Dark matter is hypothesized to interact with ordinary matter solely through gravity and may be present in compact objects such as strange quark stars. We treat strange quark stars admixed with dark matter as two-fluid systems to investigate the potential effects of dark matter on strange quark stars. Quark matter is described by the quasiparticle model and the extended MIT bag model for comparison. Dark matter is treated as asymmetric, self-interacting, and composed of massive fermionic particles. The two-fluid Tolman-Oppenheimer-Volkoff (TOV) equations are employed to solve for specific stellar properties. Our analysis yields relations between central energy density and mass, radius and mass, as well as tidal deformability and mass. The calculated curves generally align with observational data. In particular, we find that the pattern in which fermionic asymmetric dark matter affects the properties of strange quark stars may not be influenced by the equation of state (EOS) of strange quark matter.
根据假设，暗物质仅通过引力与普通物质相互作用，并可能存在于奇异夸克星等紧凑物体中。为了研究暗物质对奇异夸克星的潜在影响，我们将奇异夸克星与暗物质混合视为双流体系统。夸克物质由准粒子模型和扩展的 MIT 袋模型描述，以作比较。暗物质被视为不对称的、自相互作用的、由大质量费米子粒子组成的物质。采用双流体托尔曼-奥本海默-沃尔科夫（TOV）方程来求解特定的恒星特性。我们的分析得出了中心能量密度与质量、半径与质量以及潮汐变形能力与质量之间的关系。计算出的曲线与观测数据基本吻合。特别是，我们发现费米不对称暗物质影响奇异夸克星性质的模式可能不受奇异夸克物质状态方程（EOS）的影响。
{"title":"Impact of dark matter on strange quark stars described by different quark models","authors":"Yida Yang, Chen Wu, Ji-Feng Yang","doi":"arxiv-2409.09275","DOIUrl":"https://doi.org/arxiv-2409.09275","url":null,"abstract":"Dark matter is hypothesized to interact with ordinary matter solely through\u0000gravity and may be present in compact objects such as strange quark stars. We\u0000treat strange quark stars admixed with dark matter as two-fluid systems to\u0000investigate the potential effects of dark matter on strange quark stars. Quark\u0000matter is described by the quasiparticle model and the extended MIT bag model\u0000for comparison. Dark matter is treated as asymmetric, self-interacting, and\u0000composed of massive fermionic particles. The two-fluid\u0000Tolman-Oppenheimer-Volkoff (TOV) equations are employed to solve for specific\u0000stellar properties. Our analysis yields relations between central energy\u0000density and mass, radius and mass, as well as tidal deformability and mass. The\u0000calculated curves generally align with observational data. In particular, we\u0000find that the pattern in which fermionic asymmetric dark matter affects the\u0000properties of strange quark stars may not be influenced by the equation of\u0000state (EOS) of strange quark matter.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ultra-high-energy (UHE) gamma-ray source 1LHAASO J0007+7303u is positionally associated with the composite SNR CTA1 that is located at high Galactic Latitude $bapprox 10.5^circ$. This provides a rare opportunity to spatially resolve the component of the pulsar wind nebula (PWN) and supernova remnant (SNR) at UHE. This paper conducted a dedicated data analysis of 1LHAASO J0007+7303u using the data collected from December 2019 to July 2023. This source is well detected with significances of 21$sigma$ and 17$sigma$ at 8$-$100 TeV and $>$100 TeV, respectively. The corresponding extensions are determined to be 0.23$^{circ}pm$0.03$^{circ}$ and 0.17$^{circ}pm$0.03$^{circ}$. The emission is proposed to originate from the relativistic electrons and positrons accelerated within the PWN of PSR J0007+7303. The energy spectrum is well described by a power-law with an exponential cutoff function $dN/dE = (42.4pm4.1)(frac{E}{20rm TeV})^{-2.31pm0.11}exp(-frac{E}{110pm25rm TeV})$ $rm TeV^{-1} cm^{-2} s^{-1}$in the energy range from 8 TeV to 300 TeV, implying a steady-state parent electron spectrum $dN_e/dE_epropto (frac{E_e}{100rm TeV})^{-3.13pm0.16}exp[(frac{-E_e}{373pm70rm TeV})^2]$ at energies above $approx 50 rm TeV$. The cutoff energy of the electron spectrum is roughly equal to the expected current maximum energy of particles accelerated at the PWN terminal shock. Combining the X-ray and gamma-ray emission, the current space-averaged magnetic field can be limited to $approx 4.5rm mu G$. To satisfy the multi-wavelength spectrum and the $gamma$-ray extensions, the transport of relativistic particles within the PWN is likely dominated by the advection process under the free-expansion phase assumption.
