SN 2014av is a type Ibn supernova(SN)characterized by the interaction between the SN ejecta and a helium-rich circumstellar medium(CSM).We use the^(56)Ni model,the ejecta-CSM interaction(CSI)model,and the CSI plus^(56...SN 2014av is a type Ibn supernova(SN)characterized by the interaction between the SN ejecta and a helium-rich circumstellar medium(CSM).We use the^(56)Ni model,the ejecta-CSM interaction(CSI)model,and the CSI plus^(56)Ni model to fit the multiband light curves(LCs)of SN 2014av.For the CSI and CSI plus^(56)Ni models,we assume that the CSM is a constant density shell(“shell”)or a steady-state stellar wind(“wind”)with density∝r-2.We find that both the^(56)Ni and CSI models fail to fit the multiband LCs of SN 2014av,while the CSI plus^(56)Ni model can account for the LCs.In the last scenario,the LCs around the peaks were mainly powered by the CSI,while the flattening of the LCs was mainly powered by the radioactive decay of^(56)Ni.For the wind case,the derived mass-loss rate of the progenitor is≈20.5-205.5 M_(⊙)yr^(-1),whose lower limit is significantly larger than the upper limit of normal stellar winds,and comparable the upper limit of hyper-winds.Hence,we suggest that the wind case is disfavored.For the shell case,the best-fitting values of the ejecta,^(56)Ni,and the CSM are2.29 M_(⊙),0.09 M_(⊙),and 5.00 M_(⊙),respectively.Provided the velocity of the CSM shell is 100-1000 km s^(-1),we infer that the shell might be expelled≈0.49-5.20 yr before the SN exploded.展开更多
In observational cosmology,a supernova la is used as a standard candle in order to extend the Hubble diagram to a higher redshift range.Astrophysicists found that the observed brightness of high redshift supernovae la...In observational cosmology,a supernova la is used as a standard candle in order to extend the Hubble diagram to a higher redshift range.Astrophysicists found that the observed brightness of high redshift supernovae la is dimmer than expected.This dimming effect is considered observational evidence for the existence of dark energy in the universe.It should be noted that this conclusion is based on an assumption that the mass density of the cosmic plasma is very small.Therefore,the dimming effect caused by the Compton scattering of free electrons in cosmic plasma can be neglected.X-ray observations suggest that the mass density of the cosmic plasma may be very large.In theory,the observed dimming effect of high redshift supernovae Ia may be caused by the Compton scattering of free electrons in the cosmic plasma.In this paper it will be shown that this idea is reasonable.Therefore,there is no need to introduce the confusing concept of dark energy into cosmology.展开更多
Cassiopeia A(Cas A) is a well-known candidate for studying cosmic-ray acceleration, in which compact features of various scales have attracted much attention. Based on observations by the Very Large Array of Cas A at ...Cassiopeia A(Cas A) is a well-known candidate for studying cosmic-ray acceleration, in which compact features of various scales have attracted much attention. Based on observations by the Very Large Array of Cas A at 6 cm and 21 cm, we measure the spectral index distribution of various scale components using the observation of the 1998 epoch. We decompose its total density image into nine scale components, and map the temperature spectral index distribution of each component, which ranges from-2.48 ± 0.01 to-2.91 ± 0.05. We find that the spectral indices increase from the small scale to large scale components. A damped post-shock magnetic field model with a strength larger than ~200 μG and a damping length scale less than ~10% of the remnant radius can account for the spectral index variation naturally.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
I analyze a new X-ray image of the youngest supernova remnant(SNR)in the Galaxy,which is the type Ia SNR G1.9+0.3,and reveal a very clear point-symmetrical structure.Since explosion models of type Ia supernovae(SNe Ia...I analyze a new X-ray image of the youngest supernova remnant(SNR)in the Galaxy,which is the type Ia SNR G1.9+0.3,and reveal a very clear point-symmetrical structure.Since explosion models of type Ia supernovae(SNe Ia)do not form such morphologies,the point-symmetrical morphology must come from the circumstellar material(CSM)into which the ejecta expands.The large-scale point-symmetry that I identify and the known substantial deceleration of the ejecta of SNR G1.9+0.3 suggest a relatively massive CSM of■1M⊙.I argue that the most likely explanation is the explosion of this SN Ia into a planetary nebula.The scenario that predicts a large fraction of SN Ia inside PNe(SNIPs)is the core degenerate scenario.Other SN Ia scenarios might lead to only a very small fraction of SNIPs or none at all.展开更多
