We develop a relativistic scenario of fast magnetic reconnection process, for general magnetohydrodynamical plasmas around Kerr black holes. Generalizing the Petschek model, we study various properties of the reconnection layer in distinct configurations. When current sheet forms in the zero-angular-momentum (ZAMO) frame which corotates with the black hole, the reconnection rate for both radial and azimuthal configurations is decreased by spacetime curvature. However, when the current sheet forms in a non-ZAMO frame, which rotates either faster or slower than the black hole, detail analysis establishes that for any given slow rotations (subrelativistic at most) and mildly relativistic inflow, the ZAMO observer will find asymmetric reconnection rates for radial configuration: it is decreased on one side of the current sheet and is increased on the other side in comparison to the unrotation limit. This is valid to both the Sweet-Parker and the Petschek scenario. The results clarify the effects of rotation on the reconnection layer in the laboratory frame in the flat spacetime limit.
{"title":"Fast magnetic reconnection in Kerr spacetime","authors":"Zhong-Ying Fan, Yuehang Li, Fan Zhou, Minyong Guo","doi":"arxiv-2409.05434","DOIUrl":"https://doi.org/arxiv-2409.05434","url":null,"abstract":"We develop a relativistic scenario of fast magnetic reconnection process, for\u0000general magnetohydrodynamical plasmas around Kerr black holes. Generalizing the\u0000Petschek model, we study various properties of the reconnection layer in\u0000distinct configurations. When current sheet forms in the zero-angular-momentum\u0000(ZAMO) frame which corotates with the black hole, the reconnection rate for\u0000both radial and azimuthal configurations is decreased by spacetime curvature.\u0000However, when the current sheet forms in a non-ZAMO frame, which rotates either\u0000faster or slower than the black hole, detail analysis establishes that for any\u0000given slow rotations (subrelativistic at most) and mildly relativistic inflow,\u0000the ZAMO observer will find asymmetric reconnection rates for radial\u0000configuration: it is decreased on one side of the current sheet and is\u0000increased on the other side in comparison to the unrotation limit. This is\u0000valid to both the Sweet-Parker and the Petschek scenario. The results clarify\u0000the effects of rotation on the reconnection layer in the laboratory frame in\u0000the flat spacetime limit.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206554","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}
Santanu Mondal, Mousumi Das, K. Rubinur, Karishma Bansal, Aniket Nath, Greg B. Taylor
We report the discovery of the Fe K line emission at $sim6.62^{+0.06}_{-0.06}$ keV with a width of $sim0.19^{+0.05}_{-0.05}$ keV using two epochs of {it Chandra} archival data from the nucleus of the galaxy 4C+37.11, which is known to host a binary supermassive black hole (BSMBH) system where the SMBHs are separated by $sim7$ mas or $sim$ 7pc. Our study reports the first detection of the Fe K line from a known binary AGN, and has an F-statistic value of 20.98 and probability $2.47times 10^{-12}$. Stacking of two spectra reveals another Fe K line component at $sim7.87^{+0.19}_{-0.09}$ keV. Different model scenarios indicate that the lines originate from the combined effects of accretion disk emission and circumnuclear collisionally ionized medium. The observed low column density favors the gas-poor merger scenario, where the high temperature of the hot ionized medium may be associated with the shocked gas in the binary merger and not with star formation activity. The estimated total BSMBH mass and disk inclination are $sim1.5times10^{10}$ M$_odot$ and $gtrsim75^circ$, indicating that the BSMBH is probably a high inclination system. The spin parameter could not be tightly constrained from the present data sets. Our results draw attention to the fact that detecting the Fe K line emissions from BSMBHs is important for estimating the individual SMBH masses, and the spins of the binary SMBHs, as well as exploring their emission regions.
