Pulsars have long been studied in the electromagnetic spectrum. Their environments are rich in high-energy cosmic-ray electrons and positrons likely enriching the interstellar medium with such particles. In this work we use recent cosmic-ray observations from the AMS-02, CALET and DAMPE collaborations to study the averaged properties of the local Milky Way pulsar population. We perform simulations of the local Milky Way pulsar population, for interstellar medium assumptions in agreement with a range of cosmic-ray nuclei measurements. Each such simulation contains $sim 10^{4}$ pulsars of unique age, location, initial spin-down power and cosmic-ray electron/positron spectra. We produce more than $7times 10^{3}$ such Milky Way pulsar simulations. We account for and study i) the pulsars' birth rates and the stochastic nature of their birth, ii) their initial spin-down power distribution, iii) their time evolution in terms of their braking index and characteristic spin-down timescale, iv) the fraction of spin-down power going to cosmic-ray electrons and positrons and v) their propagation through the interstellar medium and the Heliosphere. We find that pulsars of ages $sim 10^{5}-10^{7}$ yr, have a braking index that on average has to be 3 or larger. Given that electromagnetic spectrum observations of young pulsars find braking indices lower than 3, our work provides strong hints that pulsars' braking index increases on average as they age, allowing them to retain some of their rotational energy. Moreover, we find that pulsars have relatively uniform properties as sources of cosmic-ray electrons and positrons in terms of the spectra they produce and likely release O($10%$) of their rotational energy to cosmic-rays in the ISM. Finally, we find at $simeq$12 GeV positrons a spectral feature that suggests a new subpopulation of positron sources contributing at these energies.
{"title":"Utilizing cosmic-ray positron and electron observations to probe the averaged properties of Milky Way pulsars","authors":"I. Cholis, Iason Krommydas","doi":"10.5281/ZENODO.5659004","DOIUrl":"https://doi.org/10.5281/ZENODO.5659004","url":null,"abstract":"Pulsars have long been studied in the electromagnetic spectrum. Their environments are rich in high-energy cosmic-ray electrons and positrons likely enriching the interstellar medium with such particles. In this work we use recent cosmic-ray observations from the AMS-02, CALET and DAMPE collaborations to study the averaged properties of the local Milky Way pulsar population. We perform simulations of the local Milky Way pulsar population, for interstellar medium assumptions in agreement with a range of cosmic-ray nuclei measurements. Each such simulation contains $sim 10^{4}$ pulsars of unique age, location, initial spin-down power and cosmic-ray electron/positron spectra. We produce more than $7times 10^{3}$ such Milky Way pulsar simulations. We account for and study i) the pulsars' birth rates and the stochastic nature of their birth, ii) their initial spin-down power distribution, iii) their time evolution in terms of their braking index and characteristic spin-down timescale, iv) the fraction of spin-down power going to cosmic-ray electrons and positrons and v) their propagation through the interstellar medium and the Heliosphere. We find that pulsars of ages $sim 10^{5}-10^{7}$ yr, have a braking index that on average has to be 3 or larger. Given that electromagnetic spectrum observations of young pulsars find braking indices lower than 3, our work provides strong hints that pulsars' braking index increases on average as they age, allowing them to retain some of their rotational