Nova outbursts are the results of thermonuclear runaways,which occur when sufficient material accretes on the surfaces of white dwarfs(WDs).Using the MESA code,we construct a detailed grid for carbon-oxygen and oxygen...Nova outbursts are the results of thermonuclear runaways,which occur when sufficient material accretes on the surfaces of white dwarfs(WDs).Using the MESA code,we construct a detailed grid for carbon-oxygen and oxygen-neon-magnesium novae.By employing population synthesis methods,we conduct a statistical analysis of the distribution of novae in the Milky Way.In our models,on average,a typical nova system may undergo about8000 eruptions and the Galactic nova rate is~130 yr^(-1).The C,N,and O elements in nova ejecta are strongly affected by the mixing degree between WD core and accreted material.Our results show that the average value of^(12)C/^(13)C in nova ejecta is about an order of magnitude lower than that on the surface of a red giant,that for^(16)O/^(17)O is about 5 times lower,and that for^(14)N/^(15)N is about 1.5 times lower.The annual yields of^(13)C,^(15)N,and^(17)O from nova ejection are larger than those from AGB stars.This indicates that compared to a red giant,nova eruptions are a more important source of the odd-numbered nuclear elements of^(13)C,^(15)N,and^(17)O in the Galactic interstellar medium.展开更多
Using an effective adiabatic index γ_(eff) to mimic the feedback of efficient shock acceleration,we simulate the temporal evolution of a young type Ia supernova remnant (SNR) with two different background magnetic fi...Using an effective adiabatic index γ_(eff) to mimic the feedback of efficient shock acceleration,we simulate the temporal evolution of a young type Ia supernova remnant (SNR) with two different background magnetic field(BMF) topologies:a uniform and a turbulent BMF.The density distribution and magnetic-field characteristics of our benchmark SNR are studied with two-dimensional cylindrical magnetohydrodynamic simulations.When γ_(eff)is considered,we find that:(1) the two-shock structure shrinks and the downstream magnetic-field orientation is dominated by the Rayleigh–Taylor instability structures;(2) there exists more quasi-radial magnetic fields inside the shocked region;and (3) inside the intershock region,both the quasi-radial magnetic energy density and the total magnetic energy density are enhanced:in the radial direction,with γ_(eff)=1.1,they are amplified about 10–26 times more than those with γ_(eff)=5/3.While in the angular direction,the total magnetic energy densities could be amplified about 350 times more than those with γ_(eff)=5/3,and there are more grid cells within the intershock region where the magnetic energy density is amplified by a factor greater than 100.展开更多
In this paper,we perform the detailed modeling for the light curves(LCs)of PTF 10iuv which is a calcium-rich(Ca-rich)supernova(SN)to constrain the physical properties of its ejecta and the energy sources,as well as th...In this paper,we perform the detailed modeling for the light curves(LCs)of PTF 10iuv which is a calcium-rich(Ca-rich)supernova(SN)to constrain the physical properties of its ejecta and the energy sources,as well as the explosion mechanism.We find that the^(56)Ni model and the56Ni plus circumstellar interaction model fail to explain the LCs,while the four-element(^(56)Ni,^(48)Cr,^(52)Fe,and^(44)Ti)model can account for the LCs.The ejecta mass of PTF10iuv derived by the model(1.52_(-0.25)^(+0.34)M_(⊙))is consistent with that of the merger of a sub-Chandrasekhar mass white dwarf.The early-time LCs were mainly powered by^(56)Ni whose mass is~0.03 M_(⊙),while the contributions of^(48)Cr and^(52)Fe can be neglected.The derived^(44)Ti mass(~0.25 M_(⊙))is~1.8 times the upper limit of the derived^(44)Ti mass of Ca-rich SN 2005E.We suggest that subtracting the contributions of the host-galaxy,which are unknown,and including the flux from other long-lived elements(e.g.,^(57)Co,^(55)Fe,^(60)Co)can reduce the amount of^(44)Ti,and that this value can be regarded as an upper limit.展开更多
