in the thin layer approximation has been extended to special relativity. Four models for the density of the circumstellar medium are analyzed, which are represented by constant...The theory of the conservation of energy in the thin layer approximation has been extended to special relativity. Four models for the density of the circumstellar medium are analyzed, which are represented by constant, power law, exponential and Emden (<em>n</em> = 5) profile for density. The astrophysical results are presented in a numerical way, except for a Taylor expansion of the four trajectories in the surrounding of the origin. The free parameters of the models are particularized for SN1993j, for which the radius versus time is known. Some evaluations on the time dilation are presented.展开更多
Supernovae are powerful explosions of massive stars that have reached a terminal stage in their evolution. A huge amount of energy is released during the explosion in a wide range of wavelengths. The supernova explosi...Supernovae are powerful explosions of massive stars that have reached a terminal stage in their evolution. A huge amount of energy is released during the explosion in a wide range of wavelengths. The supernova explosion causes a sudden rise in the dead star’s luminosity which may outshine momentarily the entire galaxy in which it resides. The explosion is produced by a catastrophic collapse of the iron core of a massive star or the collapse of a white dwarf after accreting enough mass from its companion to reach the Chandrasekhar limit. The first record of a supernova occurrence goes back to 185 CE. Subsequently, humans have witnessed across the centuries a series of such violent events that appear suddenly in the sky and illuminate the darkness of the night for several weeks or months. In the first part of this paper, we briefly describe the processes that lead to a supernova explosion. In the second part, we discuss historical supernovae as appearing in the records of human civilizations. In the third part, we highlight ancient records relating the sudden appearance of a supernova or a comet to the spread of epidemics in certain regions of the world.展开更多
Recent observations of young volcanism on the near-Earth terrestrial planets require a new understanding. Magmatic/volcanic episodes on Venus, Mars and Mercury, as well as on Earth’s Moon, are apparently contemporane...Recent observations of young volcanism on the near-Earth terrestrial planets require a new understanding. Magmatic/volcanic episodes on Venus, Mars and Mercury, as well as on Earth’s Moon, are apparently contemporaneous thermal events that accompanied increased magmatic/volcanic activity on Earth, following a 300-Myr cycle. A collateral galactic thermal source in the Milky Way appears to be needed that would predominantly affect the interior of the planets and, perhaps indirectly, Earth’s biosphere, compared to other galactic sources, such as intense cosmic rays or large, rocky bolides. The search for such a source leads to near-Earth supernovae, with their neutrino output, and to the question of whether those neutrinos could act as energy transmitters to heat up the body of Earth, and also enhance its short-term magmatic processes;for example, Cenozoic anorogenic volcanism. This observation challenges present assumptions and paradigms about Earth’s history, and requires the following reconsiderations: 1) the real origin of the end-Cretaceous mass extinction;2) the general radioactive age determinations of rocks;and 3) geodynamic modelling using additional, external heat sources.展开更多
I review studies of core collapse supernovae(CCSNe) and similar transient events that attribute major roles to jets in powering most CCSNe and in shaping their ejecta. I start with reviewing the jittering jets explosi...I review studies of core collapse supernovae(CCSNe) and similar transient events that attribute major roles to jets in powering most CCSNe and in shaping their ejecta. I start with reviewing the jittering jets explosion mechanism that I take to power most CCSN explosions. Neutrino heating does play a role in boosting the jets. I compare the morphologies of some CCSN remnants to planetary nebulae to conclude that jets and instabilities are behind the shaping of their ejecta. I then discuss CCSNe that are descendants of rapidly rotating collapsing cores that result in fixed-axis jets(with small jittering) that shape bipolar ejecta. A large fraction of the bipolar CCSNe are superluminous supernovae(SLSNe). I conclude that modeling of SLSN light curves and bumps in the light curves must include jets, even when considering energetic magnetars and/or ejecta interaction with the circumstellar matter(CSM). I connect the properties of bipolar CCSNe to common envelope jets supernovae(CEJSNe) where an old neutron star or a black hole spirals-in inside the envelope and then inside the core of a red supergiant. I discuss how jets can shape the pre-explosion CSM, as in Supernova 1987A, and can power pre-explosion outbursts(precursors)in binary system progenitors of CCSNe and CEJSNe. Binary interaction also facilitates the launching of postexplosion jets.展开更多