energy. Moreover, we find that pulsars have relatively uniform properties as sources of cosmic-ray electrons and positrons in terms of the spectra they produce and likely release O($10%$) of their rotational energy to cosmic-rays in the ISM. Finally, we find at $simeq$12 GeV positrons a spectral feature that suggests a new subpopulation of positron sources contributing at these energies.","PeriodicalId":8437,"journal":{"name":"arXiv: High Energy Astrophysical Phenomena","volume":"75 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88176695","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}
R. A. Batista, M. Amin, G. Barenboim, N. Bartolo, D. Baumann, A. Bauswein, E. Bellini, D. Benisty, G. Bertone, P. Blasi, C. Bohmer, vZ. Bovsnjak, T. Bringmann, C. Burrage, M. Bustamante, J. C. Bustillo, C. Byrnes, F. Calore, R. Catena, D. Cerdeño, S. Cerri, M. Chianese, K. Clough, A. Cole, P. Coloma, A. Coogan, L. Covi, D. Cutting, A. Davis, C. Rham, A. Matteo, G. Domènech, M. Drewes, T. Dietrich, T. Edwards, I. Esteban, R. Erdem, Carmelo Evoli, M. Fasiello, S. Feeney, R. Z. Ferreira, A. Fialkov, N. Fornengo, S. Gabici, T. Galatyuk, D.Gaggero, D. Grasso, C. Gu'epin, J. Harz, M. Herrero-Valea, T. Hinderer, N. B. Hogg, D. C. Hooper, F. Iocco, J. Isern, K. Karchev, B. Kavanagh, M. Korsmeier, K. Kotera, K. Koyama, B. Krishnan, J. Lesgourgues, J. Said, L. Lombriser, C. S. Lorenz, S. Manconi, M. Mapelli, A. Marcowith, S. Markoff, D. Marsh, M. Martinelli, C. Martins, J. Matthews, A. Meli, O. Mena, J. Mifsud, M. M. Bertolami, P. Millington, P. Moesta, K. Nippel, V. Niro, E. O’Connor, F. Oikonomou, C. Paganini, G.
Astroparticle physics is undergoing a profound transformation, due to a series of extraordinary new results, such as the discovery of high-energy cosmic neutrinos with IceCube, the direct detection of gravitational waves with LIGO and Virgo, and many others. This white paper is the result of a collaborative effort that involved hundreds of theoretical astroparticle physicists and cosmologists, under the coordination of the European Consortium for Astroparticle Theory (EuCAPT). Addressed to the whole astroparticle physics community, it explores upcoming theoretical opportunities and challenges for our field of research, with particular emphasis on the possible synergies among different subfields, and the prospects for solving the most fundamental open questions with multi-messenger observations.
{"title":"EuCAPT White Paper: Opportunities and Challenges for Theoretical Astroparticle Physics in the Next Decade","authors":"R. A. Batista, M. Amin, G. Barenboim, N. Bartolo, D. Baumann, A. Bauswein, E. Bellini, D. Benisty, G. Bertone, P. Blasi, C. Bohmer, vZ. Bovsnjak, T. Bringmann, C. Burrage, M. Bustamante, J. C. Bustillo, C. Byrnes, F. Calore, R. Catena, D. Cerdeño, S. Cerri, M. Chianese, K. Clough, A. Cole, P. Coloma, A. Coogan, L. Covi, D. Cutting, A. Davis, C. Rham, A. Matteo, G. Domènech, M. Drewes, T. Dietrich, T. Edwards, I. Esteban, R. Erdem, Carmelo Evoli, M. Fasiello, S. Feeney, R. Z. Ferreira, A. Fialkov, N. Fornengo, S. Gabici, T. Galatyuk, D.Gaggero, D. Grasso, C. Gu'epin, J. Harz, M. Herrero-Valea, T. Hinderer, N. B. Hogg, D. C. Hooper, F. Iocco, J. Isern, K. Karchev, B. Kavanagh, M. Korsmeier, K. Kotera, K. Koyama, B. Krishnan, J. Lesgourgues, J. Said, L. Lombriser, C. S. Lorenz, S. Manconi, M. Mapelli, A. Marcowith, S. Markoff, D. Marsh, M. Martinelli, C. Martins, J. Matthews, A. Meli, O. Mena, J. Mifsud, M. M. Bertolami, P. Millington, P. Moesta, K. Nippel, V. Niro, E. O’Connor, F. Oikonomou, C. Paganini, G.","doi":"10.5445/IR/1000139254","DOIUrl":"https://doi.org/10.5445/IR/1000139254","url":null,"abstract":"Astroparticle