超高能（UHE）伽马射线源1LHAASO J0007+7303u与位于银河系高纬度$bapprox 10.5^circ$的复合SNR CTA1位置相关。这为空间解析UHE上的脉冲星风星云（PWN）和超新星（SNR）的成分提供了一个难得的机会。本文利用2019年12月至2023年7月收集的数据对1LHAASOJ0007+7303u进行了专门的数据分析。该源被很好地探测到，在8$-$100 TeV和$>$100 TeV的显著性分别为21$sigma$和17$sigma$。相应的扩展值分别为0.23$^{circ}/pm$0.03$^{circ}$和0.17$^{circ}/pm$0.03$^{circ}$。据推测，这些发射源于在PSRJ0007+7303的PWN内加速的相对论电子和正电子。能谱可以用一个幂律来描述，其指数截止函数为 $dN/dE = (42.4pm4.1)(frac{E}{20rmTeV})^{-2.31pm0.11}exp(-frac{E}{110pm25rmTeV})$ $rmTeV^{-1}cm^{-2}s^{-1}$ in the energy range from 8 TeV to 300 TeV, implying a steady-stateparent electron spectrum $dN_e/dE_epropto (frac{E_e}{100rmTeV})^{-3.13pm0.16}exp[(frac{E_e}{373pm70rmTeV})^2]$ 在能量超过$approx 50 rmTeV$ 时。电子能谱的截止能量大致等于目前在PWN末端冲击加速的粒子的预期最大能量。结合X射线和伽马射线发射，当前空间平均磁场可以限制在大约4.5rmmu G$。为了满足多波长频谱和伽马射线的扩展，在自由膨胀阶段假设下，相对论粒子在PWN内的传输可能是由对流过程主导的。
{"title":"Deep view of Composite SNR CTA1 with LHAASO in $γ$-rays up to 300 TeV","authors":"LHAASO Collaboration","doi":"arxiv-2409.09499","DOIUrl":"https://doi.org/arxiv-2409.09499","url":null,"abstract":"The ultra-high-energy (UHE) gamma-ray source 1LHAASO J0007+7303u is\u0000positionally associated with the composite SNR CTA1 that is located at high\u0000Galactic Latitude $bapprox 10.5^circ$. This provides a rare opportunity to\u0000spatially resolve the component of the pulsar wind nebula (PWN) and supernova\u0000remnant (SNR) at UHE. This paper conducted a dedicated data analysis of 1LHAASO\u0000J0007+7303u using the data collected from December 2019 to July 2023. This\u0000source is well detected with significances of 21$sigma$ and 17$sigma$ at\u00008$-$100 TeV and $>$100 TeV, respectively. The corresponding extensions are\u0000determined to be 0.23$^{circ}pm$0.03$^{circ}$ and\u00000.17$^{circ}pm$0.03$^{circ}$. The emission is proposed to originate from the\u0000relativistic electrons and positrons accelerated within the PWN of PSR\u0000J0007+7303. The energy spectrum is well described by a power-law with an\u0000exponential cutoff function $dN/dE = (42.4pm4.1)(frac{E}{20rm\u0000TeV})^{-2.31pm0.11}exp(-frac{E}{110pm25rm TeV})$ $rm TeV^{-1} cm^{-2}\u0000s^{-1}$in the energy range from 8 TeV to 300 TeV, implying a steady-state\u0000parent electron spectrum $dN_e/dE_epropto (frac{E_e}{100rm\u0000TeV})^{-3.13pm0.16}exp[(frac{-E_e}{373pm70rm TeV})^2]$ at energies above\u0000$approx 50 rm TeV$. The cutoff energy of the electron spectrum is roughly\u0000equal to the expected current maximum energy of particles accelerated at the\u0000PWN terminal shock. Combining the X-ray and gamma-ray emission, the current\u0000space-averaged magnetic field can be limited to $approx 4.5rm mu G$. To\u0000satisfy the multi-wavelength spectrum and the $gamma$-ray extensions, the\u0000transport of relativistic particles within the PWN is likely dominated by the\u0000advection process under the free-expansion phase assumption.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142269461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The merger of two neutron stars probes dense matter in a hot, neutrino-trapped regime. In this work, we investigate how fully accounting for pions, muons, and muon-type neutrinos in the trapped regime may affect the outcome of the merger. By performing fully general-relativistic hydrodynamics simulations of merging neutron stars with equations of state to which we systematically add those different particle species, we aim to provide a detailed assessment of the impact of muons and pions on the merger and post-merger phase. In particular, we investigate the merger thermodynamics, mass ejection and gravitational wave emission. Our findings are consistent with previous expectations, that the inclusion of such microphysical degrees of freedom and finite temperature corrections leads to frequency shifts on the order of 100-200 Hz in the post-merger gravitational wave signal, relative to a fiducial cold nucleonic equation of state model.
