Цикл работ на конкурс статей

«Исследование оптического проявления космических гамма-всплесков с помощью сети наблюдения за гамма-всплесками, объединяющей телескопы стран СНГ»

Аннотация

В шести работах цикла, опубликованных в 2008-2010 гг., приведены результаты наблюдения, исследования и интерпретации различных оптических проявлений гамма-всплесков: излучения в их активной фазе (GRB 060111B), послесвечения (GRB 060111B, GRB 070419A, GRB 080319B), поиска и исследования родительских галактик (GRB 920925C, GRB 051008, GRB 060111B) и исследование загадочных «темных» гамма-всплесков, не обладающих оптическим послесвечением (GRB 051008). В заключительной работе цикла (The Afterglows of Swift-era Gamma-ray Bursts. I. ) статистически исследованы кривые блеска большого числа гамма-всплесков и найдены характерные особенности оптического излучения в различных его фазах. Причем около 20% данных для данного статистического анализа было получено на телескопах сети наблюдения за гамма-всплесками, организованной ИКИ РАН и объединяющей следующие телескопы (обсерватории): 50 см телескоп (Уссурийская Астрофизическая обсерватория), АЗТ-33ИК (ИСЗФ СО РАН), АЗТ-22 (г.Майданак, Институт Астрономии Уз. АН), Цейсс-2000, Цейсс-600 (пик Терскол, ИНАСАН), АЗТ-8, АЗТ-11, Цейсс-1000, ЗТШ (КрАО), Цейсс-600, ЗТЭ (Южная станция ГАИШ), а также наблюдения, проводимые на телескопе NOT (Испания) по заявкам ИКИ РАН.

1.
Stratta, G.; Pozanenko, A.; Atteia, J.-L.; Klotz, A.; Basa, S.; Gendre, B.; Verrecchia, F.; Boër, M.; Cutini, S.; Henze, M.; Holland, S.; Ibrahimov, M.; Ienna, F.; Khamitov, I.; Klose, S.; Rumyantsev, V.; Biryukov, V.; Sharapov, D.; Vachier, F.; Arnouts, S.; Perley, D. A.

A multiwavelength study of Swift GRB 060111B constraining the origin of its prompt optical emission

Astronomy and Astrophysics, Volume 503, Issue 3, 2009, pp.783-795

Publication Date: 09/2009

 

Context: The detection of bright optical emission measured with good temporal resolution during the prompt phase of GRB 060111Bmakes this GRB a rare event that is especially useful for constraining theories of the prompt emission.
Aims: For this reason an extended multi-wavelength campaign was performed to further constrain the physical interpretation of the observations.
Methods: In this work, we present the results obtained from our multi-wavelength campaign, as well as from the public Swift/BAT, XRT, and UVOT data.
Results: We identified the host galaxy at R˜25 mag from deep R-band exposures taken 5 months after the trigger. Its featureless spectrum and brightness, as well as the non-detection of any associated supernova 16 days after the trigger, enabled us to constrain the distance scale of GRB 060111B11 within 0.4≤ z ≤3 in the most conservative case. The host galaxy spectral continuum is best fit with a redshift of z~2, and other independent estimates converge to z~1-2. From the analysis of the early afterglow SED, we find that non-negligible host galaxy dust extinction, in addition to the Galactic one, affects the observed flux in the optical regime. The extinction-corrected optical-to-gamma-ray SED during the prompt emission shows a flux density ratio F_γ/F_opt=10^-2-10^-4 with spectral index β_γ,opt > β_γ, strongly suggesting a separate origin of the optical and gamma-ray components. This result is supported by the lack of correlated behavior in the prompt emission light curves observed in the two energy domains. The temporal properties of the prompt optical emission observed during GRB 060111B11 and their similarities to other rapidly-observed events favor interpretation of this optical light as radiation from the reverse shock. Observations are in good agreement with theoretical expectations for a thick shell limit in slow cooling regime. The expected peak flux is consistent with the observed one corrected for the host extinction, likely indicating that the starting time of the TAROT observations is very near to or coincident with the peak time. The estimated fireball initial Lorentz factor is Γ≥260-360 at z=1-2, similar to the Lorentz factors obtained from other GRBs. GRB 060111B11 is a rare case of a GRB with both a bright, well-observed optical counterpart and a “canonical” early X-ray light curve, thus providing a good test case of the reverse shock emission mechanism in both energy ranges.