We use the magnitude-redshift relation for the type Ia supernova datacompiled by Riess et al. to analyze the Cardassian expansion scenario. This scenario assumes theuniverse to be flat, matter dominated, and accelerat...We use the magnitude-redshift relation for the type Ia supernova datacompiled by Riess et al. to analyze the Cardassian expansion scenario. This scenario assumes theuniverse to be flat, matter dominated, and accelerating, but contains no vacuum contribution. Thebest fitting model parameters are H_0 = 65.3 km s^(-1) Mpc^(-1), n = 0.35 and Ω_m = 0.05. When thehighest redshift supernova, SN 1997ck, is excluded, H_0 remains the same, but n becomes 0.20 andΩ_m, 0.15, and the matter density remains unreasonably low. Our result shows that this particularscenario is strongly disfavoured by the SNeIa data.展开更多
The amount of 56↑Ni produced in Type Ia supernova （SN Ia） explosion is probably the most important physical parameter underlying the observed correlation of SN Ia luminosities with their light curves. Based on an e...The amount of 56↑Ni produced in Type Ia supernova （SN Ia） explosion is probably the most important physical parameter underlying the observed correlation of SN Ia luminosities with their light curves. Based on an empirical relation between the 56↑Ni mass and the light curve parameter △m15, we obtained rough estimates of the 56↑Ni mass for a large sample of nearby SNe Ia with the aim of exploring the diversity in SN Ia. We found that the derived 56↑Ni masses for different SNe Ia could vary by a factor of ten （e.g., MNi = 0.1 - 1.3 M⊙）, which cannot be explained in terms of the standard Chandrasekhar-mass model （with a 56↑Ni mass production of 0.4 - 0.8 M⊙）. Different explosion and/or progenitor models are clearly required for various SNe Ia, in particular, for those extremely nickel-poor and nickel-rich producers. The nickel-rich （with MNi 〉 0.8 M⊙） SNe Ia are very luminous and may have massive progenitors exceeding the Chandrasekhar-mass limit since extra progenitor fuel is required to produce more 56↑Ni to power the light curve. This is also consistent with the finding that the intrinsically bright SNe Ia prefer to occur in stellar environments of young and massive stars. For example, 75% SNe Ia in spirals have △ml5 〈 1.2 while this ratio is only 18% in E/S0 galaxies. The nickel-poor SNe Ia （with MNi 〈 0.2 M⊙） may invoke the sub- Chandrasekhar model, as most of them were found in early-type E/S0 galaxies dominated by the older and low-mass stellar populations. This indicates that SNe Ia in spiral and E/S0 galaxies have progenitors of different properties.展开更多
Based on an analysis of 280 Type SNIa supernovae and gamma-ray bursts redshifts in the range of z = 0.0104 - 8.1 the Hubble diagram is shown to follow a strictly exponential slope predicting an exponentially expanding...Based on an analysis of 280 Type SNIa supernovae and gamma-ray bursts redshifts in the range of z = 0.0104 - 8.1 the Hubble diagram is shown to follow a strictly exponential slope predicting an exponentially expanding or static universe. At redshifts > 2 - 3 ΛCDM models show a poor agreement with the observed data. Based on the results presented in this paper, the Hubble diagram test does not necessarily support the idea of expansion according to the big-bang concordance model.展开更多
In this letter,the cosmic distance-duality relation has been constrained with a model-independent method by combining the baryon acoustic oscillation(BAO)data and the type Ia supernova(SNe Ia)data.The results show tha...In this letter,the cosmic distance-duality relation has been constrained with a model-independent method by combining the baryon acoustic oscillation(BAO)data and the type Ia supernova(SNe Ia)data.The results show that this relation is consistent with the observational data in the 68.27%error range,except for the instance of Union 2.1 plus BAO with the statistic errors only,where the relation is consistent with the observations in the 95.45%error range.To study the result of the uncertainty of the Hubble constant on the investigation of this relation,we treat the dimensionless Hubble constant h as a free parameter and get that the observational data favors the relation in the 68.27%error range.And then h has been marginalized and the results support that this relation is favored by the observations in the 68.27%error range too.展开更多
