Bas Dorsman, Tuomo Salmi, Anna L. Watts, Mason Ng, Satish Kamath, Anna Bobrikova, Juri Poutanen, Vladislav Loktev, Yves Kini, Devarshi Choudhury, Serena Vinciguerra, Slavko Bogdanov, Deepto Chakrabarty
Pulse profile modelling (PPM) is a technique for inferring mass, radius and hotspot properties of millisecond pulsars. PPM is now regularly used for analysis of rotation-powered millisecond pulsars (RMPs) with data from the Neutron Star Interior Composition ExploreR (NICER). Extending PPM to accreting millisecond pulsars (AMPs) is attractive, because they are a different source class featuring bright X-ray radiation from hotspots powered by accretion. In this paper, we present a modification of one of the PPM codes, X-PSI, so that it can be used for AMPs. In particular, we implement a model of an accretion disc and atmosphere model appropriate for the hotspots of AMPs, and improve the overall computational efficiency. We then test parameter recovery with synthetic NICER data in two scenarios with reasonable parameters for AMPs. We find in the first scenario, where the hotspot is large, that we are able to tightly and accurately constrain all parameters including mass and radius. In the second scenario, which is a high inclination system with a smaller hotspot, we find degeneracy between a subset of model parameters and a slight bias in the inferred mass and radius. This analysis of synthetic data lays the ground work for future analysis of AMPs with NICER data. Such an analysis could be complemented by future (joint) analysis of polarization data from the Imaging X-ray Polarimetry Explorer (IXPE).
{"title":"Parameter constraints for accreting millisecond pulsars with synthetic NICER data","authors":"Bas Dorsman, Tuomo Salmi, Anna L. Watts, Mason Ng, Satish Kamath, Anna Bobrikova, Juri Poutanen, Vladislav Loktev, Yves Kini, Devarshi Choudhury, Serena Vinciguerra, Slavko Bogdanov, Deepto Chakrabarty","doi":"arxiv-2409.07908","DOIUrl":"https://doi.org/arxiv-2409.07908","url":null,"abstract":"Pulse profile modelling (PPM) is a technique for inferring mass, radius and\u0000hotspot properties of millisecond pulsars. PPM is now regularly used for\u0000analysis of rotation-powered millisecond pulsars (RMPs) with data from the\u0000Neutron Star Interior Composition ExploreR (NICER). Extending PPM to accreting\u0000millisecond pulsars (AMPs) is attractive, because they are a different source\u0000class featuring bright X-ray radiation from hotspots powered by accretion. In\u0000this paper, we present a modification of one of the PPM codes, X-PSI, so that\u0000it can be used for AMPs. In particular, we implement a model of an accretion\u0000disc and atmosphere model appropriate for the hotspots of AMPs, and improve the\u0000overall computational efficiency. We then test parameter recovery with\u0000synthetic NICER data in two scenarios with reasonable parameters for AMPs. We\u0000find in the first scenario, where the hotspot is large, that we are able to\u0000tightly and accurately constrain all parameters including mass and radius. In\u0000the second scenario, which is a high inclination system with a smaller hotspot,\u0000we find degeneracy between a subset of model parameters and a slight bias in\u0000the inferred mass and radius. This analysis of synthetic data lays the ground\u0000work for future analysis of AMPs with NICER data. Such an analysis could be\u0000complemented by future (joint) analysis of polarization data from the Imaging\u0000X-ray Polarimetry Explorer (IXPE).","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"57 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206791","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 present an integral-based technique (IBT) algorithm to accelerate supernova (SN) radiative transfer calculations. The algorithm utilizes ``integral packets'', which are calculated by the path integral of the Monte-Carlo energy packets, to synthesize the observed spectropolarimetric signal at a given viewing direction in a 3-D time-dependent radiative transfer program. Compared to the event-based technique (EBT) proposed by (Bulla et al. 2015), our algorithm significantly reduces the computation time and increases the Monte-Carlo signal-to-noise ratio. Using a 1-D spherical symmetric type Ia supernova (SN Ia) ejecta model DDC10 and its derived 3-D model, the IBT algorithm has successfully passed the verification of: (1) spherical symmetry; (2) mirror symmetry; (3) cross comparison on a 3-D SN model with direct-counting technique (DCT) and EBT. Notably, with our algorithm implemented in the 3-D Monte-Carlo radiative transfer code SEDONA, the computation time is faster than EBT by a factor of $10-30$, and the signal-to-noise (S/N) ratio is better by a factor of $5-10$, with the same number of Monte-Carlo quanta.
