21 research outputs found
The June 2016 Optical and Gamma-Ray Outburst and Optical Micro-Variability of the Blazar 3C454.3
The quasar 3C454.3 underwent a uniquely-structured multi-frequency outburst
in June 2016. The blazar was observed in the optical band by several
ground-based telescopes in photometric and polarimetric modes, at -ray
frequencies by the \emph{Fermi}\ Large Area Telescope, and at 43 GHz with the
Very Long Baseline Array. The maximum flux density was observed on 2016 June 24
at both optical and -ray frequencies, reaching
mJy and ph cm s, respectively. The June 2016
outburst possessed a precipitous decay at both -ray and optical
frequencies, with the source decreasing in flux density by a factor of 4 over a
24-hour period in band. Intraday variability was observed throughout the
outburst, with flux density changes between 1 and 5 mJy over the course of a
night. The precipitous decay featured statistically significant quasi-periodic
micro-variability oscillations with an amplitude of - about the
mean trend and a characteristic period of 36 minutes. The optical degree of
polarization jumped from to nearly 20\% during the outburst, while
the position angle varied by \sim120\degr. A knot was ejected from the 43 GHz
core on 2016 Feb 25, moving at an apparent speed .
From the observed minimum timescale of variability
hr and derived Doppler factor
, we find a size of the emission region
cm. If the quasi-periodic micro-variability
oscillations are caused by periodic variations of the Doppler factor of
emission from a turbulent vortex, we derive a rotational speed of the vortex
.Comment: 19 pages, 13 figures, 3 tables, accepted to the Astrophysical Journal
2019 March
Emission-line Variability during a Nonthermal Outburst in the Gamma-Ray Bright Quasar 1156+295
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.We present multi-epoch optical spectra of the γ-ray bright blazar 1156+295 (4C +29.45, Ton 599) obtained with the 4.3 m Lowell Discovery Telescope. During a multiwavelength outburst in late 2017, when the γ-ray flux increased to 2.5 × 10−6 phot cm−2 s−1 and the quasar was first detected at energies ≥100 GeV, the flux of the Mg ii λ2798 emission line changed, as did that of the Fe emission complex at shorter wavelengths. These emission-line fluxes increased along with the highly polarized optical continuum flux, which is presumably synchrotron radiation from the relativistic jet, with a relative time delay of ≲2 weeks. This implies that the line-emitting clouds lie near the jet, which points almost directly toward the line of sight. The emission-line radiation from such clouds, which are located outside the canonical accretion-disk related broad-line region, may be a primary source of seed photons that are up-scattered to γ-ray energies by relativistic electrons in the jet. © 2022. The Author(s). Published by the American Astronomical Society.This research was supported in part by NASA Fermi guest investigator program grants 80NSSC19K1504 and 80NSSC20K1565. We thank A. Tchekhovskoy for discussion of possible origins of the variable line-emitting clouds. These results made use of the Lowell Discovery Telescope (LDT) at Lowell Observatory. Lowell Observatory is a private, non-profit institution dedicated to astrophysical research and public appreciation of astronomy, and operates the LDT in partnership with Boston University, the University of Maryland, the University of Toledo, Northern Arizona University and Yale University. This study was based in part on observations conducted using the 1.8 m Perkins Telescope Observatory (PTO) in Arizona, which is owned and operated by Boston University. I.A. acknowledges financial support from the Spanish "Ministerio de Ciencia e Innovación" (MCINN) through the "Center of Excellence Severo Ochoa" award for the Instituto de Astrofísica de Andalucía-CSIC (SEV-2017-0709). Acquisition and reduction of the MAPCAT data were supported in part by MICINN through grants AYA2016-80889-P and PID2019-107847RB-C44. The MAPCAT observations were carried out at the German-Spanish Calar Alto Observatory, which is jointly operated by Junta de Andalucía and Consejo Superior de Investigaciones Científicas. Data from the Steward Observatory spectropolarimetric monitoring project were used; this program was supported by Fermi Guest Investigator grants NNX08AW56G, NNX09AU10G, NNX12AO93G, and NNX15AU81G. C.C. acknowledges support from the European Research Council (ERC) under the European Union Horizon 2020 research and innovation program under the grant agreement No. 771282.Peer reviewe
Multiwavelength behaviour of the blazar 3C 279: Decade-long study from γ -ray to radio
