The gravitational wave background(GWB) produced by extreme-mass-ratio inspirals(EMRIs) serves as a powerful tool for probing the astrophysical and dynamical processes in galactic centers. EMRI systems are a primary ta...The gravitational wave background(GWB) produced by extreme-mass-ratio inspirals(EMRIs) serves as a powerful tool for probing the astrophysical and dynamical processes in galactic centers. EMRI systems are a primary target for the space-based detector laser interferometer space antenna due to their long-lived signals and high signal-to-noise ratios. This study explores the statistical properties of the GWB from EMRI, focusing on the calculation methods for the GWB, the astrophysical distribution of EMRI sources, and the influence of key parameters, including the spin of supermassive black holes(SMBHs) and the masses of compact objects(COs). By analyzing these factors, we determine the distribution range of the characteristic strain of the GWB from EMRIs. We find that the final eccentricity distributions appear to have negligible effect on the intensity of the GWB due to rapid circularization before they become detectable and the spin of the SMBH enhances the gravitational wave characteristic strain by approximately 1% compared to cases without spin effects. The masses of COs can also significantly affect the characteristic strain of the GWB from EMRIs, with black hole as CO producing a gravitational wave signal intensity that is approximately one order of magnitude higher compared to cases where neutron star or white dwarf are the COs.展开更多
How gamma-ray bursts(GRBs),the most powerful and spectacular explosions known in the universe since the Big Bang,fuel their high-energy radiations?What kind of physical reactions can trigger and sustain such violent,e...How gamma-ray bursts(GRBs),the most powerful and spectacular explosions known in the universe since the Big Bang,fuel their high-energy radiations?What kind of physical reactions can trigger and sustain such violent,energetic outflow?This has captivated astronomers.Over the past decades,thousands of GRBs have been observed;however,the origin and the product of the burst-the central celestial body,or the“central engine”,is still pending for identification.展开更多
LB-1 is a binary system that has drawn great attention since its discovery in 2019.The two components of LB-1 are suggested to be a B-type star plus a black hole (BH).In this paper,we first calculate the wind mass-los...LB-1 is a binary system that has drawn great attention since its discovery in 2019.The two components of LB-1 are suggested to be a B-type star plus a black hole (BH).In this paper,we first calculate the wind mass-loss rate of the B-type star.We then calculate the mass capture rate by the BH,with which as the initial mass accretion rate,we calculate the truncation radius of the accretion disk and the corresponding emergent spectra of the accretion flow(comprising an inner advection-dominated accretion flow (ADAF)+an outer truncated accretion disk) within the framework of the disk evaporation model.It is found that the predicted truncation radius of the accretion disk with appropriate model parameters is consistent with observations inferred from the observed broad H_(α) emission line.The predicted X-ray luminosity is definitely below the estimated upper limits with the sensitivity of the Chandra X-ray Observatory of the X-ray luminosity≈2×10^(31)ergs^(-1),which is also consistent with observations.Finally,we argue that the disk evaporation model can indeed reflect the intrinsic physics of the accretion flow in LB-1,and has potential to be applied to other quiescent BHs in the future.展开更多
This study employs two-dimensional axisymmetric relativistic magnetohydrodynamic simulations to investigate the evolution of supernova remnant(SNR) and pulsar wind nebula(PWN) composite systems in two distinct interst...This study employs two-dimensional axisymmetric relativistic magnetohydrodynamic simulations to investigate the evolution of supernova remnant(SNR) and pulsar wind nebula(PWN) composite systems in two distinct interstellar medium(ISM) configurations: a uniform density distribution and a medium with a sharp density discontinuity. Compared to the uniform density distribution, the ISM with this density discontinuity better reflects the actual conditions and explains the overall morphological characteristics of specific types of SNR-PWN composite systems. These systems exhibit asymmetries, such as an SNR shell with differing radii or an inner PWN located nearer to the shell on one side. The simulation results suggest that the density discontinuity in the ISM is a contributing factor to both the shell asymmetry and the PWN displacement. Specifically, this density variation directly causes the inconsistency in the forward shock speeds of the SNR between high and low density regions, resulting in discrepancies in the shell layer radii. Furthermore, the asymmetric morphology of the PWN and its positional offset emerge through interactions with the reverse shock. The PWN tends to shift toward the SNR shell on one side. The greater the density jump in the background field, the more pronounced the shell radius differences and PWN offset become.展开更多
