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Low-mass active galactic nuclei on the fundamental plane of black hole activity

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arXiv 2017年

作者： Qian, Lei Dong, Xiao-Bo Xie, Fu-Guo Liu, Wenjuan Li, Di CAS Key Laboratory of FAST NAOC Chinese Academy of Sciences Beijing100012 China Yunnan Observatories Chinese Academy of Sciences Kunming Yunnan650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming Yunnan650011 China Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China

It is widely known that in active galactic nuclei (AGNs) and black hole X-ray binaries (BHXBs), there is a tight correlation among their radio luminosity (LR), X-ray luminosity (LX) and BH mass (MBH), the so-called 'fundamental plane' (FP) of BH activity. Yet the supporting data are very limited in the MBH regime between stellar mass (i.e., BHXBs) and 106.5 M☉ (namely, the lower bound of supermassive BHs in common AGNs). In this work, we developed a new method to measure the 1.4 GHz flux directly from the images of the VLA FIRST survey, and apply it to the type-1 low-mass AGNs in the Dong et al. (2012) sample. As a result, we obtained 19 new low-mass AGNs for FP research with both MBH estimates (MBH ≈ 105.5−6.5 M☉), reliable X-ray measurements, and (candidate) radio detections, tripling the number of such candidate sources in the literature. Most (if not all) of the low-mass AGNs follow the standard radio/X-ray correlation and the universal FP relation fitted with the combined dataset of BHXBs and supermassive AGNs by Gültekin et al. (2009);the consistency in the radio/X-ray correlation slope among those accretion systems supports the picture that the accretion and ejection (jet) processes are quite similar in all accretion systems of different MBH. In view of the FP relation, we speculate that the radio loudness R (i.e., the luminosity ratio of the jet to the accretion disk) of AGNs depends not only on Eddington ratio, but probably also on MBH. Copyright © 2017, The Authors. All rights reserved.

关键词： Galaxies

Synchrotron spectrum of fast cooling electrons in GRBs

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arXiv 2017年

作者： Zhao, Xiao-Hong Bai, Jin-Ming Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China

We discuss the synchrotron emission of fast cooling electrons in shocks. The fast cooling electrons behind the shocks can generate a position-dependent inhomogeneous electron distribution if they have not enough time to mix homogeneously. This would lead to a very different synchrotron spectrum in low frequency bands from that in the homogeneous case due to the synchrotron absorption. In this paper, we calculate the synchrotron spectrum in this inhomogeneous case in a gamma-ray burst (GRB). Both the forward shock and the reverse shock are considered. We find for the reverse shock dominated case, we would expect a "reverse shock bump" in the low frequency spectrum. The spectral bump is due to the combining synchrotron absorption in both the forward and reverse shock regions. In the forward shock spectrum in the low frequencies has two unconventional segments with spectral slopes of 1 and 11/8. The slope of 11/8 has been found by some authors, while the slope of 1 is new, which is due to the approximately constant electron temperature in the optically thick region. In the future, simultaneous observations in multiple bands (especially in the low frequency bands) in the GRB early afterglow or prompt emission phases will possibly reveal these spectral characteristics and enable us to identify the reverse shock component and distinguish between the forward and reverse shock emissions. This also may be as a method to diagnose the electron distribution status (homogeneous or inhomogeneous) after fast cooling in relativistic shock region. Copyright © 2017, The Authors. All rights reserved.

关键词： Cooling

Close binary evolution. III. impact of tides, wind magnetic braking, and internal angular momentum transport

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arXiv 2017年

作者： Song, H.F. Meynet, G. Maeder, A. Ekström, S. Eggenberger, P. Georgy, C. Qin, Y. Fragos, T. Soerensen, M. Barblan, F. Wade, G.A. College of Physics Guizhou University Guiyang CityGuizhou Province550025 China Geneva Observatory Geneva University SauvernyCH-1290 Switzerland Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 Guangxi Key Laboratory for Relativistic Astrophysics Department of Physics Guangxi University Nanning530004 China Department of Physics Royal Military College of Canada Ontario Canada

