Photometric observations of the supernova 2009nr

We present the results of our UBVRI CCD photometry for the second brightest supernova of 2009, SN 2009nr, discovered during a sky survey with the telescopes of the MASTER robotic network. Its light and color curves and bolometric light curves have been constructed. The light-curve parameters and the maximum luminosity have been determined. SN 2009nr is shown to be similar in light-curve shape and maximum luminosity to SN 1991T, which is the prototype of the class of supernovae Ia with an enhanced luminosity. SN 2009nr exploded far from the center of the spiral galaxy UGC 8255 and most likely belongs to its old halo population. We hypothesize that this explosion is a consequence of the merger of white dwarfs

Optical polarization observations with the MASTER robotic net

We present results of optical polarization observations performed with the MASTER robotic net for three types of objects: gamma-ray bursts, supernovae, and blazars. For the Swift gamma-ray bursts GRB100906A, GRB110422A, GRB121011A, polarization observations were obtained during very early stages of optical emission. For GRB100906A it was the first prompt optical polarization observation in the world. Photometry in polarizers is presented for Type Ia Supernova 2012bh during 20 days, starting on March 27, 2012. We find that the linear polarization of SN 2012bh at the early stage of the envelope expansion was less than 3%. Polarization measurements for the blazars OC 457, 3C 454.3, QSO B1215+303, 87GB 165943.2+395846 at single nights are presented. We infer the degree of the linear polarization and polarization angle. The blazars OC 457 and 3C 454.3 were observed during their periods of activity. The results show that MASTER is able to measure substantially polarized light; at the same time it is not suitable for determining weak polarization (less than 5%) of dim objects (fainter than 16$^m$). Polarimetric observations of the optical emission from gamma-ray bursts and supernovae are necessary to investigate the nature of these transient objects.Comment: 31 pages, 12 figures, 4 tables; Exposure times in Table 2 have been correcte

Peculiar velocities of supernovae Ia in clusters of galaxies

Наблюдения сверхновых Ia позволяют оценить значения космологических параметров при помощи диаграммы Хаббла. В первую очередь такие наблюдения дают значение постоянной Хаббла, которая является одним из основных космологических параметров. Повышение точности измерений данной величины представляет важную задачу для современной космологии, поэтому необходимо учитывать влияние пекулярных скоростей сверхновых на измерение красного смещения, используемое при построении диаграммы Хаббла. Мы изучаем вклад пекулярных скоростей, обусловленных движением родительских галактик в поле тяготения скопления галактик, для космологической выборки сверхновых Pantheon.Observations of supernovae Ia make it possible to estimate the values of cosmological parameters using the Hubble diagram. First of all, such observations give us a value of the Hubble constant, which is one of the most important cosmological parameters. Improving the accuracy of measurements of this parameter is a priority for modern cosmological analysis. Therefore, it is necessary to take into account the influence of the peculiar velocities of supernovae Ia on the measurement of the redshift, which is used in constructing the Hubble diagram. We study the contribution of peculiar velocities due to the motion of host galaxies in the gravitational field of galaxy clusters for a cosmological sample of supernovae Pantheon.Е. А. Б. благодарит Фонд развития теоретической физики и математики «БАЗИС» 20-2-1-34-1. Исследование выполнено при поддержке Междисциплинарной научно-образовательной школы Московского университета «Фундаментальные и прикладные исследования космоса»

`Pure' Supernovae and Accelerated Expansion of the Universe

A special class of type Ia supernovae that is not subject to ordinary and additional intragalactic gray absorption and chemical evolution has been identified. Analysis of the Hubble diagrams constructed for these supernovae confirms the accelerated expansion of the Universe irrespective of the chemical evolution and possible gray absorption in galaxies.Comment: 2 figures, 1 tabl

Vector Gaussian Processes and Their Application to Supernova Light Curve Modelling

