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1. A wiggling filamentary jet at the origin of the blazar multi-wavelength behaviour

Author

Raiteri, C. M., Villata, M., Carnerero, M. I., Kurtanidze, S. O., Mirzaqulov, D. O., Benítez, E., Bonnoli, G., Carosati, D., Acosta-Pulido, J. A., Agudo, I., Andreeva, T. S., Apolonio, G., Bachev, R., Borman, G. A., Bozhilov, V., Brown, L. F., Carbonell, W., Casadio, C., Chen, W. P., Damljanovic, G., Ehgamberdiev, S. A., Elsaesser, D., Escudero, J., Feige, M., Fuentes, A., Gabellini, D., Gazeas, K., Giroletti, M., Grishina, T. S., Gupta, A. C., Gurwell, M. A., Hagen-Thorn, V. A., Hamed, G. M., Hiriart, D., Hodges, M., ivanidze, R. Z., Ivanov, D. V., Joner, M. D., Jorstad, S. G., Jovanovic, M. D., Kiehlmann, S., Kimeridze, G. N., Kopatskaya, E. N., Kovalev, Yu. A., Kovalev, Y. Y., Kurtanidze, O. M., Kurtenkov, A., Larionova, E. G., Lessing, A., Lin, H. C., López, J. M., Lorey, C., Ludwig, J., Marchili, N., Marchini, A., Marscher, A. P., Matsumoto, K., Max-Moerbeck, W., Mihov, B., Minev, M., Mingaliev, M. G., Modaressi, A., Morozova, D. A., Mortari, F., Mufakharov, T. V., Myserlis, I., Nikolashvili, M. G., Pearson, T. J., Popkov, A. V., Rahimov, I. A., Readhead, A. C. S., Reinhart, D., Reeves, R., Righini, S., Romanov, F. D., Savchenko, S. S., Semkov, E., Shishkina, E. V., Sigua, L. A., Slavcheva-Mihova, L., Sotnikova, Yu. V., Steineke, R., Stojanovic, M., Strigachev, A., Takey, A., Traianou, E., Troitskaya, Yu. V., Troitskiy, I. S., Tsai, A. L., Valcheva, A., Vasilyev, A. A., Verna, G., Vince, O., Vrontaki, K., Weaver, Z. R., Webb, J., Yuldoshev, Q. X., Zaharieva, E., and Zhovtan, A. V.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Blazars are beamed active galactic nuclei known for their strong multi-wavelength variability on timescales from years down to minutes. We aim to investigate the suitability of the twisting jet model presented in previous works to explain the multi-wavelength behaviour of BL Lacertae, the prototype of one of the blazar classes. According to this model, the jet is inhomogeneous, curved, and twisting, and the long-term variability is due to changes in the Doppler factor due to variations in the orientation of the jet-emitting regions. We analysed optical data of the source obtained during monitoring campaigns organised by the Whole Earth Blazar Telescope (WEBT) in 2019-2022, together with radio data from the WEBT and other teams, and gamma-ray data from the Fermi satellite. In this period, BL Lacertae underwent an extraordinary activity phase, reaching its historical optical and gamma-ray brightness maxima. The application of the twisting jet model to the source light curves allows us to infer the wiggling motion of the optical, radio, and gamma-ray jet-emitting regions. The optical-radio correlation shows that the changes in the radio viewing angle follow those in the optical viewing angle by about 120 days, and it suggests that the jet is composed of plasma filaments, which is in agreement with some radio high-resolution observations of other sources. The gamma-ray emitting region is found to be co-spatial with the optical one, and the analysis of the gamma-optical correlation is consistent with both the geometric interpretation and a synchrotron self-Compton (SSC) origin of the high-energy photons. We propose a geometric scenario where the jet is made up of a pair of emitting plasma filaments in a sort of double-helix curved rotating structure, whose wiggling motion produces changes in the Doppler beaming and can thus explain the observed multi-wavelength long-term variability., Comment: In press for A&A