{"title":"The Influence of Muons, Pions, and Trapped Neutrinos on Neutron Star Mergers","authors":"Michael A. Pajkos, Elias R. Most","doi":"arxiv-2409.09147","DOIUrl":"https://doi.org/arxiv-2409.09147","url":null,"abstract":"The merger of two neutron stars probes dense matter in a hot,\u0000neutrino-trapped regime. In this work, we investigate how fully accounting for\u0000pions, muons, and muon-type neutrinos in the trapped regime may affect the\u0000outcome of the merger. By performing fully general-relativistic hydrodynamics\u0000simulations of merging neutron stars with equations of state to which we\u0000systematically add those different particle species, we aim to provide a\u0000detailed assessment of the impact of muons and pions on the merger and\u0000post-merger phase. In particular, we investigate the merger thermodynamics,\u0000mass ejection and gravitational wave emission. Our findings are consistent with\u0000previous expectations, that the inclusion of such microphysical degrees of\u0000freedom and finite temperature corrections leads to frequency shifts on the\u0000order of 100-200 Hz in the post-merger gravitational wave signal, relative to a\u0000fiducial cold nucleonic equation of state model.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"86 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Collin Lewin, Erin Kara, Aaron J. Barth, Edward M. Cackett, Gisella De Rosa, Yasaman Homayouni, Keith Horne, Gerard A. Kriss, Hermine Landt, Jonathan Gelbord, John Montano, Nahum Arav, Misty C. Bentz, Benjamin D. Boizelle, Elena Dalla Bontà, Michael S. Brotherton, Maryam Dehghanian, Gary J. Ferland, Carina Fian, Michael R. Goad, Juan V. Hernández Santisteban, Dragana Ilić, Jelle Kaastra, Shai Kaspi, Kirk T. Korista, Peter Kosec, Andjelka Kovačević, Missagh Mehdipour, Jake A. Miller, Hagai Netzer, Jack M. M. Neustadt, Christos Panagiotou, Ethan R. Partington, Luka Č. Popović, David Sanmartim, Marianne Vestergaard, Martin J. Ward, Fatima Zaidouni
X-ray reverberation mapping is a powerful technique for probing the innermost accretion disk, whereas continuum reverberation mapping in the UV, optical, and infrared (UVOIR) reveals reprocessing by the rest of the accretion disk and broad-line region (BLR). We present the time lags of Mrk 817 as a function of temporal frequency measured from 14 months of high-cadence monitoring from Swift and ground-based telescopes, in addition to an XMM-Newton observation, as part of the AGN STORM 2 campaign. The XMM-Newton lags reveal the first detection of a soft lag in this source, consistent with reverberation from the innermost accretion flow. These results mark the first simultaneous measurement of X-ray reverberation and UVOIR disk reprocessing lags$unicode{x2013}$effectively allowing us to map the entire accretion disk surrounding the black hole. Similar to previous continuum reverberation mapping campaigns, the UVOIR time lags arising at low temporal frequencies are longer than those expected from standard disk reprocessing by a factor of 2-3. The lags agree with the anticipated disk reverberation lags when isolating short-timescale variability, namely timescales shorter than the H$beta$ lag. Modeling the lags requires additional reprocessing constrained at a radius consistent with the BLR size scale inferred from contemporaneous H$beta$-lag measurements. When we divide the campaign light curves, the UVOIR lags show substantial variations, with longer lags measured when obscuration from an ionized outflow is greatest. We suggest that, when the obscurer is strongest, reprocessing by the BLR elongates the lags most significantly. As the wind weakens, the lags are dominated by shorter accretion disk lags.