physics is undergoing a profound transformation, due to a series of extraordinary new results, such as the discovery of high-energy cosmic neutrinos with IceCube, the direct detection of gravitational waves with LIGO and Virgo, and many others. This white paper is the result of a collaborative effort that involved hundreds of theoretical astroparticle physicists and cosmologists, under the coordination of the European Consortium for Astroparticle Theory (EuCAPT). Addressed to the whole astroparticle physics community, it explores upcoming theoretical opportunities and challenges for our field of research, with particular emphasis on the possible synergies among different subfields, and the prospects for solving the most fundamental open questions with multi-messenger observations.","PeriodicalId":8437,"journal":{"name":"arXiv: High Energy Astrophysical Phenomena","volume":"79 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79690246","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 Galactic Center Excess (GCE) is an extended gamma-ray source in the central region of the Galaxy found in Fermi Large Area Telescope data. In recent years it has become apparent that the GCE may not be spherically symmetric, but may be spatially correlated with the distribution of stellar mass in the Galactic bulge, potentially favoring an unresolved population of millisecond pulsars (MSPs) scenario. In this thesis, we perform detailed modelling of the Galactic MSP population. Including in our model the spin down between formation and observation, we find a model in which luminosity $L propto E_{rm cut}^{1.2 pm 0.3} B^{0.1 pm 0.4} dot{E}^{0.5 pm 0.1}$ provides the best fit to the data, where $E_{rm cut}$ is spectral energy cutoff, $B$ is magnetic field strength, and $dot{E}$ is the spin-down power. Due to differing star formation histories it is expected that the MSPs in the Galactic bulge are older and therefore dimmer than those in the Galactic disk. Our results demonstrate that we do not require that there is anything systematically different about the inner Galaxy MSPs to explain the GCE. In the "recycling" channel of MSP formation the neutron star forms from a core collapse supernovae that undergoes a random "kick" due to the asymmetry of the explosion. This would imply a smoothing out of the spatial distribution of the MSPs. We use N-body simulations to model how the MSP spatial distribution changes. We estimate the probability distribution of natal kick velocities using the resolved gamma-ray MSP proper motions, where MSPs have velocities relative to circular motion of 77 +/- 6 km/s, as determined as part of our Galactic MSP population model. We find that, due to the natal kicks, there is an approximately 10% increase in each of the bulge MSP spatial distribution dimensions and also the bulge MSP distribution becomes less boxy but is still far from being spherical.
银河中心过剩(GCE)是在费米大面积望远镜的数据中发现的银河系中心区域的一个扩展的伽马射线源。近年来，很明显，GCE可能不是球对称的，但可能与银河系凸起的恒星质量分布在空间上相关，这可能有利于尚未解决的毫秒脉冲星(MSPs)种群的情况。在本文中，我们对银河系MSP种群进行了详细的建模。在我们的模型中，包括形成和观测之间的自旋下降，我们发现一个光度$L propto E_{rm cut}^{1.2 pm 0.3} B^{0.1 pm 0.4} dot{E}^{0.5 pm 0.1}$最适合数据的模型，其中$E_{rm cut}$是光谱能量截止，$B$是磁场强度，$dot{E}$是自旋下降功率。由于不同的恒星形成历史，预计银河系凸起中的msp比银河系盘中的msp更老，因此更暗。我们的结果表明，我们不需要银河系内部的msp有任何系统的不同来解释GCE。在MSP形成的“循环”通道中，中子星由核心坍缩超新星形成，由于爆炸的不对称性，该超新星经历了随机的“踢”。这将意味着对msp的空间分布进行平滑处理。我们使用n体模拟来模拟MSP空间分布的变化。我们利用伽玛射线MSP固有运动来估计出生踢速的概率分布，其中MSP相对于圆周运动的速度为77 +/- 6 km/s，这是我们银河系MSP人口模型的一部分。我们发现，由于出生时的踢腿，大约有10% increase in each of the bulge MSP spatial distribution dimensions and also the bulge MSP distribution becomes less boxy but is still far from being spherical.