In this paper,we determine the photosphere evolution of PTF11rka which is a type Ic supernova (SN) by fitting its spectral energy distributions at different epochs.We find that the photosphere of PTF11rka expanded at ...In this paper,we determine the photosphere evolution of PTF11rka which is a type Ic supernova (SN) by fitting its spectral energy distributions at different epochs.We find that the photosphere of PTF11rka expanded at a constant velocity at early epochs,and the photosphere temperature increased slightly after reaching a minimum.These features are reminiscent of those of SN 2017dio.Based on the photosphere module that can describe the photosphere evolution of PTF11rka,we use the ^(56)Ni cascade decay model to fit its multiband light curves (LCs),finding that the model can well fit the photometric data.The derived ejecta mass and ^(56)Ni mass are respectively 8.76■ and 0.29-0.41■;the derived peak luminosity and the rise time of the theoretical bolometric LC of PTF11rka are ~8.24×10^(42)erg s^(-1) and ~35 days,respectively.Moreover,we find that the theoretical multiband LCs and the theoretical bolometric LC of PTF11rka do not show early-time excesses proposed in the literature.This indicates that additional energy sources (e.g.,the interaction between the ejecta and the circumstellar material)suggested to be responsible for the early-time excess can be neglected.展开更多
In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the...In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the DM halo parameter and the cloud string parameter affect BH attributes such as quasinormal modes(QNMs)and shadow cast.To do this,we first look into the effective potential of perturbation equations for three types of perturbation fields with different spins:massless scalar field,electromagnetic field and gravitational field.Then,using the sixth-order Wentzel-Kramers-Brillouin approximation,we examine QNMs of the BH disturbed by the three fields and derive quasinormal frequencies.The changes in QNM versus the core density parameter and the cloud string parameter for three disturbances are explored.We also investigate how the core density and the cloud string parameter affect the photon sphere and shadow radius.Interestingly,the study shows that the influence of Dehnen-type DM and cloud strings increases both the photon sphere and the shadow radius.Finally,we employ observational data from Sgr A^(*) and M87^(*) to set limitations on the BH parameters.展开更多
This paper presents the design and optimization of a lutetium yttrium oxyorthosilicate(LYSO)crystal electromagnetic calorimeter(ECAL)for the DarkSHINE experiment,which aims to identify dark photons as potential mediat...This paper presents the design and optimization of a lutetium yttrium oxyorthosilicate(LYSO)crystal electromagnetic calorimeter(ECAL)for the DarkSHINE experiment,which aims to identify dark photons as potential mediators of dark forces.The ECAL design was evaluated through comprehensive simulations,focusing on optimizing dimensions,material selection,energy distribution,and energy resolution.The configuration consisted of 21×21×11 LYSO crystals,each measuring 2.5 cm×2.5 cm×4 cm,arranged in a staggered layout to enhance signal detection efficiency.A 4 GeV energy dynamic range was established to ensure accurate energy measurements without saturation,which is essential for background rejection and signal identification.A detailed digitization model was developed to simulate scintillation,silicon photomultiplier,and analog-to-digital converter behaviors,providing a realistic representation of the detector's performance.Additionally,the study assessed radiation damage in the ECAL region,emphasizing the importance of using radiation-resistant scintillators and silicon sensors.展开更多
We demonstrate by three-dimensional hydrodynamical simulations of energy deposition into the envelope of a red supergiant model the inflation of a Rayleigh–Taylor unstable envelope that forms a compact clumpy circums...We demonstrate by three-dimensional hydrodynamical simulations of energy deposition into the envelope of a red supergiant model the inflation of a Rayleigh–Taylor unstable envelope that forms a compact clumpy circumstellar material(CSM).Our simulations mimic vigorous core activity years to months before a core-collapse supernova(CCSN)explosion that deposits energy to the outer envelope.The fierce core nuclear activity in the pre-CCSN explosion phase might excite waves that propagate to the envelope.The wave energy is dissipated where envelope convection cannot carry the energy.We deposit this energy into a shell in the outer envelope with a power of L_(wave)=2.6×10^(6)L■or L_(wave)=5.2×10^(5)L■for 0.32 yr.The energy-deposition shell expands while its pressure is higher than its surroundings,but its density is lower.Therefore,this expansion is Rayleigh–Taylor unstable and develops instability fingers.Most of the inflated envelope does not reach the escape velocity in the year of simulation but forms a compact and clumpy CSM.The high density of the inflated envelope implies that if a companion is present in that zone,it will accrete mass at a very high rate and power a pre-explosion outburst.展开更多