I estimate the frequencies of gravitational waves from jittering jets that explode core collapse supernovae(CCSNe)to crudely be 5–30 Hz,and with strains that might allow detection of Galactic CCSNe.The jittering jets...I estimate the frequencies of gravitational waves from jittering jets that explode core collapse supernovae(CCSNe)to crudely be 5–30 Hz,and with strains that might allow detection of Galactic CCSNe.The jittering jets explosion mechanism(JJEM)asserts that most CCSNe are exploded by jittering jets that the newly born neutron star(NS)launches within a few seconds.According to the JJEM,instabilities in the accreted gas lead to the formation of intermittent accretion disks that launch the jittering jets.Earlier studies that did not include jets calculated the gravitational frequencies that instabilities around the NS emit to have a peak in the crude frequency range of 100–2000Hz.Based on a recent study,I take the source of the gravitational waves of jittering jets to be the turbulent bubbles(cocoons)that the jets inflate as they interact with the outer layers of the core of the star at thousands of kilometers from the NS.The lower frequencies and larger strains than those of gravitational waves from instabilities in CCSNe allow future,and maybe present,detectors to identify the gravitational wave signals of jittering jets.Detection of gravitational waves from local CCSNe might distinguish between the neutrino-driven explosion mechanism and the JJEM.展开更多
Type Ia supernovae （SNe Ia） play a key role in measuring cosmological parameters, in which the Phillips relation is adopted. However, the origin of the relation is still unclear. Several parameters are suggested, e....Type Ia supernovae （SNe Ia） play a key role in measuring cosmological parameters, in which the Phillips relation is adopted. However, the origin of the relation is still unclear. Several parameters are suggested, e.g. the relative content of carbon to oxygen （C/O） and the central density of the white dwarf （WD） at ignition. These parameters are mainly determined by the WD＇s initial mass and its cooling time, respectively. Using the progenitor model developed by Meng ＆ Yang, we present the distributions of the initial WD mass and the cooling time. We do not find any correlation between these parameters. However, we notice that as the range of the WD＇s mass decreases, its average value increases with the cooling time. These results could provide a constraint when simulating the SN Ia explosion, i.e. the WDs with a high C/O ratio usually have a lower central density at ignition, while those having the highest central density at ignition generally have a lower C/O ratio. The cooling time is mainly determined by the evolutionary age of secondaries, and the scatter of the cooling time decreases with the evolutionary age. Our results may indicate that WDs with a long cooling time have more uniform properties than those with a short cooling time, which may be helpful to explain why SNe Ia in elliptical galaxies have a more uniform maximum luminosity than those in spiral galaxies.展开更多
Type Ia supernovae（SNe Ia） play a prominent role in understanding the evolution of the Universe. They are thought to be thermonuclear explosions of mass-accreting carbon-oxygen white dwarfs（CO WDs） in binaries, al...Type Ia supernovae（SNe Ia） play a prominent role in understanding the evolution of the Universe. They are thought to be thermonuclear explosions of mass-accreting carbon-oxygen white dwarfs（CO WDs） in binaries, although the mass donors of the accreting WDs are still not well determined. In this article, I review recent studies on mass-accreting WDs, including H-and He-accreting WDs. I also review currently most studied progenitor models of SNe Ia, i.e., the single-degenerate model（including the WD＋MS channel, the WD＋RG channel and the WD＋He star channel）, the doubledegenerate model（including the violent merger scenario） and the sub-Chandrasekhar mass model.Recent progress on these progenitor models is discussed, including the initial parameter space for producing SNe Ia, the binary evolutionary paths to SNe Ia, the progenitor candidates for SNe Ia, the possible surviving companion stars of SNe Ia, some observational constraints, etc. Some other potential progenitor models of SNe Ia are also summarized, including the hybrid CONe WD model, the core-degenerate model, the double WD collision model, the spin-up/spin-down model and the model of WDs near black holes. To date, it seems that two or more progenitor models are needed to explain the observed diversity among SNe Ia.展开更多
基金supported by the National Natural Science Foundation of China(Projects 12373040 and 12021003)the National SKA Program of China(2022SKA0130100)the Fundamental Research Funds for the Central Universities.
