«Pure» supernovae and accelerating expansion of the Universe

Pruzhinskaya M.V., Gorbovskoy E.S., Lipunov V.M., 2011, Astronomy Letters, 37, 10, pp. 663-669

Abstract. 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.

Keywords. Supernovae: general, cosmological parameters

Figure. Hubble diagram for «pure» SNe Ia. The red curve is the best fit to the observational data. The green curve corresponds to the Universe without dark energy.

The mechanism of supernova Ia explosion in elliptical galaxies

Lipunov V.M., Panchenko I.E., Pruzhinskaya M.V., 2011, New Astronomy, 16, 4, pp. 250-252

Abstract. Recent observational data on the type Ia supernova rates are in excellent agreement with the earlier results of the population synthesis of binary stars and confirm that the overwhelming majority of type Ia supernovas (≈99%) in elliptical galaxies form via mergers of binary white dwarfs with a total mass exceeding the Chandrasekhar limit.

Keywords. Galaxies: evolution, galaxies: stellar content, stars: statistics, supernovae: general

Figure. The SN Ia rate per century for a single starburst population whose total K-band luminosity is 10¹⁰ L_K,Sun at the age of 11 Gyr (predicted by Jorgensen et al., 1997). The filled squares are the observational points. The open circle is observational SN Ia rate in elliptical galaxies in the local Universe (Mannuci et. al. 2006).

Scenario Machine: fast radio bursts, short gamma-ray burst, dark energy and Laser Interferometer Gravitational-wave Observatory silence

Lipunov V.M. and Pruzhinskaya M.V., 2014, MNRAS, 440, 2, pp. 1193-1199

Abstract. We discuss the recently reported discovery of fast radio bursts (FRBs) in the framework of the neutron star-neutron star (NS+NS) or neutron star-black hole (NS+BH) binary merger model. We concentrate on what we consider to be an issue of greatest importance: what is the NS merger rate given that the FRB rate (1/1000 yr^–1 per galaxy) is inconsistent with gamma-ray burst rate as discussed by Thornton and should be significantly higher. We show that there is no discrepancy between NS merger rate and observed FRB rates in the framework of the Scenario Machine population synthesis — for a kick velocity of 100–150 km s^–1 an average NS merger rate is 1/500–1/2000 yr^–1 per galaxy up to z = 0.5–1. Based on the Scenario Machine NS merger rate estimates, we discuss the lack of positive detections on the ground-based interferometers, considering the Laser Interferometer Gravitational-wave Observatory.

Keywords. Gravitational waves, gamma-ray burst: general

Figure. The number of NS+NS mergers per year inside the sphere of distance D in terms of the Scenario Machine prediction for kick velocities in the 100–150 km s^–1 interval. The black and blue curves correspond to modified Salpeter (1955) and Baldry & Glazebrook (2003) IMF, respectively. The asterisk shows the LIGO S6 limit (Abadie et al. 2012).

Optical polarization observations with the MASTER robotic net

Pruzhinskaya M.V., Krushinsky V.V., Lipunova G.V., Gorbovskoy E.S., Balanutsa P.V., Kuznetsov A.S., Denisenko D.V., Kornilov V.G., Tyurina N.V., Lipunov V.M., Tlatov A.G., Parkhomenko A.V., Budnev N.M., Yazev S.A., Ivanov K.I., Gress O.A., Yurkov V.V., Gabovich A.V., Sergienko Yu.P., Sinyakov E.V., 2014, New Astronomy, 29, pp. 65-74

Abstract. We present results of optical polarization observations performed with the MASTER robotic net (Lipunov et al., 2004, 2010; Kornilov et al., 2012) for three types of objects: gamma-ray bursts, supernovae, and blazars. For the gamma-ray bursts GRB100906A, GRB110422A, GRB121011A, polarization observations were obtained Shift during very early stages of optical emission. For GRB100906A it was the first prompt optical polarization observation in the world. Photometry in polarisers 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 16m). Polarimetric observations of the optical emission from gamma-ray bursts and supernovae are necessary to investigate the nature of these transient objects.