我们提出了一种基于积分技术（IBT）的算法来加速超新星（SN）辐射传递计算。该算法利用蒙特卡洛能量包的路径积分计算出的 "积分包"，在三维时变辐射传递程序中合成在给定观测方向上观测到的能谱信号。与（Bulla et al.2015）提出的基于事件的技术（EBT）相比，我们的算法大大缩短了计算时间，提高了蒙特卡洛信噪比。利用一维球面对称 I 型超新星（SN Ia）喷出物模型 DDC10 及其衍生的三维模型，IBT 算法成功通过了以下验证：(1)球面对称性；(2)镜面对称性；(3)直接计数技术（DCT）和EBT在三维SN模型上的交叉比较。值得注意的是，在三维蒙特卡洛辐射传递代码 SEDONA 中实施我们的算法，在蒙特卡洛量子数相同的情况下，计算时间比 EBT 快 10-30 美元，信噪比（S/N）好 5-10 美元。
{"title":"An Integral-Based Technique (IBT) to Accelerate the Monte-Carlo Radiative Transfer Computation for Supernovae","authors":"Xingzhuo Chen, Lifan Wang, Daniel Kasen","doi":"arxiv-2409.07729","DOIUrl":"https://doi.org/arxiv-2409.07729","url":null,"abstract":"We present an integral-based technique (IBT) algorithm to accelerate\u0000supernova (SN) radiative transfer calculations. The algorithm utilizes\u0000``integral packets'', which are calculated by the path integral of the\u0000Monte-Carlo energy packets, to synthesize the observed spectropolarimetric\u0000signal at a given viewing direction in a 3-D time-dependent radiative transfer\u0000program. Compared to the event-based technique (EBT) proposed by (Bulla et al.\u00002015), our algorithm significantly reduces the computation time and increases\u0000the Monte-Carlo signal-to-noise ratio. Using a 1-D spherical symmetric type Ia\u0000supernova (SN Ia) ejecta model DDC10 and its derived 3-D model, the IBT\u0000algorithm has successfully passed the verification of: (1) spherical symmetry;\u0000(2) mirror symmetry; (3) cross comparison on a 3-D SN model with\u0000direct-counting technique (DCT) and EBT. Notably, with our algorithm\u0000implemented in the 3-D Monte-Carlo radiative transfer code SEDONA, the\u0000computation time is faster than EBT by a factor of $10-30$, and the\u0000signal-to-noise (S/N) ratio is better by a factor of $5-10$, with the same\u0000number of Monte-Carlo quanta.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"50 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206792","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 joint gravitational wave (GW) and electromagnetic observations of the binary neutron star (BNS) merger GW170817 marked a giant leap in multi-messenger astrophysics. The extensive observation campaign of the associated Gamma-Ray Burst (GRB) and its afterglow has strengthened the hypothesis associating GRBs with BNS mergers and provided insights on mass ejection, particularly the relativistic outflow launched in BNS mergers. In this paper, we investigate the joint detection probabilities of BNS mergers by GW detectors and the upcoming ground-based very-high-energy (VHE) $gamma$-ray instrument, the Cherenkov Telescope Array (CTA). Using an empirical relation that constrains the distance-inclination angle plane, we simulated BNS mergers detectable in the O5 run of the LIGO/Virgo/Kagra (LVK) network with $300$~Mpc BNS horizon. Assuming Gaussian structured jets and ignoring large sky localization challenges of GW detectors, we estimated VHE afterglow detection probability by CTA. We have explored the afterglow parameter space to identify conditions favourable for detecting synchrotron self-Compton emission by CTA. Our study reveals that events viewed at angles $lesssim3$ times the jet core angle are detectable by CTA when the initial bulk Lorentz factor at the jet axis ranges between 100 and 800. We find high kinetic energy ($E_k>10^{50}$ erg), ambient density ($n_0>10^{-1}$ $cm^{-3}$), and energy content in non-thermal electrons significantly enhance the likelihood of CTA detection within 300 Mpc. The joint detection rate varies significantly with afterglow parameter distributions, ranging from $0.003$ to $0.5$ per year.