The f(R)modified gravity theory can explain the accelerating expansion of the late Universe without introducing dark energy.In this study,we predict the constraint strength on the f(R)theory using the mock data genera...The f(R)modified gravity theory can explain the accelerating expansion of the late Universe without introducing dark energy.In this study,we predict the constraint strength on the f(R)theory using the mock data generated from the Chinese Space Station Telescope(CSST)Ultra-Deep Field Type Ia supernova(SN Ia)survey and wide-field slitless spectroscopic baryon acoustic oscillation(BAO)survey.We explore three popular f(R)models and introduce a parameter b to characterize the deviation of the f(R)theory from theΛCDM theory.The Markov Chain Monte Carlo method is employed to constrain the parameters in the f(R)models,and the nuisance parameters and systematic uncertainties are also considered in the model fitting process.Besides,we also perform model comparisons between the f(R)models and theΛCDM model.We find that the constraint accuracy using the CSST SN Ia+BAO data set alone is comparable to or even better than the result given by the combination of the current relevant observations,and the CSST SN Ia+BAO survey can distinguish the f(R)models from theΛCDM model.This indicates that the CSST SN Ia and BAO surveys can effectively constrain and test the f(R)theory.展开更多
The early time observations of Type Ia supernovae(SNe Ia)play a crucial role in investigating and resolving longstanding questions about progenitor stars and the explosion mechanisms of these events.Colors of supernov...The early time observations of Type Ia supernovae(SNe Ia)play a crucial role in investigating and resolving longstanding questions about progenitor stars and the explosion mechanisms of these events.Colors of supernovae(SNe)in the initial days after the explosion can help differentiate between different types of SNe.However,the use of true color information to identify SNe Ia at the early-time explosion is still in its infancy.The Multi-channel Photometric Survey Telescope(Mephisto)is a photometric survey telescope equipped with three CCD cameras,capable of simultaneously imaging the same patch of sky in three bands(u,g,i or v,r,z),yielding real-time colors of astronomical objects.In this paper,we introduce a new time-series classification tool named Mephisto Early Supernovae Ia Rapid Identifier(Mesiri),which,for the first time,utilizes real-time color information to distinguish early-time SNe Ia from core-collapse supernovae.Mesiri is based on the deep learning approach and can achieve an accuracy of 96.75%±0.79%,and AUC of 98.87%±0.53%in case of single epoch random observation before the peak brightness.These values reach towards perfectness if additional data points on several night observations are considered.The classification with real-time color significantly outperforms that with pseudo-color,especially at the early time,i.e.,with only a few points of observations.The BiLSTM architecture shows the best performance compared to others that have been tested in this work.展开更多
In this paper, we utilize recent observational data from gamma-ray bursts(GRBs) and Pantheon+ supernovae Ia(SNe Ia) samples to explore the interacting dark energy(IDE) model in a phenomenological scenario. Results fro...In this paper, we utilize recent observational data from gamma-ray bursts(GRBs) and Pantheon+ supernovae Ia(SNe Ia) samples to explore the interacting dark energy(IDE) model in a phenomenological scenario. Results from GRBs alone, SNe Ia and GRBs+SNe Ia indicate that the energy is transferred from dark energy to dark matter and the coincidence problem is alleviated. The value of H0from GRBs+SNe Ia in the IDE scenario shows agreement with the SH0ES measurement. Considering the age estimate of the quasar APM 08279+5255 at z = 3.91, we find that the phenomenological IDE scenario can predict a cosmic age greater than that of the ΛCDM model, thus the cosmic age problem can be alleviated.展开更多
The middle-aged Galactic supernova remnant (SNR)-the Cygnus Loop (CL)-displays a peculiar morphology in X-rays,featuring a blowout in the southern region.The underlying process accounting for the formation of the pecu...The middle-aged Galactic supernova remnant (SNR)-the Cygnus Loop (CL)-displays a peculiar morphology in X-rays,featuring a blowout in the southern region.The underlying process accounting for the formation of the peculiar periphery remains a mystery.To this end,we conduct hydrodynamical simulations to investigate the SNR evolution coupled with a tailored stellar-wind model:a bipolar stellar wind emanating from a runaway red supergiant progenitor,excavating a wind-blown cavity elongated along the-z-direction.Our simulation results reveal that the forward shock of the consequent SNR sweeps up the modified ambient media,shaping the