Keywords. Gamma-ray bursts, supernovae, quasars and active galactic nuclei, astronomical techniques

Figure. Light curve of GRB110422A in mutually perpendicular polarizers and R filter obtained with MASTER Tunka (Gorbovskoy et al., 2013).

On the nature of rapidly fading Type II supernovae

Takashi J. Moriya, Maria V. Pruzhinskaya, Mattias Ergon, Sergei I. Blinnikov, 2016, MNRAS, 455, 1, pp. 423-430

Abstract. It has been suggested that Type II supernovae with rapidly fading light curves (a.k.a. Type IIL supernovae) are explosions of progenitors with low-mass hydrogen-rich envelopes which are of the order of 1 M_⊙. We investigate light-curve properties of supernovae from such progenitors. We confirm that such progenitors lead to rapidly fading Type II supernovae. We find that the luminosity of supernovae from such progenitors with the canonical explosion energy of 10⁵¹ erg and ⁵⁶Ni mass of 0.05 M_⊙ can increase temporarily shortly before all the hydrogen in the envelope recombines. As a result, a bump appears in their light curves. The bump appears because the heating from the nuclear decay of ⁵⁶Ni can keep the bottom of hydrogen-rich layers in the ejecta ionized, and thus the photosphere can stay there for a while. We find that the light-curve bump becomes less significant when we make explosion energy larger (≳2 × 10⁵¹ erg), ⁵⁶Ni mass smaller (≲0.01 M_⊙), ⁵⁶Ni mixed in the ejecta, or the progenitor radius larger. Helium mixing in hydrogen-rich layers makes the light-curve decline rates large but does not help reducing the light-curve bump. Because the light-curve bump we found in our light-curve models has not been observed in rapidly fading Type II supernovae, they may be characterized by not only low-mass hydrogen-rich envelopes but also higher explosion energy, larger degrees of ⁵⁶Ni mixing, and/or larger progenitor radii than slowly fading Type II supernovae, so that the light-curve bump does not become significant.

Keywords. Stars: evolution, stars: massive, stars: mass-loss, supernovae: general

Figure. Bolometric LCs from simplified progenitors with different radii. We also show the original model with the same mass (M_fin = 14.0 M_⊙ and M_fin = 4.1 M_⊙) whose radius is 1100 R_⊙.

The optical identification of events with poorly defined locations: the case of the Fermi GBM GRB 140801A

Lipunov V.M., Gorosabel J., Pruzhinskaya M.V., Postigo A. de Ugarte, Pelassa V., Tsvetkova A.E., Sokolov I.V., Kann D.A., Xu Dong, Gorbovskoy E.S., Krushinski V.V., Kornilov V.G., Balanutsa P.V., Boronina S.V., Budnev N.M., Cano Z., Castro-Tirado A.J., Chazov V.V., Connaughton V., Delvaux C., Frederiks D.D., Fynbo J.F.U., Gabovich A.V., Goldstein A., Greiner J., Gress O.A., Ivanov K.I., Jakobsson P., Klose S., Knust F., Komarova V.N., Konstantinov E., Krylov A.V., Kuvshinov D.A., Kuznetsov A.S., Lipunova G.V., Moskvitin A.S., Pal'shin V.D., Pandey S.B., Poleshchuk V.A., Schmidl S., Sergienko Yu.P., Sinyakov E.V., Schulze S., Sokolov V.V., Sokolova T.N., Sparre M., Thöne C.C., Tlatov A.G., Tyurina N.V., Ulanov M.V., Yazev S.A., Yurkov V.V., 2016, MNRAS, 455, 1, pp. 423-430

Abstract. We report the early discovery of the optical afterglow of gamma-ray burst (GRB) 140801A in the 137 deg² 3-σ error-box of the Fermi Gamma-ray Burst Monitor (GBM). MASTER is the only observatory that automatically reacts 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 Big Telescope Alt-azimuth of the Special Astrophysical Observatory of the Russian Academy of Sciences 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 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 are E_iso = 5.54–0.24
+0.26 × 10⁵² erg and E_p, rest ≃ 280 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 θ = 6.1°. The observed E_peak is consistent with the limit derived from the Ghirlanda relation. The joint Fermi GBM and Konus-Wind analysis show 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.