文摘Superluminous supernovae(SLSNe)and luminous supernovae(LSNe)exhibit extreme luminosities,which require additional energy supply mechanisms such as central engines or circumstellar interaction.In the centralengine scenario,jets inject energy into the polar ejecta,modifying its evolution and shaping the explosion geometry.This study investigates the polarization signatures of jet-driven bipolar explosions in SLSNe/LSNe,where the asymmetric ejecta structure and differential photospheric evolution imprint distinct observational features.We develop a two-component ejecta model,consisting of fast-expanding polar ejecta(powered by jets)and slower equatorial ejecta.We find that polarization exhibits complex temporal evolution,where the ejecta geometry and flux asymmetry between the two regions jointly produce a double-peaked feature.In addition,the line opacity in the polar region further enhances the wavelength dependence of the polarization.Spectropolarimetric observations,particularly during early phases,can constrain the geometry and energy sources of SLSNe/LSNe,advancing our understanding of their explosion mechanisms.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(grant Nos.XDB1160303,XDB1160000)the National Natural Science Foundation of China(NSFC,Nos.12288102,12333008,12090040/1,11873016,11973080,and 11803030)+3 种基金the National Key R&D Program of China(Nos.2021YFA1600403,2021YFA1600401 and 2021YFA1600400)the Chinese Academy of Sciences(CAS),the Yunnan Ten Thousand Talents Plan–Young&Elite Talents Project,and the CAS“Light of West China”Program,the International Centre of Supernovae,Yunnan Key Laboratory(No.202302AN360001)the Yunnan Fundamental Research Projects(grant Nos.202401BC070007,202201BC070003,and 202001AW070007)the“Yunnan Revitalization Talent Support Program”—Science&Technology Champion Project and Yunling Scholar Project(No.202305AB350003).
文摘The nature of progenitors of Type Ia supernovae(SNe Ia)and their explosion mechanism remains unclear.It has been suggested that SNe Ia may have resulted from thermonuclear explosions of hybrid carbon-oxygen-neon white dwarfs(CONe WDs)when they grow in mass to approach the Chandrasekhar mass limit by accreting matter from a binary main-sequence(MS)companion.In this work,we combine the results of detailed binary evolution calculations with population synthesis models to investigate the rates and delay times of SNe Ia in the CONe WD+MS channel at a low metallicity environment of Z=0.0001.For a constant star formation rate of 5M_(⊙)yr^(−1),our calculations predict that the SN Ia rates in the CONe WD+MS channel at low metallicity of Z=0.0001 is about 0.11−3.89×10^(−4) yr^(−1).In addition,delay times in this channel cover a wide range of 0.05−2.5 Gyr.We further compare our results to those given by a previous study for the CONe WD+MS channel with a higher metallicity of Z=0.02 to explore the influence of metallicity on the results.We find that these two metallicity environments give a slight difference in rates and delay times of SNe Ia from the CONe WD+MS channel,although SNe Ia produced at a low metallicity environment of Z=0.0001 have relatively longer delay times.
文摘We use a simple dynamical scheme to simulate the ejecta of type Ⅰa supernova(SN Ia) scenarios with two exploding white dwarfs(WDs) and find that the velocity distribution of the ejecta has difficulties accounting for bimodal emission line profiles with a large separation between the two emission peaks.The essence of the dynamical code is in including the fact that the ejecta does not leave the system instantaneously.We find that the final separation velocity between the centers of masses of the two WDs' ejecta is ≃80% of the pre-explosion WDs' orbital velocity,i.e.,we find separation velocities of 4200-5400 km s^(-1) for two WDs of masses M_(1)=M_(2)=0.94 M⊙.The lower separation velocities we find challenge scenarios with two exploding WDs to explain bimodal emission line profiles with observed velocity separations of up to ≃7000 km s^(-1).Only the mass in the ejecta of one WD with an explosion velocity lower than the separation velocity contributes to one peak of the bimodal profile;this is the inner ejecta.We find the inner ejecta to be only≲15% of the ejecta mass in energetic explosions.Less energetic explosions yield higher inner mass but lower separation velocities.We encourage searching for alternative explanations of bimodal line profiles.