Context. Massive stars with solar metallicity lose important amounts of rotational angular momentum through their winds. When a magnetic field is present at the surface of a star, efficient angular momentum losses can still be achieved even when the mass-loss rate is very modest, at lower metallicities, or for lower-initial-mass stars. In a close binary system, the effect of wind magnetic braking also interacts with the influence of tides, resulting in a complex evolution of rotation. Aims. We study the interactions between the process of wind magnetic braking and tides in close binary systems. Methods. We discuss the evolution of a 10 M☉ star in a close binary system with a 7 M☉ companion using the Geneva stellar evolution code. The initial orbital period is 1.2 days. The 10 M☉ star has a surface magnetic field of 1 kG. Various initial rotations are considered. We use two different approaches for the internal angular momentum transport. In one of them, angular momentum is transported by shear and meridional currents. In the other, a strong internal magnetic field imposes nearly perfect solid-body rotation. The evolution of the primary is computed until the first mass-transfer episode occurs. The cases of different values for the magnetic fields and for various orbital periods and mass ratios are briefly discussed. Results. We show that, independently of the initial rotation rate of the primary and the efficiency of the internal angular momentum transport, the surface rotation of the primary will converge, in a time that is short with respect to the main-sequence lifetime, towards a slowly evolving velocity that is different from the synchronization velocity. This "equilibrium angular velocity" is always inferior to the angular orbital velocity. In a given close binary system at this equilibrium stage, the difference between the spin and the orbital angular velocities becomes larger when the mass losses and/or the surface magnetic field increase. The treatment of th

关键词： Angular momentum

Can turbulence dominate depolarization of optical blazars?

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arXiv 2017年

作者： Guo, Xiaotong Mao, Jirong Wang, Jiancheng Yunnan Observatories Chinese Academy of Sciences Kunming Yunnan Province650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang Dis-trict Beijing100012 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China University of Chinese Academy of Sciences Beijing100049 China

We carefully examine the depolarization feature of blazars in the optical and near-infrared bands using the sample of Mead et al. Magnetohydrodynamics (MHD) turbulence could be one possible reason for the depolarization of optical/infrared blazars when we apply the theoretical analysis of Lazarian & Pogosyan. We further identify in the sample that the depolarization results shown in most blazars roughly obey the form of the three-dimensional anisotropic Kolmogorov scaling. The effective Faraday rotation window length scale is not small enough to resolve the polarization correlation length scale in the blazar sample. The depolarization and the related turbulent features show diversities in different blazar sources. We suggest more simultaneous observations in both the optical/infrared and the high-energy bands for the study of the blazar polarization. Copyright © 2017, The Authors. All rights reserved.

关键词： Depolarization

Variable stars in the open cluster NGC 2141

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Research in Astronomy and Astrophysics 2015年第5期15卷 733-741页

作者： Yang-Ping Luo School of Physics & Electronic Information China West Normal University Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences

We report the results of a search for variable stars in the open cluster NGC 2141. Ten variable stars are detected, among which nine are new variable stars and they are classified as three short-period W UMa-type eclipsing binaries, two EA- type eclipsing binaries, one EB-type eclipsing binary, one very short-period RS CVn- type eclipsing binary, one d-type RR Lyrae variable star, and one unknown type of variable star. The membership and physical properties are discussed, based on their light curves, positions in the color magnitude diagrams, spatial locations and periods. A known EB-type eclipsing binary is also identified as a blue straggler candidate in the cluster. Furthermore, we find that all eclipsing contact binaries have prominent asymmetric eclipses and display the O＇Connell effect, which increases with a decrease in orbital periods. This suggests that the O＇Connell effect is probably related to the evolution of the orbital period in short period eclipsing binary systems.

关键词： stars binaries general -- open clusters and associations individual （NGC 2141） -- variables general

A method for locating high energy dissipation region in blazar

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arXiv 2017年

作者： Yan, Dahai Wu, Qingwen Fan, Xuliang Wang, Jiancheng Zhang, Li Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatory Chinese Academy of Sciences Kunming650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China School of Physics Huazhong University of Science and Technology Wuhan430074 China Key Laboratory of Astroparticle Physics of Yunnan Province Yunnan University Kunming650091 China