{"title":"Follow-up of Neutron Star Mergers with CTA and Prospects for Joint Detection with Gravitational-Wave Detectors","authors":"T. Mondal, S. Chakraborty, L. Resmi, D. Bose","doi":"arxiv-2409.07916","DOIUrl":"https://doi.org/arxiv-2409.07916","url":null,"abstract":"The joint gravitational wave (GW) and electromagnetic observations of the\u0000binary neutron star (BNS) merger GW170817 marked a giant leap in\u0000multi-messenger astrophysics. The extensive observation campaign of the\u0000associated Gamma-Ray Burst (GRB) and its afterglow has strengthened the\u0000hypothesis associating GRBs with BNS mergers and provided insights on mass\u0000ejection, particularly the relativistic outflow launched in BNS mergers. In\u0000this paper, we investigate the joint detection probabilities of BNS mergers by\u0000GW detectors and the upcoming ground-based very-high-energy (VHE) $gamma$-ray\u0000instrument, the Cherenkov Telescope Array (CTA). Using an empirical relation\u0000that constrains the distance-inclination angle plane, we simulated BNS mergers\u0000detectable in the O5 run of the LIGO/Virgo/Kagra (LVK) network with $300$~Mpc\u0000BNS horizon. Assuming Gaussian structured jets and ignoring large sky\u0000localization challenges of GW detectors, we estimated VHE afterglow detection\u0000probability by CTA. We have explored the afterglow parameter space to identify\u0000conditions favourable for detecting synchrotron self-Compton emission by CTA.\u0000Our study reveals that events viewed at angles $lesssim3$ times the jet core\u0000angle are detectable by CTA when the initial bulk Lorentz factor at the jet\u0000axis ranges between 100 and 800. We find high kinetic energy ($E_k>10^{50}$\u0000erg), ambient density ($n_0>10^{-1}$ $cm^{-3}$), and energy content in\u0000non-thermal electrons significantly enhance the likelihood of CTA detection\u0000within 300 Mpc. The joint detection rate varies significantly with afterglow\u0000parameter distributions, ranging from $0.003$ to $0.5$ per year.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206788","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}
Polarized synchrotron emission is a fundamental process in high-energy astrophysics, particularly in the environments around black holes and pulsars. Accurate modeling of this emission requires precise computation of the emission, absorption, rotation, and conversion coefficients, which are critical for radiative transfer simulations. Traditionally, these coefficients are derived using fit functions based on precomputed ground truth values. However, these fit functions often lack accuracy, particularly in specific plasma conditions not well represented in the datasets used to generate them. In this work, we introduce ${tt MLody}$, a deep neural network designed to compute polarized synchrotron coefficients with high accuracy across a wide range of plasma parameters. We demonstrate ${tt MLody}$'s capabilities by integrating it with a radiative transfer code to generate synthetic polarized synchrotron images for an accreting black hole simulation. Our results reveal significant differences, up to a factor of two, in both linear and circular polarization compared to traditional methods. These differences could have important implications for parameter estimation in Event Horizon Telescope observations, suggesting that ${tt MLody}$ could enhance the accuracy of future astrophysical analyses.
