arXiv subjects

V. P. Utrobin

Publications and source records attributed to V. P. Utrobin.

At least 19 recordsLinked to original sources

arXiv2026

Constraining hydrodynamic model of nearby type IIP SN 2023ixf

Despite proximity of SN 2023ixf and a wealth of observational data, the released hydrodynamic models leave too broad range of the derived explosion energy and the ejected mass. We revisit the hydrodynamic modeling based on a broader set of observables than have been previously used. Among those of top priority is the early maximum ejecta velocity that is crucial in removing parameter degeneracy. The inferred parameters of SN 2023ixf are the explosion energy of 2.8x10^{51} erg, ejecta mass of 13.2 Msun, presupernova radius of 1540 Rsun, and Ni-56 mass of 0.07 Msun. The circumstellar matter is composed by the dense circumstellar shell with the mass of 0.01 Msun and radius of 5x10^{14} cm, as well as the external rarefied wind. Both circumstellar components are consistent with the early H-alpha broad wings caused by the Thomson scattering and the intrinsic column density provided by X-ray data. Based on the radiation hydrodynamics we, for the first time, simulate the SN 2023ixf phenomenon from the explosion to the emergence of the hard X-ray radiation.

astro-ph.HE↗

arXiv2026

Southern eROSITA bubble as a forward shock and the low-metallicity CGM. South-east side story

Unlike the complicated X-ray and radio structure observed in the North Polar Spur area, the South-Eastern part of the eROSITA bubbles can be reasonably well described as a propagating forward shock, plausibly created by the transient energy release at the Galactic Center. In this model, the physical radius of the bubble is $R_{\rm b}\sim 7-8\,{\rm kpc}$ and the age of the outburst is $t_{\rm age}\sim 5-8\,{\rm Myr}$. The latter quantity is plausibly a lower limit on the true age. The visible segment of the shock front (located at a distance of $\sim 10-12\,{\rm kpc}$ above the Galactic Disk and at a similar distance from the Sun) is currently expanding with the velocity $\sim 700\,{\rm km\,s^{-1}}$ through the gas with density $n_e\sim 3\times 10^{-4}\,{\rm cm^{-3}}$, and the abundance of heavy elements in this gas is low $Z\sim 0.1-0.2 \times Z_\odot$ (depending on the adopted reference Solar abundances). Unlike constraints derived from the line-of-sight-integrated quantities, these are effectively in situ measurements of the circumgalactic medium (CGM) properties. Given the simplifying assumptions used in deriving the density and abundance, we assign a factor of 2 systematic uncertainty to the final estimates. An eventual decisive test for the shock properties can be provided by the velocity measurements of the X-ray-emitting gas with soft X-ray bolometers. The extended forward shock propagating through low-metallicity gas is a favorable site to accelerate very high-energy cosmic rays, which might contribute to the recently discovered proton-rich Galactic cosmic ray component at PeV energies impinging on the Earth's atmosphere.

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arXiv2025

Type IIP SN 2024bch: Hydrodynamic model, shock breakout, and circumstellar interaction

The well-observed type IIP SN 2024bch with the short plateau is shown to be an outcome of the red supergiant explosion with the presupernova mass of 14-15 Msun, the explosion energy of 2x10^{51} erg, and presupernova radius of 1250 Rsun. The early gamma-ray escape demonstrated by the radioactive tail is due to the large Ni-56 extension up to 7400 km/s. The early-time spectral evolution indicates the presence of the circumstellar dense confined envelope with the mass of 0.003-0.006 Msun within 6x10^{14} cm. The deceleration of the outermost ejecta implies the wind with the mass-loss rate of about 6x10^{-4} Msun/yr. The inferred mass-loss rate is by one-two order larger compared to most of type IIP supernovae, but comparable to the wind of type IIL SN 1998S. The asymmetry of the broad H-alpha component on day 144 powered by the circumstellar interaction is the outcome of the Thomson scattering and absorption in the Paschen continuum in the unshocked ejecta.

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arXiv2024

North Polar Spur: gaseous plume(s) from star-forming regions at $\sim$3-5 kpc from Galactic Center?