We report the results of decade-long (2008-2018) γ -ray to 1 GHz radio monitoring of the blazar 3C 279, including GASP/WEBT, Fermi and Swift data, as well as polarimetric and spectroscopic data. The X-ray and γ -ray light curves correlate well, with no delay ≳ 3 h, implying general cospatiality of the emission regions. The γ -ray-optical flux-flux relation changes with activity state, ranging from a linear to amore complex dependence. The behaviour of the Stokes parameters at optical and radio wavelengths, including 43 GHz Very Long Baseline Array images, supports either a predominantly helical magnetic field or motion of the radiating plasma along a spiral path. Apparent speeds of emission knots range from 10 to 37c, with the highest values requiring bulk Lorentz factors close to those needed to explain γ -ray variability on very short time-scales. The MgII emission line flux in the 'blue' and 'red' wings correlates with the optical synchrotron continuum flux density, possibly providing a variable source of seed photons for inverse Compton scattering. In the radio bands, we find progressive delays of the most prominent light-curve maxima with decreasing frequency, as expected from the frequency dependence of the τ= 1 surface of synchrotron self-absorption. The global maximum in the 86 GHz light curve becomes less prominent at lower frequencies, while a local maximum, appearing in 2014, strengthens toward decreasing frequencies, becoming pronounced at ∼5 GHz. These tendencies suggest different Doppler boosting of stratified radio-emitting zones in the jet. © 2020 The Author(s).We thank the referee for attentive reading and comments that helped to improve presentation of the manuscript. The data collected by the WEBT collaboration are stored in the WEBT archive at the Osservatorio Astrofisico di Torino -INAF (ht tp://www.oato.inaf.it/blazars/webt/); for questions regarding their availability, please contact the WEBT President Massimo Villata([email protected]).TheSt.Petersburg University team acknowledges support from Russian Science Foundation grant 17-12-01029. The research at BU was supported in part by National Science Foundation grant AST-1615796 and NASA Fermi Guest Investigator grants 80NSSC17K0649, 80NSSC19K1504, and 80NSSC19K1505. The PRISM camera at Lowell Observatory was developed by K. Janes et al. at BU and Lowell Observatory, with funding from the NSF, BU, and Lowell Observatory. The emission-line observations made use of the DCT at Lowell Observatory, supported by Discovery Communications, Inc., BU, the University of Maryland, the University of Toledo, and Northern Arizona University. The VLBA is an instrument of the National Radio Astronomy Observatory. The National Radio Astronomy Observatory is a facility of the US NSF, operated under cooperative agreement by Associated Universities, Inc. This research has used data from the UMRAO which was supported by the University of Michigan; research at this facility was supported by NASA under awards NNX09AU16G, NNX10AP16G, NNX11AO13G, and NNX13AP18G, and by the NSF under award AST-0607523. The Steward Observatory spectropolarimetric monitoring project was supported by NASA Fermi Guest Investigator grants NNX08AW56G, NNX09AU10G, NNX12AO93G, and NNX15AU81G. The Torino group acknowledges financial contribution from agreement ASI-INAF n.2017-14-H.0 and from contract PRIN-SKA-CTA-INAF 2016. I.A. acknowledges support by a Ramon y Cajal grant (RYC-2013-14511) of the 'Ministerio de Ciencia, Innovacion, y Universidades (MICIU)' of Spain and from MCIU through the 'Center of Excellence Severo Ochoa' award for the Instituto de Astrofisica de Andalucia-CSIC (SEV-20170709). Acquisition and reduction of the POLAMI and MAPCAT data were supported by MICIU through grant AYA2016-80889-P. The POLAMI observations were carried out at the IRAM 30-m Telescope, supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). The MAPCAT observations were carried out at theGerman-Spanish Calar Alto Observatory, jointly operated by the Max-Plank-Institut fur Astronomie and the Instituto de Astrofisica de Andalucia-CSIC. The study is based partly on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated by AIP and IAC. The OVRO 40-m monitoring program is supported in part by NASA grants NNX08AW31G, NNX11A043G, and NNX14AQ89G, and NSF grants AST-0808050 and AST-1109911. TH was supported by the Academy of Finland projects 317383 and 320085. AZT-24 observations were made within an agreement between Pulkovo, Rome and Teramo observatories. The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. The Abastumani team acknowledges financial support by the Shota Rustaveli National Science Foundation under contract FR/217950/16.