Published
2024

2. Constraints on Triton atmospheric evolution from occultations: 1989-2022

Author

Sicardy, B., Tej, A., Gomes-Junior, A. R., Romanov, F. D., Bertrand, T., Ashok, N. M., Lellouch, E., Morgado, B. E., Assafin, M., Desmars, J., Camargo, J. I. B., Kilic, Y., Ortiz, J. L., Vieira-Martins, R., Braga-Ribas, F., Ninan, J. P., Bhatt, B. C., Kumar, S. Pramod, Swain, V., Sharma, S., Saha, A., Ojha, D. K., Pawar, G., Deshmukh, S., Deshpande, A., Ganesh, S., Jain, J. K., Mathew, S. K., Kumar, H., Bhalerao, V., Anupama, G. C., Barway, S., Brandeker, A., Floren, H. G., Olofsson, G., Bruno, G., Mao, Y. M., Ye, R. H., Zou, Q. Y., Sun, Y. K., Shen, Y. Y., Zhao, J. Y., Grishin, D. N., Romanova, L. V., Marchis, F., Fukui, K., Kukita, R., Benedetti-Rossi, G., Santos-Sanz, P., Dhyani, N., Gokhale, A., and Kate, A.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Context - Around the year 2000, Triton's south pole experienced an extreme summer solstice that occurs every about 650 years, when the subsolar latitude reached about 50{\deg}. Bracketing this epoch, a few occultations probed Triton's atmosphere in 1989, 1995, 1997, 2008 and 2017. A recent ground-based stellar occultation observed on 6 October 2022 provides a new measurement of Triton's atmospheric pressure which is presented here. Aims- The goal is to constrain the Volatile Transport Models (VTMs) of Triton's atmosphere that is basically in vapor pressure equilibrium with the nitrogen ice at its surface. Methods - Fits to the occultation light curves yield Triton's atmospheric pressure at the reference radius 1400 km, from which the surface pressure is induced. Results - The fits provide a pressure p_1400= 1.211 +/- 0.039 microbar at radius 1400 km (47 km altitude), from which a surface pressure of p_surf= 14.54 +/- 0.47 microbar is induced (1-sigma error bars). To within error bars, this is identical to the pressure derived from the previous occultation of 5 October 2017, p_1400 = 1.18 +/- 0.03 microbar and p_surf= 14.1 +/- 0.4 microbar, respectively. Based on recent models of Triton's volatile cycles, the overall evolution over the last 30 years of the surface pressure is consistent with N2 condensation taking place in the northern hemisphere. However, models typically predict a steady decrease in surface pressure for the period 2005-2060, which is not confirmed by this observation. Complex surface-atmosphere interactions, such as ice albedo runaway and formation of local N2 frosts in the equatorial regions of Triton could explain the relatively constant pressure between 2017 and 2022., Comment: 8 pages, 4 figures, accepted for publication in Astronomy and Astrophysics

Published
2024

3. Extreme photometric and polarimetric variability of blazar S4 0954+65 at its maximum optical and $\gamma$-ray brightness levels

Author

Raiteri, C. M., Villata, M., Carnerero, M. I., Savchenko, S. S., Kurtanidze, S. O., Vlasyuk, V. V., Marchini, A., Matsumoto, K., Lorey, C., Joner, M. D., Gazeas, K., Carosati, D., Mirzaqulov, D. O., Pulido, J. A. Acosta, Agudo, I., Bachev, R., Benítez, E., Borman, G. A., Calcidese, P., Chen, W. P., Damljanovic, G., Ehgamberdiev, S. A., Elsässer, D., Feige, M., Frasca, A., Gaur, H., Grishina, T. S., Gupta, A. C., Hiriart, D., Holland, M., Horst, B., Ibryamov, S., Ivanidze, R. Z., Jensen, J., Jithesh, V., Jovanovic, M. D., Kiehlmann, S., Kimeridze, G. N., Kishore, S., Kopatskaya, E. N., Kurtanidze, O. M., Larionova, E. G., Lin, H. C., Mannheim, K., Marinelli, C., Reyes, J. Moreira, Morozova, D. A., Nikolashvili, M. G., Reinhart, D., Romanov, F. D., Semkov, E., Seufert, J., Shishkina, E. V., Sigua, L. A., Skalidis, R., Spiridonova, O. I., Stojanovic, M., Strigachev, A., Troitskaya, Y. V., Troitskiy, I. S., Tsai, A., Vasilyev, A. A., Vince, O., Vrontaki, K., Wani, K., Watts, D., and Zhovtan, A. V.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

In 2022 the BL Lac object S4 0954+65 underwent a major variability phase, reaching its historical maximum brightness in the optical and $\gamma$-ray bands. We present optical photometric and polarimetric data acquired by the Whole Earth Blazar Telescope (WEBT) Collaboration from 2022 April 6 to July 6. Many episodes of unprecedented fast variability were detected, implying an upper limit to the size of the emitting region as low as $10^{-4}$ parsec. The WEBT data show rapid variability in both the degree and angle of polarization. We analyse different models to explain the polarization behaviour in the framework of a twisting jet model, which assumes that the long-term trend of the flux is produced by variations in the emitting region viewing angle. All the models can reproduce the average trend of the polarization degree, and can account for its general anticorrelation with the flux, but the dispersion of the data requires the presence of intrinsic mechanisms, such as turbulence, shocks, or magnetic reconnection. The WEBT optical data are compared to $\gamma$-ray data from the Fermi satellite. These are analysed with both fixed and adaptive binning procedures. We show that the strong correlation between optical and $\gamma$-ray data without measurable delay assumes different slopes in faint and high brightness states, and this is compatible with a scenario where in faint states we mainly see the imprint of the geometrical effects, while in bright states the synchrotron self-Compton process dominates., Comment: 12 pages, 13 figures, in press for MNRAS