文摘I further study the manner by which a pair of opposite jets shape the“keyhole”morphological structure of the core-collapse supernova(CCSN)SN 1997A,now the CCSN remnant(CCSNR)1987A.By doing so,I strengthen the claim that the jittering-jet explosion mechanism accounts for most,likely all,CCSNe.The“keyhole”structure comprises a northern low-intensity zone closed with a bright rim on its front and an elongated low-intensity nozzle in the south.This rim-nozzle asymmetry is observed in some cooling flow clusters and planetary nebulae that are observed to be shaped by jets.I build a toy model that uses the planar jittering jets pattern,where consecutive pairs of jets tend to jitter in a common plane,implying that the accreted gas onto the newly born neutron star at the late explosion phase flows perpendicular to that plane.This allows for a long-lived jet-launching episode.This long-lasting jet-launching episode launches more mass into the jets that can inflate larger pairs of ears or bubbles,forming the main jets'axis of the CCSNR that is not necessarily related to a possible pre-collapse core rotation.I discuss the relation of the main jets'axis to the neutron star's natal kick velocity.
文摘The thin layer approximation applied to the expansion of a supernova remnant assumes that all the swept mass resides in a thin shell. The law of motion in the thin layer approximation is therefore found using the conservation of momentum. Here we instead introduce the conservation of energy in the framework of the thin layer approximation. The first case to be analysed is that of an interstellar medium with constant density and the second case is that of 7 profiles of decreasing density with respect to the centre of the explosion. The analytical and numerical results are applied to 4 supernova remnants: Tycho, Cas A, Cygnus loop, and SN 1006. The back reaction due to the radiative losses for the law of motion is evaluated in the case of constant density of the interstellar medium.
基金supported by the National Key R&D Program of China(2021YFA1600404)the National Natural Science Foundation of China(NSFC,grant No.12173082)+11 种基金science research grants from the China Manned Space Project(CMS-CSST-2021-A12)the Yunnan Province Foundation(202201AT070069)the Top-notch Young Talents Program of Yunnan Provincethe Light of West China Program provided by the Chinese Academy of Sciencesthe International Centre of Supernovae,Yunnan Key Laboratory(202302AN360001)Funding for the LJT has been provided by the CAS and the People’s Government of Yunnan Provincefunded by the“Yunnan University Development Plan for World-Class University”“Yunnan University Development Plan for World-Class Astronomy Discipline”obtained supports from the“Science&Technology Champion Project”(202005AB160002)from two“Team Projects”—the“Innovation Team”(202105AE160021)the“Top Team”(202305AT350002)funded by the“Yunnan Revitalization Talent Support Program.”。
文摘The Multi-channel Photometric Survey Telescope(Mephisto)is a real-time,three-color photometric system designed to capture the color evolution of stars and transients accurately.This telescope system can be crucial in cosmological distance measurements of low-redshift(low-z,z■0.1)Type Ia supernovae(SNe Ia).To optimize the capabilities of this instrument,we perform a comprehensive simulation study before its official operation is scheduled to start.By considering the impact of atmospheric extinction,weather conditions,and the lunar phase at the observing site involving the instrumental features,we simulate light curves of SNe Ia obtained by Mephisto.The best strategy in the case of SN Ia cosmology is to take the image at an exposure time of 130 s with a cadence of 3 days.In this condition,Mephisto can obtain hundreds of high-quality SNe Ia to achieve a distance measurement better than 4.5%.Given the on-time spectral classification and monitoring of the Lijiang 2.4 m Telescope at the same observatory,Mephisto,in the whole operation,can significantly enrich the well-calibrated sample of supernovae at low-z and improve the calibration accuracy of high-z SNe Ia.
文摘Here we extend the conservation of energy in the framework of the thin layer approximation to the asymmetrical case. Four types of interstellar mediums are analysed, in which the density follows an inverse square profile, a power law profile, an exponential profile and a toroidal profile. An analytical solution for the radius as a function of time and the polar angle in spherical coordinates is derived in the case of the inverse square profile. The analytical and numerical results are applied to two supernova remnants: SN 1987A and SN 1006. The back reaction due to the radiative losses is evaluated in the case of the inverse square profile for the surrounding medium. Two models for the image formation are presented, which explain the triple ring visible in SN 1987A and the jet feature of SN 1006.