We present simulation results examining the presence and behavior of standing shocks in zero-energy low angular momentum advective accretion flows and explore their(in)stability properties,taking into account various ...We present simulation results examining the presence and behavior of standing shocks in zero-energy low angular momentum advective accretion flows and explore their(in)stability properties,taking into account various values of specific angular momentum,λ_(0).Within the range 10-50R_(g)(where R_(g)denotes the Schwarzschild radius),shocks are discernible forλ_(0)≥1.75.In the special relativistic hydrodynamic simulation whenλ_(0)=1.80,we find the merger of two shocks resulted in a dramatic increase in luminosity.We present the impact of external and internal flow collisions from the funnel region on luminosity.Notably,oscillatory behavior characterizes shocks within 1.70≤λ_(0)≤1.80.Using free–free emission as a proxy for analysis,we show that the luminosity oscillations between frequencies of 0.1-10 Hz forλ_(0)range as 1.7≤λ_(0)≤1.80.These findings offer insights into quasiperiodic oscillation emissions from certain black hole X-ray binaries,exemplified by GX 339-4.Furthermore,for the supermassive black hole at the Milky Way's center,Sgr A*,oscillation frequencies between 10^(-6)and 10^(-5)Hz were observed.This frequency range,translating to one cycle every few days,aligns with observational data from X-ray telescopes such as Chandra,Swift,and XMM-Newton.展开更多
Understanding the nature of dark matter remains one of the most enigmatic and unresolved issues in astrophysics.Certain theoretical models address this by introducing a novel component to account for dark matter.In th...Understanding the nature of dark matter remains one of the most enigmatic and unresolved issues in astrophysics.Certain theoretical models address this by introducing a novel component to account for dark matter.In this study,we propose a new scalar field derived from string T-duality,where its associated density represents the density of the surrounding matter field,in the spherically symmetric and static medium.Our exploration reveals that this scalar field behaves as the baryonic fluid,characterized by a positive effective state equation,ωe>0.Furthermore,a detailed investigation demonstrates that this model satisfies all energy conditions beyond the event horizon of a central black hole.Considering the light deflection and radar echo delay suggests that in this scalar field,the dark matter grows up in the halo and surrounding regions of galaxy systems.This indicates that dark matter accumulates as an effective field outside the observable regions of galaxies.展开更多
In this work,we analyze black hole-neutron star(BHNS)events using an astrophysically-motivated prior to derive updated,more tightly constrained estimates for component masses,mass ratios,and effective inspiral spin.Fo...In this work,we analyze black hole-neutron star(BHNS)events using an astrophysically-motivated prior to derive updated,more tightly constrained estimates for component masses,mass ratios,and effective inspiral spin.For most BHNS systems,the mean primary mass shifts to higher values,with significant cases such as GW190426 and GW200115,where the primary mass is entirely excluded from the lower-mass gap.While the primary mass of GW230529 remains within the gap,its mean value shifts slightly upward.In contrast,the secondary mass generally shifts toward the higher end of the mass spectrum.These changes highlight the substantial influence of prior choices-particularly the spin prior-on the inferred mass distributions.Additionally,for all BHNS events,the effective inspiral spin is tightly concentrated around zero,reinforcing the expectation of nearly nonspinning components in these systems.We also discuss the classical common-envelope formation scenario,which is widely considered the dominant channel for BHNS formation,where the BH formed from the more massive progenitor star is typically expected to have negligible spin.展开更多
We simulate the gravitational redshift of quantum matter waves with a long de Broglie wavelength by tracing particle beams along geodesics,when they propagate within the rotation plane of binary black holes.The angula...We simulate the gravitational redshift of quantum matter waves with a long de Broglie wavelength by tracing particle beams along geodesics,when they propagate within the rotation plane of binary black holes.The angular momentum of the binary black hole causes an asymmetric gravitational redshift distribution around the two black holes.The gravitational redshift changes the frequency of quantum matter waves and their wavelength,resulting in the different interference patterns of quantum matter waves with respect to different wavelengths.The interference pattern demonstrates strong contrast intensity and spatial order with respect to different wavelengths and the rotational angle of the binary black hole.A bright semicircular arc emerges from the interference pattern to bridge the two black holes,when they rotate to certain angles,which provides a theoretical understanding on the gravitational lensing effect of quantum matter waves.展开更多