Published
2023

4. GRANDMA and HXMT Observations of GRB 221009A -- the Standard-Luminosity Afterglow of a Hyper-Luminous Gamma-Ray Burst

Author

Kann, D. A., Agayeva, S., Aivazyan, V., Alishov, S., Andrade, C. M., Antier, S., Baransky, A., Bendjoya, P., Benkhaldoun, Z., Beradze, S., Berezin, D., Boër, M., Broens, E., Brunier, S., Bulla, M., Burkhonov, O., Burns, E., Chen, Y., Chen, Y. P., Conti, M., Coughlin, M. W., Cui, W. W., Daigne, F., Delaveau, B., Devillepoix, H. A. R., Dietrich, T., Dornic, D., Dubois, F., Ducoin, J. -G., Durand, E., Duverne, P. -A., Eggenstein, H. -B., Ehgamberdiev, S., Fouad, A., Freeberg, M., Froebrich, D., Ge, M. Y., Gervasoni, S., Godunova, V., Gokuldass, P., Gurbanov, E., Han, D. W., Hasanov, E., Hello, P., Hussenot-Desenonges, T., Inasaridze, R., Iskandar, A., Ismailov, N., Janati, A., Laz, T. Jegou du, Jia, S. M., Karpov, S., Kaeouach, A., Kiendrebeogo, R. W., Klotz, A., Kneip, R., Kochiashvili, N., Kunert, N., Lekic, A., Leonini, S., Li, C. K., Li, W., Li, X. B., Liao, J. Y., Logie, L., Lu, F. J., Mao, J., Marchais, D., Ménard, R., Morris, D., Natsvlishvili, R., Nedora, V., Noonan, K., Noysena, K., Orange, N. B., Pang, P. T. H., Peng, H. W., Pellouin, C., Peloton, J., Pradier, T., Pyshna, O., Rajabo, Y., Rau, S., Rinner, C., Rivet, J. -P., Romanov, F. D., Rosi, P., Rupchandani, V. A., Serrau, M., Shokry, A., Simon, A., Smith, K., Sokoliuk, O., Soliman, M., Song, L. M., Takey, A., Tillayev, Y., Ramirez, L. M. Tinjaca, Melo, I. Tosta e, Turpin, D., Postigo, A. de Ugarte, Vanaverbeke, S., Vasylenko, V., Vernet, D., Vidadi, Z., Wang, C., Wang, J., Wang, L. T., Wang, X. F., Xiong, Shaolin L., Xu, Y. P., Xue, W. C., Zeng, X., Zhang, S. N., Zhao, H. S., and Zhao, X. F.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

GRB 221009A is the brightest Gamma-Ray Burst (GRB) detected in more than 50 years of study. In this paper, we present observations in the X-ray and optical domains after the GRB obtained by the GRANDMA Collaboration (which includes observations from more than 30 professional and amateur telescopes) and the Insight-HXMT Collaboration. We study the optical afterglow with empirical fitting from GRANDMA+HXMT data, augmented with data from the literature up to 60 days. We then model numerically, using a Bayesian approach, the GRANDMA and HXMT-LE afterglow observations, that we augment with Swift-XRT and additional optical/NIR observations reported in the literature. We find that the GRB afterglow, extinguished by a large dust column, is most likely behind a combination of a large Milky-Way dust column combined with moderate low-metallicity dust in the host galaxy. Using the GRANDMA+HXMT-LE+XRT dataset, we find that the simplest model, where the observed afterglow is produced by synchrotron radiation at the forward external shock during the deceleration of a top-hat relativistic jet by a uniform medium, fits the multi-wavelength observations only moderately well, with a tension between the observed temporal and spectral evolution. This tension is confirmed when using the extended dataset. We find that the consideration of a jet structure (Gaussian or power-law), the inclusion of synchrotron self-Compton emission, or the presence of an underlying supernova do not improve the predictions, showing that the modelling of GRB22109A will require going beyond the most standard GRB afterglow model. Placed in the global context of GRB optical afterglows, we find the afterglow of GRB 221009A is luminous but not extraordinarily so, highlighting that some aspects of this GRB do not deviate from the global known sample despite its extreme energetics and the peculiar afterglow evolution., Comment: Accepted to ApJL for the special issue, 37 pages, 23 pages main text, 6 tables, 13 figures

Published
2023
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5. The multi-wavelength view of shocks in the fastest nova V1674 Her

