arXiv: High Energy Astrophysical Phenomena最新文献_第4页

Locating the gamma-ray emission region in the brightest Fermi-LAT flat-spectrum radio quasars 在最亮的Fermi-LAT平谱射电类星体中定位伽玛射线发射区域

arXiv: High Energy Astrophysical Phenomena Pub Date : 2020-11-02 DOI: 10.1093/mnras/staa3483

A. Acharyya, P. Chadwick, A. Brown

{"title":"Locating the gamma-ray emission region in the brightest Fermi-LAT flat-spectrum radio quasars","authors":"A. Acharyya, P. Chadwick, A. Brown","doi":"10.1093/mnras/staa3483","DOIUrl":"https://doi.org/10.1093/mnras/staa3483","url":null,"abstract":"We present a temporal and spectral analysis of the gamma-ray flux from nine of the brightest flat spectrum radio quasars (FSRQs) detected with the Fermi Large Area Telescope (LAT) during its first eight years of operation, with the aim of constraining the location of the emission region. Using the increased photon statistics provided from the two brightest flares of each source, we find evidence of sub-hour variability from B2 1520+31, PKS 1502+106 and PKS 1424-41, with the remaining sources showing variability on timescales of a few hours. These indicate gamma-ray emission from extremely compact regions in the jet, potentially compatible with emission from within the broad line region (BLR). The flare spectra show evidence of a spectral cut-off in 7 of the 18 flares studied, further supporting the argument for BLR emission in these sources. An investigation into the energy dependence of cooling timescales finds evidence for both BLR origin and emission from within the molecular torus (MT). However, Monte Carlo simulations show that the very high energy (VHE) emission from all sources except 3C 279, 3C 454.3 and 4C 21.35 is incompatible with a BLR origin. The combined findings of all the approaches used suggest that the gamma-ray emission in the brightest FSRQs originates in multiple compact emission regions throughout the jet, within both the BLR and the MT.","PeriodicalId":8437,"journal":{"name":"arXiv: High Energy Astrophysical Phenomena","volume":"os-54 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87369687","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}

引用次数: 13

Radiative-transfer modeling of supernovae in the nebular-phase 超新星在星云期的辐射传输模型

arXiv: High Energy Astrophysical Phenomena Pub Date : 2020-11-01 DOI: 10.1051/0004-6361/202039287

L. Dessart, D. Hillier

{"title":"Radiative-transfer modeling of supernovae in the nebular-phase","authors":"L. Dessart, D. Hillier","doi":"10.1051/0004-6361/202039287","DOIUrl":"https://doi.org/10.1051/0004-6361/202039287","url":null,"abstract":"Supernova (SN) explosions, through the metals they release, play a pivotal role in the chemical evolution of the Universe and the origin of life. Nebular phase spectroscopy constrains such metal yields, for example through forbidden line emission associated with OI, CaII, FeII, or FeIII. Fluid instabilities during the explosion produce a complex 3D ejecta structure, with considerable macroscopic, but no microscopic, mixing of elements. This structure sets a formidable challenge for detailed nonlocal thermodynamic equilibrium radiative transfer modeling, which is generally limited to 1D in grid-based codes. Here, we present a novel and simple method that allows for macroscopic mixing without any microscopic mixing, thereby capturing the essence of mixing in SN explosions. With this new technique, the macroscopically mixed ejecta is built by shuffling in mass space, or equivalently in velocity space, the shells from the unmixed coasting ejecta. The method requires no change to the radiative transfer, but necessitates high spatial resolution to resolve the rapid variation in composition with depth inherent to this shuffled-shell structure. We show results for a few radiative-transfer simulations for a Type II SN explosion from a 15Msun progenitor star. Our simulations capture the strong variations in temperature or ionization between the various shells that are rich in H, He, O, or Si. Because of nonlocal energy deposition, gamma rays permeate through an extended region of the ejecta, making the details of the shell arrangement unimportant. The greater physical consistency of the method delivers spectral properties at nebular times that are more reliable, in particular in terms of individual emission line strengths, which may serve to constrain the SN yields and, for core collapse SNe, the progenitor mass. The method works for all SN types.","PeriodicalId":8437,"journal":{"name":"arXiv: High Energy Astrophysical Phenomena","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86957279","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}

引用次数: 2

Optical spectral characterization of the gamma-ray blazars S4 0954+65, TXS 1515−273, and RX J0812.0+0237 伽玛射线耀变体S4 0954+65、TXS 1515−273和RX J0812.0+0237的光谱特征

arXiv: High Energy Astrophysical Phenomena Pub Date : 2020-10-27 DOI: 10.1093/mnras/stab1274