The production site of gamma-rays in blazar jet is an unresolved problem. We present a method to locate gamma-ray emission region in the framework of one-zone emission model. From measurements of core-shift effect, the relation between the magnetic field strengths (B′) in the radio cores of jet and the distances (R) of these radio cores from central supermassive black hole (SMBH) can be inferred. Therefore once the magnetic field strength in gamma-ray emission region (Bdiss′ ) is obtained, one can use the relation of B′-R to derive the distance (Rdiss) of gamma-ray emission region from SMBH. Here we evaluate the lower limit of Bdiss′ by using the criteria that the optical variability timescale tvar should be longer or equal to the synchrotron radiation cooling timescale of the electrons that emit optical photons. We test the method with the observations of PSK 1510-089 and BL Lacertae, and derive Rdiss D1/3(1 + A)2/3 pc for PSK 1510-089 with tvar ∼ a few hours, and Rdiss D1/3(1 + A)2/3 pc for BL Lacertae with tvar ∼ a few minutes. Here δD is the Doppler factor and A is the Compton dominance (i.e., the ratio of the Compton to the synchrotron peak luminosities). Copyright © 2017, The Authors. All rights reserved.

关键词： Synchrotron radiation

X-ray light curve in GRB 170714a: evidence for quark star?

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arXiv 2017年

作者： Hou, Shu-Jin Liu, Tong Xu, Ren-Xin Mu, Hui-Jun Song, Cui-Ying Lin, Da-Bin Gu, Wei-Min College of Physics and Electronic Engineering Nanyang Normal University Nanyang Henan473061 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming Yunnan650011 China Laboratory for Relativistic Astrophysics Department of Physics Guangxi University Nanning Guangxi530004 China Department of Astronomy Xiamen University XiamenFujian361005 China School of Physics Peking University Beijing100871 China

Two plateaus and one following bump in the X-ray light curve of GRB 170714A have been detected by the Swift/X-Ray Telescope, which could be very meaningful for the central engine of gamma-ray bursts (GRBs), implying that the origin of this burst might be different from that of other ultra-long GRBs. We propose that merging two neutron stars into a hyper-massive quark star (QS) and then collapsing into a black hole (BH), with a delay time around 104 s, could be responsible for those X-ray components. The hyper-massive QS is initially in a fluid state, being turbulent and differentially rotating, but would be solidified and release its latent heat injected into the GRB fireball (lasting about 103 s during the liquid-solid phase transition). Magnetic field as high as ∼ 1015 G could be created by dynamo action of the newborn liquid QS, and a magnetar-like central engine (after solidification) supplies significant energy for the second plateau. More energy could be released during a fall-back accretion after the post-merger QS collapses to a BH, and the X-ray bump forms. This post-merger QS model might be tested by future observations, with either advanced gravitational wave detectors (e.g., advanced LIGO and VIRGO) or X-ray/optical telescopes. Copyright © 2017, The Authors. All rights reserved.

关键词： Stars

Strong Carbon Features and a Red Early Color in the Underluminous Type Ia SN 2022xkq