{"title":"Detection of the Fe K lines from the binary AGN in 4C+37.11","authors":"Santanu Mondal, Mousumi Das, K. Rubinur, Karishma Bansal, Aniket Nath, Greg B. Taylor","doi":"arxiv-2409.05717","DOIUrl":"https://doi.org/arxiv-2409.05717","url":null,"abstract":"We report the discovery of the Fe K line emission at\u0000$sim6.62^{+0.06}_{-0.06}$ keV with a width of $sim0.19^{+0.05}_{-0.05}$ keV\u0000using two epochs of {it Chandra} archival data from the nucleus of the galaxy\u00004C+37.11, which is known to host a binary supermassive black hole (BSMBH)\u0000system where the SMBHs are separated by $sim7$ mas or $sim$ 7pc. Our study\u0000reports the first detection of the Fe K line from a known binary AGN, and has\u0000an F-statistic value of 20.98 and probability $2.47times 10^{-12}$. Stacking\u0000of two spectra reveals another Fe K line component at\u0000$sim7.87^{+0.19}_{-0.09}$ keV. Different model scenarios indicate that the\u0000lines originate from the combined effects of accretion disk emission and\u0000circumnuclear collisionally ionized medium. The observed low column density\u0000favors the gas-poor merger scenario, where the high temperature of the hot\u0000ionized medium may be associated with the shocked gas in the binary merger and\u0000not with star formation activity. The estimated total BSMBH mass and disk\u0000inclination are $sim1.5times10^{10}$ M$_odot$ and $gtrsim75^circ$,\u0000indicating that the BSMBH is probably a high inclination system. The spin\u0000parameter could not be tightly constrained from the present data sets. Our\u0000results draw attention to the fact that detecting the Fe K line emissions from\u0000BSMBHs is important for estimating the individual SMBH masses, and the spins of\u0000the binary SMBHs, as well as exploring their emission regions.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206850","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}
J. SpeicherCenter for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, D. R. BallantyneCenter for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, P. C. FragileDepartment of Physics & Astronomy, College of Charleston
The accretion flow onto a neutron star will be impacted due to irradiation by a Type I X-ray burst. The burst radiation exerts Poynting-Robertson (PR) drag on the accretion disk, leading to an enhanced mass accretion rate. Observations of X-ray bursts often find evidence that the normalization of the disk-generated persistent emission (commonly denoted by the factor $f_a$) increases during a burst, and changes in $f_a$ have been used to infer the evolution in the mass accretion rate due to PR drag. Here, we examine this proposed relationship between $f_a$ and mass accretion rate enhancement using time-resolved data from simulations of accretion disks impacted by Type I X-ray bursts. We consider bursts from both spinning and non-spinning neutron stars and track both the change in accretion rate due to PR grad and the disk emission spectra during the burst. Regardless of the neutron star spin, we find that $f_a$ strongly correlates with the disk temperature and only weakly follows the mass accretion rate (the Pearson correlation coefficients are $leq 0.63$ in the latter case). Additionally, heating causes the disk to emit at higher energies, reducing its contribution to a soft excess. We conclude that $f_a$ cannot accurately capture the mass accretion rate enhancement and is rather a tracer of the disk temperature.
中子星上的吸积流会受到 I 型 X 射线暴的辐照。爆发辐射会对吸积盘施加波因廷-罗伯逊（PR）龙，从而导致质量吸积速率的增强。对X射线暴的观测经常发现这样的证据：在暴发期间，盘产生的持续辐射的归一化（通常用因子$f_a$表示）会增加，而$f_a$的变化被用来推断PR阻力导致的质量增殖率的变化。在这里，我们利用受I型X射线爆发影响的吸积盘模拟的时间分辨数据，研究了$f_a$和质量吸积率增强之间的关系。我们考虑了来自自旋和非自旋中子星的爆发，并在爆发过程中跟踪了PR级引起的吸积率变化和磁盘发射光谱。无论中子星自旋与否，我们发现$f_a$与磁盘温度密切相关，而与质量吸积率的相关性很弱（在后一种情况下，皮尔逊相关系数为$leq0.63$）。此外，加热会导致磁盘发射出更高的能量，从而减少它对软过剩的贡献。我们的结论是，$f_a$ 无法准确捕捉质量吸积率的增强，而只是磁盘温度的示踪剂。