{"title":"AGN STORM 2. VII. A Frequency-resolved Map of the Accretion Disk in Mrk 817: Simultaneous X-ray Reverberation and UVOIR Disk Reprocessing Time Lags","authors":"Collin Lewin, Erin Kara, Aaron J. Barth, Edward M. Cackett, Gisella De Rosa, Yasaman Homayouni, Keith Horne, Gerard A. Kriss, Hermine Landt, Jonathan Gelbord, John Montano, Nahum Arav, Misty C. Bentz, Benjamin D. Boizelle, Elena Dalla Bontà, Michael S. Brotherton, Maryam Dehghanian, Gary J. Ferland, Carina Fian, Michael R. Goad, Juan V. Hernández Santisteban, Dragana Ilić, Jelle Kaastra, Shai Kaspi, Kirk T. Korista, Peter Kosec, Andjelka Kovačević, Missagh Mehdipour, Jake A. Miller, Hagai Netzer, Jack M. M. Neustadt, Christos Panagiotou, Ethan R. Partington, Luka Č. Popović, David Sanmartim, Marianne Vestergaard, Martin J. Ward, Fatima Zaidouni","doi":"arxiv-2409.09115","DOIUrl":"https://doi.org/arxiv-2409.09115","url":null,"abstract":"X-ray reverberation mapping is a powerful technique for probing the innermost\u0000accretion disk, whereas continuum reverberation mapping in the UV, optical, and\u0000infrared (UVOIR) reveals reprocessing by the rest of the accretion disk and\u0000broad-line region (BLR). We present the time lags of Mrk 817 as a function of\u0000temporal frequency measured from 14 months of high-cadence monitoring from\u0000Swift and ground-based telescopes, in addition to an XMM-Newton observation, as\u0000part of the AGN STORM 2 campaign. The XMM-Newton lags reveal the first\u0000detection of a soft lag in this source, consistent with reverberation from the\u0000innermost accretion flow. These results mark the first simultaneous measurement\u0000of X-ray reverberation and UVOIR disk reprocessing\u0000lags$unicode{x2013}$effectively allowing us to map the entire accretion disk\u0000surrounding the black hole. Similar to previous continuum reverberation mapping\u0000campaigns, the UVOIR time lags arising at low temporal frequencies are longer\u0000than those expected from standard disk reprocessing by a factor of 2-3. The\u0000lags agree with the anticipated disk reverberation lags when isolating\u0000short-timescale variability, namely timescales shorter than the H$beta$ lag.\u0000Modeling the lags requires additional reprocessing constrained at a radius\u0000consistent with the BLR size scale inferred from contemporaneous H$beta$-lag\u0000measurements. When we divide the campaign light curves, the UVOIR lags show\u0000substantial variations, with longer lags measured when obscuration from an\u0000ionized outflow is greatest. We suggest that, when the obscurer is strongest,\u0000reprocessing by the BLR elongates the lags most significantly. As the wind\u0000weakens, the lags are dominated by shorter accretion disk lags.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cosmic ray (CR) feedback plays a vital role in shaping the formation and evolution of galaxies through their interaction with magnetohydrodynamic waves. In the CR self-confinement scenario, the waves are generated by the CR gyro-resonant instabilities via CR streaming or CR pressure anisotropy, and saturate by balancing wave damping. The resulting effective particle scattering rate by the waves, {nu}eff, critically sets the coupling between the CRs and background gas, but the efficiency of CR feedback is yet poorly constrained. We employ 1D kinetic simulations under the Magnetohydrodynamic-Particle-In-Cell (MHD-PIC) framework with the adaptive {delta}f method to quantify {nu}eff for the saturated state of the CR pressure anisotropy instability (CRPAI) with ion-neutral friction. We drive CR pressure anisotropy by expanding/compressing box, mimicking background evolution of magnetic field strength, and the CR pressure anisotropy eventually reaches a quasi-steady state by balancing quasi-linear diffusion. At the saturated state, we measure {nu}eff and the CR pressure anisotropy level, establishing a calibrated scaling relation with environmental parameters. The scaling relation is consistent with quasi-linear theory and can be incorporated to CR fluid models, in either the single-fluid or p-by-p treatments. Our results serve as a basis towards accurately calibrating the subgrid physics in macroscopic studies of CR feedback and transport.