r This research was partially supported by the Bulgarian National Science Fund of the Ministry of Education and Science under grants DN 081/2016, DN 18-13/2017, KP-06-H28/3 (2018), and KP-06-PN38/1 (2019), Bulgarian National Science Programme 'Young Scientists and Postdoctoral Students 2019', Bulgarian National Science Fund under grant DN18-10/2017 and National RI Roadmap Projects DO1-157/28.08.2018 and DO1-153/28.08.2018 of the Ministry of Education and Science of the Republic of Bulgaria. GD and OV gratefully acknowledge observing grant support from the Institute of Astronomy and Rozhen National Astronomical Observatory via bilateral joint research project `Study of ICRF radio-sources and fast variable astronomical objects' (head -G. Damljanovic). This work was partly supported by the National Science Fund of the Ministry of Education and Science of Bulgaria under grant DN 08-20/2016, and by project RD-08-37/2019 of the University of Shumen. This work is a part of projects nos 176011, 176004, and 176021, supported by theMinistry of Education, Science and Technological Development of the Republic of Serbia. MGM acknowledges support through the Russian Government Program of Competitive Growth of Kazan Federal University. The Astronomical Observatory of the Autonomous Region of the Aosta Valley (OAVdA) is managed by the Fondazione Clement Fillietroz-ONLUS, which is supported by the Regional Government of the Aosta Valley, the Town Municipality of Nus and the 'Unite des Communes vald 'otainesMont-Emilius'. The research at the OAVdA was partially funded by several `Research and Education' annual grants from Fondazione CRT. This article is partly based on observations made with the IAC80 and TCS telescopes operated by the Instituto de Astrofisica de Canarias in the Spanish Observatorio del Teide on the island of Tenerife. A part of the observations were carried out using theRATAN-600 scientific equipment (SAO of the Russian Academy of Sciences)
Detection of the blazar S4 0954+65 at very-high-energy with the MAGIC telescopes during an exceptionally high optical state
The very high energy (VHE ¿ 100 GeV) -ray MAGIC observations of the blazar S4 0954+65, were triggered by an exceptionally high flux state of emission in the optical. This blazar has a disputed redshift of z = 0.368 or z ¿ 0.45 and an uncertain classification among blazar subclasses. The exceptional source state described here makes for an excellent opportunity to understand physical processes in the jet of S4 0954+65 and thus contribute to its classification. Methods. We investigated the multiwavelength (MWL) light curve and spectral energy distribution (SED) of the S4 0954+65 blazar during an enhanced state in February 2015 and have put it in context with possible emission scenarios. We collected photometric data in radio, optical, X-ray, and ¿-ray. We studied both the optical polarization and the inner parsec-scale jet behavior with 43 GHz data. Results. Observations with the MAGIC telescopes led to the first detection of S4 0954+65 at VHE. Simultaneous data with Fermi-LAT at high energy ¿-ray(HE, 100 MeV < E < 100 GeV) also show a period of increased activity. Imaging at 43 GHz reveals the emergence of a new feature in the radio jet in coincidence with the VHE flare. Simultaneous monitoring of the optical polarization angle reveals a rotation of approximately 100. Conclusions. The high emission state during the flare allows us to compile the simultaneous broadband SED and to characterize it in the scope of blazar jet emission models. The broadband spectrum can be modeled with an emission mechanism commonly invoked for flat spectrum radio quasars (FSRQs), that is, inverse Compton scattering on an external soft photon field from the dust torus, also known as external Compton. The light curve and SED phenomenology is consistent with an interpretation of a blob propagating through a helical structured magnetic field and eventually crossing a standing shock in the jet, a scenario typically applied to FSRQs and low-frequency peaked BL Lac objects (LBL). © ESO 2018.The financial support of the German BMBF and MPG, the Italian INFN and INAF, the Swiss National Fund SNF, the ERDF under the Spanish MINECO (FPA2015-69818-P, FPA2012-36668, FPA2015-68378-P, FPA2015-69210-C6-2-R, FPA2015-69210-C6-4-R, FPA2015-69210-C6-6-R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP2015-71662-C2-2-P, CSD2009-00064), and the Japanese JSPS and MEXT is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia “Severo Ochoa” SEV-2012-0234 and SEV-2015-0548, and Unidad de Excelencia “María de Maeztu” MDM-2014-0369, by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382 and by the Brazilian MCTIC, CNPq, and FAPERJ. IA acknowledges support by a Ramón y Cajal grant of the Ministerio de Economía, Industria y Competitividad (MINECO) of Spain. The research at the IAA–CSIC was supported in part by the MINECO through grants AYA2016–80889–P, AYA2013–40825–P, and AYA2010–14844, and by the regional government of Andalucía through grant P09–FQM–4784.Peer Reviewe
Proper Electromagnetic Fields of Sea Hydrodynamic Sources and Use thereof in Sea Geophysics and Hydrophysics
Available from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio
ОПТИЧНИЙ П'ЄЗОМЕТР ТА ПРЕЦИЗІЙНІ ДОСЛІДЖЕННЯ ВЛАСТИВОСТЕЙ ХАРЧОВИХ ПРОДУКТІВ ПРИ ТИСКАХ ВІД 0 ДО 1000 МПА