{"title":"Examining the Relationship Between the Persistent Emission and the Accretion Rate During a Type I X-ray Burst","authors":"J. SpeicherCenter for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, D. R. BallantyneCenter for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, P. C. FragileDepartment of Physics & Astronomy, College of Charleston","doi":"arxiv-2409.05737","DOIUrl":"https://doi.org/arxiv-2409.05737","url":null,"abstract":"The accretion flow onto a neutron star will be impacted due to irradiation by\u0000a Type I X-ray burst. The burst radiation exerts Poynting-Robertson (PR) drag\u0000on the accretion disk, leading to an enhanced mass accretion rate. Observations\u0000of X-ray bursts often find evidence that the normalization of the\u0000disk-generated persistent emission (commonly denoted by the factor $f_a$)\u0000increases during a burst, and changes in $f_a$ have been used to infer the\u0000evolution in the mass accretion rate due to PR drag. Here, we examine this\u0000proposed relationship between $f_a$ and mass accretion rate enhancement using\u0000time-resolved data from simulations of accretion disks impacted by Type I X-ray\u0000bursts. We consider bursts from both spinning and non-spinning neutron stars\u0000and track both the change in accretion rate due to PR grad and the disk\u0000emission spectra during the burst. Regardless of the neutron star spin, we find\u0000that $f_a$ strongly correlates with the disk temperature and only weakly\u0000follows the mass accretion rate (the Pearson correlation coefficients are $leq\u00000.63$ in the latter case). Additionally, heating causes the disk to emit at\u0000higher energies, reducing its contribution to a soft excess. We conclude that\u0000$f_a$ cannot accurately capture the mass accretion rate enhancement and is\u0000rather a tracer of the disk temperature.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206849","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}
Recent measurements of the cosmic-ray electron plus positron spectrum by several experiments have confirmed the presence of a break at $sim,1$ TeV. The origin of the break is still not clearly understood. In this work, we explore different possibilities for the origin which include an electron source spectrum with a broken power-law, a power-law with an exponential or super-exponential cut-offs and the absence of potential nearby cosmic-ray sources. Based on the observed electron plus positron data from the DAMPE and the H.E.S.S experiments, and considering supernova remnants as the main sources of cosmic rays in the Galaxy, we find statistical evidence in favour of the scenario with a broken power-law source spectrum with the best-fit source parameters obtained as $Gamma=2.39$ for the source spectral index, $E_0approx 1.6$ TeV for the break energy and $f=1.59times 10^{48}$ ergs for the amount of supernova kinetic energy injected into cosmic-ray electrons. Such a power-law break in the spectrum has been predicted for electrons confined inside supernova remnants after acceleration via diffusive shock acceleration process, and also indicated by the multi-wavelength study of supernova remnants. All these evidences have shown that the observed spectral break provides a strong indication of a direct link between cosmic-ray electrons and their sources. Our findings further show that electrons must undergo spectral changes while escaping the source region in order to reconcile the difference between the spectral index of electrons observed inside supernova remnants and that obtained from Galactic cosmic-ray propagation studies.