Author

Sokolovsky, K. V., Johnson, T. J., Buson, S., Jean, P., Cheung, C. C., Mukai, K., Chomiuk, L., Aydi, E., Molina, B., Kawash, A., Linford, J. D., Mioduszewski, A. J., Rupen, M. P., Sokoloski, J. L., Williams, M. N., Steinberg, E., Vurm, I., Metzger, B. D., Page, K. L., Orio, M., Quimby, R. M., Shafter, A. W., Corbett, H., Bolzoni, S., DeYoung, J., Menzies, K., Romanov, F. D., Richmond, M., Ulowetz, J., Vanmunster, T., Williamson, G., Lane, D. J., Bartnik, M., Bellaver, M., Bruinsma, E., Dugan, E., Fedewa, J., Gerhard, C., Painter, S., Peterson, D. -M., Rodriguez, J. E., Smith, C., Sullivan, H., and Watson, S.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Classical novae are shock-powered multi-wavelength transients triggered by a thermonuclear runaway on an accreting white dwarf. V1674 Her is the fastest nova ever recorded (time to declined by two magnitudes is t_2=1.1 d) that challenges our understanding of shock formation in novae. We investigate the physical mechanisms behind nova emission from GeV gamma-rays to cm-band radio using coordinated Fermi-LAT, NuSTAR, Swift and VLA observations supported by optical photometry. Fermi-LAT detected short-lived (18 h) 0.1-100 GeV emission from V1674 Her that appeared 6 h after the eruption began; this was at a level of (1.6 +/- 0.4)x10^-6 photons cm^-2 s^-1. Eleven days later, simultaneous NuSTAR and Swift X-ray observations revealed optically thin thermal plasma shock-heated to kT_shock = 4 keV. The lack of a detectable 6.7 keV Fe K_alpha emission suggests super-solar CNO abundances. The radio emission from V1674 Her was consistent with thermal emission at early times and synchrotron at late times. The radio spectrum steeply rising with frequency may be a result of either free-free absorption of synchrotron and thermal emission by unshocked outer regions of the nova shell or the Razin-Tsytovich effect attenuating synchrotron emission in dense plasma. The development of the shock inside the ejecta is unaffected by the extraordinarily rapid evolution and the intermediate polar host of this nova., Comment: 20 pages, 9 figures, 3 tables. Accepted to MNRAS

Published
2023
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6. The Fast Evolving, Tremendous and Blue Superoutburst in ASASSN-21au Reveals a Dichotomy in the Outbursts of Long-period AM CVns

Author

Sandoval, L. E. Rivera, Heinke, C. O., Hameury, J. M., Cavecchi, Y., Vanmunster, T., Tordai, T., and Romanov, F.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics
Abstract

ASASSN-21au is an ultracompact accreting white dwarf binary (AM CVn) with a period of approx. 58 min. Using multiwavelength observations of the system, we discovered a dichotomy in the behavior of outbursts in AM CVns. The binary showed an initial brightness increase which lasted for at least 82 days, followed by an additional increase which lasted 2 weeks. Afterwards ASASSN-21au went into superoutburst with a total duration of 19 days, showing an amplitude with respect to quiescence of approx. 7.5 mags in g, with a precursor and an echo outburst. A correlation between X-rays, UV and optical was identified for the first time in an AM CVn during this stage. The color evolution of ASASSN-21au indicates that during the superoutburst the dominant component was the accretion disk. The short duration, large amplitude and color evolution of the superoutburst agree with expectations from the disk instability model. These characteristics are opposite to the ones observed in SDSS J080710+485259 and SDSS J113732+405458, which have periods of approx. 53 min and 60 min, respectively. The initially slow brightness increase in the light curve of ASASSN-21au and the behavior after the superoutburst favors a scenario in which changes in the mass-transfer rate led to disk instabilities, while the outburst mechanism of SDSS J080710+485259 and SDSS J113732+405458 has been attributed to enhanced mass-transfer alone. Further observations are needed to understand the origin of this dichotomy., Comment: Published in ApJ in February 2022

Published
2021
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7. Possible dwarf nova on the Digitized Sky Survey plates

Author

Romanov, F. D.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

I report the discovery of a new bright variable star in the constellation Scorpius. It is most likely star OGLE BUL-SC23 396060 with position (J2000.0): RA 17:57:59.75, DEC -31:38:07.4. Magnitude range is 14.4 (B) - 21.7 (V). It is visible in the possible outburst on two digitized Palomar Sky Survey photographic plates, which were made 60 years ago. This object was registered as a variable star in the AAVSO VSX under the name of Romanov V1 and with UG: variability type., Comment: 6 pages, 4 figures, 2 tables. Published in OEJV #190

Published
2018

8. Extreme photometric and polarimetric variability of blazar S4 0954+65 at its maximum optical and γ-ray brightness levels