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arXiv 2023年

作者： Pearson, Jeniveve Sand, David J. Lundqvist, Peter Galbany, Lluís Andrews, Jennifer E. Bostroem, K. Azalee Dong, Yize Hoang, Emily Hosseinzadeh, Griffin Janzen, Daryl Jencson, Jacob E. Lundquist, Michael J. Mehta, Darshana Retamal, Nicolás Meza Shrestha, Manisha Valenti, Stefano Wyatt, Samuel Anderson, Joseph P. Ashall, Chris Auchettl, Katie Baron, Eddie Blondin, Stéphane Burns, Christopher R. Cai, Yongzhi Chen, Ting-Wan Chomiuk, Laura Coulter, David A. Cross, Dane Davis, Kyle W. de Jaeger, Thomas DerKacy, James M. Desai, Dhvanil D. Dimitriadis, Georgios Do, Aaron Farah, Joseph R. Foley, Ryan J. Gromadzki, Mariusz Gutiérrez, Claudia P. Haislip, Joshua González Hernández, Jonay I. Hinkle, Jason T. Hoogendam, Willem B. Howell, D. Andrew Hoeflich, Peter Hsiao, Eric Huber, Mark E. Jha, Saurabh W. Palau, Cristina Jiménez Kilpatrick, Charles D. Kouprianov, Vladimir Kumar, Sahana Kwok, Lindsey A. Larison, Conor LeBaron, Natalie Le Saux, Xavier Lu, Jing McCully, Curtis Evans, Tycho Mera Milne, Peter Modjaz, Maryam Morrell, Nidia Müller-Bravo, Tomás E. Newsome, Megan Nicholl, Matt Gonzalez, Estefania Padilla Payne, Anna V. Pellegrino, Craig Phan, Kim Pineda-García, Jonathan Piro, Anthony L. Piscarreta, Lara Polin, Abigail Reichart, Daniel E. Rojas-Bravo, César Ryder, Stuart D. Salmaso, Irene Schwab, Michaela Shahbandeh, Melissa Shappee, Benjamin J. Siebert, Matthew R. Smith, Nathan Strader, Jay Taggart, Kirsty Terreran, Giacomo Tinyanont, Samaporn Tucker, M.A. Valerin, Giorgio Young, D.R. Steward Observatory University of Arizona 933 North Cherry Avenue TucsonAZ85721-0065 United States Oskar Klein Centre Department of Astronomy Stockholm University Albanova University Centre StockholmSE-106 91 Sweden Campus UAB Carrer de Can Magrans s/n BarcelonaE-08193 Spain Institut d’Estudis Espacials de Catalunya Gran Capità 2-4 Edifici Nexus Desp. 201 BarcelonaE-08034 Spain Gemini Observatory 670 North A‘ohoku Place HiloHI96720-2700 United States Department of Physics and Astronomy University of California Davis 1 Shields Avenue DavisCA95616-5270 United States Department of Physics & Engineering Physics University of Saskatchewan 116 Science Place SaskatoonSKS7N 5E2 Canada Department of Physics and Astronomy The Johns Hopkins University 3400 North Charles Street BaltimoreMD21218 United States W. M. Keck Observatory 65-1120 Māmalahoa Highway KamuelaHI96743-8431 United States Department of Astronomy University of Washington 3910 15th Avenue NE SeattleWA98195-0002 United States European Southern Observatory Alonso de Córdova 3107 Casilla 19 Santiago Chile Millennium Institute of Astrophysics MAS Nuncio Monsenor Sotero Sanz 100 Off. 104 Providencia Santiago Chile Department of Physics Virginia Tech 850 West Campus Drive BlacksburgVA24061 United States School of Physics The University of Melbourne ParkvilleVIC3010 Australia Department of Astronomy and Astrophysics University of California Santa CruzCA95064-1077 United States Planetary Science Institute 1700 East Fort Lowell Road Suite 106 TucsonAZ85719-2395 United States Hamburger Sternwarte Gojenbergsweg 112 Hamburg21029 Germany Homer L. Dodge Department of Physics and Astronomy University of Oklahoma 440 W. Brooks NormanOK73019-2061 United States Aix-Marseille Univ CNRS CNES LAM Marseille13388 France Observatories of the Carnegie Institute for Science 813 Santa Barbara Street PasadenaCA91101-1232 United States Yunnan Observatories Chinese Academy of

We present optical, infrared, ultraviolet, and radio observations of SN 2022xkq, an underluminous fast-declining type Ia supernova (SN Ia) in NGC 1784 (D ≈ 31 Mpc), from Copyright © 2023, The Authors. All rights... 详细信息

关键词： Explosions

A study in scarlet - II. Spectroscopic properties of a sample of Intermediate Luminosity Red Transients