overall morphology with a blowout comparable to that of CL.Besides,a series of simulation runs are performed to assess the impacts of different model parameters and the projection effect (observational angle θobs) on the final SNR profile.Three physical quantities are extracted from simulation results to characterize the simulated SNR and make a direct comparison with the X-ray observations of CL.We find that the final SNR morphology is sensitive to both stellar-wind properties and θ_(obs).A Cygnus-Loop-like SNR could be reproduced under appropriate parameter combinations at θ_(obs)=0°.While for θ_(obs)■30°,the projected morphology akin to CL could be also generated under specific conditions.展开更多
The origin of intermediate helium (He)-rich hot subdwarfs is still unclear.Previous studies have suggested that some surviving Type Ia supernovae (SNe Ia) companions from the white dwarf+main-sequence (WD+MS)channel m...The origin of intermediate helium (He)-rich hot subdwarfs is still unclear.Previous studies have suggested that some surviving Type Ia supernovae (SNe Ia) companions from the white dwarf+main-sequence (WD+MS)channel may contribute to the intermediate He-rich hot subdwarfs.However,previous studies ignored the impact of atomic diffusion on the post-explosion evolution of surviving companion stars of SNe Ia,leading to the aspect that they could not explain the observed surface He abundance of intermediate He-rich hot subdwarfs.In this work,by taking the atomic diffusion and stellar wind into account,we trace the surviving companions of SNe Ia from the WD+MS channel using the one-dimensional stellar evolution code MESA until they evolve into hot subdwarfs.We find that the surface He-abundances of our surviving companion models during their core He-burning phases are in a range of-1■log(N_(He) N_(H))■0,which are consistent with those observed in intermediate He-rich hot subdwarfs.This seems to further support the notion that it is possible for surviving companions of SNe Ia in the WD+MS channel to form some intermediate He-rich hot subdwarfs.展开更多
基金supported by the National Key R&D Program(2024YFA1611700)the National Natural Science Foundation of China(grant Nos.12133003,12494571 and 11963001)supported by the Guangxi Talent Program(“Highland of Innovation Talents”)and Program of Bagui Scholars(LHJ)。
文摘SN 2014av is a type Ibn supernova(SN)characterized by the interaction between the SN ejecta and a helium-rich circumstellar medium(CSM).We use the^(56)Ni model,the ejecta-CSM interaction(CSI)model,and the CSI plus^(56)Ni model to fit the multiband light curves(LCs)of SN 2014av.For the CSI and CSI plus^(56)Ni models,we assume that the CSM is a constant density shell(“shell”)or a steady-state stellar wind(“wind”)with density∝r-2.We find that both the^(56)Ni and CSI models fail to fit the multiband LCs of SN 2014av,while the CSI plus^(56)Ni model can account for the LCs.In the last scenario,the LCs around the peaks were mainly powered by the CSI,while the flattening of the LCs was mainly powered by the radioactive decay of^(56)Ni.For the wind case,the derived mass-loss rate of the progenitor is≈20.5-205.5 M_(⊙)yr^(-1),whose lower limit is significantly larger than the upper limit of normal stellar winds,and comparable the upper limit of hyper-winds.Hence,we suggest that the wind case is disfavored.For the shell case,the best-fitting values of the ejecta,^(56)Ni,and the CSM are2.29 M_(⊙),0.09 M_(⊙),and 5.00 M_(⊙),respectively.Provided the velocity of the CSM shell is 100-1000 km s^(-1),we infer that the shell might be expelled≈0.49-5.20 yr before the SN exploded.
文摘In observational cosmology,a supernova la is used as a standard candle in order to extend the Hubble diagram to a higher redshift range.Astrophysicists found that the observed brightness of high redshift supernovae la is dimmer than expected.This dimming effect is considered observational evidence for the existence of dark energy in the universe.It should be noted that this conclusion is based on an assumption that the mass density of the cosmic plasma is very small.Therefore,the dimming effect caused by the Compton scattering of free electrons in cosmic plasma can be neglected.X-ray observations suggest that the mass density of the cosmic plasma may be very large.In theory,the observed dimming effect of high redshift supernovae Ia may be caused by the Compton scattering of free electrons in the cosmic plasma.In this paper it will be shown that this idea is reasonable.Therefore,there is no need to introduce the confusing concept of dark energy into cosmology.