{"title":"The galactic millisecond pulsar population : implications for the Galactic Center Excess.","authors":"H. Ploeg","doi":"10.26021/11711","DOIUrl":"https://doi.org/10.26021/11711","url":null,"abstract":"The Galactic Center Excess (GCE) is an extended gamma-ray source in the central region of the Galaxy found in Fermi Large Area Telescope data. In recent years it has become apparent that the GCE may not be spherically symmetric, but may be spatially correlated with the distribution of stellar mass in the Galactic bulge, potentially favoring an unresolved population of millisecond pulsars (MSPs) scenario. In this thesis, we perform detailed modelling of the Galactic MSP population. Including in our model the spin down between formation and observation, we find a model in which luminosity $L propto E_{rm cut}^{1.2 pm 0.3} B^{0.1 pm 0.4} dot{E}^{0.5 pm 0.1}$ provides the best fit to the data, where $E_{rm cut}$ is spectral energy cutoff, $B$ is magnetic field strength, and $dot{E}$ is the spin-down power. Due to differing star formation histories it is expected that the MSPs in the Galactic bulge are older and therefore dimmer than those in the Galactic disk. Our results demonstrate that we do not require that there is anything systematically different about the inner Galaxy MSPs to explain the GCE. In the \"recycling\" channel of MSP formation the neutron star forms from a core collapse supernovae that undergoes a random \"kick\" due to the asymmetry of the explosion. This would imply a smoothing out of the spatial distribution of the MSPs. We use N-body simulations to model how the MSP spatial distribution changes. We estimate the probability distribution of natal kick velocities using the resolved gamma-ray MSP proper motions, where MSPs have velocities relative to circular motion of 77 +/- 6 km/s, as determined as part of our Galactic MSP population model. We find that, due to the natal kicks, there is an approximately 10% increase in each of the bulge MSP spatial distribution dimensions and also the bulge MSP distribution becomes less boxy but is still far from being spherical.","PeriodicalId":8437,"journal":{"name":"arXiv: High Energy Astrophysical Phenomena","volume":"175 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86523465","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}
Pub Date : 2021-04-23DOI: 10.1103/PhysRevD.104.043022
A. Iwazaki
The fast radio bursts ( FRBs ) are energetic radio bursts with millisecond duration only observed at radio frequencies. The generation mechanism is still mysterious. We have proposed a generation mechanism of both repeating and one-off FRBs. They arise from the axion star collision with neutron star or magnetized accretion disk of galactic black hole. Once we accept the existence of the axions, we find that the mechanism well explain previously observed spectral-temporal features. In this paper we show that it also explains recently observed phenomena such as downward drifting in the repeating FRBs, etc.. Analysis of the downward drifting based on Doppler effects has been presented in recent papers, in which a superradiance system of molecular or atom has been proposed as a source of FRBs. We apply the analysis to our mechanism and find that it well explains the relation between the downward drifting rate and the duration of the repeating FRBs. The Doppler effects lead to the fact that the duration of radio burst with higher center frequency is shorter than that of radio burst with lower center frequency in the repeating FRBs. Our generation mechanism naturally explain polarization angle swing observed in the repeating FRB180301 and one-off FRBs. We also discuss the association between the FRB200428 and magnetar SGR J1935+2154. The X ray burst observed just after the observation of the FRB could be triggered by the axion star collision with the magnetar. We also explain the consistency of our generation mechanism with observed spectral-temporal differences in the repeating and one-off FRBs, e.g. longer duration ( smaller flux density ) of repeating FRBs than duration ( flux density ) of one-off FRBs.