{"title":"MLody -- Deep Learning Generated Polarized Synchrotron Coefficients","authors":"Jordy Davelaar","doi":"arxiv-2409.08007","DOIUrl":"https://doi.org/arxiv-2409.08007","url":null,"abstract":"Polarized synchrotron emission is a fundamental process in high-energy\u0000astrophysics, particularly in the environments around black holes and pulsars.\u0000Accurate modeling of this emission requires precise computation of the\u0000emission, absorption, rotation, and conversion coefficients, which are critical\u0000for radiative transfer simulations. Traditionally, these coefficients are\u0000derived using fit functions based on precomputed ground truth values. However,\u0000these fit functions often lack accuracy, particularly in specific plasma\u0000conditions not well represented in the datasets used to generate them. In this\u0000work, we introduce ${tt MLody}$, a deep neural network designed to compute\u0000polarized synchrotron coefficients with high accuracy across a wide range of\u0000plasma parameters. We demonstrate ${tt MLody}$'s capabilities by integrating\u0000it with a radiative transfer code to generate synthetic polarized synchrotron\u0000images for an accreting black hole simulation. Our results reveal significant\u0000differences, up to a factor of two, in both linear and circular polarization\u0000compared to traditional methods. These differences could have important\u0000implications for parameter estimation in Event Horizon Telescope observations,\u0000suggesting that ${tt MLody}$ could enhance the accuracy of future\u0000astrophysical analyses.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"62 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206547","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}
N. Lyskova, E. Churazov, I. Khabibullin, I. F. Bikmaev, R. A. Burenin, W. R. Forman, I. M. Khamitov, K. Rajpurohit, R. Sunyaev, C. Jones, R. Kraft, I. Zaznobin, M. A. Gorbachev, M. V. Suslikov, R. I. Gumerov, N. A. Sakhibullin
Massive clusters of galaxies are very rare in the observable Universe. Even rarer are mergers of such clusters observed close to pericenter passage. Here, we report on one such case: a massive (~ $10^{15},M_odot$) and hot (kT ~ 10 keV) cluster CL0238.3+2005 at $zapprox 0.42$. For this cluster, we combine X-ray data from SRG/eROSITA and Chandra, optical images from DESI, and spectroscopy from BTA and RTT-150 telescopes. The X-ray and optical morphologies suggest an ongoing merger with the projected separation of subhalos of $sim 200$ kpc. The line-of-sight velocity of galaxies tentatively associated with the two merging halos differs by 2000-3000 km/s. We conclude that, most plausibly, the merger axis is neither close to the line of sight nor to the sky plane. We compare CL0238 with two well-known clusters MACS0416 and Bullet, and conclude that CL0238 corresponds to an intermediate phase between the pre-merging MACS0416 cluster and the post-merger Bullet cluster. Namely, this cluster has recently (only $lesssim 0.1$ Gyr ago) experienced an almost head-on merger. We argue that this "just after" system is a very rare case and an excellent target for lensing, Sunyaev-Zeldovich effect, and X-ray studies that can constrain properties ranging from dynamics of mergers to self-interacting dark matter, and plasma effects in intracluster medium that are associated with shock waves, e.g., electron-ion equilibration efficiency and relativistic particle acceleration.
{"title":"Merger of massive galaxy cluster CL0238.3+2005 at z~0.4: just after pericenter passage?","authors":"N. Lyskova, E. Churazov, I. Khabibullin, I. F. Bikmaev, R. A. Burenin, W. R. Forman, I. M. Khamitov, K. Rajpurohit, R. Sunyaev, C. Jones, R. Kraft, I. Zaznobin, M. A. Gorbachev, M. V. Suslikov, R. I. Gumerov, N. A. Sakhibullin","doi":"arxiv-2409.07856","DOIUrl":"https://doi.org/arxiv-2409.07856","url":null,"abstract":"Massive clusters of galaxies are very rare in the observable Universe. Even\u0000rarer are mergers of such clusters observed close to pericenter passage. Here,\u0000we report on one such case: a massive (~ $10^{15},M_odot$) and hot (kT ~ 10\u0000keV) cluster CL0238.3+2005 at $zapprox 0.42$. For this cluster, we combine\u0000X-ray data from SRG/eROSITA and Chandra, optical images from DESI, and\u0000spectroscopy from BTA and RTT-150 telescopes. The X-ray and optical\u0000morphologies suggest an ongoing merger with the projected separation of\u0000subhalos of $sim 200$ kpc. The line-of-sight velocity of galaxies tentatively\u0000associated with the two merging halos differs by 2000-3000 km/s. We conclude\u0000that, most plausibly, the merger axis is neither close to the line of sight nor\u0000to the sky plane. We compare CL0238 with two well-known clusters MACS0416 and\u0000Bullet, and conclude that CL0238 corresponds to an intermediate phase between\u0000the pre-merging MACS0416 cluster and the post-merger Bullet cluster. Namely,\u0000this cluster has recently (only $lesssim 0.1$ Gyr ago) experienced an almost\u0000head-on merger. We argue that this \"just after\" system is a very rare case and\u0000an excellent target for lensing, Sunyaev-Zeldovich effect, and X-ray studies\u0000that can constrain properties ranging from dynamics of mergers to\u0000self-interacting dark matter, and plasma effects in intracluster medium that\u0000are associated with shock waves, e.g., electron-ion equilibration efficiency\u0000and relativistic particle acceleration.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"63 1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206839","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}