Keywords. Acceleration of particles, black hole physics, magnetic field, gamma-ray: general, x-ray: general

Figure. MASTER OT discovery of GRB 140801A in the Fermi GBM error-box. The left panel illustrates the final GRB localizations (red circle: 3° of statistical error (3-σ) and 3° of systematic error GBM; blue lines: 3-σ IPN). Gray squares are fields covered by MASTER. The black square is the location of the MASTER OT. The right panels show MASTER images of the OT position: discovery image (bottom), reference image (top). The IPN localization was published after the MASTER discovery circular (Hurley et al. 2014; Gorbovskoy et al. 2014).

How supernovae became the basis of the observational cosmology

Pruzhinskaya M.V. & Lisakov S.M., 2016, JAH&H, 19(2), pp. 203-215

Abstract. This paper is dedicated to the discovery of one of the most important relation in supernova cosmology — the relation between the peak luminosity of Type Ia supernovae and their luminosity decline rate after the maximum light. The history of this relation is quite long and interesting. The relation was independently discovered by the American statistician and astronomer Bert Woodard Rust and Soviet astronomer Yury Pavlovich Pskovskii in the 70th years of the XX century. Using a limited sample of Type I supernovae they were able to show that the brighter the supernova, the slower its luminosity declines after the maximum. Only with the appearance of CCD astronomy could Mark Phillips re-inspect this relation on the new level of accuracy using the better sample of supernovae. His investigations confirmed the idea earlier proposed by Rust and Pskovskii.

Keywords. Rust-Pskovskii relation

Figure. The typical light curve of SN Ia in B filter. The β parameter introduced by Yu. Pskovskii and ∆m₁₅ parameter introduced by M. Phillips are shown. The blue point is the point at which the decline in brightness begins to slow down.

The influence of host galaxy morphology on properties of Type Ia supernovae from the JLA compilation

Henne V., Pruzhinskaya M.V., Rosnet P., Léget P.-F., Ishida E.E.O., Ciulli A., Gris P., Says L.-P. and Gangler E., 2017, New Astronomy, 51, pp. 43-50

Abstract. The observational cosmology with distant Type Ia supernovae (SNe) as standard candles claims that the Universe is in accelerated expansion, caused by a large fraction of dark energy. In this paper we investigate SN Ia environment, studying the impact of the nature of their host galaxies on the Hubble diagram fitting. The supernovae (192 SNe) used in the analysis were extracted from Joint-Light-curves-Analysis (JLA) compilation of high-redshift and nearby supernovae which is the best one to date. The analysis is based on the empirical fact that SN Ia luminosities depend on their light curve shapes and colors. We confirm that the stretch parameter of Type Ia supernovae is correlated with the host galaxy type. The supernovae with lower stretch are hosted mainly in elliptical and lenticular galaxies. No significant correlation between SN Ia colour and host morphology was found. We also examine how the luminosities of SN Ia change depending on host galaxy morphology after stretch and colour corrections. Our results show that in old stellar population and low dust environment, supernovae are slightly fainter. SN Ia in elliptical and lenticular galaxies have a higher α (slope in luminosity-stretch) and β (slope in luminosity-colour) parameters than in spirals. However, the observed shift is within 1-σ uncertainties and, therefore, can not be considered as significant. We confirm that supernova properties depend on their environment and that the incorporation of a host galaxy term into the Hubble diagram fit is crucial for the future cosmological analysis.

Keywords. Supernovae, cosmological parameters

Figure. The distribution of the SALT2 parameters, stretch X₁ (left) and colour C (right) for different host galaxy morphology.