Работа посвящена обработке астрофизических данных при помощи векторных гауссовых процессов. Мы рассмотрели задачу аппроксимации многоцветных кривых блеска сверхмощных сверхновых, представленных в Открытом каталоге сверхновых. В выборку вошли объекты, подтвержденные спектрально, имеющие наблюдения минимум в трех фотометрических полосах. После аппроксимации векторными гауссовыми процессами из выборки отбрасывались те объекты, максимальная светимость которых приходилась на первые или последние шесть дней наблюдений. Таким образом, было отобрано 29 сверхмощных сверхновых. После того как для всех объектов из выборки были получены аппроксимации многоцветных кривых блеска, мы построили по ним болометрические кривые блеска в чернотельном приближении.This work is devoted to the astrophysical data processing using vector Gaussian processes. We considered the problem of approximating multicolor light curves of superluminous supernovae taken from the Open Supernova Catalog. Sample included objects that were spectroscopically confirmed, had observations in at least three photometric bands. After approximations by vector Gaussian processes those objects were discarded from the sample, which maximum luminosity was in the first or last six days of observations. Thus, 29 SLSNe remained in the sample under study. After all objects from the sample were approximated, we constructed bolometric light curves for them in black body approximation.Исследование выполнено при финансовой поддержке РФФИ и Национального центра научных исследований Франции в рамках научного проекта No 21-52-15024, а также при поддержке Междисциплинарной научно-образовательной школы Московского университета «Фундаментальные и прикладные исследования космоса»

The optical identifcation of events with poorly defined locations: The case of the Fermi GBM GRB140801A

We report the early discovery of the optical afterglow of gamma-ray burst (GRB) 140801A in the 137 deg$^2$ 3-$\sigma$ error-box of the Fermi Gamma-ray Burst Monitor (GBM). MASTER is the only observatory that automatically react to all Fermi alerts. GRB 140801A is one of the few GRBs whose optical counterpart was discovered solely from its GBM localization. The optical afterglow of GRB 140801A was found by MASTER Global Robotic Net 53 sec after receiving the alert, making it the fastest optical detection of a GRB from a GBM error-box. Spectroscopy obtained with the 10.4-m Gran Telescopio Canarias and the 6-m BTA of SAO RAS reveals a redshift of $z=1.32$. We performed optical and near-infrared photometry of GRB 140801A using different telescopes with apertures ranging from 0.4-m to 10.4-m. GRB 140801A is a typical burst in many ways. The rest-frame bolometric isotropic energy release and peak energy of the burst is $E_\mathrm{iso} = 5.54_{-0.24}^{+0.26} \times 10^{52}$ erg and $E_\mathrm{p, rest}\simeq280$ keV, respectively, which is consistent with the Amati relation. The absence of a jet break in the optical light curve provides a lower limit on the half-opening angle of the jet $\theta=6.1$ deg. The observed $E_\mathrm{peak}$ is consistent with the limit derived from the Ghirlanda relation. The joint Fermi GBM and Konus-Wind analysis shows that GRB 140801A could belong to the class of intermediate duration. The rapid detection of the optical counterpart of GRB 140801A is especially important regarding the upcoming experiments with large coordinate error-box areas.Comment: in press MNRAS, 201

The Influence of Host Galaxy Morphology on the Properties of Type IA Supernovae

In this work we determine the correlation between host galaxy morphology and light curve parameters of Type Ia supernovae. The analysis is based on the data from Pantheon cosmological sample of 1048 supernovae. We confirm that the stretch-parameter depends on the host morphology, but there is no any correlation for the color. We stress the importance of including the host morphology term to the standardization procedure of Type Ia supernovae.В работе определяется корреляция морфологии родительской галактики с параметрами кривых блеска сверхновых типа Ia (СН Ia). Анализ основан на данных выборки космологических СН Ia Pantheon. Подтверждено наличие зависимости параметра растяжения от морфологии родительской галактики, но с цветом никакой корреляции нет. Мы подчеркиваем необходимость учета морфологического типа родительской галактики в процедуре стандартизации сверхновых типа Ia.Исследование выполнено за счет гранта Российского научного фонда (проект № 18-72-00159) и при поддержке Программы развития МГУ «Выдающиеся научные школы МГУ: Физика звезд, релятивистских компактных объектов и галактик»