文摘Here, using the Scale-Symmetric Theory (SST) we explain the cosmological tension and the origin of the largest cosmic structures. We show that a change in value of strong coupling constant for cold baryonic matter leads to the disagreement in the galaxy clustering amplitude, quantified by the parameter S8. Within the same model we described the Hubble tension. We described also the mechanism that transforms the gravitational collapse into an explosion—it concerns the dynamics of virtual fields that lead to dark energy. Our calculations concern the Type Ia supernovae and the core-collapse supernovae. We calculated the quantized masses of the progenitors of supernovae, emitted total energy during explosion, and we calculated how much of the released energy was transferred to neutrinos. Value of the speed of sound in the strongly interacting matter measured at the LHC confirms that presented here model is correct. Our calculations show that the Universe is cyclic.
文摘The light curves (LC) for Supernova (SN) can be modeled adopting the conversion of the flux of kinetic energy into radiation. This conversion requires an analytical or a numerical law of motion for the expanding radius of the SN. In the framework of conservation of energy for the thin layer approximation, we present a classical trajectory based on a power law profile for the density, a relativistic trajectory based on the Navarro-Frenk-White profile for the density, and a relativistic trajectory based on a power law behaviour for the swept mass. A detailed simulation of the LC requires the evaluation of the optical depth as a function of time. We modeled the LC of SN 1993J in different astronomical bands, the LC of GRB 050814 and the LC GRB 060729 in the keV region. The time dependence of the magnetic field of equipartition is derived from the theoretical formula for the luminosity.
文摘The theory of the conservation of energy in the thin layer approximation has been extended to special relativity. Four models for the density of the circumstellar medium are analyzed, which are represented by constant, power law, exponential and Emden (<em>n</em> = 5) profile for density. The astrophysical results are presented in a numerical way, except for a Taylor expansion of the four trajectories in the surrounding of the origin. The free parameters of the models are particularized for SN1993j, for which the radius versus time is known. Some evaluations on the time dilation are presented.
文摘Supernovae are powerful explosions of massive stars that have reached a terminal stage in their evolution. A huge amount of energy is released during the explosion in a wide range of wavelengths. The supernova explosion causes a sudden rise in the dead star’s luminosity which may outshine momentarily the entire galaxy in which it resides. The explosion is produced by a catastrophic collapse of the iron core of a massive star or the collapse of a white dwarf after accreting enough mass from its companion to reach the Chandrasekhar limit. The first record of a supernova occurrence goes back to 185 CE. Subsequently, humans have witnessed across the centuries a series of such violent events that appear suddenly in the sky and illuminate the darkness of the night for several weeks or months. In the first part of this paper, we briefly describe the processes that lead to a supernova explosion. In the second part, we discuss historical supernovae as appearing in the records of human civilizations. In the third part, we highlight ancient records relating the sudden appearance of a supernova or a comet to the spread of epidemics in certain regions of the world.
文摘Recent observations of young volcanism on the near-Earth terrestrial planets require a new understanding. Magmatic/volcanic episodes on Venus, Mars and Mercury, as well as on Earth’s Moon, are apparently contemporaneous thermal events that accompanied increased magmatic/volcanic activity on Earth, following a 300-Myr cycle. A collateral galactic thermal source in the Milky Way appears to be needed that would predominantly affect the interior of the planets and, perhaps indirectly, Earth’s biosphere, compared to other galactic sources, such as intense cosmic rays or large, rocky bolides. The search for such a source leads to near-Earth supernovae, with their neutrino output, and to the question of whether those neutrinos could act as energy transmitters to heat up the body of Earth, and also enhance its short-term magmatic processes;for example, Cenozoic anorogenic volcanism. This observation challenges present assumptions and paradigms about Earth’s history, and requires the following reconsiderations: 1) the real origin of the end-Cretaceous mass extinction;2) the general radioactive age determinations of rocks;and 3) geodynamic modelling using additional, external heat sources.