Novae are found to have GeV to TeVγ-ray emission,which reveals the shock acceleration from the white dwarfs.Recently,V1405 Cas was reported to radiate suspiciousγ-ray by Fermi-LAT with low signi?cance(4.1σ)after th...Novae are found to have GeV to TeVγ-ray emission,which reveals the shock acceleration from the white dwarfs.Recently,V1405 Cas was reported to radiate suspiciousγ-ray by Fermi-LAT with low signi?cance(4.1σ)after the optical maximum.Radio observations reveal that it is one of the?ve brightest novae surrounded by low-density ionized gas columns.Here we report a continuous search for GeVγ-ray from Fermi-LAT.Noγ-ray was found.For V1405 Cas the?ux level is lower than other well-studied Fermi novae,and theγ-ray maximum appears at t0+145 days.γ-ray of V1405 Cas is used to search potentialγ-ray periodicity.Noγ-ray periodicity was found during the time of observation.By comparing multi-wavelength data,theγ-ray upper limit to optical?ux ratio with a value at around 10^(-4)is obtained to constrain the shock acceleration.Long-term analysis from Swift-XRT gets X-ray spectral in the post-shock phase,which indicates that V1405 Cas became a super-soft source.The best-?t black body temperature at the super soft state is 0.11-0.19 keV.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
We investigate the impact of inelastic collisions between dark matter(DM)and heavy cosmic ray(CR)nuclei on CR propagation.We approximate the fragmentation cross-sections for DM-CR collisions using collider-measured pr...We investigate the impact of inelastic collisions between dark matter(DM)and heavy cosmic ray(CR)nuclei on CR propagation.We approximate the fragmentation cross-sections for DM-CR collisions using collider-measured proton-nuclei scattering cross-sections,allowing us to assess how these collisions affect the spectra of CR boron and carbon.We derive new CR spectra from DM-CR collisions by incorporating their cross-sections into the source terms and solving the diffusion equation for the complete network of reactions involved in generating secondary species.In a specific example with a coupling strength of b_(χ)=0.1 and a DM mass of m_(χ)=0.1 GeV,considering a simplified scenario where DM interacts exclusively with oxygen,a notable modification in the boron-to-carbon spectrum due to the DM-CR interaction is observed.Particularly,the peak within the spectrum,spanning from 0.1 to 10 GeV,experiences an enhancement of approximately 1.5 times.However,in a more realistic scenario where DM particles interact with all CRs,this peak can be amplified to twice its original value.Utilizing the latest data from AMS-02 and DAMPE on the boron-to-carbon ratio,we estimate a 95%upper limit for the effective inelastic cross-section of DM-proton as a function of DM mass.Our findings reveal that at m_(χ)?2 MeV,the effective inelastic cross-section between DM and protons must be less than O(10^(-32))cm^(2).展开更多
In the background of f(R,L_(m))gravity,this work investigates three distinct dark matter halo profiles to test the possibility of generalised wormhole geometry within the galactic halo regions.The current study aims t...In the background of f(R,L_(m))gravity,this work investigates three distinct dark matter halo profiles to test the possibility of generalised wormhole geometry within the galactic halo regions.The current study aims to accomplish these goals by examining various dark matter profiles including universal rotation curves(URC),Navarro-Frenk-White(NFW)model-Ⅰ,and NFW model-Ⅱinside two distinct f(R,L_(m))gravity models.According to the f(R,L_(m))=R/2+L^(a)_(m)model,the dark matter(DM)halo density profiles produce suitable shape functions that meet all the necessary requirements for exhibiting the wormhole geometries with appropriate choice of free parameters.In addition,to examine DM profiles under the f(R,L_(m))=R/2+(1+λR)L_(m) model,we consider a specific shape function.Further,we observed that the derived solution from both two models violates the null energy constraints,confirming that the DM supports wormholes to maintain in the galactic halo.展开更多
基金supported by the National Key R&D Program of China (Grant No. 2020YFC2201400)。
文摘The gravitational wave background(GWB) produced by extreme-mass-ratio inspirals(EMRIs) serves as a powerful tool for probing the astrophysical and dynamical processes in galactic centers. EMRI systems are a primary target for the space-based detector laser interferometer space antenna due to their long-lived signals and high signal-to-noise ratios. This study explores the statistical properties of the GWB from EMRI, focusing on the calculation methods for the GWB, the astrophysical distribution of EMRI sources, and the influence of key parameters, including the spin of supermassive black holes(SMBHs) and the masses of compact objects(COs). By analyzing these factors, we determine the distribution range of the characteristic strain of the GWB from EMRIs. We find that the final eccentricity distributions appear to have negligible effect on the intensity of the GWB due to rapid circularization before they become detectable and the spin of the SMBH enhances the gravitational wave characteristic strain by approximately 1% compared to cases without spin effects. The masses of COs can also significantly affect the characteristic strain of the GWB from EMRIs, with black hole as CO producing a gravitational wave signal intensity that is approximately one order of magnitude higher compared to cases where neutron star or white dwarf are the COs.