2.
Pozanenko, A. S.; Rumyantsev, V. V.; Loznikov, V. M.; Volnova, A. A.; Shulga, A. P.

Searching for the host galaxy of GRB 920925C

Astronomy Letters, Volume 34, Issue 3, pp.141-144

Publication Date: 03/2008

GRB 920925C is probably the first cosmic gamma-ray burst with an optical afterglow detected from archival data. We present the results of our observations with the Shajn mirror telescope of the Crimean Astrophysical Observatory aimed at searching for the host galaxy at the afterglow location; we have determined the boundaries of distances to the possible host galaxy.

3.

Melandri, A.; Guidorzi, C.; Kobayashi, S.; Bersier, D.; Mundell, C. G.; Milne, P.; Pozanenko, A.; Li, W.; Filippenko, A. V.; Urata, Y.; Ibrahimov, M.; Steele, I. A.; Gomboc, A.; Smith, R. J.; Tanvir, N. R.; Rol, E.; Huang, K.

Evidence for energy injection and a fine-tuned central engine at optical wavelengths in GRB 070419A

Monthly Notices of the Royal Astronomical Society, Volume 395, Issue 4, pp. 1941-1949

Publication Date: 06/2009

We present a comprehensive multiwavelength temporal and spectral analysis of the `fast rise exponential decay' GRB 070419A. The early-time emission in the γ-ray and X-ray bands can be explained by a central engine active for at least 250 s, while at late times the X-ray light curve displays a simple power-law decay. In contrast, the observed behaviour in the optical band is complex (from 10² up to 10⁶ s). We investigate the light-curve behaviour in the context of the standard forward/reverse shock model; associating the peak in the optical light curve at ~450 s with the fireball deceleration time results in a Lorenz factor Γ ~ 350 at this time. In contrast, the shallow optical decay between 450 and 1500 s remains problematic, requiring a reverse shock component whose typical frequency is above the optical band at the optical peak time for it to be explained within the standard model. This predicts an increasing flux density for the forward shock component until t ~ 4 × 10⁶ s, inconsistent with the observed decay of the optical emission from t ~ 10⁴ s. A highly magnetized fireball is also ruled out due to unrealistic microphysic parameters and predicted light-curve behaviour that is not observed. We conclude that a long-lived central engine with a finely tuned energy injection rate and a sudden cessation of the injection is required to create the observed light curves, consistent with the same conditions that are invoked to explain the plateau phase of canonical X-ray light curves of γ-ray bursts.

4.

Kann, D. A.; Klose, S.; Zhang, B.; Malesani, D.; Nakar, E.; Pozanenko, A.; Wilson, A. C.; Butler, N. R.; Jakobsson, P.; Schulze, S.; Andreev, M.; Antonelli, L. A.; Bikmaev, I. F.; Biryukov, V.; Böttcher, M.; Burenin, R. A.; Castro Cerón, J. M.; Castro-Tirado, A. J.; Chincarini, G.; Cobb, B. E.; Covino, S.; D'Avanzo, P.; D'Elia, V.; Della Valle, M.; de Ugarte Postigo, A.; Efimov, Yu.; Ferrero, P.; Fugazza, D.; Fynbo, J. P. U.; Gålfalk, M.; Grundahl, F.; Gorosabel, J.; Gupta, S.; Guziy, S.; Hafizov, B.; Hjorth, J.; Holhjem, K.; Ibrahimov, M.; Im, M.; Israel, G. L.; Jeĺinek, M.; Jensen, B. L.; Karimov, R.; Khamitov, I. M.; Kiziloǧlu, Ü.; Klunko, E.; Kubánek, P.; Kutyrev, A. S.; Laursen, P.; Levan, A. J.; Mannucci, F.; Martin, C. M.; Mescheryakov, A.; Mirabal, N.; Norris, J. P.; Ovaldsen, J.-E.; Paraficz, D.; Pavlenko, E.; Piranomonte, S.; Rossi, A.; Rumyantsev, V.; Salinas, R.; Sergeev, A.; Sharapov, D.; Sollerman, J.; Stecklum, B.; Stella, L.; Tagliaferri, G.; Tanvir, N. R.; Telting, J.; Testa, V.; Updike, A. C.; Volnova, A.; Watson, D.; Wiersema, K.; Xu, D.