基金supported by a grant from the Israel Science Foundation (769/20)。
文摘I review studies of core collapse supernovae(CCSNe) and similar transient events that attribute major roles to jets in powering most CCSNe and in shaping their ejecta. I start with reviewing the jittering jets explosion mechanism that I take to power most CCSN explosions. Neutrino heating does play a role in boosting the jets. I compare the morphologies of some CCSN remnants to planetary nebulae to conclude that jets and instabilities are behind the shaping of their ejecta. I then discuss CCSNe that are descendants of rapidly rotating collapsing cores that result in fixed-axis jets(with small jittering) that shape bipolar ejecta. A large fraction of the bipolar CCSNe are superluminous supernovae(SLSNe). I conclude that modeling of SLSN light curves and bumps in the light curves must include jets, even when considering energetic magnetars and/or ejecta interaction with the circumstellar matter(CSM). I connect the properties of bipolar CCSNe to common envelope jets supernovae(CEJSNe) where an old neutron star or a black hole spirals-in inside the envelope and then inside the core of a red supergiant. I discuss how jets can shape the pre-explosion CSM, as in Supernova 1987A, and can power pre-explosion outbursts(precursors)in binary system progenitors of CCSNe and CEJSNe. Binary interaction also facilitates the launching of postexplosion jets.
文摘We use the magnitude-redshift relation for the type Ia supernova datacompiled by Riess et al. to analyze the Cardassian expansion scenario. This scenario assumes theuniverse to be flat, matter dominated, and accelerating, but contains no vacuum contribution. Thebest fitting model parameters are H_0 = 65.3 km s^(-1) Mpc^(-1), n = 0.35 and Ω_m = 0.05. When thehighest redshift supernova, SN 1997ck, is excluded, H_0 remains the same, but n becomes 0.20 andΩ_m, 0.15, and the matter density remains unreasonably low. Our result shows that this particularscenario is strongly disfavoured by the SNeIa data.
基金Supported by the National Natural Science Foundation of China.
文摘The amount of 56↑Ni produced in Type Ia supernova （SN Ia） explosion is probably the most important physical parameter underlying the observed correlation of SN Ia luminosities with their light curves. Based on an empirical relation between the 56↑Ni mass and the light curve parameter △m15, we obtained rough estimates of the 56↑Ni mass for a large sample of nearby SNe Ia with the aim of exploring the diversity in SN Ia. We found that the derived 56↑Ni masses for different SNe Ia could vary by a factor of ten （e.g., MNi = 0.1 - 1.3 M⊙）, which cannot be explained in terms of the standard Chandrasekhar-mass model （with a 56↑Ni mass production of 0.4 - 0.8 M⊙）. Different explosion and/or progenitor models are clearly required for various SNe Ia, in particular, for those extremely nickel-poor and nickel-rich producers. The nickel-rich （with MNi 〉 0.8 M⊙） SNe Ia are very luminous and may have massive progenitors exceeding the Chandrasekhar-mass limit since extra progenitor fuel is required to produce more 56↑Ni to power the light curve. This is also consistent with the finding that the intrinsically bright SNe Ia prefer to occur in stellar environments of young and massive stars. For example, 75% SNe Ia in spirals have △ml5 〈 1.2 while this ratio is only 18% in E/S0 galaxies. The nickel-poor SNe Ia （with MNi 〈 0.2 M⊙） may invoke the sub- Chandrasekhar model, as most of them were found in early-type E/S0 galaxies dominated by the older and low-mass stellar populations. This indicates that SNe Ia in spiral and E/S0 galaxies have progenitors of different properties.
文摘Based on an analysis of 280 Type SNIa supernovae and gamma-ray bursts redshifts in the range of z = 0.0104 - 8.1 the Hubble diagram is shown to follow a strictly exponential slope predicting an exponentially expanding or static universe. At redshifts > 2 - 3 ΛCDM models show a poor agreement with the observed data. Based on the results presented in this paper, the Hubble diagram test does not necessarily support the idea of expansion according to the big-bang concordance model.
基金supported by the Foundation of the Guizhou Provincial Education Department of China under Grants No.KY[2016]104the National Natural Science Foundation of China under Grants Nos.11465011 and 11865018the Foundation of Guizhou Provincial Science and Technology of China under Grants No.J[2014]2150.
文摘In this letter,the cosmic distance-duality relation has been constrained with a model-independent method by combining the baryon acoustic oscillation(BAO)data and the type Ia supernova(SNe Ia)data.The results show that this relation is consistent with the observational data in the 68.27%error range,except for the instance of Union 2.1 plus BAO with the statistic errors only,where the relation is consistent with the observations in the 95.45%error range.To study the result of the uncertainty of the Hubble constant on the investigation of this relation,we treat the dimensionless Hubble constant h as a free parameter and get that the observational data favors the relation in the 68.27%error range.And then h has been marginalized and the results support that this relation is favored by the observations in the 68.27%error range too.