文摘How gamma-ray bursts(GRBs),the most powerful and spectacular explosions known in the universe since the Big Bang,fuel their high-energy radiations?What kind of physical reactions can trigger and sustain such violent,energetic outflow?This has captivated astronomers.Over the past decades,thousands of GRBs have been observed;however,the origin and the product of the burst-the central celestial body,or the“central engine”,is still pending for identification.
基金supported by the National Natural Science Foundation of China (grant Nos.12173048,12333004,11988101,and 12273057)the National Key R&D Program of China (No.2023YFA1607903)the support from the K.C.Wong Education Foundation。
文摘LB-1 is a binary system that has drawn great attention since its discovery in 2019.The two components of LB-1 are suggested to be a B-type star plus a black hole (BH).In this paper,we first calculate the wind mass-loss rate of the B-type star.We then calculate the mass capture rate by the BH,with which as the initial mass accretion rate,we calculate the truncation radius of the accretion disk and the corresponding emergent spectra of the accretion flow(comprising an inner advection-dominated accretion flow (ADAF)+an outer truncated accretion disk) within the framework of the disk evaporation model.It is found that the predicted truncation radius of the accretion disk with appropriate model parameters is consistent with observations inferred from the observed broad H_(α) emission line.The predicted X-ray luminosity is definitely below the estimated upper limits with the sensitivity of the Chandra X-ray Observatory of the X-ray luminosity≈2×10^(31)ergs^(-1),which is also consistent with observations.Finally,we argue that the disk evaporation model can indeed reflect the intrinsic physics of the accretion flow in LB-1,and has potential to be applied to other quiescent BHs in the future.
基金supported by the National Natural Science Foundation of China(NSFC,grants No.12393852)the Yunnan Fundamental Research Projects(grant No.202501AS070068)the Program of Graduate Research and Innovation Fund Project of Yunnan University(KC-24249493).
文摘This study employs two-dimensional axisymmetric relativistic magnetohydrodynamic simulations to investigate the evolution of supernova remnant(SNR) and pulsar wind nebula(PWN) composite systems in two distinct interstellar medium(ISM) configurations: a uniform density distribution and a medium with a sharp density discontinuity. Compared to the uniform density distribution, the ISM with this density discontinuity better reflects the actual conditions and explains the overall morphological characteristics of specific types of SNR-PWN composite systems. These systems exhibit asymmetries, such as an SNR shell with differing radii or an inner PWN located nearer to the shell on one side. The simulation results suggest that the density discontinuity in the ISM is a contributing factor to both the shell asymmetry and the PWN displacement. Specifically, this density variation directly causes the inconsistency in the forward shock speeds of the SNR between high and low density regions, resulting in discrepancies in the shell layer radii. Furthermore, the asymmetric morphology of the PWN and its positional offset emerge through interactions with the reverse shock. The PWN tends to shift toward the SNR shell on one side. The greater the density jump in the background field, the more pronounced the shell radius differences and PWN offset become.