{"title":"Spectral-temporal features of repeating ( one-off ) FRBs and Axion Star.","authors":"A. Iwazaki","doi":"10.1103/PhysRevD.104.043022","DOIUrl":"https://doi.org/10.1103/PhysRevD.104.043022","url":null,"abstract":"The fast radio bursts ( FRBs ) are energetic radio bursts with millisecond duration only observed at radio frequencies. The generation mechanism is still mysterious. We have proposed a generation mechanism of both repeating and one-off FRBs. They arise from the axion star collision with neutron star or magnetized accretion disk of galactic black hole. Once we accept the existence of the axions, we find that the mechanism well explain previously observed spectral-temporal features. In this paper we show that it also explains recently observed phenomena such as downward drifting in the repeating FRBs, etc.. Analysis of the downward drifting based on Doppler effects has been presented in recent papers, in which a superradiance system of molecular or atom has been proposed as a source of FRBs. We apply the analysis to our mechanism and find that it well explains the relation between the downward drifting rate and the duration of the repeating FRBs. The Doppler effects lead to the fact that the duration of radio burst with higher center frequency is shorter than that of radio burst with lower center frequency in the repeating FRBs. Our generation mechanism naturally explain polarization angle swing observed in the repeating FRB180301 and one-off FRBs. We also discuss the association between the FRB200428 and magnetar SGR J1935+2154. The X ray burst observed just after the observation of the FRB could be triggered by the axion star collision with the magnetar. We also explain the consistency of our generation mechanism with observed spectral-temporal differences in the repeating and one-off FRBs, e.g. longer duration ( smaller flux density ) of repeating FRBs than duration ( flux density ) of one-off FRBs.","PeriodicalId":8437,"journal":{"name":"arXiv: High Energy Astrophysical Phenomena","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88457710","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. Dewangan, P. Tripathi, I. Papadakis, K. P. Singh
We present a study of far and near-ultraviolet emission from the accretion disk in a powerful Seyfert 1 galaxy IC4329A using observations performed with the Ultraviolet Imaging Telescope (UVIT) onboard AstroSat. These data provide the highest spatial resolution and deepest images of IC4329A in the far and near UV bands acquired to date. The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far and near UV bands. We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening, as well as for the contribution of emission lines from the broad and narrow-line regions. The intrinsic UV continuum emission shows a marked deficit compared to that expected from the "standard" models of the accretion disk around an estimated black hole mass of 1-2x10^8Msun when the disk extends to the innermost stable circular orbit. We find that the intrinsic UV continuum is fully consistent with the standard disk models, but only if the disk emits from distances larger than 80-150 gravitational radii.
{"title":"AstroSat/UVIT observations of IC 4329A: constraining the accretion disc inner radius","authors":"G. Dewangan, P. Tripathi, I. Papadakis, K. P. Singh","doi":"10.1093/mnras/stab1113","DOIUrl":"https://doi.org/10.1093/mnras/stab1113","url":null,"abstract":"We present a study of far and near-ultraviolet emission from the accretion disk in a powerful Seyfert 1 galaxy IC4329A using observations performed with the Ultraviolet Imaging Telescope (UVIT) onboard AstroSat. These data provide the highest spatial resolution and deepest images of IC4329A in the far and near UV bands acquired to date. The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far and near UV bands. We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening, as well as for the contribution of emission lines from the broad and narrow-line regions. The intrinsic UV continuum emission shows a marked deficit compared to that expected from the \"standard\" models of the accretion disk around an estimated black hole mass of 1-2x10^8Msun when the disk extends to the innermost stable circular orbit. We find that the intrinsic UV continuum is fully consistent with the standard disk models, but only if the disk emits from distances larger than 80-150 gravitational radii.","PeriodicalId":8437,"journal":{"name":"arXiv: High Energy Astrophysical Phenomena","volume":"74 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86878183","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}
Pub Date : 2021-04-12DOI: 10.31857/S0320010821030037
G. Khorunzhev, A. Meshcheryakov, P. Medvedev, V. Borisov, R. Burenin, R. Krivonos, R. Uklein, E. Shablovinskaya, V. Afanasyev, S. Dodonov, R. Sunyaev, S. Sazonov, M. Gilfanov