Multicolour modelling of SN 2013dx associated with GRB 130702A

Volnova A.A, Pruzhinskaya M.V., Pozanenko A.S., Blinnikov S.I., Minaev P.Yu., Burkhonov O.A., Chernenko A.M., Ehgamberdiev Sh.A., Inasaridze R., Jelinek M., Khorunzhev G.A., Klunko E.V., Krugly Yu.N., Mazaeva E.D., Rumyantsev V.V., Volvach A.E., 2017, MNRAS, 467, 3, pp. 3500-3512

Abstract. We present optical observations of SN 2013dx, related to the Fermi burst GRB 130702A occurred at a redshift z = 0.145. It is the second-best sampled GRB-SN after SN 1998bw: the observational light curves contain more than 280 data points in uBgrRiz filters until 88 day after the burst, and the data were collected from our observational collaboration (Maidanak Observatory, Abastumani Observatory, Crimean Astrophysical Observatory, Mondy Observatory, National Observatory of Turkey, Observatorio del Roque de los Muchachos) and from the literature. We model numerically the multicolour light curves using the one-dimensional radiation hydrodynamical code STELLA, previously widely implemented for the modelling of typical non-GRB SNe. The best-fitted model has the following parameters: pre-supernova star mass M = 25 M_⊙, mass of a compact remnant M_CR = 6 M_⊙, total energy of the outburst E_oburst = 3.5 × 10⁵² erg, pre-supernova star radius R = 100 R_⊙, M_{56_Ni} = 0.2 M_⊙ which is totally mixed through the ejecta; M_O = 16.6 M_⊙, M_Si = 1.2 M_⊙, and M_Fe = 1.2 M_⊙, and the radiative efficiency of the SN is 0.1 per cent.

Keywords. Supernovae, gamma-ray bursts

Figure. The multicolour light curves of SN 2013dx. The Galactic extinction, the flux from the host galaxy and the optical afterglow contribution are excluded. Solid lines show the best model of the SN light curve obtained by STELLA.

Anomaly Detection in the Open Supernova Catalog

Pruzhinskaya M., Malanchev K., Kornilov M., Ishida E., Mondon F., Volnova A., Korolev V., 2019, MNRAS, 489, 3, pp. 3591-3608

Abstract. In the upcoming decade, large astronomical surveys will discover millions of transients raising unprecedented data challenges in the process. Only the use of the machine learning algorithms can process such large data volumes. Most of the discovered transients will belong to the known classes of astronomical objects. However, it is expected that some transients will be rare or completely new events of unknown physical nature. The task of finding them can be framed as an anomaly detection problem. In this work, we perform for the first time an automated anomaly detection analysis in the photometric data of the Open Supernova Catalog (OSC), which serves as a proof of concept for the applicability of these methods to future large-scale surveys. The analysis consists of the following steps: (1) data selection from the OSC and approximation of the pre-processed data with Gaussian processes, (2) dimensionality reduction, (3) searching for outliers with the use of the isolation forest algorithm, and (4) expert analysis of the identified outliers. The pipeline returned 81 candidate anomalies, 27 (33 per cent) of which were confirmed to be from astrophysically peculiar objects. Found anomalies correspond to a selected sample of 1.4 per cent of the initial automatically identified data sample of approximately 2000 objects. Among the identified outliers we recognized superluminous supernovae, non-classical Type Ia supernovae, unusual Type II supernovae, one active galactic nucleus and one binary microlensing event. We also found that 16 anomalies classified as supernovae in the literature are likely to be quasars or stars. Our proposed pipeline represents an effective strategy to guarantee we shall not overlook exciting new science hidden in the data we fought so hard to acquire. All code and products of this investigation are made publicly available.

Keywords. Methods: data analysis, catalogues, supernovae: general

Figure. Light curves of superluminous supernova PTF10aagc. Solid lines are the results of our approximation by Multivariate Gaussian Process.