Author

Raiteri, C M, primary, Villata, M, additional, Carnerero, M I, additional, Savchenko, S S, additional, Kurtanidze, S O, additional, Vlasyuk, V V, additional, Marchini, A, additional, Matsumoto, K, additional, Lorey, C, additional, Joner, M D, additional, Gazeas, K, additional, Carosati, D, additional, Mirzaqulov, D O, additional, Acosta Pulido, J A, additional, Agudo, I, additional, Bachev, R, additional, Benítez, E, additional, Borman, G A, additional, Calcidese, P, additional, Chen, W P, additional, Damljanovic, G, additional, Ehgamberdiev, S A, additional, Elsässer, D, additional, Feige, M, additional, Frasca, A, additional, Gaur, H, additional, Grishina, T S, additional, Gupta, A C, additional, Hiriart, D, additional, Holland, M, additional, Horst, B, additional, Ibryamov, S, additional, Ivanidze, R Z, additional, Jensen, J, additional, Jithesh, V, additional, Jovanovic, M D, additional, Kiehlmann, S, additional, Kimeridze, G N, additional, Kishore, S, additional, Kopatskaya, E N, additional, Kurtanidze, O M, additional, Larionova, E G, additional, Lin, H C, additional, Mannheim, K, additional, Marinelli, C, additional, Moreira Reyes, J, additional, Morozova, D A, additional, Nikolashvili, M G, additional, Reinhart, D, additional, Romanov, F D, additional, Semkov, E, additional, Seufert, J, additional, Shishkina, E V, additional, Sigua, L A, additional, Skalidis, R, additional, Spiridonova, O I, additional, Stojanovic, M, additional, Strigachev, A, additional, Troitskaya, Y V, additional, Troitskiy, I S, additional, Tsai, A, additional, Vasilyev, A A, additional, Vince, O, additional, Vrontaki, K, additional, Wani, K, additional, Watts, D, additional, and Zhovtan, A V, additional

Published
2023
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9. Constraints on the evolution of the Triton atmosphere from occultations: 1989–2022.

Author

Sicardy, B., Tej, A., Gomes-Júnior, A. R., Romanov, F. D., Bertrand, T., Ashok, N. M., Lellouch, E., Morgado, B. E., Assafin, M., Desmars, J., Camargo, J. I. B., Kilic, Y., Ortiz, J. L., Vieira-Martins, R., Braga-Ribas, F., Ninan, J. P., Bhatt, B. C., Pramod Kumar, S., Swain, V., and Sharma, S.

Subjects
ATMOSPHERIC pressure measurement, SURFACE pressure, VAPOR pressure, ATMOSPHERE, ATMOSPHERIC pressure
Abstract

Context. In about 2000, the south pole of Triton experienced an extreme summer solstice that occurs every ∼650 years, when the subsolar latitude reached about 50°S. Bracketing this epoch, a few occultations probed the Triton atmosphere in 1989, 1995, 1997, 2008, and 2017. A recent ground-based stellar occultation observed on 6 October 2022 provides a new measurement of the atmospheric pressure on Triton. This is presented here. Aims. The goal is to constrain the volatile transport models (VTMs) of the Triton atmosphere. The atmosphere is basically in vapor pressure equilibrium with the nitrogen ice at its surface. Methods. Fits to the occultation light curves yield the atmospheric pressure of Triton at the reference radius 1400 km, from which the surface pressure is deduced. Results. The fits provide a pressure p1400 = 1.211 ± 0.039 μbar at radius 1400 km (47 km altitude), from which a surface pressure of psurf = 14.54 ± 0.47 μbar is deduced (1σ error bars). To within the error bars, this is identical to the pressure derived from the previous occultation of 5 October 2017, p1400 = 1.18 ± 0.03 μbar and psurf = 14.1 ± 0.4 μbar, respectively. Based on recent models of the volatile cycles of Triton, the overall evolution of the surface pressure over the last 30 years is consistent with N2 condensation taking place in the northern hemisphere. However, models typically predict a steady decrease in the surface pressure for the period 2005-2060, which is not confirmed by this observation. Complex surface-atmosphere interactions, such as ice albedo runaway and formation of local N2 frosts in the equatorial regions of Triton, could explain the relatively constant pressure between 2017 and 2022. [ABSTRACT FROM AUTHOR]

Published
2024
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10. GRANDMA and HXMT Observations of GRB 221009A: The Standard Luminosity Afterglow of a Hyperluminous Gamma-Ray Burst—In Gedenken an David Alexander Kann