SRGE J170245.3+130104 was discovered by the eROSITA telescope aboard the SRG space observatory on March 13-15, 2020 during the first half-year scan of its all-sky X-ray survey. The optical counterpart of the X-ray source was photometrically identified as a distant quasar candidate at $zapprox5.5$. Follow-up spectroscopic observations, done in August/September 2020 with the SCORPIO-II instrument at the BTA 6-m telescope, confirmed that SRGE J170245.3+130104 is a distant quasar at redshift z=5.466. The X-ray luminosity of the quasar during the first half-year scan of the eROSITA all-sky survey was $3.6^{+2.1}_{-1.5}times 10^{46}$ erg/s (in the 2-10 keV energy range), whereas its X-ray spectrum could be described by a power law with a slope of $Gamma=1.8^{+0.9}_{-0.8}$. Six months later (September 13-14, 2020), during the second half-year scan of the eROSITA all-sky survey, the quasar was detected again and its X-ray luminosity had decreased by a factor of 2 (at the $approx 1.9sigma$ confidence level). The SRGE J170245.3+130104 proves to be the most X-ray luminous among all known X-ray quasars at $z>5$. It is also one of the radio-loudest distant quasars (with radio-loudness $Rsim10^3$), which may imply that it is a blazar. In the Appendix, we present the list of all $z>5$ quasars detected in X-rays to date.
{"title":"Discovery of the most X-ray luminous quasar SRGE J170245.3+130104 at redshift z$approx5.5$","authors":"G. Khorunzhev, A. Meshcheryakov, P. Medvedev, V. Borisov, R. Burenin, R. Krivonos, R. Uklein, E. Shablovinskaya, V. Afanasyev, S. Dodonov, R. Sunyaev, S. Sazonov, M. Gilfanov","doi":"10.31857/S0320010821030037","DOIUrl":"https://doi.org/10.31857/S0320010821030037","url":null,"abstract":"SRGE J170245.3+130104 was discovered by the eROSITA telescope aboard the SRG space observatory on March 13-15, 2020 during the first half-year scan of its all-sky X-ray survey. The optical counterpart of the X-ray source was photometrically identified as a distant quasar candidate at $zapprox5.5$. Follow-up spectroscopic observations, done in August/September 2020 with the SCORPIO-II instrument at the BTA 6-m telescope, confirmed that SRGE J170245.3+130104 is a distant quasar at redshift z=5.466. The X-ray luminosity of the quasar during the first half-year scan of the eROSITA all-sky survey was $3.6^{+2.1}_{-1.5}times 10^{46}$ erg/s (in the 2-10 keV energy range), whereas its X-ray spectrum could be described by a power law with a slope of $Gamma=1.8^{+0.9}_{-0.8}$. Six months later (September 13-14, 2020), during the second half-year scan of the eROSITA all-sky survey, the quasar was detected again and its X-ray luminosity had decreased by a factor of 2 (at the $approx 1.9sigma$ confidence level). The SRGE J170245.3+130104 proves to be the most X-ray luminous among all known X-ray quasars at $z>5$. It is also one of the radio-loudest distant quasars (with radio-loudness $Rsim10^3$), which may imply that it is a blazar. In the Appendix, we present the list of all $z>5$ quasars detected in X-rays to date.","PeriodicalId":8437,"journal":{"name":"arXiv: High Energy Astrophysical Phenomena","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90105431","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}
Pub Date : 2020-12-16DOI: 10.1051/0004-6361/202038621
A. Ratheesh, F. Tombesi, K. Fukumura, P. Soffitta, E. Costa, D. Kazanas
GRS 1915+105 being one of the brightest transient black hole binary (BHB) in the X-rays, offers a unique test-bed for the study of the connection between accretion and ejection mechanisms in BHBs. In particular, this source can be used to study the accretion disc wind and how it depends on the state changes in BHBs. Our aim is to investigate the origin and geometry of the accretion disc wind in GRS 1915+105. We analysed the spectra of GRS 1915+105 in the soft $phi$ and hard $chi$ classes, using the high resolution spectroscopy offered by Chandra HETGS. In the soft state, we find a series of wind absorption lines that follow a non linear dependence of velocity width, velocity shift and equivalent width with respect to ionisation, indicating a multiple component or stratified outflow. In the hard state we find only a faint Fe XXVI absorption line. We model the absorption lines in both the states using a dedicated MHD wind model to investigate a magnetic origin of the wind and to probe the cause of variability in the observed lines flux between the two states. The MHD disc wind model provides a good fit for both states, indicating the possibility of a magnetic origin of the wind. The multiple ionisation components of the wind are well characterised as a stratification of the same magnetic outflow. We find that the observed variability in the lines flux between soft and hard states cannot be explained by photo-ionisation alone but it is most likely due to a large (three orders of magnitude) increase in the wind density. We find the mass outflow rate of the wind to be comparable to the accretion rate, suggesting a intimate link between accretion and ejection processes that lead to state changes in BHBs.