{"title":"Origin of the break in the cosmic-ray electron plus positron spectrum at ~ 1 TeV","authors":"Satyendra Thoudam","doi":"arxiv-2409.05509","DOIUrl":"https://doi.org/arxiv-2409.05509","url":null,"abstract":"Recent measurements of the cosmic-ray electron plus positron spectrum by\u0000several experiments have confirmed the presence of a break at $sim,1$ TeV.\u0000The origin of the break is still not clearly understood. In this work, we\u0000explore different possibilities for the origin which include an electron source\u0000spectrum with a broken power-law, a power-law with an exponential or\u0000super-exponential cut-offs and the absence of potential nearby cosmic-ray\u0000sources. Based on the observed electron plus positron data from the DAMPE and\u0000the H.E.S.S experiments, and considering supernova remnants as the main sources\u0000of cosmic rays in the Galaxy, we find statistical evidence in favour of the\u0000scenario with a broken power-law source spectrum with the best-fit source\u0000parameters obtained as $Gamma=2.39$ for the source spectral index, $E_0approx\u00001.6$ TeV for the break energy and $f=1.59times 10^{48}$ ergs for the amount of\u0000supernova kinetic energy injected into cosmic-ray electrons. Such a power-law\u0000break in the spectrum has been predicted for electrons confined inside\u0000supernova remnants after acceleration via diffusive shock acceleration process,\u0000and also indicated by the multi-wavelength study of supernova remnants. All\u0000these evidences have shown that the observed spectral break provides a strong\u0000indication of a direct link between cosmic-ray electrons and their sources. Our\u0000findings further show that electrons must undergo spectral changes while\u0000escaping the source region in order to reconcile the difference between the\u0000spectral index of electrons observed inside supernova remnants and that\u0000obtained from Galactic cosmic-ray propagation studies.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206544","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}
Gerrit Schellenberger, Ewan O'Sullivan, Laurence David, Jan Vrtilek, Charles Romero, Glen Petitpas, William Forman, Simona Giacintucci, Mark Gurwell, Christine Jones, Kamlesh Rajpurohit, Francesco Ubertosi, Tiziana Venturi
The active galactic nucleus (AGN) feeding and feedback process in the centers of galaxy clusters and groups is still not well understood. NGC5044 is the ideal system in which to study AGN feedback. It hosts the largest known reservoir of cold gas in any cool-core galaxy group, and features several past epochs of AGN feedback imprinted as cavities in the X-ray bright intragroup medium (IGrM), as well as parsec scale jets. We present Submillimeter Array (SMA) and Karl G. Jansky Very Large Array (VLA) high frequency observations of NGC5044 to assess the time variability of the mm-waveband emission from the accretion disk, and quantify the Spectral Energy Distribution (SED) from the radio to sub-millimeter band. The SED is well described by advection dominated accretion flow (ADAF) model and self-absorbed jet emission from an aging plasma with tau ~1kyr. We find a characteristic variability timescale of 150 days, which constrains the ADAF emission region to about 0.1pc, and the magnetic field to 4.7mG in the jets and and 870G in the accretion disk. A longer monitoring/sampling will allow to understand if the underlying process is truly periodic in nature.
{"title":"Probing the high frequency variability of NGC 5044: the key to AGN feedback","authors":"Gerrit Schellenberger, Ewan O'Sullivan, Laurence David, Jan Vrtilek, Charles Romero, Glen Petitpas, William Forman, Simona Giacintucci, Mark Gurwell, Christine Jones, Kamlesh Rajpurohit, Francesco Ubertosi, Tiziana Venturi","doi":"arxiv-2409.06039","DOIUrl":"https://doi.org/arxiv-2409.06039","url":null,"abstract":"The active galactic nucleus (AGN) feeding and feedback process in the centers\u0000of galaxy clusters and groups is still not well understood. NGC5044 is the\u0000ideal system in which to study AGN feedback. It hosts the largest known\u0000reservoir of cold gas in any cool-core galaxy group, and features several past\u0000epochs of AGN feedback imprinted as cavities in the X-ray bright intragroup\u0000medium (IGrM), as well as parsec scale jets. We present Submillimeter Array\u0000(SMA) and Karl G. Jansky Very Large Array (VLA) high frequency observations of\u0000NGC5044 to assess the time variability of the mm-waveband emission from the\u0000accretion disk, and quantify the Spectral Energy Distribution (SED) from the\u0000radio to sub-millimeter band. The SED is well described by advection dominated\u0000accretion flow (ADAF) model and self-absorbed jet emission from an aging plasma\u0000with tau ~1kyr. We find a characteristic variability timescale of 150 days,\u0000which constrains the ADAF emission region to about 0.1pc, and the magnetic\u0000field to 4.7mG in the jets and and 870G in the accretion disk. A longer\u0000monitoring/sampling will allow to understand if the underlying process is truly\u0000periodic in nature.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206848","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}
Stellar mass black holes in the disks around active galactic nuclei (AGN) are promising sources for gravitational wave detections by LIGO/VIRGO. Recent studies suggest this environment fosters the formation and merger of binary black holes. Many of these studies often assumed a simple, laminar AGN disk without magnetic fields or turbulence. In this work, we present the first 3D magnetohydrodynamical simulations of circum-single disks around isolated and binary black holes in strongly magnetized, stratified accretion disks with turbulence driven by magneto-rotational instability. We simulated three scenarios with varying initial net-vertical magnetic field strengths: weak, intermediate, and strong. Our results show that weakly magnetized models produce circum-single disks aligned with the AGN disk's equatorial plane, similar to past hydrodynamic simulations. However, intermediate and strong magnetic fields result in randomly misaligned disks, contingent upon the availability of local ambient angular momentum within turbulent regions. Our findings emphasize the significant impact of ambient gas in the AGN disk on the inclination of circum-single disks, linked to magnetically induced inhomogeneity and angular momentum during disk formation. The presence of misaligned disks, both in single and binary black hole systems, could have profound implications for the long-term evolution of black hole spin and the inclination of the disk at the horizon scale.