The Afterglows of Swift-era Gamma-ray Bursts. I. Comparing pre-Swift and Swift-era Long/Soft (Type II) GRB Optical Afterglows

The Astrophysical Journal, Volume 720, Issue 2, pp. 1513-1558 (2010)

Publication Date: 09/2010

We have gathered optical photometry data from the literature on a large sample of Swift-era gamma-ray burst (GRB) afterglows including GRBs up to 2009 September, for a total of 76 GRBs, and present an additional three pre-Swift GRBs not included in an earlier sample. Furthermore, we publish 840 additional new photometry data points on a total of 42 GRB afterglows, including large data sets for GRBs 050319, 050408, 050802, 050820A, 050922C, 060418, 080413A, and 080810. We analyzed the light curves of all GRBs in the sample and derived spectral energy distributions for the sample with the best data quality, allowing us to estimate the host-galaxy extinction. We transformed the afterglow light curves into an extinction-corrected z = 1 system and compared their luminosities with a sample of pre-Swift afterglows. The results of a former study, which showed that GRB afterglows clustered and exhibited a bimodal distribution in luminosity space, are weakened by the larger sample. We found that the luminosity distribution of the two afterglow samples (Swift-era and pre-Swift) is very similar, and that a subsample for which we were not able to estimate the extinction, which is fainter than the main sample, can be explained by assuming a moderate amount of line-of-sight host extinction. We derived bolometric isotropic energies for all GRBs in our sample, and found only a tentative correlation between the prompt energy release and the optical afterglow luminosity at 1 day after the GRB in the z = 1 system. A comparative study of the optical luminosities of GRB afterglows with echelle spectra (which show a high number of foreground absorbing systems) and those without, reveals no indication that the former are statistically significantly more luminous. Furthermore, we propose the existence of an upper ceiling on afterglow luminosities and study the luminosity distribution at early times, which was not accessible before the advent of the Swift satellite. Most GRBs feature afterglows that are dominated by the forward shock from early times on. Finally, we present the first indications of a class of long GRBs, which form a bridge between the typical high-luminosity, high-redshift events and nearby low-luminosity events (which are also associated with spectroscopic supernovae) in terms of energetics and observed redshift distribution, indicating a continuous distribution overall.

5.
Pandey, S. B.; Castro-Tirado, A. J.; Jelínek, M.; Kamble, A. P.; Gorosabel, J.; de Ugarte Postigo, A.; Prins, S.; Oreiro, R.; Chantry, V.; Trushkin, S.; Bremer, M.; Winters, J. M.; Pozanenko, A.; Krugly, Yu.; Slyusarev, I.; Kornienko, G.; Erofeeva, A.; Misra, K.; Ramprakash, A. N.; Mohan, V.; Bhattacharya, D.; Volnova, A.; Plá, J.; Ibrahimov, M.; Im, M.; Volvach, A.; Wijers, R. A. M. J.

Multi-wavelength observations of the GRB 080319B afterglow and the modeling constraints

Astronomy and Astrophysics, Volume 504, Issue 1, 2009, pp.45-51

Publication Date: 09/2009

Context: We present observations of the GRB 080319B afterglow at optical, mm, and radio frequencies between a few hours and 67 days after the burst.
Aims: We attempt to understand the nature of this extraordinarily bright explosion based on the observed properties and its comparison with afterglow models.
Methods: Our observations and other published multiwavelength data were used to reconstruct the light curves and spectral energy distributions of the burst afterglow.
Results: Our results indicate that the observed features of the afterglow agrees equally well with the inter stellar matter and the stellar wind density profiles of the circumburst medium. In the case of both density profiles, the maximum synchrotron frequency ν_m is below optical value and the cooling break frequency ν_c is below X-rays, ~10⁴ s after the burst. The derived value of the Lorentz factor at the time of naked-eye brightness is also ~300 for a corresponding blast-wave size of ~10¹⁸ cm.
Conclusions: The numerical fit to the multiwavelength afterglow data constraints the values of physical parameters and the emission mechanism of the burst.

6.

А.А. Вольнова, А.С. Позаненко, В.В. Румянцев, В.В. Бирюков, М.А. Ибрагимов, Д.А. Шарапов, Д.А. Канн, Х. Горосабль, A.Х. Кастро-Тирадо, A. де Угарте Постиго

Родительская галактика тёмного гамма-всплеска GRB 051008.

принято к публикации в Астрофизический Бюллетень, 2010,

Найдена и исследована родительская галактика "темного" гамма-всплеска GRB051008 (β_OX < 0.18) - всплеска, от которого не было зарегистрировано оптического послесвечения. Исследованы свойства и определено красное смещение родительской галактики z=1.07 ± 0.13, изучено ее окружение. Приводится сравнительный анализ свойств GRB051008 и его родительской галактики с другими известными темными гамма-всплесками. Проведен анализ причин отсутствия оптического послесвечения у данного гамма-всплеска.