{"title":"Kinetic simulations of the cosmic ray pressure anisotropy instability: cosmic ray scattering rate in the saturated state","authors":"Xiaochen Sun, Xue-Ning Bai, Xihui Zhao","doi":"arxiv-2409.08592","DOIUrl":"https://doi.org/arxiv-2409.08592","url":null,"abstract":"Cosmic ray (CR) feedback plays a vital role in shaping the formation and\u0000evolution of galaxies through their interaction with magnetohydrodynamic waves.\u0000In the CR self-confinement scenario, the waves are generated by the CR\u0000gyro-resonant instabilities via CR streaming or CR pressure anisotropy, and\u0000saturate by balancing wave damping. The resulting effective particle scattering\u0000rate by the waves, {nu}eff, critically sets the coupling between the CRs and\u0000background gas, but the efficiency of CR feedback is yet poorly constrained. We\u0000employ 1D kinetic simulations under the Magnetohydrodynamic-Particle-In-Cell\u0000(MHD-PIC) framework with the adaptive {delta}f method to quantify {nu}eff for\u0000the saturated state of the CR pressure anisotropy instability (CRPAI) with\u0000ion-neutral friction. We drive CR pressure anisotropy by expanding/compressing\u0000box, mimicking background evolution of magnetic field strength, and the CR\u0000pressure anisotropy eventually reaches a quasi-steady state by balancing\u0000quasi-linear diffusion. At the saturated state, we measure {nu}eff and the CR\u0000pressure anisotropy level, establishing a calibrated scaling relation with\u0000environmental parameters. The scaling relation is consistent with quasi-linear\u0000theory and can be incorporated to CR fluid models, in either the single-fluid\u0000or p-by-p treatments. Our results serve as a basis towards accurately\u0000calibrating the subgrid physics in macroscopic studies of CR feedback and\u0000transport.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We carry out idealized three-dimensional general-relativistic magnetohydrodynamic (GRMHD) simulations of prograde, weakly magnetized, and geometrically thick accretion flows where the gas distribution is misaligned from the black hole spin axis. We evolve the disk for three black hole spins: $a = 0.5, 0.75$, and $0.9375$, and we contrast them with a standard aligned disk simulation with $a = 0.9375$. The tilted disks achieve a warped and twisted steady-state structure, with the outer disk misaligning further away from the black hole and surpassing the initial $24^circ$ misalignment. However, closer to the black hole, there is evidence of partial alignment, as the inclination angle decreases with radius in this regime. Standing shocks also emerged in proximity to the black hole, roughly at $sim$ 6 gravitational radii. We show that these shocks act to partially align the inner disk with the black hole spin. The rate of alignment increases with increasing black hole spin magnitude, but in all cases is insufficient to fully align the gas before it accretes. Additionally, we present a toy model of orbit crowding that can predict the location of the shocks in moderate-to-fast rotating black holes, illustrating a potential physical origin for the behavior seen in simulationstextemdash with possible applications in determining the positions of shocks in real misaligned astrophysical systems.