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arXiv 2024年

作者： Valerin, G. Pastorello, A. Mason, E. Reguitti, A. Benetti, S. Cai, Y.-Z. Chen, T.-W. Eappachen, D. Elias-Rosa, N. Fraser, M. Gangopadhyay, A. Hsiao, E.Y. Howell, D.A. Inserra, C. Izzo, L. Jencson, J. Kankare, E. Kotak, R. Lundqvist, P. Mazzali, P.A. Misra, K. Pignata, G. Prentice, S.J. Sand, D.J. Smartt, S.J. Stritzinger, M.D. Tartaglia, L. Valenti, S. Anderson, J.P. Andrews, J.E. Amaro, R.C. Barbarino, C. Brennan, S. Bufano, F. Callis, E. Cappellaro, E. Dastidar, R. Valle, M. Della Fiore, A. Fulton, M.D. Galbany, L. Gromadzki, M. Heikkilä, T. Hiramatsu, D. Karamehmetoglu, E. Kuncarayakti, H. Leloudas, G. Limongi, M. Lundquist, M. Müller-Bravo, T.E. Nicholl, M. Ochner, P. Gonzalez, E. Padilla Paraskeva, E. Pellegrino, C. Rau, A. Reichart, D.E. Reynolds, T.M. Roy, R. Salmaso, I. Shahbandeh, M. Singh, M. Sollerman, J. Turatto, M. Tomasella, L. Wyatt, S. Young, D.R. INAF – Osservatorio Astronomico di Padova Vicolo dell’Osservatorio 5 PadovaI-35122 Italy INAF – OATS Via G.B. Tiepolo 11 Trieste34143 Italy INAF – Osservatorio Astronomico di Brera Via E. Bianchi 46 LC Merate23807 Italy Yunnan Observatories Chinese Academy of Sciences Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Graduate Institute of Astronomy National Central University 300 Jhongda Road Jhongli32001 Taiwan SRON Netherlands Institute for Space Research Niels Bohrweg 4 Leiden2333 CA Netherlands Department of Astrophysics IMAPP Radboud University Nijmegen P.O. Box 9010 Nijmegen6500 GL Netherlands Campus UAB Carrer de Can Magrans s/n BarcelonaE-08193 Spain School of Physics O’Brien Centre for Science North University College Dublin BelfieldDublin 4 Ireland The Oskar Klein Centre Department of Astronomy Stockholm University AlbaNova StockholmSE-10691 Sweden Hiroshima Astrophysical Science Center Hiroshima University Japan Department of Physics Florida State University 77 Chieftan Way TallahasseeFL32306 United States Las Cumbres Observatory 6740 Cortona Dr. Suite 102 GoletaCA93117 United States Department of Physics University of California Santa BarbaraCA93106 United States Cardiff Hub for Astrophysics Research and Technology School of Physics & Astronomy Cardiff University Queens Buildings The Parade CardiffCF24 3AA United Kingdom INAF Osservatorio Astronomico di Capodimonte Salita Moiariello 16 NapoliI-80131 Italy DARK Niels Bohr Institute University of Copenhagen Jagtvej 128 Copenhagen2200 Denmark Caltech/IPAC Mailcode 100-22 PasadenaCA91125 United States Tuorla Observatory Department of Physics and Astronomy University of Turku Turku20014 Finland Department of Astronomy AlbaNova University Center Stockholm University StockholmSE-10691 Swede

Aims. We investigate the spectroscopic characteristics of Intermediate Luminosity Red Transients (ILRTs), a class of elusive objects with peak luminosity between that of classical novae and standard supernovae. Our goal is to provide a stepping stone in the path to unveil the physical origin of such events, thanks to the analysis of the datasets collected. Methods. We present the extensive optical and near-infrared (NIR) spectroscopic monitoring of four ILRTs, namely NGC 300 2008OT-1, AT 2019abn, AT 2019ahd and AT 2019udc. First we focus on the evolution of the most prominent spectral features observed in the low resolution spectra, then we discuss more in detail the high resolution spectrum collected for NGC 300 2008OT-1 with the Very Large Telescope equipped with UVES. Finally we analyse late time spectra of NGC 300 2008OT-1 and AT 2019ahd through comparisons with both synthetic and observed spectra. Results. Balmer and Ca lines dominate the optical spectra, revealing the presence of slowly moving circumstellar medium (CSM) around the objects. The line luminosity of Hα, Hβ and Ca II NIR triplet presents a double peaked evolution with time, possibly indicative of interaction between fast ejecta and the slow CSM. The high resolution spectrum of NGC 300 2008OT-1 reveals a complex circumstellar environment, with the transient being surrounded by a slow (∼30 km s−1) progenitor wind. At late epochs, optical spectra of NGC 300 2008OT-1 and AT 2019ahd show broad (∼2500 km s−1) emission features at ∼6170Å and ∼7000Å which are unprecedented for ILRTs. We find that these lines originate most likely from the blending of several narrow lines, possibly of iron-peak elements. © 2024, CC BY.

关键词： Infrared devices