{"title":"A variable magnetic disc wind in the black hole X-ray binary GRS 1915+105?","authors":"A. Ratheesh, F. Tombesi, K. Fukumura, P. Soffitta, E. Costa, D. Kazanas","doi":"10.1051/0004-6361/202038621","DOIUrl":"https://doi.org/10.1051/0004-6361/202038621","url":null,"abstract":"GRS 1915+105 being one of the brightest transient black hole binary (BHB) in the X-rays, offers a unique test-bed for the study of the connection between accretion and ejection mechanisms in BHBs. In particular, this source can be used to study the accretion disc wind and how it depends on the state changes in BHBs. Our aim is to investigate the origin and geometry of the accretion disc wind in GRS 1915+105. We analysed the spectra of GRS 1915+105 in the soft $phi$ and hard $chi$ classes, using the high resolution spectroscopy offered by Chandra HETGS. In the soft state, we find a series of wind absorption lines that follow a non linear dependence of velocity width, velocity shift and equivalent width with respect to ionisation, indicating a multiple component or stratified outflow. In the hard state we find only a faint Fe XXVI absorption line. We model the absorption lines in both the states using a dedicated MHD wind model to investigate a magnetic origin of the wind and to probe the cause of variability in the observed lines flux between the two states. The MHD disc wind model provides a good fit for both states, indicating the possibility of a magnetic origin of the wind. The multiple ionisation components of the wind are well characterised as a stratification of the same magnetic outflow. We find that the observed variability in the lines flux between soft and hard states cannot be explained by photo-ionisation alone but it is most likely due to a large (three orders of magnitude) increase in the wind density. We find the mass outflow rate of the wind to be comparable to the accretion rate, suggesting a intimate link between accretion and ejection processes that lead to state changes in BHBs.","PeriodicalId":8437,"journal":{"name":"arXiv: High Energy Astrophysical Phenomena","volume":"93 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90609377","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 report the emission variations in PSR J1047$-$6709 observed at 1369 MHz using the Parkes 64 m radio telescope. This pulsar shows two distinct emission states: a weak state and a bright emission state. We detected giant pulses (GPs) in the bright state for the first time. We found 75 GPs with pulse width ranging from 0.6 to 2.6 ms. The energy of GPs follows a power-law distribution with the index $alpha=-3.26pm0.22$. The peak flux density of the brightest GP is 19 Jy which is 110 times stronger than the mean pulse profile. The polarization properties of the average profile of GPs are similar to that of the pulses with energy less than 10 times average pulse energy in the bright state. This indicates that the emission mechanism is basically the same for them. Our results provide a new insight into the origin of the GPs in pulsars.