Author

Kann, D. A., primary, Agayeva, S., additional, Aivazyan, V., additional, Alishov, S., additional, Andrade, C. M., additional, Antier, S., additional, Baransky, A., additional, Bendjoya, P., additional, Benkhaldoun, Z., additional, Beradze, S., additional, Berezin, D., additional, Boër, M., additional, Broens, E., additional, Brunier, S., additional, Bulla, M., additional, Burkhonov, O., additional, Burns, E., additional, Chen, Y., additional, Chen, Y. P., additional, Conti, M., additional, Coughlin, M. W., additional, Cui, W. W., additional, Daigne, F., additional, Delaveau, B., additional, Devillepoix, H. A. R., additional, Dietrich, T., additional, Dornic, D., additional, Dubois, F., additional, Ducoin, J.-G., additional, Durand, E., additional, Duverne, P.-A., additional, Eggenstein, H.-B., additional, Ehgamberdiev, S., additional, Fouad, A., additional, Freeberg, M., additional, Froebrich, D., additional, Ge, M. Y., additional, Gervasoni, S., additional, Godunova, V., additional, Gokuldass, P., additional, Gurbanov, E., additional, Han, D. W., additional, Hasanov, E., additional, Hello, P., additional, Hussenot-Desenonges, T., additional, Inasaridze, R., additional, Iskandar, A., additional, Ismailov, N., additional, Janati, A., additional, du Laz, T. Jegou, additional, Jia, S. M., additional, Karpov, S., additional, Kaeouach, A., additional, Kiendrebeogo, R. W., additional, Klotz, A., additional, Kneip, R., additional, Kochiashvili, N., additional, Kunert, N., additional, Lekic, A., additional, Leonini, S., additional, Li, C. K., additional, Li, W., additional, Li, X. B., additional, Liao, J. Y., additional, Logie, L., additional, Lu, F. J., additional, Mao, J., additional, Marchais, D., additional, Ménard, R., additional, Morris, D., additional, Natsvlishvili, R., additional, Nedora, V., additional, Noonan, K., additional, Noysena, K., additional, Orange, N. B., additional, Pang, P. T. H., additional, Peng, H. W., additional, Pellouin, C., additional, Peloton, J., additional, Pradier, T., additional, Pyshna, O., additional, Rajabov, Y., additional, Rau, S., additional, Rinner, C., additional, Rivet, J.-P., additional, Romanov, F. D., additional, Rosi, P., additional, Rupchandani, V. A., additional, Serrau, M., additional, Shokry, A., additional, Simon, A., additional, Smith, K., additional, Sokoliuk, O., additional, Soliman, M., additional, Song, L. M., additional, Takey, A., additional, Tillayev, Y., additional, Ramirez, L. M. Tinjaca, additional, e Melo, I. Tosta, additional, Turpin, D., additional, de Ugarte Postigo, A., additional, Vanaverbeke, S., additional, Vasylenko, V., additional, Vernet, D., additional, Vidadi, Z., additional, Wang, C., additional, Wang, J., additional, Wang, L. T., additional, Wang, X. F., additional, Xiong, S. L., additional, Xu, Y. P., additional, Xue, W. C., additional, Zeng, X., additional, Zhang, S. N., additional, Zhao, H. S., additional, and Zhao, X. F., additional

Published
2023
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11. The optical behaviour of BL Lacertae at its maximum brightness levels: a blend of geometry and energetics

Author

Raiteri, C M, primary, Villata, M, additional, Jorstad, S G, additional, Marscher, A P, additional, Acosta Pulido, J A, additional, Carosati, D, additional, Chen, W P, additional, Joner, M D, additional, Kurtanidze, S O, additional, Lorey, C, additional, Marchini, A, additional, Matsumoto, K, additional, Mirzaqulov, D O, additional, Savchenko, S S, additional, Strigachev, A, additional, Vince, O, additional, Aceti, P, additional, Apolonio, G, additional, Arena, C, additional, Arkharov, A, additional, Bachev, R, additional, Bader, N, additional, Banfi, M, additional, Bonnoli, G, additional, Borman, G A, additional, Bozhilov, V, additional, Brown, L F, additional, Carbonell, W, additional, Carnerero, M I, additional, Damljanovic, G, additional, Dhiman, V, additional, Ehgamberdiev, S A, additional, Elsaesser, D, additional, Feige, M, additional, Gabellini, D, additional, Galán, D, additional, Galli, G, additional, Gaur, H, additional, Gazeas, K, additional, Grishina, T S, additional, Gupta, A C, additional, Hagen-Thorn, V A, additional, Hallum, M K, additional, Hart, M, additional, Hasuda, K, additional, Heidemann, K, additional, Horst, B, additional, Hou, W-J, additional, Ibryamov, S, additional, Ivanidze, R Z, additional, Jovanovic, M D, additional, Kimeridze, G N, additional, Kishore, S, additional, Klimanov, S, additional, Kopatskaya, E N, additional, Kurtanidze, O M, additional, Kushwaha, P, additional, Lane, D J, additional, Larionova, E G, additional, Leonini, S, additional, Lin, H C, additional, Mannheim, K, additional, Marino, G, additional, Minev, M, additional, Modaressi, A, additional, Morozova, D A, additional, Mortari, F, additional, Nazarov, S V, additional, Nikolashvili, M G, additional, Otero Santos, J, additional, Ovcharov, E, additional, Papini, R, additional, Pinter, V, additional, Privitera, C A, additional, Pursimo, T, additional, Reinhart, D, additional, Roberts, J, additional, Romanov, F D, additional, Rosenlehner, K, additional, Sakamoto, T, additional, Salvaggio, F, additional, Schoch, K, additional, Semkov, E, additional, Seufert, J, additional, Shakhovskoy, D, additional, Sigua, L A, additional, Singh, C, additional, Steineke, R, additional, Stojanovic, M, additional, Tripathi, T, additional, Troitskaya, Y V, additional, Troitskiy, I S, additional, Tsai, A, additional, Valcheva, A, additional, Vasilyev, A A, additional, Vrontaki, K, additional, Weaver, Z R, additional, Wooley, J H F, additional, Zaharieva, E, additional, and Zhovtan, A V, additional