基金support from the National Natural Science Foundation of China(NSFC,Grant Nos.12041301 and 12073039)the China Manned Space Project(CMS-CSST2021-A09)the Youth Innovation Promotion Association of CAS(2023000015)。
文摘Cassiopeia A(Cas A) is a well-known candidate for studying cosmic-ray acceleration, in which compact features of various scales have attracted much attention. Based on observations by the Very Large Array of Cas A at 6 cm and 21 cm, we measure the spectral index distribution of various scale components using the observation of the 1998 epoch. We decompose its total density image into nine scale components, and map the temperature spectral index distribution of each component, which ranges from-2.48 ± 0.01 to-2.91 ± 0.05. We find that the spectral indices increase from the small scale to large scale components. A damped post-shock magnetic field model with a strength larger than ~200 μG and a damping length scale less than ~10% of the remnant radius can account for the spectral index variation naturally.
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.
基金supported by a grant from the Israel Science Foundation(769/20)。
文摘I analyze a new X-ray image of the youngest supernova remnant(SNR)in the Galaxy,which is the type Ia SNR G1.9+0.3,and reveal a very clear point-symmetrical structure.Since explosion models of type Ia supernovae(SNe Ia)do not form such morphologies,the point-symmetrical morphology must come from the circumstellar material(CSM)into which the ejecta expands.The large-scale point-symmetry that I identify and the known substantial deceleration of the ejecta of SNR G1.9+0.3 suggest a relatively massive CSM of■1M⊙.I argue that the most likely explanation is the explosion of this SN Ia into a planetary nebula.The scenario that predicts a large fraction of SN Ia inside PNe(SNIPs)is the core degenerate scenario.Other SN Ia scenarios might lead to only a very small fraction of SNIPs or none at all.
文摘Nova outbursts are the results of thermonuclear runaways,which occur when sufficient material accretes on the surfaces of white dwarfs(WDs).Using the MESA code,we construct a detailed grid for carbon-oxygen and oxygen-neon-magnesium novae.By employing population synthesis methods,we conduct a statistical analysis of the distribution of novae in the Milky Way.In our models,on average,a typical nova system may undergo about8000 eruptions and the Galactic nova rate is~130 yr^(-1).The C,N,and O elements in nova ejecta are strongly affected by the mixing degree between WD core and accreted material.Our results show that the average value of^(12)C/^(13)C in nova ejecta is about an order of magnitude lower than that on the surface of a red giant,that for^(16)O/^(17)O is about 5 times lower,and that for^(14)N/^(15)N is about 1.5 times lower.The annual yields of^(13)C,^(15)N,and^(17)O from nova ejection are larger than those from AGB stars.This indicates that compared to a red giant,nova eruptions are a more important source of the odd-numbered nuclear elements of^(13)C,^(15)N,and^(17)O in the Galactic interstellar medium.
基金supported by the National Natural Science Foundation of China 12233006partially supported by the National Natural Science Foundation of China 12203042the Foundations of Yunnan Province 202301AU070009。
文摘Using an effective adiabatic index γ_(eff) to mimic the feedback of efficient shock acceleration,we simulate the temporal evolution of a young type Ia supernova remnant (SNR) with two different background magnetic field(BMF) topologies:a uniform and a turbulent BMF.The density distribution and magnetic-field characteristics of our benchmark SNR are studied with two-dimensional cylindrical magnetohydrodynamic simulations.When γ_(eff)is considered,we find that:(1) the two-shock structure shrinks and the downstream magnetic-field orientation is dominated by the Rayleigh–Taylor instability structures;(2) there exists more quasi-radial magnetic fields inside the shocked region;and (3) inside the intershock region,both the quasi-radial magnetic energy density and the total magnetic energy density are enhanced:in the radial direction,with γ_(eff)=1.1,they are amplified about 10–26 times more than those with γ_(eff)=5/3.While in the angular direction,the total magnetic energy densities could be amplified about 350 times more than those with γ_(eff)=5/3,and there are more grid cells within the intershock region where the magnetic energy density is amplified by a factor greater than 100.
