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Wyszukujesz frazę "Sonbas, Eda" wg kryterium: Autor


Wyświetlanie 1-6 z 6
Tytuł:
Catching profound optical flares in blazars
Autorzy:
Bhatta, Gopal
Sonbas, Eda
Simon, A.
Drozdz, Marek
Provencal, J.
Góra, Dariusz
Zoła, Stanisław
Matsumoto, Katsura
Pajdosz-Śmierciak, Urszula
Haislip, Joshua
Stachowski, Grzegorz
Reichart, Daniel
Kouprianov, Vladimir
Caton, D.
Opis:
Flaring episodes in blazars represent one of the most violent processes observed in extra-galactic objects. Studies of such events shed light on the energetics of the physical processes occurring in the innermost regions of blazars, which cannot otherwise be resolved by any current instruments. In this work, we present some of the largest and most rapid flares captured in the optical band in the blazars 3C 279, OJ 49, S4 0954+658, TXS 1156+295, and PG 1553+113. The source flux was observed to increase by nearly ten times within a time-scale of a few weeks. We applied several methods of time series analysis and symmetry analysis. Moreover, we also performed searches for periodicity in the light curves of 3C 279, OJ 49 and PG 1553+113 using the Lomb–Scargle method and found plausible indications of quasi-periodic oscillations (QPOs). In particular, the 33- and 22-day periods found in 3C 279, i.e. a 3:2 ratio, are intriguing. These violent events might originate from magnetohydrodynamical instabilities near the base of the jets, triggered by processes modulated by the magnetic field of the accretion disc. We present a qualitative treatment as the possible explanation for the observed large amplitude flux changes in both the source-intrinsic and source-extrinsic scenarios.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Profound optical flares from the relativistic jets of active galactic nuclei
Autorzy:
Haislip, Joshua
Stachowski, Grzegorz
Kouprianov, Vladimir
Zoła, Stanisław
Drozdz, M.
Bhatta, Gopal
Caton, D.
Pajdosz-Śmierciak, Urszula
Provencal, J.
Matsumoto, Katsura
Sonbas, Eda
Reichart, Daniel
Simon, A.
Góra, Dariusz
Opis:
Intense outbursts in blazars are among the most extreme phenomena seen in extragalactic objects. Studying these events can offer important information about the energetic physical processes taking place within the innermost regions of blazars, which are beyond the resolution of current instruments. This work presents some of the largest and most rapid flares detected in the optical band from the sources 3C 279, OJ 49, S4 0954+658, Ton 599, and PG 1553+113, which are mostly TeV blazars. The source flux increased by nearly ten times within a few weeks, indicating the violent nature of these events. Such energetic events might originate from magnetohydrodynamical instabilities near the base of the jets, triggered by processes modulated by the magnetic field of the accretion disc. We explain the emergence of flares owing to the injection of high energy particles by the shock wave passing along the relativistic jets. Alternatively, the flares may have also arisen due to geometrical effects related to the jets. We discuss both source-intrinsic and source-extrinsic scenarios as possible explanations for the observed large amplitude flux changes
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Inne
Tytuł:
The morphology of the asteroidal dust around white dwarf stars : optical and near-infrared pulsations in G29-38
Autorzy:
Ogloza, W.
Sargent, J.
Cooper, W.
Provencal, J. L.
Sonbas, Eda
Pringle, J. E.
Pakštienė, Erika
Kim, V.
Walter, B.
Zejmo, M.
Moss, A.
von Hippel, Ted
Kleinman, S. J.
Savery, Z.
Swan, A.
Kusakin, A.
Krugov, M.
Fontaine, G.
Kozyreva, V.
Farihi, J.
Zoła, Stanisław
Serebryanskiy, A.
Hermes, J. J.
Opis:
More than 36 yr have passed since the discovery of the infrared excess from circumstellar dust orbiting the white dwarf G29-38, which at 17.5 pc it is the nearest and brightest of its class. The precise morphology of the orbiting dust remains only marginally constrained by existing data, subject to model-dependent inferences, and thus fundamental questions of its dynamical origin and evolution persist. This study presents a means to constrain the geometric distribution of the emitting dust using stellar pulsations measured at optical wavelengths as a variable illumination source of the dust, which reradiates primarily in the infrared. By combining optical photometry from the Whole Earth Telescope with 0.7–2.5 μm spectroscopy obtained with SpeX at NASA's Infrared Telescope Facility, we detect luminosity variations at all observed wavelengths, with variations at most wavelengths corresponding to the behavior of the pulsating stellar photosphere, but toward the longest wavelengths the light curves probe the corresponding time variability of the circumstellar dust. In addition to developing methodology, we find the pulsation amplitudes decrease with increasing wavelength for principal pulsation modes, yet increase beyond ≈2 μm for nonlinear combination frequencies. We interpret these results as combination modes derived from the principal modes of identical ℓ values and discuss the implications for the morphology of the warm dust. We also draw attention to some discrepancies between our findings and theoretical expectations for the results of the nonlinearity imposed by the surface convection zone on mode–mode interactions and on the behavior of the first harmonic of the highest-amplitude pulsation mode.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Apophis planetary defense campaign
Autorzy:
Sonbas, Eda
Bressi, Terry H.