Published
2023
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12. The multiwavelength view of shocks in the fastest nova V1674 Her

Author

Sokolovsky, K V, primary, Johnson, T J, additional, Buson, S, additional, Jean, P, additional, Cheung, C C, additional, Mukai, K, additional, Chomiuk, L, additional, Aydi, E, additional, Molina, B, additional, Kawash, A, additional, Linford, J D, additional, Mioduszewski, A J, additional, Rupen, M P, additional, Sokoloski, J L, additional, Williams, M N, additional, Steinberg, E, additional, Vurm, I, additional, Metzger, B D, additional, Page, K L, additional, Orio, M, additional, Quimby, R M, additional, Shafter, A W, additional, Corbett, H, additional, Bolzoni, S, additional, DeYoung, J, additional, Menzies, K, additional, Romanov, F D, additional, Richmond, M, additional, Ulowetz, J, additional, Vanmunster, T, additional, Williamson, G, additional, Lane, D J, additional, Bartnik, M, additional, Bellaver, M, additional, Bruinsma, E, additional, Dugan, E, additional, Fedewa, J, additional, Gerhard, C, additional, Painter, S, additional, Peterson, D-M, additional, Rodriguez, J E, additional, Smith, C, additional, Sullivan, H, additional, and Watson, S, additional

Published
2023
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13. GRANDMA and HXMT Observations of GRB 221009A: The Standard Luminosity Afterglow of a Hyperluminous Gamma-Ray Burst—In Gedenken an David Alexander Kann

Author

Kann, D. A., Agayeva, S., Aivazyan, V., Alishov, S., Andrade, C. M., Antier, S., Baransky, A., Bendjoya, P., Benkhaldoun, Z., Beradze, S., Berezin, D., Boër, M., Broens, E., Brunier, S., Bulla, M., Burkhonov, O., Burns, E., Chen, Y., Chen, Y. P., Conti, M., Coughlin, M. W., Cui, W. W., Daigne, F., Delaveau, B., Devillepoix, H. A. R., Dietrich, T., Dornic, D., Dubois, F., Ducoin, J.-G., Durand, E., Duverne, P.-A., Eggenstein, H.-B., Ehgamberdiev, S., Fouad, A., Freeberg, M., Froebrich, Dirk, Ge, M. Y., Gervasoni, S., Godunova, V., Gokuldass, P., Gurbanov, E., Han, D. W., Hasanov, E., Hello, P., Hussenot-Desenonges, T., Inasaridze, R., Iskandar, A., Ismailov, N., Janati, A., du Laz, T. Jegou, Jia, S. M., Karpov, S., Kaeouach, A., Kiendrebeogo, R. W., Klotz, A., Kneip, R., Kochiashvili, N., Kunert, N., Lekic, A., Leonini, S., Li, C. K., Li, W., Li, X. B., Liao, J. Y., Logie, L., Lu, F. J., Mao, J., Marchais, D., Ménard, R., Morris, D., Natsvlishvili, R., Nedora, V., Noonan, K., Noysena, K., Orange, N. B., Pang, P. T. H., Peng, H. W., Pellouin, C., Peloton, J., Pradier, T., Pyshna, O., Rajabov, Y., Rau, S., Rinner, C., Rivet, J.-P., Romanov, F. D., Rosi, P., Rupchandani, V. A., Serrau, M., Shokry, A., Simon, A., Smith, K., Sokoliuk, O., Soliman, M., Song, L. M., Takey, A., Tillayev, Y., Ramirez, L. M. Tinjaca, e Melo, I. Tosta, Turpin, D., de Ugarte Postigo, A., Vanaverbeke, S., Vasylenko, V., Vernet, D., Vidadi, Z., Wang, C., Wang, J., Wang, L. T., Wang, X. F., Xiong, S. L., Xu, Y. P., Xue, W. C., Zeng, X., Zhang, S. N., Zhao, H. S., Zhao, X. F., Kann, D. A., Agayeva, S., Aivazyan, V., Alishov, S., Andrade, C. M., Antier, S., Baransky, A., Bendjoya, P., Benkhaldoun, Z., Beradze, S., Berezin, D., Boër, M., Broens, E., Brunier, S., Bulla, M., Burkhonov, O., Burns, E., Chen, Y., Chen, Y. P., Conti, M., Coughlin, M. W., Cui, W. W., Daigne, F., Delaveau, B., Devillepoix, H. A. R., Dietrich, T., Dornic, D., Dubois, F., Ducoin, J.-G., Durand, E., Duverne, P.-A., Eggenstein, H.-B., Ehgamberdiev, S., Fouad, A., Freeberg, M., Froebrich, Dirk, Ge, M. Y., Gervasoni, S., Godunova, V., Gokuldass, P., Gurbanov, E., Han, D. W., Hasanov, E., Hello, P., Hussenot-Desenonges, T., Inasaridze, R., Iskandar, A., Ismailov, N., Janati, A., du Laz, T. Jegou, Jia, S. M., Karpov, S., Kaeouach, A., Kiendrebeogo, R. W., Klotz, A., Kneip, R., Kochiashvili, N., Kunert, N., Lekic, A., Leonini, S., Li, C. K., Li, W., Li, X. B., Liao, J. Y., Logie, L., Lu, F. J., Mao, J., Marchais, D., Ménard, R., Morris, D., Natsvlishvili, R., Nedora, V., Noonan, K., Noysena, K., Orange, N. B., Pang, P. T. H., Peng, H. W., Pellouin, C., Peloton, J., Pradier, T., Pyshna, O., Rajabov, Y., Rau, S., Rinner, C., Rivet, J.-P., Romanov, F. D., Rosi, P., Rupchandani, V. A., Serrau, M., Shokry, A., Simon, A., Smith, K., Sokoliuk, O., Soliman, M., Song, L. M., Takey, A., Tillayev, Y., Ramirez, L. M. Tinjaca, e Melo, I. Tosta, Turpin, D., de Ugarte Postigo, A., Vanaverbeke, S., Vasylenko, V., Vernet, D., Vidadi, Z., Wang, C., Wang, J., Wang, L. T., Wang, X. F., Xiong, S. L., Xu, Y. P., Xue, W. C., Zeng, X., Zhang, S. N., Zhao, H. S., and Zhao, X. F.