基金supported by National Natural Science Foundation of China(NSFC,grant Nos.11963001,12133003,11833003,11973020(C0035736),and U1938201)supported by the Guangxi Talent Program(“Highland of Innovation Talents”)。
文摘In this paper,we perform the detailed modeling for the light curves(LCs)of PTF 10iuv which is a calcium-rich(Ca-rich)supernova(SN)to constrain the physical properties of its ejecta and the energy sources,as well as the explosion mechanism.We find that the^(56)Ni model and the56Ni plus circumstellar interaction model fail to explain the LCs,while the four-element(^(56)Ni,^(48)Cr,^(52)Fe,and^(44)Ti)model can account for the LCs.The ejecta mass of PTF10iuv derived by the model(1.52_(-0.25)^(+0.34)M_(⊙))is consistent with that of the merger of a sub-Chandrasekhar mass white dwarf.The early-time LCs were mainly powered by^(56)Ni whose mass is~0.03 M_(⊙),while the contributions of^(48)Cr and^(52)Fe can be neglected.The derived^(44)Ti mass(~0.25 M_(⊙))is~1.8 times the upper limit of the derived^(44)Ti mass of Ca-rich SN 2005E.We suggest that subtracting the contributions of the host-galaxy,which are unknown,and including the flux from other long-lived elements(e.g.,^(57)Co,^(55)Fe,^(60)Co)can reduce the amount of^(44)Ti,and that this value can be regarded as an upper limit.
基金support from the National Key R&D Program of China grant Nos.2022YFF0503404,2020SKA0110402the CAS Project for Young Scientists in Basic Research(No.YSBR092)+2 种基金the support of the National Natural Science Foundation of China(NSFC,grant Nos.11473044 and 11973047)the Chinese Academy of Science grants ZDKYYQ20200008,QYZDJ-SSW-SLH017,XDB 23040100,and XDA15020200supported by science research grants from the China Manned Space Project with grant Nos.CMS-CSST-2021-B01 and CMS-CSST-2021-A01。
文摘The f(R)modified gravity theory can explain the accelerating expansion of the late Universe without introducing dark energy.In this study,we predict the constraint strength on the f(R)theory using the mock data generated from the Chinese Space Station Telescope(CSST)Ultra-Deep Field Type Ia supernova(SN Ia)survey and wide-field slitless spectroscopic baryon acoustic oscillation(BAO)survey.We explore three popular f(R)models and introduce a parameter b to characterize the deviation of the f(R)theory from theΛCDM theory.The Markov Chain Monte Carlo method is employed to constrain the parameters in the f(R)models,and the nuisance parameters and systematic uncertainties are also considered in the model fitting process.Besides,we also perform model comparisons between the f(R)models and theΛCDM model.We find that the constraint accuracy using the CSST SN Ia+BAO data set alone is comparable to or even better than the result given by the combination of the current relevant observations,and the CSST SN Ia+BAO survey can distinguish the f(R)models from theΛCDM model.This indicates that the CSST SN Ia and BAO surveys can effectively constrain and test the f(R)theory.
文摘The early time observations of Type Ia supernovae(SNe Ia)play a crucial role in investigating and resolving longstanding questions about progenitor stars and the explosion mechanisms of these events.Colors of supernovae(SNe)in the initial days after the explosion can help differentiate between different types of SNe.However,the use of true color information to identify SNe Ia at the early-time explosion is still in its infancy.The Multi-channel Photometric Survey Telescope(Mephisto)is a photometric survey telescope equipped with three CCD cameras,capable of simultaneously imaging the same patch of sky in three bands(u,g,i or v,r,z),yielding real-time colors of astronomical objects.In this paper,we introduce a new time-series classification tool named Mephisto Early Supernovae Ia Rapid Identifier(Mesiri),which,for the first time,utilizes real-time color information to distinguish early-time SNe Ia from core-collapse supernovae.Mesiri is based on the deep learning approach and can achieve an accuracy of 96.75%±0.79%,and AUC of 98.87%±0.53%in case of single epoch random observation before the peak brightness.These values reach towards perfectness if additional data points on several night observations are considered.The classification with real-time color significantly outperforms that with pseudo-color,especially at the early time,i.e.,with only a few points of observations.The BiLSTM architecture shows the best performance compared to others that have been tested in this work.