{"title":"Nature vs Nurture: Three Dimensional MHD Simulations of Misaligned Embedded Circum-Single Disks within an AGN Disk","authors":"Bhupendra Mishra, Josh Calcino","doi":"arxiv-2409.05614","DOIUrl":"https://doi.org/arxiv-2409.05614","url":null,"abstract":"Stellar mass black holes in the disks around active galactic nuclei (AGN) are\u0000promising sources for gravitational wave detections by LIGO/VIRGO. Recent\u0000studies suggest this environment fosters the formation and merger of binary\u0000black holes. Many of these studies often assumed a simple, laminar AGN disk\u0000without magnetic fields or turbulence. In this work, we present the first 3D\u0000magnetohydrodynamical simulations of circum-single disks around isolated and\u0000binary black holes in strongly magnetized, stratified accretion disks with\u0000turbulence driven by magneto-rotational instability. We simulated three\u0000scenarios with varying initial net-vertical magnetic field strengths: weak,\u0000intermediate, and strong. Our results show that weakly magnetized models\u0000produce circum-single disks aligned with the AGN disk's equatorial plane,\u0000similar to past hydrodynamic simulations. However, intermediate and strong\u0000magnetic fields result in randomly misaligned disks, contingent upon the\u0000availability of local ambient angular momentum within turbulent regions. Our\u0000findings emphasize the significant impact of ambient gas in the AGN disk on the\u0000inclination of circum-single disks, linked to magnetically induced\u0000inhomogeneity and angular momentum during disk formation. The presence of\u0000misaligned disks, both in single and binary black hole systems, could have\u0000profound implications for the long-term evolution of black hole spin and the\u0000inclination of the disk at the horizon scale.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206837","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}
A growing population of long-period radio transients has been discovered and their physical origin is still up to debate. Recently, a new such source named ILT J1101 + 5521 was discovered, which is in a white dwarf (WD) -- M dwarf (MD) binary system, with the observed 125.5 min period being identified as the orbital period and the radio emission phase coinciding with the conjunction configuration when the MD is at the far end. We suggest that the radio emission properties of the system can be well explained within the framework of the unipolar inductor magnetic interaction model between the magnetized WD and the MD with low magnetization, with the electron cyclotron maser being the most likely radiation mechanism. This mechanism is similar to that of Jupiter decametric emission due to Jupiter-Io interaction. We suggest that this mechanism can interpret at least some long-period radio transients, especially the ultra-long period sub-population.