G. E. Anderson, G. Schroeder, A. J. van der Horst, L. Rhodes, A. Rowlinson, A. Bahramian, S. I. Chastain, B. P. Gompertz, P. J. Hancock, T. Laskar, J. K. Leung, R. A. M. J. Wijers
We present the radio afterglow of short gamma-ray burst (GRB) 230217A, which was detected less than 1 day after the gamma-ray prompt emission with the Australia Telescope Compact Array (ATCA) and the Karl G. Jansky Very Large Array (VLA). The ATCA rapid-response system automatically triggered an observation of GRB 230217A following its detection by the Neil Gehrels Swift Observatory and began observing the event just 32 minutes post-burst at 5.5 and 9 GHz for 7 hours. Dividing the 7-hour observation into three time-binned images allowed us to obtain radio detections with logarithmic central times of 1, 2.8 and 5.2 hours post-burst, the first of which represents the earliest radio detection of any GRB to date. The decline of the light curve is consistent with reverse shock emission if the observing bands are below the spectral peak and not affected by synchrotron self-absorption. This makes GRB 230217A the fifth short GRB with radio detections attributed to a reverse shock at early times ($<1$ day post-burst). Following brightness temperature arguments, we have used our early radio detections to place the highest minimum Lorentz factor (${Gamma}_{min} > 50$ at $sim1$ hour) constraints on a GRB in the radio band. Our results demonstrate the importance of rapid radio follow-up observations with long integrations and good sensitivity for detecting the fast-evolving radio emission from short GRBs and probing their reverse shocks.
我们展示了短伽马射线暴（GRB）230217A的射电余辉，它是在伽马射线迅速发射后不到1天的时间里由澳大利亚望远镜紧凑阵列（ATCA）和卡尔-G-扬斯基甚大阵列（VLA）探测到的。在 Neil Gehrels Swift 天文台探测到 GRB 230217A 之后，ATCA 快速反应系统自动触发了对它的观测，并在爆发后仅 32 分钟就开始以 5.5 和 9 千兆赫的频率对该事件进行了长达 7 小时的观测。将 7 小时的观测分成三个时间分段图像，使我们能够获得爆发后对数中心时间分别为 1、2.8 和 5.2 小时的射电探测结果，其中第一个射电探测结果是迄今为止对任何 GRB 的最早射电探测结果。如果观测波段低于光谱峰值，并且不受同步加速器自吸收的影响，那么光曲线的下降与反向冲击发射是一致的。这使得GRB230217A成为第五个射电探测到反向冲击的短GRB。我们的结果表明，具有长积分和高灵敏度的快速射电跟踪观测对于探测短GRB的快速演变射电发射和探测其反向冲击非常重要。
{"title":"The early radio afterglow of short GRB 230217A","authors":"G. E. Anderson, G. Schroeder, A. J. van der Horst, L. Rhodes, A. Rowlinson, A. Bahramian, S. I. Chastain, B. P. Gompertz, P. J. Hancock, T. Laskar, J. K. Leung, R. A. M. J. Wijers","doi":"arxiv-2409.07686","DOIUrl":"https://doi.org/arxiv-2409.07686","url":null,"abstract":"We present the radio afterglow of short gamma-ray burst (GRB) 230217A, which\u0000was detected less than 1 day after the gamma-ray prompt emission with the\u0000Australia Telescope Compact Array (ATCA) and the Karl G. Jansky Very Large\u0000Array (VLA). The ATCA rapid-response system automatically triggered an\u0000observation of GRB 230217A following its detection by the Neil Gehrels Swift\u0000Observatory and began observing the event just 32 minutes post-burst at 5.5 and\u00009 GHz for 7 hours. Dividing the 7-hour observation into three time-binned\u0000images allowed us to obtain radio detections with logarithmic central times of\u00001, 2.8 and 5.2 hours post-burst, the first of which represents the earliest\u0000radio detection of any GRB to date. The decline of the light curve is\u0000consistent with reverse shock emission if the observing bands are below the\u0000spectral peak and not affected by synchrotron self-absorption. This makes GRB\u0000230217A the fifth short GRB with radio detections attributed to a reverse shock\u0000at early times ($<1$ day post-burst). Following brightness temperature\u0000arguments, we have used our early radio detections to place the highest minimum\u0000Lorentz factor (${Gamma}_{min} > 50$ at $sim1$ hour) constraints on a GRB in\u0000the radio band. Our results demonstrate the importance of rapid radio follow-up\u0000observations with long integrations and good sensitivity for detecting the\u0000fast-evolving radio emission from short GRBs and probing their reverse shocks.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206790","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 update and extend a previous model by Higdon and Lingenfelter for the longitudinal profile of the N,II intensity in the Galactic plane. The model is based on four logarithmic spiral arms, to which features like the Local Arm and local sources are added. Connecting then the N,II to the H,II emission, we use this model to determine the average spatial distribution of OBassociations in the Milky Way. Combined with a stellar mass and cluster distribution function, the model predicts the average spatial and temporal distribution of core-collapse supernovae in the Milky Way. In addition to this average population, we account for supernovae from observed OB associations, providing thereby a more accurate description of the nearby Galaxy. The complete model is made publicly available in the python code SNOB.