基金supported by the Guizhou Provincial Science and Technology Foundations (QKHJC-ZK[2021] Key 020 and QKHJC-ZK [2024] general 443)。
文摘In this paper, we utilize recent observational data from gamma-ray bursts(GRBs) and Pantheon+ supernovae Ia(SNe Ia) samples to explore the interacting dark energy(IDE) model in a phenomenological scenario. Results from GRBs alone, SNe Ia and GRBs+SNe Ia indicate that the energy is transferred from dark energy to dark matter and the coincidence problem is alleviated. The value of H0from GRBs+SNe Ia in the IDE scenario shows agreement with the SH0ES measurement. Considering the age estimate of the quasar APM 08279+5255 at z = 3.91, we find that the phenomenological IDE scenario can predict a cosmic age greater than that of the ΛCDM model, thus the cosmic age problem can be alleviated.
基金supported by the National Natural Science Foundation of China (NSFC,12233006)supported by the NSFC 12203042the Foundations of Yunnan Province 202301AU070009。
文摘The middle-aged Galactic supernova remnant (SNR)-the Cygnus Loop (CL)-displays a peculiar morphology in X-rays,featuring a blowout in the southern region.The underlying process accounting for the formation of the peculiar periphery remains a mystery.To this end,we conduct hydrodynamical simulations to investigate the SNR evolution coupled with a tailored stellar-wind model:a bipolar stellar wind emanating from a runaway red supergiant progenitor,excavating a wind-blown cavity elongated along the-z-direction.Our simulation results reveal that the forward shock of the consequent SNR sweeps up the modified ambient media,shaping the overall morphology with a blowout comparable to that of CL.Besides,a series of simulation runs are performed to assess the impacts of different model parameters and the projection effect (observational angle θobs) on the final SNR profile.Three physical quantities are extracted from simulation results to characterize the simulated SNR and make a direct comparison with the X-ray observations of CL.We find that the final SNR morphology is sensitive to both stellar-wind properties and θ_(obs).A Cygnus-Loop-like SNR could be reproduced under appropriate parameter combinations at θ_(obs)=0°.While for θ_(obs)■30°,the projected morphology akin to CL could be also generated under specific conditions.
基金supported by the National Natural Science Foundation of China(NSFC.Grant Nos.12288102 and 12333008)the National Key R&D Program of China(No.2021YFA1600403)+5 种基金support from the Yunnan Ten Thousand Talents Plan-Young&Elite Talents Projectthe CAS“Light of West China”Programsupport from International Centre of Supernovae,Yunnan Key Laboratory(No.202302AN360001)the Yunnan Revitalization Talent Support Program-Science&Technology Champion Project(NO.202305AB350003)Yunnan Fundamental Research Projects(NOs.202401BC070007,202201BC070003)the science research grants from the China Manned Space Project。
文摘The origin of intermediate helium (He)-rich hot subdwarfs is still unclear.Previous studies have suggested that some surviving Type Ia supernovae (SNe Ia) companions from the white dwarf+main-sequence (WD+MS)channel may contribute to the intermediate He-rich hot subdwarfs.However,previous studies ignored the impact of atomic diffusion on the post-explosion evolution of surviving companion stars of SNe Ia,leading to the aspect that they could not explain the observed surface He abundance of intermediate He-rich hot subdwarfs.In this work,by taking the atomic diffusion and stellar wind into account,we trace the surviving companions of SNe Ia from the WD+MS channel using the one-dimensional stellar evolution code MESA until they evolve into hot subdwarfs.We find that the surface He-abundances of our surviving companion models during their core He-burning phases are in a range of-1■log(N_(He) N_(H))■0,which are consistent with those observed in intermediate He-rich hot subdwarfs.This seems to further support the notion that it is possible for surviving companions of SNe Ia in the WD+MS channel to form some intermediate He-rich hot subdwarfs.