J. Gonz'alez, J. Acosta-Pulido, W. Boschin, R. Clavero, J. Otero-Santos, J. Carballo-Bello, L. Domínguez-Palmero

{"title":"Optical spectral characterization of the gamma-ray blazars S4 0954+65, TXS 1515−273, and RX J0812.0+0237","authors":"J. Gonz'alez, J. Acosta-Pulido, W. Boschin, R. Clavero, J. Otero-Santos, J. Carballo-Bello, L. Domínguez-Palmero","doi":"10.1093/mnras/stab1274","DOIUrl":"https://doi.org/10.1093/mnras/stab1274","url":null,"abstract":"The study of gamma-ray blazars is usually hindered due to the lack of information on their redshifts and on their low energy photon fields. This information is key to understand the effect on the gamma-ray absorption due to either extragalactic background light and/or intrinsic absorption and emission processes. All this information has also an impact on the determination of the location of the emitting region within the relativistic jets. In this work a new optical spectroscopic characterization is presented for three gamma-ray blazars: S4 0954+65, TXS 1515-273 and RX J0812.0+0237. For all the three targets the redshift determination was successful as well as their classification, belonging all of them to the BL Lac type. For S4 0954+65 (z=$0.3694pm0.0011$) an estimation on the disk, broad line region and torus luminosities was performed based on the observed optical emission lines. The results from this study are compatible with the nature of S4 0954+65 as a transitional blazar. In the case of TXS 1515-273 ($z=0.1281pm 0.0004$), although its optical spectrum is dominated by the continuum emission from the jet, applying the pPXF technique, the stellar population is compatible with an old and metallic population. It is also the case of RX J0812.0+0237 ($z=0.1721pm 0.0002$). Moreover, this work confirms that the optical spectrum from RX J0812.0+0237 is compatible with an extreme blazar classification.","PeriodicalId":8437,"journal":{"name":"arXiv: High Energy Astrophysical Phenomena","volume":"156 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73636131","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}

引用次数: 6

Neutrino emission from an off-axis jet driven by the tidal disruption event AT2019dsg 由潮汐破坏事件AT2019dsg驱动的离轴射流发射的中微子

arXiv: High Energy Astrophysical Phenomena Pub Date : 2020-10-26 DOI: 10.1103/PhysRevD.102.083028

Ruo-Yu Liu, S. Xi, Xiang-Yu Wang

{"title":"Neutrino emission from an off-axis jet driven by the tidal disruption event AT2019dsg","authors":"Ruo-Yu Liu, S. Xi, Xiang-Yu Wang","doi":"10.1103/PhysRevD.102.083028","DOIUrl":"https://doi.org/10.1103/PhysRevD.102.083028","url":null,"abstract":"Recently, a high-energy muon neutrino event was detected in association with a tidal disruption event (TDE) AT2019dsg at the time about 150 days after the peak of the optical/UV luminosity. We propose that such a association could be interpreted as arising from hadronic interactions between relativistic protons accelerated in the jet launched from the TDE and the intense radiation field of TDE inside the optical/UV photosphere, if we are observing the jet at a moderate angle (i.e., approximately 10-30 degree) with respect to the jet axis. Such an off-axis viewing angle leads to a high gas column density in the line of sight which provides a high opacity for the photoionization and the Bethe-Heitler process, {and allows the existence of an intrinsic long-term X-ray radiation of comparatively high emissivity}. As a result, the cascade emission accompanying the neutrino production, which would otherwise overshoot the flux limits in X-ray and/or GeV band, is significantly obscured or absorbed. Since the jets of TDEs are supposed to be randomly oriented in the sky, the source density rate of TDE with an off-axis jet is significantly higher than that of TDE with an on-axis jet. Therefore, an off-axis jet is naturally expected in a nearby TDE being discovered, supporting the proposed scenario.","PeriodicalId":8437,"journal":{"name":"arXiv: High Energy Astrophysical Phenomena","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88007768","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}

引用次数: 9

Is PSR J0855−4644 responsible for the 1.4 TeV electron spectral bump hinted by DAMPE? PSR J0855−4644是DAMPE暗示的1.4 TeV电子能谱碰撞的原因吗?

arXiv: High Energy Astrophysical Phenomena Pub Date : 2020-10-23 DOI: 10.1093/mnras/staa3311

Y. Bao, Yang Chen, Siming Liu

引用次数: 2

AstroSat soft X-ray observations of the symbiotic recurrent nova V3890 Sgr during its 2019 outburst AstroSat在2019年爆发期间对共生复发新星V3890 Sgr的软x射线观测

arXiv: High Energy Astrophysical Phenomena Pub Date : 2020-10-22 DOI: 10.1093/mnras/staa3303