{"title":"Shock-induced partial alignment in geometrically-thick tilted accretion disks around black holes","authors":"Sajal Gupta, Jason Dexter","doi":"arxiv-2409.09165","DOIUrl":"https://doi.org/arxiv-2409.09165","url":null,"abstract":"We carry out idealized three-dimensional general-relativistic\u0000magnetohydrodynamic (GRMHD) simulations of prograde, weakly magnetized, and\u0000geometrically thick accretion flows where the gas distribution is misaligned\u0000from the black hole spin axis. We evolve the disk for three black hole spins:\u0000$a = 0.5, 0.75$, and $0.9375$, and we contrast them with a standard aligned\u0000disk simulation with $a = 0.9375$. The tilted disks achieve a warped and\u0000twisted steady-state structure, with the outer disk misaligning further away\u0000from the black hole and surpassing the initial $24^circ$ misalignment.\u0000However, closer to the black hole, there is evidence of partial alignment, as\u0000the inclination angle decreases with radius in this regime. Standing shocks\u0000also emerged in proximity to the black hole, roughly at $sim$ 6 gravitational\u0000radii. We show that these shocks act to partially align the inner disk with the\u0000black hole spin. The rate of alignment increases with increasing black hole\u0000spin magnitude, but in all cases is insufficient to fully align the gas before\u0000it accretes. Additionally, we present a toy model of orbit crowding that can\u0000predict the location of the shocks in moderate-to-fast rotating black holes,\u0000illustrating a potential physical origin for the behavior seen in\u0000simulationstextemdash with possible applications in determining the positions\u0000of shocks in real misaligned astrophysical systems.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Because of the previously observed stability of the 171-day period, the superorbital modulation of the low-mass X-ray binary 4U 1820-30 was considered a consequence of a third star orbiting around the binary. This study aims to further verify this triple model by testing the stability of superorbital period using the light curves collected by X-ray sky monitoring/scanning telescopes from 1987 to 2023. Both power spectral and phase analysis results indicate a significant change in the superorbital period from 171 days to 167 days over this 36-year span. The evolution of the superorbital phase suggests that the superorbital period may have experienced an abrupt change between late 2000 and early 2023 or changed gradually with a period derivative of $dot P_{sup}=(-3.58 pm 0.72) times 10^{-4}$ day/day. We conclude that the superorbital period of 4U 1820-30 was not as stable as anticipated by the triple model, which strongly challenges this hypothesis. Instead, we propose an irradiation-induced mass transfer instability scenario to explain the superorbital modulation of 4U 1820-30.
{"title":"The Puzzling Superorbital Period Variation of the Low-mass X-ray Binary 4U 1820-30","authors":"Yi Chou, Jun-Lei Wu, Bo-Chun Chen, Wei-Yun Chang","doi":"arxiv-2409.08451","DOIUrl":"https://doi.org/arxiv-2409.08451","url":null,"abstract":"Because of the previously observed stability of the 171-day period, the\u0000superorbital modulation of the low-mass X-ray binary 4U 1820-30 was considered\u0000a consequence of a third star orbiting around the binary. This study aims to\u0000further verify this triple model by testing the stability of superorbital\u0000period using the light curves collected by X-ray sky monitoring/scanning\u0000telescopes from 1987 to 2023. Both power spectral and phase analysis results\u0000indicate a significant change in the superorbital period from 171 days to 167\u0000days over this 36-year span. The evolution of the superorbital phase suggests\u0000that the superorbital period may have experienced an abrupt change between late\u00002000 and early 2023 or changed gradually with a period derivative of $dot\u0000P_{sup}=(-3.58 pm 0.72) times 10^{-4}$ day/day. We conclude that the\u0000superorbital period of 4U 1820-30 was not as stable as anticipated by the\u0000triple model, which strongly challenges this hypothesis. Instead, we propose an\u0000irradiation-induced mass transfer instability scenario to explain the\u0000superorbital modulation of 4U 1820-30.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Rashidi, V. Anari, A. Bartkiewicz, P. Wolak, M. Szymczak, F. Rajabi
We present a comprehensive analysis of the periodic flares observed in the 6.7 GHz methanol transition in G22.356+0.066, utilizing the Maxwell-Bloch equations (MBEs) as a framework to model these phenomena. By solving the one-dimensional MBEs, we describe the behavior of both the quasi-steady-state maser and transient superradiance regimes. Our findings indicate that the observed periodic flares, with varying timescales across different velocities, are consistent with the characteristics of Dicke's superradiance, triggered by a common radiative pump in regions of varying inverted column densities. This work provides new insights into the physical processes governing variability in maser-hosting regions and underscores the significance of superradiance as a powerful radiation mechanism in astrophysical environments.