{"title":"Galactic Distribution of Supernovae and OB Associations","authors":"M. Kachelriess, V. Mikalsen","doi":"arxiv-2409.07124","DOIUrl":"https://doi.org/arxiv-2409.07124","url":null,"abstract":"We update and extend a previous model by Higdon and Lingenfelter for the\u0000longitudinal profile of the N,II intensity in the Galactic plane. The model is\u0000based on four logarithmic spiral arms, to which features like the Local Arm and\u0000local sources are added. Connecting then the N,II to the H,II emission, we\u0000use this model to determine the average spatial distribution of OBassociations\u0000in the Milky Way. Combined with a stellar mass and cluster distribution\u0000function, the model predicts the average spatial and temporal distribution of\u0000core-collapse supernovae in the Milky Way. In addition to this average\u0000population, we account for supernovae from observed OB associations, providing\u0000thereby a more accurate description of the nearby Galaxy. The complete model is\u0000made publicly available in the python code SNOB.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"255 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206842","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}
Ramij Raja, Oleg M. Smirnov, Tiziana Venturi, Majidul Rahaman, H. -Y. Karen Yang
CIZA J2242.8+5301, or the Sausage cluster, is well studied over a range of frequencies. Since its first discovery, a lot of interesting features and unique characteristics have been uncovered. In this work, we report some more new morphological features using the uGMRT band-3 and band-4 data. In the north relic, we observe variation in spectral index profiles across the relic width from the east to west, which may indicate a decrease in downstream cooling rate in that direction. We re-confirm the presence of an additional ~ 930 kpc relic in the north. We classify the filamentary source in the downstream region to be a narrow angle tail (NAT) radio galaxy. The bright arc in the east relic shows sub-structure in the spectral index profile, which may indicate the presence of finer filaments. We further report the presence of a double-strand structure in the east relic similar to the 'Toothbrush' relic. We categorize the bright 'L' shaped structure in the southern relic to be a NAT radio galaxy, as well as trace the actual ~ 1.1 Mpc relic component. We re-confirm the existence of the faint southern extent, measuring the relic length to be ~ 1.8 Mpc. Furthermore, we suggest the southern relic to be a union of individual component relics rather than a single giant filamentary relic. Lastly, based on the morphological symmetry between northern and southern relics, we suggest a schematic shock structure associated with the merger event in an attempt to explain their formation scenario.
{"title":"uGMRT sub-GHz view of the Sausage cluster diffuse radio sources","authors":"Ramij Raja, Oleg M. Smirnov, Tiziana Venturi, Majidul Rahaman, H. -Y. Karen Yang","doi":"arxiv-2409.07504","DOIUrl":"https://doi.org/arxiv-2409.07504","url":null,"abstract":"CIZA J2242.8+5301, or the Sausage cluster, is well studied over a range of\u0000frequencies. Since its first discovery, a lot of interesting features and\u0000unique characteristics have been uncovered. In this work, we report some more\u0000new morphological features using the uGMRT band-3 and band-4 data. In the north\u0000relic, we observe variation in spectral index profiles across the relic width\u0000from the east to west, which may indicate a decrease in downstream cooling rate\u0000in that direction. We re-confirm the presence of an additional ~ 930 kpc relic\u0000in the north. We classify the filamentary source in the downstream region to be\u0000a narrow angle tail (NAT) radio galaxy. The bright arc in the east relic shows\u0000sub-structure in the spectral index profile, which may indicate the presence of\u0000finer filaments. We further report the presence of a double-strand structure in\u0000the east relic similar to the 'Toothbrush' relic. We categorize the bright 'L'\u0000shaped structure in the southern relic to be a NAT radio galaxy, as well as\u0000trace the actual ~ 1.1 Mpc relic component. We re-confirm the existence of the\u0000faint southern extent, measuring the relic length to be ~ 1.8 Mpc. Furthermore,\u0000we suggest the southern relic to be a union of individual component relics\u0000rather than a single giant filamentary relic. Lastly, based on the\u0000morphological symmetry between northern and southern relics, we suggest a\u0000schematic shock structure associated with the merger event in an attempt to\u0000explain their formation scenario.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"75 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206840","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}
Si-Si SunYunnan University, Zhongxiang WangYunnan University, Shun-hao JiYunnan University