{"title":"Magnetic Interaction in White Dwarf Binaries as Mechanism for Long-Period Radio Transients","authors":"Yuanhong Qu, Bing Zhang","doi":"arxiv-2409.05978","DOIUrl":"https://doi.org/arxiv-2409.05978","url":null,"abstract":"A growing population of long-period radio transients has been discovered and\u0000their physical origin is still up to debate. Recently, a new such source named\u0000ILT J1101 + 5521 was discovered, which is in a white dwarf (WD) -- M dwarf (MD)\u0000binary system, with the observed 125.5 min period being identified as the\u0000orbital period and the radio emission phase coinciding with the conjunction\u0000configuration when the MD is at the far end. We suggest that the radio emission\u0000properties of the system can be well explained within the framework of the\u0000unipolar inductor magnetic interaction model between the magnetized WD and the\u0000MD with low magnetization, with the electron cyclotron maser being the most\u0000likely radiation mechanism. This mechanism is similar to that of Jupiter\u0000decametric emission due to Jupiter-Io interaction. We suggest that this\u0000mechanism can interpret at least some long-period radio transients, especially\u0000the ultra-long period sub-population.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206847","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}
A. Yu. IgnatovskiyNIC "Kurchatov Institute"Moscow Institute of Physics and Technology, I. V. PanovNIC "Kurchatov Institute", A. V. YudinNIC "Kurchatov Institute"
This paper examines nucleosynthesis in a low-mass neutron star crust that loses mass due to accretion in a close binary system and, reaching a hydrodynamically unstable configuration explodes. The r-process proceeds mainly in the inner crust. Nucleosynthesis in the outer crust is an explosive process with a sharp increase in temperature caused by an outward-propagating shockwave (shock-wave nucleosynthesis). The number of heavy elements produced in a low-mass neutron star crust during the explosion is approximately equals 0.041 solar masses, which exceeds the number of heavy elements ejected as jets in the neutron star merger scenario.
{"title":"Low-mass neutron star nucleosynthesis -- stripping scenario","authors":"A. Yu. IgnatovskiyNIC \"Kurchatov Institute\"Moscow Institute of Physics and Technology, I. V. PanovNIC \"Kurchatov Institute\", A. V. YudinNIC \"Kurchatov Institute\"","doi":"arxiv-2409.05059","DOIUrl":"https://doi.org/arxiv-2409.05059","url":null,"abstract":"This paper examines nucleosynthesis in a low-mass neutron star crust that\u0000loses mass due to accretion in a close binary system and, reaching a\u0000hydrodynamically unstable configuration explodes. The r-process proceeds mainly\u0000in the inner crust. Nucleosynthesis in the outer crust is an explosive process\u0000with a sharp increase in temperature caused by an outward-propagating shockwave\u0000(shock-wave nucleosynthesis). The number of heavy elements produced in a\u0000low-mass neutron star crust during the explosion is approximately equals 0.041\u0000solar masses, which exceeds the number of heavy elements ejected as jets in the\u0000neutron star merger scenario.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206556","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}
Swift J1858.6$-$0814 (hereafter J1858) is a transient neutron star low-mass X-ray binary (NS LMXB). There is controversy regarding its donor mass derived from observations and theoretical calculations. In this paper, we adopt seven magnetic braking (MB) prescriptions suggested in the literature and different metallicity $Z$ to simulate the evolution of the LMXB. Our results show that, employing the MB model proposed by citet{2012ApJ...746...43R} ("rm12"), the Convection And Rotation Boosted ("carb") model citep{2019ApJ...886L..31V}, as well as the Intermediate ("inter") and Convection-boosted ("cboost") models in citet{2019MNRAS.483.5595V} can match (part of) the observational parameters of J1858 well. We then apply our method to other observed LMXBs and find that the "rm12" and "inter" MB laws are most promising in explaining transient LMXBs. In comparison, the simulations with the "cboost" and "carb" MB laws are more inclined to reproduce persistent LMXBs and ultra-compact X-ray binaries (UCXBs), respectively. Our results, though subject to computational and/or observational bias, show that it is challenging to find a unified MB law that applies to the NS LMXB sub-populations simultaneously, indicating our lack of understanding of the true MB law. In addition, we explore the influence of various MB laws on the magnitude of the bifurcation periods in LMXBs.