Abstract

Object GRB 221009A is the brightest gamma-ray burst (GRB) detected in more than 50 yr of study. In this paper, we present observations in the X-ray and optical domains obtained by the GRANDMA Collaboration and the Insight Collaboration. We study the optical afterglow with empirical fitting using the GRANDMA+HXMT-LE data sets augmented with data from the literature up to 60 days. We then model numerically using a Bayesian approach, and we find that the GRB afterglow, extinguished by a large dust column, is most likely behind a combination of a large Milky Way dust column and moderate low-metallicity dust in the host galaxy. Using the GRANDMA+HXMT-LE+XRT data set, we find that the simplest model, where the observed afterglow is produced by synchrotron radiation at the forward external shock during the deceleration of a top-hat relativistic jet by a uniform medium, fits the multiwavelength observations only moderately well, with a tension between the observed temporal and spectral evolution. This tension is confirmed when using the augmented data set. We find that the consideration of a jet structure (Gaussian or power law), the inclusion of synchrotron self-Compton emission, or the presence of an underlying supernova do not improve the predictions. Placed in the global context of GRB optical afterglows, we find that the afterglow of GRB 221009A is luminous but not extraordinarily so, highlighting that some aspects of this GRB do not deviate from the global known sample despite its extreme energetics and the peculiar afterglow evolution.

Published
2023

15. The Fast Evolving, Tremendous and Blue Superoutburst in ASASSN-21au Reveals a Dichotomy in the Outbursts of Long Period AM CVns

Author

Rivera Sandoval, L.E., Heinke, C.O., Hameury, J.M., Cavecchi, Y., Vanmunster, T., Tordai, T., Romanov, F., Observatoire astronomique de Strasbourg (ObAS), and Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

We report on the discovery of a dichotomy in the behavior of outbursts in ultracompact accreting white dwarf binaries (AM CVns), using multiwavelength observations of the new AM CVn system ASASSN-21au which has a period of ~58 min. The binary showed a first brightness increase with respect to its quiescent g level of ~0.8 mag which lasted for at least 82 days, followed by an additional 0.5 mag increase which lasted 2 weeks. Afterwards ASASSN-21au went into superoutburst for the first time. Such superoutburst lasted a total of 19 days, showing an amplitude with respect to quiescence of ~7.5 mags in g, with a precursor and an echo outburst. During the superoutburst of ASASSN-21au we also detected the first correlation between the X-rays, UV and optical emission in an AM CVn. The color evolution of ASASSN-21au indicates that during the superoutburst the dominant component was the accretion disk. The short duration, large amplitude and color evolution of the superoutburst agree with expectations from the disk instability model, but they contrast with the long duration (longer than a year), small amplitude and red color evolution of the outbursts of SDSS~J080710+485259 and SDSS J113732+405458, which have periods of ~53 min and ~60 min, respectively. The initial slow brightness increase in the light curve of ASASSN-21au and the behavior after the superoutburst favors a scenario in which changes in the mass-transfer rate led to disk instabilities, while the outburst mechanism of SDSS J080710+485259 and SDSS J113732+405458 has been attributed to enhanced mass-transfer alone. Further observations are needed to understand the origin of this dichotomy.

Published
2021

16. Space suits

Author

Romanov, F

Subjects
Masers
Abstract

Space suit - life support system

Published
1964

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