We analyze the optical light-curve data, obtained with the Zwicky Transient Facility (ZTF) survey, for 47 gamma-ray blazars monitored by the Large Area Telescope onboard {it the Fermi Gamma-ray Space Telescope (Fermi)}. These 47 sources are selected because they are among the Fermi blazars with the largest optical variations in the ZTF data. Two color-magnitude variation patterns are seen in them, one being redder to stable when brighter (RSWB; in 31 sources) and the other being stable when brighter (in 16 sources). The patterns fit with the results recently reported in several similar studies with different data. Moreover, we find that the colors in the stable state of the sources share similar values, which (after corrected for the Galactic extinction) of most sources are in a range of 0.4--0.55. This feature could be intrinsic and may be applied in, for example, the study of intragalactic medium. We also determine the turning points for the sources showing the RSWB pattern, after which the color changes saturate and become stable. We find a correlation between optical fluxes and gamma-ray fluxes at the turning points. The physical implications of the correlation remain to be investigated, probably better with a sample of high-quality gamma-ray flux measurements.
我们分析了由费米伽马射线太空望远镜（Fermi）上的大面积望远镜（Large AreaTelescope onboard {it the Fermi Gam-ray Space Telescope (Fermi)}）监测的47个伽马射线闪烁星的光学光曲线数据，这些数据是通过兹威基瞬变设施（Zwicky TransientFacility，ZTF）巡天获得的。之所以选择这47个源，是因为它们是ZTF数据中光学变化最大的费米闪星。在它们身上可以看到两种颜色-星等变化模式，一种是由红变亮到稳定（RSWB；31 个源中），另一种是由亮变稳定（16 个源中）。此外，我们还发现，稳定状态下的星源颜色具有相似的数值，大多数星源的数值（经银河消光校正后）在 0.4-0.55 之间。这一特征可能是固有的，可以应用于星系内介质的研究等。我们还确定了显示 RSWB 模式的星源的转折点，在这些转折点之后，颜色变化趋于饱和并趋于稳定。我们发现在转折点处光学通量和伽马射线通量之间存在着相关性。这种相关性的物理意义还有待研究，也许用高质量的伽马射线通量测量样本会更好。
{"title":"Fermi Blazars in the Zwicky Transient Facility Survey: Properties of Large Optical Variations","authors":"Si-Si SunYunnan University, Zhongxiang WangYunnan University, Shun-hao JiYunnan University","doi":"arxiv-2409.06917","DOIUrl":"https://doi.org/arxiv-2409.06917","url":null,"abstract":"We analyze the optical light-curve data, obtained with the Zwicky Transient\u0000Facility (ZTF) survey, for 47 gamma-ray blazars monitored by the Large Area\u0000Telescope onboard {it the Fermi Gamma-ray Space Telescope (Fermi)}. These 47\u0000sources are selected because they are among the Fermi blazars with the largest\u0000optical variations in the ZTF data. Two color-magnitude variation patterns are\u0000seen in them, one being redder to stable when brighter (RSWB; in 31 sources)\u0000and the other being stable when brighter (in 16 sources). The patterns fit with\u0000the results recently reported in several similar studies with different data.\u0000Moreover, we find that the colors in the stable state of the sources share\u0000similar values, which (after corrected for the Galactic extinction) of most\u0000sources are in a range of 0.4--0.55. This feature could be intrinsic and may be\u0000applied in, for example, the study of intragalactic medium. We also determine\u0000the turning points for the sources showing the RSWB pattern, after which the\u0000color changes saturate and become stable. We find a correlation between optical\u0000fluxes and gamma-ray fluxes at the turning points. The physical implications of\u0000the correlation remain to be investigated, probably better with a sample of\u0000high-quality gamma-ray flux measurements.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206843","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}
Observations of gamma-ray burst afterglows have begun to readily reveal contamination from a kilonova or a supernova. This contamination presents significant challenges towards traditional methods of inferring the properties of these phenomena from observations. Given current knowledge of kilonova and afterglow modelling, observations (as expected) with near-infrared bands and at early observing times provide the greatest diagnostic power for both observing the presence of a kilonova and inferences on its properties in gamma-ray burst afterglows. However, contemporaneous observations in radio and X-ray are critical for reducing the afterglow parameter space and for more efficient parameter estimation. We compare different methods for fitting joint kilonova and afterglow observations under different scenarios. We find that ignoring the contribution of one source (even in scenarios where the source is sub-dominant) can lead to significantly biased estimated parameters but could still produce great light curve fits that do not raise suspicion. This bias is also present for analyses that fit data where one source is "subtracted". In most scenarios, the bias is smaller than the systematic uncertainty inherent to kilonova models but significant for afterglow parameters, particularly in the absence of high-quality radio and X-ray observations. Instead, we show that the most reliable method for inference in any scenario where contamination can not be confidently dismissed is to jointly fit for both an afterglow and kilonova/supernova, and showcase a Bayesian framework to make this joint analysis computationally feasible.