基金supported by the National Natural Science Foundation of China (NSFC,grant Nos.12494571,11963001 and 12133003)supported by the Program of Bagui Scholars (LHJ)。
文摘In this paper,we determine the photosphere evolution of PTF11rka which is a type Ic supernova (SN) by fitting its spectral energy distributions at different epochs.We find that the photosphere of PTF11rka expanded at a constant velocity at early epochs,and the photosphere temperature increased slightly after reaching a minimum.These features are reminiscent of those of SN 2017dio.Based on the photosphere module that can describe the photosphere evolution of PTF11rka,we use the ^(56)Ni cascade decay model to fit its multiband light curves (LCs),finding that the model can well fit the photometric data.The derived ejecta mass and ^(56)Ni mass are respectively 8.76■ and 0.29-0.41■;the derived peak luminosity and the rise time of the theoretical bolometric LC of PTF11rka are ~8.24×10^(42)erg s^(-1) and ~35 days,respectively.Moreover,we find that the theoretical multiband LCs and the theoretical bolometric LC of PTF11rka do not show early-time excesses proposed in the literature.This indicates that additional energy sources (e.g.,the interaction between the ejecta and the circumstellar material)suggested to be responsible for the early-time excess can be neglected.
基金supported by the National Natural Science Foundation of China under Grant No.11675143the National Key Research and Development Program of China under Grant No.2020YFC2201503。
文摘In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the DM halo parameter and the cloud string parameter affect BH attributes such as quasinormal modes(QNMs)and shadow cast.To do this,we first look into the effective potential of perturbation equations for three types of perturbation fields with different spins:massless scalar field,electromagnetic field and gravitational field.Then,using the sixth-order Wentzel-Kramers-Brillouin approximation,we examine QNMs of the BH disturbed by the three fields and derive quasinormal frequencies.The changes in QNM versus the core density parameter and the cloud string parameter for three disturbances are explored.We also investigate how the core density and the cloud string parameter affect the photon sphere and shadow radius.Interestingly,the study shows that the influence of Dehnen-type DM and cloud strings increases both the photon sphere and the shadow radius.Finally,we employ observational data from Sgr A^(*) and M87^(*) to set limitations on the BH parameters.
基金supported by National Key R&D Program of China(Nos.2023YFA1606904 and 2023YFA1606900)National Natural Science Foundation of China(No.12150006)+1 种基金Shanghai Pilot Program for Basic Research-Shanghai Jiao Tong University(No.21TQ1400209)National Center for High-Level Talent Training in Mathematics,Physics,Chemistry,and Biology。
文摘This paper presents the design and optimization of a lutetium yttrium oxyorthosilicate(LYSO)crystal electromagnetic calorimeter(ECAL)for the DarkSHINE experiment,which aims to identify dark photons as potential mediators of dark forces.The ECAL design was evaluated through comprehensive simulations,focusing on optimizing dimensions,material selection,energy distribution,and energy resolution.The configuration consisted of 21×21×11 LYSO crystals,each measuring 2.5 cm×2.5 cm×4 cm,arranged in a staggered layout to enhance signal detection efficiency.A 4 GeV energy dynamic range was established to ensure accurate energy measurements without saturation,which is essential for background rejection and signal identification.A detailed digitization model was developed to simulate scintillation,silicon photomultiplier,and analog-to-digital converter behaviors,providing a realistic representation of the detector's performance.Additionally,the study assessed radiation damage in the ECAL region,emphasizing the importance of using radiation-resistant scintillators and silicon sensors.
基金A grant from the Pazy Foundation supported this research。
文摘We demonstrate by three-dimensional hydrodynamical simulations of energy deposition into the envelope of a red supergiant model the inflation of a Rayleigh–Taylor unstable envelope that forms a compact clumpy circumstellar material(CSM).Our simulations mimic vigorous core activity years to months before a core-collapse supernova(CCSN)explosion that deposits energy to the outer envelope.The fierce core nuclear activity in the pre-CCSN explosion phase might excite waves that propagate to the envelope.The wave energy is dissipated where envelope convection cannot carry the energy.We deposit this energy into a shell in the outer envelope with a power of L_(wave)=2.6×10^(6)L■or L_(wave)=5.2×10^(5)L■for 0.32 yr.The energy-deposition shell expands while its pressure is higher than its surroundings,but its density is lower.Therefore,this expansion is Rayleigh–Taylor unstable and develops instability fingers.Most of the inflated envelope does not reach the escape velocity in the year of simulation but forms a compact and clumpy CSM.The high density of the inflated envelope implies that if a companion is present in that zone,it will accrete mass at a very high rate and power a pre-explosion outburst.