The purpose of the research is to create an optical piezometer and a working chamber of a high-pressure apparatus for spectral studies of food products (liquid and viscous plastic) in situ; to obtain indicators of compression and spectral (optical) properties of food products of animal and plant origin with precision at pressures from 0 to 1000 MPa. Methods. The developed optical piezometer is based on the Michelson principle of interferometer. Changes in the volume of the studied food samples under pressure are recorded when the concentrically located interference rings from the laser module change. The precision of pressure recording is provided by measuring the change in the position of a more intense R2, the line of the luminescence spectrum of a ruby located in the working chamber, when the pressure changes. Result. For the first time, the design of the high-pressure working chamber allows obtaining in situ experimental data on changes in the compressive parameters (absolute and relative volume, density, volume modulus of compression, isothermal compression coefficient) of solid, viscoplastic and liquid food products with precision. The accuracy of measuring the change in the volume of the studied samples is not less than 0.0003 mm3. To obtain the spectral characteristics of food products in situ, the windows of the working chamber are composed of NaCl, a ruby crystal, and protective plates made of sapphire crystals. The test sample is in a developed hydrostatic cuvette installed in a high-pressure chamber and consisting of a fluoroplastic glass, sodium chloride plates and a ruby plate 0.5 mm thick. Conclusions. The research results allow us to reasonably develop high-pressure food processing technologies and design the appropriate technological equipment.Цель исследований – создание оптического пьезометра и рабочей камеры установки высокого давления для спектральных исследований пищевых продуктов (жидких и вязкопластичных) in situ; получение показателей компрессионных и спектральных (оптических) свойств пищевых продуктов животного и растительного происхождения с прецизионной точностью при давлениях от 0 до 1000 МПа. Методы. В основу разработанного оптического пьезометра положен принцип интерферометра Майкельсона. Изменения объема исследуемых образцов пищевых продуктов под действием давления фиксируются при изменении концентрически расположенных интерференционных колец от лазерного модуля. Прецизионная точность регистрации давления обеспечена измерениями изменения положения более интенсивной R2-линии спектра люминесценции рубина, расположенного в рабочей камере, при изменении давления. Результат. Конструкция рабочей камеры высокого давления впервые позволила получать экспериментальные данные in suti об изменении компрессионных показателей (абсолютный и относительный объем, плотность, значение модуля объемного сжатия, изотермический коэффициент сжатия) твердых, вязкопластичных и жидких пищевых продуктов с прецизионной точностью. Точность измерения изменения объема исследуемых образцов не меньше 0.0003 мм3. Для получения спектральных характеристик пищевых продуктов in situ в конструкции рабочей камеры расположены окна, состоящие из NaCl, кристалла рубина и защитных пластин из кристаллов сапфира. Исследуемый образец находится в разработанной гидростатической кювете, установленной в камеру высокого давления, и состоящей из фторопластового стакана, пластин из хлорида натрия и пластинки рубина толщиной 0.5 мм. Выводы. Результаты исследований позволяют обоснованно разрабатывать технологии обработки пищевых продуктов высоким давлением и проектировать соответствующее технологическое оборудование.Мета досліджень – створення оптичного п’єзометра і робочої камери установки високого тиску для спектральних досліджень харчових продуктів (рідких та в’язкопластичних) in situ; отримання показників компресійних та спектральних (оптичних) властивостей харчових продуктів тваринного та рослинного походження з прецизійною точністю при тисках від 0 до 1000 МПa. Методи. В основу розробленого оптичного п’єзометра покладено принцип інтерферометра Майкельсона. Зміни об'єму досліджуваних зразків харчових продуктів під дію тиску фіксуються при зміні концентрично розташованих інтерференційних кілець від лазерного модуля. Прецизійна точність реєстрації тиску забезпечена вимірами зміни положення більш інтенсивної R2-лінії спектра люмінесценції рубіна, розташованого в робочий камері, при зміні тиску. Результат. Конструкція робочої камери високого тиску вперше дозволяє отримувати експериментальні дані in suti про зміну компресійних показників (абсолютний та відносний об'єм, густина), значення модуля об'ємного стиснення, ізотермічний коефіцієнт стисливості) твердих, в’язкоплатичних та рідких харчових продуктів з прецизійною точністю. Точність вимірювання зміни об'єму досліджуваних зразків не нижче 0.0003 мм3. Для отримання спектральних характеристик харчових продуктів in situ в конструкції робочої камери розташовані вікна з NaCl, кристалу рубіну та захисних пластин вікон камери із кристалів сапфіру. Досліджуваний зразок розташовано в розробленій гідростатичній кюветі, яка складається з фторопластового стакана, пластин із хлориду натрію та пластинки рубіну товщиною 0.5 мм та яку встановлено у камеру високого тиску. Висновки. Результати досліджень дозволяють обґрунтовано розробляти технології обробки харчових продуктів високим тиском і проектувати відповідне технологічне обладнання