K. Singh, V. Girish, M. Pavana, M. Pavana, J. Ness, G. Anupama, M. Orio, M. Orio

{"title":"AstroSat soft X-ray observations of the symbiotic recurrent nova V3890 Sgr during its 2019 outburst","authors":"K. Singh, V. Girish, M. Pavana, M. Pavana, J. Ness, G. Anupama, M. Orio, M. Orio","doi":"10.1093/mnras/staa3303","DOIUrl":"https://doi.org/10.1093/mnras/staa3303","url":null,"abstract":"Two long AstroSat Soft X-ray Telescope observations were taken of the third recorded outburst of the Symbiotic Recurrent Nova, V3890 Sgr. The first observing run, 8.1-9.9 days after the outburst, initially showed a stable intensity level with a hard X-ray spectrum that we attribute to shocks between the nova ejecta and the pre-existing stellar companion. On day 8.57, the first, weak, signs appeared of Super Soft Source (SSS) emission powered by residual burning on the surface of the White Dwarf. The SSS emission was observed to be highly variable on time scales of hours. After day 8.9, the SSS component was more stable and brighter. In the second observing run, on days 15.9-19.6 after the outburst, the SSS component was even brighter but still highly variable. The SSS emission was observed to fade significantly during days 16.8-17.8 followed by re-brightening. Meanwhile the shock component was stable leading to increase in hardness ratio during the period of fading. AstroSat and XMM-Newton observations have been used to study the spectral properties of V3890 Sgr to draw quantitative conclusions even if their drawback is model-dependence. We used the xspec to fit spectral models of plasma emission, and the best fits are consistent with the elemental abundances being lower during the second observing run compared to the first for spectra >1 keV. The SSS emission is well fit by non-local thermal equilibrium model atmosphere used for white dwarfs. The resulting spectral parameters, however, are subject to systematic uncertainties such as completeness of atomic data.","PeriodicalId":8437,"journal":{"name":"arXiv: High Energy Astrophysical Phenomena","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76536667","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}

引用次数: 5

QCD color superconductivity in compact stars: Color-flavor locked quark star candidate for the gravitational-wave signal GW190814 致密恒星中的QCD彩色超导性:引力波信号GW190814的色味锁定夸克星候选者

arXiv: High Energy Astrophysical Phenomena Pub Date : 2020-10-21 DOI: 10.1103/PHYSREVD.103.083015

Z. Roupas, G. Panotopoulos, I. Lopes

{"title":"QCD color superconductivity in compact stars: Color-flavor locked quark star candidate for the gravitational-wave signal GW190814","authors":"Z. Roupas, G. Panotopoulos, I. Lopes","doi":"10.1103/PHYSREVD.103.083015","DOIUrl":"https://doi.org/10.1103/PHYSREVD.103.083015","url":null,"abstract":"At sufficiently high densities and low temperatures matter is expected to behave as a degenerate Fermi gas of quarks forming Cooper pairs, namely a color superconductor, as was originally suggested by Alford, Rajagopal and Wilczek. The ground state is a superfluid, an electromagnetic insulator that breaks chiral symmetry, called the color-flavor locked phase. If such a phase occurs in the cores of compact stars, the maximum mass may exceed that of hadronic matter. The gravitational-wave signal GW190814 involves a compact object with mass $2.6{rm M}_odot$, within the so-called low mass gap. Since it is too heavy to be a neutron star and too light to be a black hole, its nature has not been identified with certainty yet. Here, we show not only that a color-flavor locked quark star with this mass is viable, but also we calculate the range of the model-parameters, namely the color superconducting gap $Delta$ and the bag constant $B$, that satisfies the strict LIGO constraints on the equation of state. We find that a color-flavor locked quark star with mass $2.6{rm M}_odot$ satisfies the observational constraints on the equation of state if $Delta geq 200{rm MeV}$ and $Bgeq 83{ rm MeV}/{rm fm^3}$ for a strange quark mass $m_s=95~{rm MeV}/c^2$, and attains a radius $(12.7-13.6) {rm km}$ and central density $(7.5-9.8) 10^{14}{rm g}/{rm cm}^3$.","PeriodicalId":8437,"journal":{"name":"arXiv: High Energy Astrophysical Phenomena","volume":"90 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83911071","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}

引用次数: 23

Transitional millisecond pulsars. 过渡毫秒脉冲星。

arXiv: High Energy Astrophysical Phenomena Pub Date : 2020-10-18 DOI: 10.1007/978-3-030-85198-9_6

A. Papitto, D. Martino

引用次数: 8

High-Frequency Variability in Neutron-Star Low-Mass X-ray Binaries 中子星低质量x射线双星的高频变异性

arXiv: High Energy Astrophysical Phenomena Pub Date : 2020-10-16 DOI: 10.1007/978-3-662-62110-3_6

M. M'endez, T. B. A. Institute, U. Groningen, The Netherlands., I. Brera, Merate, Italy.

引用次数: 3

Magnetic field evolution time-scales in superconducting neutron stars 超导中子星磁场演化时标

arXiv: High Energy Astrophysical Phenomena Pub Date : 2020-10-15 DOI: 10.1093/mnras/staa3160

M. Gusakov, E. Kantor, D. Ofengeim

引用次数: 12