{"title":"Superradiance and Periodic 6.7 GHz Methanol Flaring in G22.356+0.066","authors":"T. Rashidi, V. Anari, A. Bartkiewicz, P. Wolak, M. Szymczak, F. Rajabi","doi":"arxiv-2409.09209","DOIUrl":"https://doi.org/arxiv-2409.09209","url":null,"abstract":"We present a comprehensive analysis of the periodic flares observed in the\u00006.7 GHz methanol transition in G22.356+0.066, utilizing the Maxwell-Bloch\u0000equations (MBEs) as a framework to model these phenomena. By solving the\u0000one-dimensional MBEs, we describe the behavior of both the quasi-steady-state\u0000maser and transient superradiance regimes. Our findings indicate that the\u0000observed periodic flares, with varying timescales across different velocities,\u0000are consistent with the characteristics of Dicke's superradiance, triggered by\u0000a common radiative pump in regions of varying inverted column densities. This\u0000work provides new insights into the physical processes governing variability in\u0000maser-hosting regions and underscores the significance of superradiance as a\u0000powerful radiation mechanism in astrophysical environments.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"215 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
For over two decades, gamma-ray burst (GRB) prompt emission spectra were modelled with smoothly-broken power laws (Band function), and a positive and tight correlation between the spectral rest-frame peak energy $E_p$ and the total isotropic-equivalent luminosity $L_{iso}$ was found, constituting the so-called Yonetoku relation. However, more recent studies show that many prompt emission spectra are well described by the synchrotron radiation model, hence significantly deviating from the Band function. In this work, we test the impact of a more suited spectral model such as an idealized synchrotron spectrum from non-thermal electrons on the Yonetoku relation and its connection with physical parameters. We select GRBs with measured redshift observed by Fermi/GBM together with high energy observations (>30 MeV), and perform spectral analysis dividing them in two samples: the single-bin sample, using the light curve peak spectrum of each GRB, and the multiple-bins sample, where we explore the whole duration of 13 bright bursts with time-resolved spectral analysis. We observed that the $E_p$ of synchrotron spectra in fast-cooling regime ($nu_m/nu_cgg1$) is generally larger than the one provided by the Band function. For this reason, we do not find any $E_p-L_{iso}$ correlation in our samples except for the GRBs in an intermediate-cooling regime ($1
{"title":"Gamma-ray burst spectral-luminosity correlations in the synchrotron scenario","authors":"Alessio Mei, Gor Oganesyan, Samanta Macera","doi":"arxiv-2409.08341","DOIUrl":"https://doi.org/arxiv-2409.08341","url":null,"abstract":"For over two decades, gamma-ray burst (GRB) prompt emission spectra were\u0000modelled with smoothly-broken power laws (Band function), and a positive and\u0000tight correlation between the spectral rest-frame peak energy $E_p$ and the\u0000total isotropic-equivalent luminosity $L_{iso}$ was found, constituting the\u0000so-called Yonetoku relation. However, more recent studies show that many prompt\u0000emission spectra are well described by the synchrotron radiation model, hence\u0000significantly deviating from the Band function. In this work, we test the\u0000impact of a more suited spectral model such as an idealized synchrotron\u0000spectrum from non-thermal electrons on the Yonetoku relation and its connection\u0000with physical parameters. We select GRBs with measured redshift observed by\u0000Fermi/GBM together with high energy observations (>30 MeV), and perform\u0000spectral analysis dividing them in two samples: the single-bin sample, using\u0000the light curve peak spectrum of each GRB, and the multiple-bins sample, where\u0000we explore the whole duration of 13 bright bursts with time-resolved spectral\u0000analysis. We observed that the $E_p$ of synchrotron spectra in fast-cooling\u0000regime ($nu_m/nu_cgg1$) is generally larger than the one provided by the\u0000Band function. For this reason, we do not find any $E_p-L_{iso}$ correlation in\u0000our samples except for the GRBs in an intermediate-cooling regime\u0000($1<nu_m/nu_c<3$), namely where peak and break energies are very close. We\u0000instead find in both our samples a new tight correlation between the rest-frame\u0000cooling frequency $nu_{c,z}$ and $L_{iso}$: $nu_{c,z} propto L_{iso}^{(0.53\u0000pm 0.06)}$. These results suggest that, assuming that prompt emission spectra\u0000are produced by synchrotron radiation, the physical relation is between\u0000$nu_{c,z}$ and $L_{iso}$. The fit of the Band function to an intrinsic\u0000synchrotron spectrum returns peak energy values $E_{p,z}^{Band} sim\u0000nu_{c,z}$.