基金supported by a grant from the Israel Science Foundation(769/20)。
文摘I estimate the frequencies of gravitational waves from jittering jets that explode core collapse supernovae(CCSNe)to crudely be 5–30 Hz,and with strains that might allow detection of Galactic CCSNe.The jittering jets explosion mechanism(JJEM)asserts that most CCSNe are exploded by jittering jets that the newly born neutron star(NS)launches within a few seconds.According to the JJEM,instabilities in the accreted gas lead to the formation of intermittent accretion disks that launch the jittering jets.Earlier studies that did not include jets calculated the gravitational frequencies that instabilities around the NS emit to have a peak in the crude frequency range of 100–2000Hz.Based on a recent study,I take the source of the gravitational waves of jittering jets to be the turbulent bubbles(cocoons)that the jets inflate as they interact with the outer layers of the core of the star at thousands of kilometers from the NS.The lower frequencies and larger strains than those of gravitational waves from instabilities in CCSNe allow future,and maybe present,detectors to identify the gravitational wave signals of jittering jets.Detection of gravitational waves from local CCSNe might distinguish between the neutrino-driven explosion mechanism and the JJEM.
基金supported by the National Natural Science Foundation of China (Grant No. 10963001)the Project of the Fundamental and Frontier Research of Henan Province (Grant No. 102300410223)
文摘Type Ia supernovae （SNe Ia） play a key role in measuring cosmological parameters, in which the Phillips relation is adopted. However, the origin of the relation is still unclear. Several parameters are suggested, e.g. the relative content of carbon to oxygen （C/O） and the central density of the white dwarf （WD） at ignition. These parameters are mainly determined by the WD＇s initial mass and its cooling time, respectively. Using the progenitor model developed by Meng ＆ Yang, we present the distributions of the initial WD mass and the cooling time. We do not find any correlation between these parameters. However, we notice that as the range of the WD＇s mass decreases, its average value increases with the cooling time. These results could provide a constraint when simulating the SN Ia explosion, i.e. the WDs with a high C/O ratio usually have a lower central density at ignition, while those having the highest central density at ignition generally have a lower C/O ratio. The cooling time is mainly determined by the evolutionary age of secondaries, and the scatter of the cooling time decreases with the evolutionary age. Our results may indicate that WDs with a long cooling time have more uniform properties than those with a short cooling time, which may be helpful to explain why SNe Ia in elliptical galaxies have a more uniform maximum luminosity than those in spiral galaxies.
基金supported by the National Basic Research Program of China(973 programme,2014CB845700)the National Natural Science Foundation of China(Nos.11673059,11521303 and 11390374)+1 种基金the Chinese Academy of Sciences(Nos.KJZD-EW-M06-01 and QYZDB-SSWSYS001)the Natural Science Foundation of Yunnan Province(Nos.2013HB097 and 2017HC018)
文摘Type Ia supernovae（SNe Ia） play a prominent role in understanding the evolution of the Universe. They are thought to be thermonuclear explosions of mass-accreting carbon-oxygen white dwarfs（CO WDs） in binaries, although the mass donors of the accreting WDs are still not well determined. In this article, I review recent studies on mass-accreting WDs, including H-and He-accreting WDs. I also review currently most studied progenitor models of SNe Ia, i.e., the single-degenerate model（including the WD＋MS channel, the WD＋RG channel and the WD＋He star channel）, the doubledegenerate model（including the violent merger scenario） and the sub-Chandrasekhar mass model.Recent progress on these progenitor models is discussed, including the initial parameter space for producing SNe Ia, the binary evolutionary paths to SNe Ia, the progenitor candidates for SNe Ia, the possible surviving companion stars of SNe Ia, some observational constraints, etc. Some other potential progenitor models of SNe Ia are also summarized, including the hybrid CONe WD model, the core-degenerate model, the double WD collision model, the spin-up/spin-down model and the model of WDs near black holes. To date, it seems that two or more progenitor models are needed to explain the observed diversity among SNe Ia.