Swift J1858.6$-$0814（以下简称 J1858）是一颗瞬态中子星低质量 X 射线双星（NS LMXB）。根据观测和理论计算得出的其供体质量存在争议。在本文中，我们采用了文献中提出的七种磁制动（MB）处方和不同的金属性$Z$来模拟LMXB的演化。我们的结果表明，采用citet{2012ApJ...746...43R}提出的MB模型（"rm12"），LMXB的演化过程与 "rm12 "模型相似。(rm12）、Convection And Rotation Boosted（"carb"）模型（citep{2019ApJ...886L...31V}）以及Intermediate（"inter"）和Convection-boosted（"cboost"）模型（citet{2019MNRAS.483.5595V}）都能很好地匹配J1858的（部分）观测参数。然后，我们将我们的方法应用于其他观测到的LMXB，发现 "rm12 "和 "inter "MB定律最有希望解释瞬态LMXB。相比之下，"cboost "和 "carb "MB定律的模拟分别更倾向于重现持久的LMXB和超紧凑X射线双星（UCXB）。我们的结果虽然受到计算和/或观测偏差的影响，但也表明要找到一个同时适用于 NS LMXB 子群的统一 MB 规律是很有挑战性的，这说明我们对真正的 MB 规律还缺乏了解。此外，我们还探讨了各种 MB 规律对 LMXB 分叉期大小的影响。
{"title":"The influence of the magnetic braking laws on the evolution of persistent and transient low-mass X-ray binaries","authors":"Hao-Ran Yang, Xiang-Dong Li","doi":"arxiv-2409.05067","DOIUrl":"https://doi.org/arxiv-2409.05067","url":null,"abstract":"Swift J1858.6$-$0814 (hereafter J1858) is a transient neutron star low-mass\u0000X-ray binary (NS LMXB). There is controversy regarding its donor mass derived\u0000from observations and theoretical calculations. In this paper, we adopt seven\u0000magnetic braking (MB) prescriptions suggested in the literature and different\u0000metallicity $Z$ to simulate the evolution of the LMXB. Our results show that,\u0000employing the MB model proposed by citet{2012ApJ...746...43R} (\"rm12\"), the\u0000Convection And Rotation Boosted (\"carb\") model citep{2019ApJ...886L..31V}, as\u0000well as the Intermediate (\"inter\") and Convection-boosted (\"cboost\") models in\u0000citet{2019MNRAS.483.5595V} can match (part of) the observational parameters of\u0000J1858 well. We then apply our method to other observed LMXBs and find that the\u0000\"rm12\" and \"inter\" MB laws are most promising in explaining transient LMXBs. In\u0000comparison, the simulations with the \"cboost\" and \"carb\" MB laws are more\u0000inclined to reproduce persistent LMXBs and ultra-compact X-ray binaries\u0000(UCXBs), respectively. Our results, though subject to computational and/or\u0000observational bias, show that it is challenging to find a unified MB law that\u0000applies to the NS LMXB sub-populations simultaneously, indicating our lack of\u0000understanding of the true MB law. In addition, we explore the influence of\u0000various MB laws on the magnitude of the bifurcation periods in LMXBs.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206555","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}
Shrabani Kumar, G. C. Dewangan, P. Gandhi, I. E. Papadakis, N. P. S. Mithun, K. P. Singh, D. Bhattacharya, A. A. Zdziarski, G. C. Stewart, S. Bhattacharyya, S. Chandra
We present a multi-wavelength spectral study of NGC 4151 based on five epochs of simultaneous AstroSat observations in the near ultra-violet (NUV) to hard X-ray band ($sim 0.005-80$ keV) during $2017 - 2018$. We derived the intrinsic accretion disk continuum after correcting for internal and Galactic extinction, contributions from broad and narrow line regions, and emission from the host galaxy. We found a bluer continuum at brighter UV flux possibly due to variations in the accretion disk continuum or the UV reddening. We estimated the intrinsic reddening, $E(B-V) sim 0.4$, using high-resolution HST/STIS spectrum acquired in March 2000. We used thermal Comptonization, neutral and ionized absorption, and X-ray reflection to model the X-ray spectra. We obtained the X-ray absorbing neutral column varying between $N_H sim 1.2-3.4 times 10^{23} cm^{-2}$, which are $sim 100$ times larger than that estimated from UV extinction, assuming the Galactic dust-to-gas ratio. To reconcile this discrepancy, we propose two plausible configurations of the obscurer: (a) a two-zone obscurer consisting of dust-free and dusty regions, divided by the sublimation radius, or (b) a two-phase obscurer consisting of clumpy, dense clouds embedded in a low-density medium, resulting in a scenario where a few dense clouds obscure the compact X-ray source substantially, while the bulk of UV emission arising from the extended accretion disk passes through the low-density medium. Furthermore, we find a positive correlation between X-ray absorption column and $NUV-FUV$ color and UV flux, indicative of enhanced winds possibly driven by the 'bluer-when-brighter' UV continuum.