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Petar Kostić, Bojan Arbutina, Branislav Vukotić, Dejan Urošević
We present an analytical model of $Sigma-D$ relation for supernova remnants (SNRs) evolving in a clumpy medium. The model and its approximations were developed using the hydrodynamic simulations of SNRs in environments of low-density bubbles and clumpy media with different densities and volume-filling factors. For calculation of SNR luminosities we developed the synchrotron emission model, implying the test-particle approximation. The goal of this work is to explain the flattened part of $Sigma-D$ relation for Galactic SNRs at $Dapprox14-50$ pc. Our model shows that the shock collision with the clumpy medium initially enhances the brightness of individual SNRs, which is followed by a steeper fall of their $Sigma-D$ curve. We used the analytical model to generate large SNR samples on $Sigma-D$ plane, within a span of different densities and distances to clumpy medium, keeping the observed distribution of diameters. After comparison with the Galactic sample, we conclude that the observed $Sigma-D$ flattening and scatter originates in sporadic emission jumps of individual SNRs while colliding with the dense clumps. Statistically, the significant impact of the clumps starts at diameters of $approx14$ pc, up to $sim70$ pc, with the average density jump at clumpy medium of $sim2-20$ times, roughly depending on the low density of circumstellar region. However, additional analysis considering the selection effects is needed, as well as the improvement of the model, considering radiation losses and thermal conduction.
{"title":"Supernova remnants in clumpy medium: A model of hydrodynamic and radio synchrotron evolution","authors":"Petar Kostić, Bojan Arbutina, Branislav Vukotić, Dejan Urošević","doi":"arxiv-2409.07905","DOIUrl":"https://doi.org/arxiv-2409.07905","url":null,"abstract":"We present an analytical model of $Sigma-D$ relation for supernova remnants\u0000(SNRs) evolving in a clumpy medium. The model and its approximations were\u0000developed using the hydrodynamic simulations of SNRs in environments of\u0000low-density bubbles and clumpy media with different densities and\u0000volume-filling factors. For calculation of SNR luminosities we developed the\u0000synchrotron emission model, implying the test-particle approximation. The goal\u0000of this work is to explain the flattened part of $Sigma-D$ relation for\u0000Galactic SNRs at $Dapprox14-50$ pc. Our model shows that the shock collision\u0000with the clumpy medium initially enhances the brightness of individual SNRs,\u0000which is followed by a steeper fall of their $Sigma-D$ curve. We used the\u0000analytical model to generate large SNR samples on $Sigma-D$ plane, within a\u0000span of different densities and distances to clumpy medium, keeping the\u0000observed distribution of diameters. After comparison with the Galactic sample,\u0000we conclude that the observed $Sigma-D$ flattening and scatter originates in\u0000sporadic emission jumps of individual SNRs while colliding with the dense\u0000clumps. Statistically, the significant impact of the clumps starts at diameters\u0000of $approx14$ pc, up to $sim70$ pc, with the average density jump at clumpy\u0000medium of $sim2-20$ times, roughly depending on the low density of\u0000circumstellar region. However, additional analysis considering the selection\u0000effects is needed, as well as the improvement of the model, considering\u0000radiation losses and thermal conduction.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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