The dependency of Type Ia Supernovae SALT2 light curve parameters on host galaxy morphology

Pruzhinskaya M.V., Novinskaya A.K., Pauna N., Rosnet P., 2020, MNRAS, 499, 4, pp. 5121–5135

Abstract. Type Ia Supernovae (SNe Ia) are widely used to measure distances in the Universe. Despite the recent progress achieved in SN Ia standardization, the Hubble diagram still shows some remaining intrinsic dispersion. The remaining scatter in supernova luminosity could be due to the environmental effects that are accounted for as mass step correction in the current cosmological analyses. In this work, we compare the local and global colour (U − V), the local star formation rate, and the host stellar mass to the host galaxy morphology. The observed trends suggest that the host galaxy morphology is a relevant parameter to characterize the SN Ia environment. Therefore, we study the influence of host galaxy morphology on light-curve parameters of SNe Ia from the pantheon cosmological supernova sample. We determine the Hubble morphological type of host galaxies for a subsample of 330 SNe Ia. We confirm that the salt2 stretch parameter x1 depends on the host morphology with the p-value ∼10⁻¹⁴. The supernovae with lower stretch value are hosted mainly by elliptical and lenticular galaxies. No correlation for the salt2 colour parameter c is found. We also examine Hubble diagram residuals for supernovae hosted by ‘early-type’ and ‘late-type’ morphological groups of galaxies. The analysis reveals that the mean distance modulus residual in early-type galaxies is smaller than the one in late-type galaxies, which means that early-type galaxies contain brighter supernovae after stretch and colour corrections. However, we do not observe any difference in the residual dispersion for these two morphological groups. The obtained results are in the line with other analyses showing environmental dependence of SN Ia light-curve parameters and luminosity. We confirm the importance of including a host galaxy parameter into the standardization procedure of SNe Ia for further cosmological studies.

Keywords. Supernovae: general, galaxies: general, distance scale

Figure. Hubble diagram for the Pantheon supernovae. Different markers correspond to supernovae belonging to galaxies of different morphological types. The model corresponds to the flat ΛCDM cosmology with Ω_Λ=0.702±0.022 (Scolnic et al., 2018).

Anomaly detection in the Zwicky Transient Facility DR3

Malanchev K. L., Pruzhinskaya M. V., Korolev V. S., Aleo P. D., Kornilov M. V., Ishida E. E. O., Krushinsky V. V., Mondon F., Sreejith S., Volnova A. A., Belinski A. A., Dodin A. V., Tatarnikov A. M., Zheltoukhov S. G., 2020, arXiv:2012.01419

Abstract. We present results from applying the SNAD anomaly detection pipeline to the third public data release of the Zwicky Transient Facility (ZTF DR3). The pipeline is composed of 3 stages: feature extraction, search of outliers with machine learning algorithms and anomaly identification with followup by human experts. Our analysis concentrates in three ZTF fields, comprising more than 2.25 million objects. A set of 4 automatic learning algorithms was used to identify 277 outliers, which were subsequently scrutinised by an expert. From these, 188 (68%) were found to be bogus light curves — including effects from the image subtraction pipeline as well as overlapping between a star and a known asteroid, 66 (24%) were previously reported sources whereas 23 (8%) correspond to non-catalogued objects, with the two latter cases of potential scientific interest (e. g. 1 spectroscopically confirmed RS Canum Venaticorum star, 4 supernovae candidates, 1 red dwarf flare). Moreover, using results from the expert analysis, we were able to identify a simple bi-dimensional relation which can be used to aid filtering potentially bogus light curves in future studies. We provide a complete list of objects with potential scientific application so they can be further scrutinised by the community. These results confirm the importance of combining automatic machine learning algorithms with domain knowledge in the construction of recommendation systems for astronomy. Our code is publicly available at https://github.com/snad-space/zwad.

Keywords. Methods: data analysis, stars: variables: general, transients: supernovae, astronomical data bases: miscellaneous

Figure. The light curves of AT 2017ixs — nova candidate from the M31 field that behaves unusually for its suspected astrophysical type.

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