我们基于2017-2018年期间AstroSat在近紫外波段（NUV）到硬X射线波段（0.005-80keV）的五个同步观测，对NGC 4151进行了多波长光谱研究。在校正了内部和银河系的消光、宽窄线区的贡献以及宿主星系的发射之后，我们得出了本征的星盘连续波。我们发现在较亮的紫外通量下有一个较蓝的连续波，这可能是由于吸积盘连续波或紫外红化的变化造成的。我们利用2000年3月获得的高分辨率HST/STIS光谱估算了其内在红度，$E(B-V) sim 0.4$。我们利用热康普顿化、中性和电离吸收以及X射线反射来模拟X射线光谱。我们得到的 X 射线吸收中性柱在 $N_H sim 1.2-3.4times 10^{23} cm^{-2}$ 之间变化，比假设银河系尘气比的紫外消光估计值大 $sim 100$。为了调和这一差异，我们提出了两种可信的遮挡器构型：（a）由无尘区和多尘区组成的两区遮挡器，以升华半径划分；或者（b）由嵌入低密度介质中的团块状高密度云组成的两相遮挡器，其结果是少数高密度云极大地遮挡了紧凑的X射线源，而来自扩展吸积盘的大部分紫外辐射则穿过低密度介质。此外，我们还发现 X 射线吸收柱与 $NUV-FUV$ 颜色和紫外通量之间存在正相关，这表明风的增强可能是由 "越蓝越亮 "的紫外连续波驱动的。
{"title":"Multi-epoch UV $-$ X-ray spectral study of NGC 4151 with AstroSat","authors":"Shrabani Kumar, G. C. Dewangan, P. Gandhi, I. E. Papadakis, N. P. S. Mithun, K. P. Singh, D. Bhattacharya, A. A. Zdziarski, G. C. Stewart, S. Bhattacharyya, S. Chandra","doi":"arxiv-2409.04762","DOIUrl":"https://doi.org/arxiv-2409.04762","url":null,"abstract":"We present a multi-wavelength spectral study of NGC 4151 based on five epochs\u0000of simultaneous AstroSat observations in the near ultra-violet (NUV) to hard\u0000X-ray band ($sim 0.005-80$ keV) during $2017 - 2018$. We derived the intrinsic\u0000accretion disk continuum after correcting for internal and Galactic extinction,\u0000contributions from broad and narrow line regions, and emission from the host\u0000galaxy. We found a bluer continuum at brighter UV flux possibly due to\u0000variations in the accretion disk continuum or the UV reddening. We estimated\u0000the intrinsic reddening, $E(B-V) sim 0.4$, using high-resolution HST/STIS\u0000spectrum acquired in March 2000. We used thermal Comptonization, neutral and\u0000ionized absorption, and X-ray reflection to model the X-ray spectra. We\u0000obtained the X-ray absorbing neutral column varying between $N_H sim 1.2-3.4\u0000times 10^{23} cm^{-2}$, which are $sim 100$ times larger than that estimated\u0000from UV extinction, assuming the Galactic dust-to-gas ratio. To reconcile this\u0000discrepancy, we propose two plausible configurations of the obscurer: (a) a\u0000two-zone obscurer consisting of dust-free and dusty regions, divided by the\u0000sublimation radius, or (b) a two-phase obscurer consisting of clumpy, dense\u0000clouds embedded in a low-density medium, resulting in a scenario where a few\u0000dense clouds obscure the compact X-ray source substantially, while the bulk of\u0000UV emission arising from the extended accretion disk passes through the\u0000low-density medium. Furthermore, we find a positive correlation between X-ray\u0000absorption column and $NUV-FUV$ color and UV flux, indicative of enhanced winds\u0000possibly driven by the 'bluer-when-brighter' UV continuum.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206562","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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