对伽马射线暴余辉的观测已经开始轻易地揭示出来自千新星或超新星的污染。这种污染对从观测中推断这些现象特性的传统方法提出了重大挑战。根据目前对千新星和余辉建模的了解，使用近红外波段和较早观测时间进行的观测（正如预期的那样）为观测千新星的存在和推断其在伽马射线暴余辉中的性质提供了最大的诊断能力。然而，同时进行的射电和 X 射线观测对于缩小余辉参数空间和更有效地估计参数至关重要。我们比较了在不同情况下拟合千新星和余辉联合观测数据的不同方法。我们发现，忽略一个光源的贡献（即使在该光源处于次主导地位的情况下）会导致估计参数出现明显偏差，但仍然可以产生很好的光曲线拟合，不会引起怀疑。这种偏差也存在于 "减去 "一个光源的数据拟合分析中。在大多数情况下，这种偏差小于千新星模型固有的系统不确定性，但对于余辉参数来说却很重要，尤其是在缺乏高质量的射电和 X 射线观测数据的情况下。相反，我们表明，在任何情况下，如果不能有把握地排除污染，最可靠的推断方法就是同时拟合余辉和基洛新星/超新星，并展示了一个贝叶斯框架，使这种联合分析在计算上可行。
{"title":"A detailed dive into fitting strategies for GRB afterglows with contamination: A case study with kilonovae","authors":"Wendy Fu Wallace, Nikhil Sarin","doi":"arxiv-2409.07539","DOIUrl":"https://doi.org/arxiv-2409.07539","url":null,"abstract":"Observations of gamma-ray burst afterglows have begun to readily reveal\u0000contamination from a kilonova or a supernova. This contamination presents\u0000significant challenges towards traditional methods of inferring the properties\u0000of these phenomena from observations. Given current knowledge of kilonova and\u0000afterglow modelling, observations (as expected) with near-infrared bands and at\u0000early observing times provide the greatest diagnostic power for both observing\u0000the presence of a kilonova and inferences on its properties in gamma-ray burst\u0000afterglows. However, contemporaneous observations in radio and X-ray are\u0000critical for reducing the afterglow parameter space and for more efficient\u0000parameter estimation. We compare different methods for fitting joint kilonova\u0000and afterglow observations under different scenarios. We find that ignoring the\u0000contribution of one source (even in scenarios where the source is sub-dominant)\u0000can lead to significantly biased estimated parameters but could still produce\u0000great light curve fits that do not raise suspicion. This bias is also present\u0000for analyses that fit data where one source is \"subtracted\". In most scenarios,\u0000the bias is smaller than the systematic uncertainty inherent to kilonova models\u0000but significant for afterglow parameters, particularly in the absence of\u0000high-quality radio and X-ray observations. Instead, we show that the most\u0000reliable method for inference in any scenario where contamination can not be\u0000confidently dismissed is to jointly fit for both an afterglow and\u0000kilonova/supernova, and showcase a Bayesian framework to make this joint\u0000analysis computationally feasible.","PeriodicalId":501343,"journal":{"name":"arXiv - PHYS - High Energy Astrophysical Phenomena","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206793","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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