{"title":"Detection of giant pulses in PSR J1047−6709","authors":"S. N. Sun, W. Yan, N. Wang","doi":"10.1093/mnras/staa3825","DOIUrl":"https://doi.org/10.1093/mnras/staa3825","url":null,"abstract":"We report the emission variations in PSR J1047$-$6709 observed at 1369 MHz using the Parkes 64 m radio telescope. This pulsar shows two distinct emission states: a weak state and a bright emission state. We detected giant pulses (GPs) in the bright state for the first time. We found 75 GPs with pulse width ranging from 0.6 to 2.6 ms. The energy of GPs follows a power-law distribution with the index $alpha=-3.26pm0.22$. The peak flux density of the brightest GP is 19 Jy which is 110 times stronger than the mean pulse profile. The polarization properties of the average profile of GPs are similar to that of the pulses with energy less than 10 times average pulse energy in the bright state. This indicates that the emission mechanism is basically the same for them. Our results provide a new insight into the origin of the GPs in pulsars.","PeriodicalId":8437,"journal":{"name":"arXiv: High Energy Astrophysical Phenomena","volume":"159 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85027745","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}
Yuh Tsunetoe, S. Mineshige, K. Ohsuga, T. Kawashima, K. Akiyama
With unprecedented angular resolution, the Event Horizon Telescope (EHT) has opened a new era of black holes. We have previously calculated the expected polarization images of M87* with the EHT observations in mind. There, we demonstrated that circular polarization (CP) images, as well as the linear polarization (LP) maps, can convey quite useful information to us, such as the flow structure and magnetic field configuration around the black hole. In this paper, we make new predictions for the cases in which disk emission dominates over jet emission, bearing Sgr A* in mind. Here we set the proton-to-electron temperature ratio of the disk component to be Tp/Te $sim$ 2 so as to suppress jet emission relative to emission from accretion flow. As a result, we obtain ring-like images and triple-forked images around the black hole for face-on and edge-on cases, respectively. We also find significant CP components in the images ($gtrsim 10%$ in fraction), both with positive and negative signs, amplified through the Faraday conversion, not sensitively depending on the inclination angles. Furthermore, we find a "separatrix" in the CP images, across which the sign of CP is reversed and on which the LP flux is brightest, that can be attributed to the helical magnetic field structure in the disk. These results indicate that future full polarization EHT images are a quite useful tracer of the magnetic field structure. We also discuss to what extent we will be able to extract information regarding the magnetic field configurations, under the scattering in the interstellar plasma, in future EHT polarimetric observations of Sgr A*.
{"title":"Polarization images of accretion flow around supermassive black holes: Imprints of toroidal field structure","authors":"Yuh Tsunetoe, S. Mineshige, K. Ohsuga, T. Kawashima, K. Akiyama","doi":"10.1093/pasj/psab054","DOIUrl":"https://doi.org/10.1093/pasj/psab054","url":null,"abstract":"With unprecedented angular resolution, the Event Horizon Telescope (EHT) has opened a new era of black holes. We have previously calculated the expected polarization images of M87* with the EHT observations in mind. There, we demonstrated that circular polarization (CP) images, as well as the linear polarization (LP) maps, can convey quite useful information to us, such as the flow structure and magnetic field configuration around the black hole. In this paper, we make new predictions for the cases in which disk emission dominates over jet emission, bearing Sgr A* in mind. Here we set the proton-to-electron temperature ratio of the disk component to be Tp/Te $sim$ 2 so as to suppress jet emission relative to emission from accretion flow. As a result, we obtain ring-like images and triple-forked images around the black hole for face-on and edge-on cases, respectively. We also find significant CP components in the images ($gtrsim 10%$ in fraction), both with positive and negative signs, amplified through the Faraday conversion, not sensitively depending on the inclination angles. Furthermore, we find a \"separatrix\" in the CP images, across which the sign of CP is reversed and on which the LP flux is brightest, that can be attributed to the helical magnetic field structure in the disk. These results indicate that future full polarization EHT images are a quite useful tracer of the magnetic field structure. We also discuss to what extent we will be able to extract information regarding the magnetic field configurations, under the scattering in the interstellar plasma, in future EHT polarimetric observations of Sgr A*.","PeriodicalId":8437,"journal":{"name":"arXiv: High Energy Astrophysical Phenomena","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75037380","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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