基金supported by the National Natural Science Foundation of China(NSFC,Grant No.12073021)。
文摘We present simulation results examining the presence and behavior of standing shocks in zero-energy low angular momentum advective accretion flows and explore their(in)stability properties,taking into account various values of specific angular momentum,λ_(0).Within the range 10-50R_(g)(where R_(g)denotes the Schwarzschild radius),shocks are discernible forλ_(0)≥1.75.In the special relativistic hydrodynamic simulation whenλ_(0)=1.80,we find the merger of two shocks resulted in a dramatic increase in luminosity.We present the impact of external and internal flow collisions from the funnel region on luminosity.Notably,oscillatory behavior characterizes shocks within 1.70≤λ_(0)≤1.80.Using free–free emission as a proxy for analysis,we show that the luminosity oscillations between frequencies of 0.1-10 Hz forλ_(0)range as 1.7≤λ_(0)≤1.80.These findings offer insights into quasiperiodic oscillation emissions from certain black hole X-ray binaries,exemplified by GX 339-4.Furthermore,for the supermassive black hole at the Milky Way's center,Sgr A*,oscillation frequencies between 10^(-6)and 10^(-5)Hz were observed.This frequency range,translating to one cycle every few days,aligns with observational data from X-ray telescopes such as Chandra,Swift,and XMM-Newton.
文摘Understanding the nature of dark matter remains one of the most enigmatic and unresolved issues in astrophysics.Certain theoretical models address this by introducing a novel component to account for dark matter.In this study,we propose a new scalar field derived from string T-duality,where its associated density represents the density of the surrounding matter field,in the spherically symmetric and static medium.Our exploration reveals that this scalar field behaves as the baryonic fluid,characterized by a positive effective state equation,ωe>0.Furthermore,a detailed investigation demonstrates that this model satisfies all energy conditions beyond the event horizon of a central black hole.Considering the light deflection and radar echo delay suggests that in this scalar field,the dark matter grows up in the halo and surrounding regions of galaxy systems.This indicates that dark matter accumulates as an effective field outside the observable regions of galaxies.
基金support of the undergraduate Innovation and Entrepreneurship Training Program(No.S202410370441)the Undergraduate Outstanding Thesis Cultivation Program(No.pyjh2024291)+2 种基金support from Anhui Provincial Natural Science Foundation(grant No.2308085MA29)supported by the National Natural Science Foundation of China(grant Nos.12473036 and 12103003)supported by Jiangxi Provincial Natural Science Foundation(grant Nos.20242BAB26012 and 20224ACB211001)。
文摘In this work,we analyze black hole-neutron star(BHNS)events using an astrophysically-motivated prior to derive updated,more tightly constrained estimates for component masses,mass ratios,and effective inspiral spin.For most BHNS systems,the mean primary mass shifts to higher values,with significant cases such as GW190426 and GW200115,where the primary mass is entirely excluded from the lower-mass gap.While the primary mass of GW230529 remains within the gap,its mean value shifts slightly upward.In contrast,the secondary mass generally shifts toward the higher end of the mass spectrum.These changes highlight the substantial influence of prior choices-particularly the spin prior-on the inferred mass distributions.Additionally,for all BHNS events,the effective inspiral spin is tightly concentrated around zero,reinforcing the expectation of nearly nonspinning components in these systems.We also discuss the classical common-envelope formation scenario,which is widely considered the dominant channel for BHNS formation,where the BH formed from the more massive progenitor star is typically expected to have negligible spin.
文摘We simulate the gravitational redshift of quantum matter waves with a long de Broglie wavelength by tracing particle beams along geodesics,when they propagate within the rotation plane of binary black holes.The angular momentum of the binary black hole causes an asymmetric gravitational redshift distribution around the two black holes.The gravitational redshift changes the frequency of quantum matter waves and their wavelength,resulting in the different interference patterns of quantum matter waves with respect to different wavelengths.The interference pattern demonstrates strong contrast intensity and spatial order with respect to different wavelengths and the rotational angle of the binary black hole.A bright semicircular arc emerges from the interference pattern to bridge the two black holes,when they rotate to certain angles,which provides a theoretical understanding on the gravitational lensing effect of quantum matter waves.