Farnocchia, Davide
Falco, Carmelo
Morate, David
Weryk, Robert
Yim, Hong-Suh
Chastel, Serge
Marsset, Michael
Larsen, Jeffrey A.
Mastaler, Ron A.
Licandro, Javier
Taylor, Patrick A.
Pérez-Toledo, Fabricio
Warner, Elizabeth
Heinze, Aren N.
Cantillo, David
Kamiński, Krzysztof
Weiland, Henry J.
Kokina, Tatiana
Kaplan, Murat
Perminov, Alexander
Reddy, Vishnu
Kim, Myung-Jin
Chingis, Omarov
Kelley, Michael S.
Brozovic, Marina
Kamińska, Monika K.
Lees, Robert C.
Micheli, Marco
Bauer, James
Mathias, Donovan L.
Satpathy, Akash
Michel, Patrick
Moon, Hong-Kyu
Alarcon, Miguel R.
Serebryanskiy, Aleksander
de León, Julia
Elenin, Leonid
Kim, Dong-Heun
Ogłoza, Waldemar
Choi, Young-Jun
Kaiser, Galina
Mainzer, Amy
Szakáts, Robert
Christensen, Eric
Janse van Rensburg, Petro
Nastasi, Alessandro
Scotti, James V.
Cennamo, Ramona
Jacques, Cristovao
Glamazda, Dmitry
Ivanov, Alexander
McMillan, Robert S.
Lee, Hee-Jae
Serra-Ricart, Miquel
Novichonok, Artem
Pál, András
Marciniak, Anna
Buzzi, Luca
Popescu, Marcel
Tubbiolo, Andrew F.
Brucker, Melissa J.
Graziani, Filippo
Medeiros, Hissa
Schmalz, Sergei
Kuznetsov, Eduard
Dróżdż, Marek
Holman, Matthew J.
Kiss, Csaba
Read, Mike T.
Mokhnatkin, Artem
Zoła, Stanisław
Bell, David
Zhornichenko, Anastasiya
Faggioli, Laura
Roh, Dong-Goo
Veres, Peter
Reva, Inna
Erasmus, Nicolas
Polishook, David
Naidu, Shantanu P.
Benner, Lance A. M.
Wiebe, Yulia
Wheeler, Lorien F.
Petrescu, Elisabeta
Tonry, John L.
Masiero, Joseph
Rumpf, Clemens
Erece, Orhan
Reichart, Daniel E.
Barnardi, Fabrizio
Denneau, Larry
Balam, David
Żejmo, Michał
Cano, Juan
Wells, Guy
Dotson, Jessie
Wainscoat, Richard
Bamberger, Daniel
Opis:
We describe results of a planetary defense exercise conducted during the close approach to Earth by the near-Earth asteroid (99942) Apophis during 2020 December–2021 March. The planetary defense community has been conducting observational campaigns since 2017 to test the operational readiness of the global planetary defense capabilities. These community-led global exercises were carried out with the support of NASA's Planetary Defense Coordination Office and the International Asteroid Warning Network. The Apophis campaign is the third in our series of planetary defense exercises. The goal of this campaign was to recover, track, and characterize Apophis as a potential impactor to exercise the planetary defense system including observations, hypothetical risk assessment and risk prediction, and hazard communication. Based on the campaign results, we present lessons learned about our ability to observe and model a potential impactor. Data products derived from astrometric observations were available for inclusion in our risk assessment model almost immediately, allowing real-time updates to the impact probability calculation and possible impact locations. An early NEOWISE diameter measurement provided a significant improvement in the uncertainty on the range of hypothetical impact outcomes. The availability of different characterization methods such as photometry, spectroscopy, and radar provided robustness to our ability to assess the potential impact risk.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
    Wyświetlanie 1-6 z 6

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