基金supported by the National Natural Science Foundation of China(NSFC,grant No.12393853)the Scientific Research Foundation of Hunan Provincial Education Department(21C0343)+1 种基金the Science Research Project of the University(Youth Project)of the Department of Education of Guizhou Province(QJJ[2022]348)the Science and Technology Foundation of Guizhou Province(QKHJC-ZK[2023]442)。
文摘Novae are found to have GeV to TeVγ-ray emission,which reveals the shock acceleration from the white dwarfs.Recently,V1405 Cas was reported to radiate suspiciousγ-ray by Fermi-LAT with low signi?cance(4.1σ)after the optical maximum.Radio observations reveal that it is one of the?ve brightest novae surrounded by low-density ionized gas columns.Here we report a continuous search for GeVγ-ray from Fermi-LAT.Noγ-ray was found.For V1405 Cas the?ux level is lower than other well-studied Fermi novae,and theγ-ray maximum appears at t0+145 days.γ-ray of V1405 Cas is used to search potentialγ-ray periodicity.Noγ-ray periodicity was found during the time of observation.By comparing multi-wavelength data,theγ-ray upper limit to optical?ux ratio with a value at around 10^(-4)is obtained to constrain the shock acceleration.Long-term analysis from Swift-XRT gets X-ray spectral in the post-shock phase,which indicates that V1405 Cas became a super-soft source.The best-?t black body temperature at the super soft state is 0.11-0.19 keV.
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.
基金supported by the National Key Research and Development Program of China(2022YFF0503304,2020YFC2201600,2018YFA0404504 and 2018YFA0404601)the Ministry of Science and Technology of China(2020SKA0110402,2020SKA0110401 and 2020SKA0110100)+4 种基金the National Natural Science Foundation of China(11890691,12205388 and 12220101003)the CAS Project for Young Scientists in Basic Research(YSBR-061,YSBR-092)the China Manned Space Project with No.CMS-CSST-2021(A02,A03 and B01)the Major Key Project of PCLthe 111 project(B20019)。
文摘We investigate the impact of inelastic collisions between dark matter(DM)and heavy cosmic ray(CR)nuclei on CR propagation.We approximate the fragmentation cross-sections for DM-CR collisions using collider-measured proton-nuclei scattering cross-sections,allowing us to assess how these collisions affect the spectra of CR boron and carbon.We derive new CR spectra from DM-CR collisions by incorporating their cross-sections into the source terms and solving the diffusion equation for the complete network of reactions involved in generating secondary species.In a specific example with a coupling strength of b_(χ)=0.1 and a DM mass of m_(χ)=0.1 GeV,considering a simplified scenario where DM interacts exclusively with oxygen,a notable modification in the boron-to-carbon spectrum due to the DM-CR interaction is observed.Particularly,the peak within the spectrum,spanning from 0.1 to 10 GeV,experiences an enhancement of approximately 1.5 times.However,in a more realistic scenario where DM particles interact with all CRs,this peak can be amplified to twice its original value.Utilizing the latest data from AMS-02 and DAMPE on the boron-to-carbon ratio,we estimate a 95%upper limit for the effective inelastic cross-section of DM-proton as a function of DM mass.Our findings reveal that at m_(χ)?2 MeV,the effective inelastic cross-section between DM and protons must be less than O(10^(-32))cm^(2).
基金University Grant Commission(UGC),Govt.of India,New Delhi,for awarding JRF(NTA Ref.No.:191620024300)University Grants Commission(UGC),New Delhi,India,for awarding National Fellowship for Scheduled Caste Students(UGC-Ref.No.:201610123801)+1 种基金PKS acknowledges the National Board for Higher Mathematics(NBHM)under the Department of Atomic Energy(DAE),Govt.of India,for financial support to carry out the Research project No.:02011/3/2022 NBHM(R.P.)/R&D II/2152 Dt.14.02.2022IUCAA,Pune,India for providing support through the visiting Associateship program.
文摘In the background of f(R,L_(m))gravity,this work investigates three distinct dark matter halo profiles to test the possibility of generalised wormhole geometry within the galactic halo regions.The current study aims to accomplish these goals by examining various dark matter profiles including universal rotation curves(URC),Navarro-Frenk-White(NFW)model-Ⅰ,and NFW model-Ⅱinside two distinct f(R,L_(m))gravity models.According to the f(R,L_(m))=R/2+L^(a)_(m)model,the dark matter(DM)halo density profiles produce suitable shape functions that meet all the necessary requirements for exhibiting the wormhole geometries with appropriate choice of free parameters.In addition,to examine DM profiles under the f(R,L_(m))=R/2+(1+λR)L_(m) model,we consider a specific shape function.Further,we observed that the derived solution from both two models violates the null energy constraints,confirming that the DM supports wormholes to maintain in the galactic halo.