We argue that the North Polar Spur (NPS) and many less prominent structures are formed by gaseous metal-rich plumes associated with star-forming regions (SFRs). The SFRs located at the tangent to the 3-5~kpc rings might be particularly relevant to NPS. A multi-temperature mixture of gaseous components and cosmic rays rises above the Galactic disk under the action of their initial momentum and buoyancy. Eventually, the plume velocity becomes equal to that of the ambient gas, which rotates with different angular speed than the stars in the disk. As a result, the plumes acquire characteristic bent shapes. An ad hoc model of plumes' trajectories shows an interesting resemblance to the morphology of structures seen in the radio continuum and X-rays.

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arXiv2024

Revisiting short-plateau SN 2018gj

We present an alternative model of unusual type-IIP SN 2018gj. Despite the short plateau and early gamma-rays escape seeming to favor low-mass ejecta, our hydrodynamic model requires a large ejected mass (about 23 Msun). The high ejecta velocity, we find from hydrogen lines in early spectra, is among crucial constraints on the hydrodynamic model. We recover the wind density that rules out a notable contribution of the circumstellar interaction to the bolometric luminosity. The early radioactive gamma-rays escape is found to be due to the high velocity of Ni-56, whereas the asymmetry of the H-alpha emission is attributed to the asymmetry of the Ni-56 ejecta. The available sample of type-IIP supernovae studied hydrodynamically in a uniform way indicates that the asymmetry of the Ni-56 ejecta is probably their intrinsic property. Hydrogen lines in the early spectra of SN 2018gi and SN 2020jfo are found to imply a clumpy structure of the outer ejecta. With two already known similar cases of SN 2008in and SN 2012A we speculate that the clumpiness of the outer ejecta is inherent to type-IIP supernovae related to the red supergiant explosion.

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arXiv2023

Uncommon SN 2020jfo: Ordinary explosion of 8 Msun red supergiant with dense wind

We present the hydrodynamic model of Type IIP SN 2020jfo with the unusually short (nearly 60 days) light curve plateau. The model suggests the explosion of about 8 Msun red supergiant that ejected nearly 6 Msun with the energy of about 0.8x10^51 erg. The presupernova wind density turns out highest among known SNe IIP. Yet the presupernova was not embedded into a very dense confined circumstellar shell that is a feature of some Type IIP supernovae, so the circumstellar interaction in close environment does not contribute noticeably to the initial (about 10 days) bolometric luminosity. Despite uncommon appearance SN 2020jfo turns out similar to SN 1970G in the V-band light curve, photospheric velocities, and, possibly, luminosity as well.

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arXiv2021

Enormous explosion energy of Type IIP SN 2017gmr with bipolar Ni-56 ejecta

The unusual Type IIP SN 2017gmr is revisited in order to pinpoint the origin of its anomalous features, including the peculiar light curve after about 100 days. The hydrodynamic modelling suggests the enormous explosion energy of about 10^52 erg. We find that the light curve with the prolonged plateau/tail transition can be reproduced either in the model with a high hydrogen abundance in the inner ejecta and a large amount of radioactive Ni-56, or in the model with an additional central energy source associated with the fallback/magnetar interaction in the propeller regime. The asymmetry of the late H-alpha emission and the reported linear polarization are reproduced by the model of the bipolar Ni-56 ejecta. The similar bipolar structure of the oxygen distribution is responsible for the two-horn structure of the [O I] 6360, 6364 A emission. The bipolar Ni-56 structure along with the high explosion energy are indicative of the magneto-rotational explosion. We identify narrow high-velocity absorption features in H-alpha and He I 10830 A lines with their origin in the fragmented cold dense shell formed due to the outer ejecta deceleration in a confined circumstellar shell.

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arXiv2021

Supernova 1987A: 3D Mixing and light curves for explosion models based on binary-merger progenitors

Six binary-merger progenitors of Supernova 1987A (SN 1987A) with properties close to those of the blue supergiant Sanduleak -69 202 are exploded by neutrino heating and evolved until long after shock breakout in three dimensions (3D), and continued for light-curve calculations in spherical symmetry. Our results confirm previous findings for single-star progenitors: (1) 3D neutrino-driven explosions with SN 1987A-like energies synthesize Ni-56 masses consistent with the radioactive light-curve tail; (2) hydrodynamic models mix hydrogen inward to minimum velocities below 40 km/s compatible with spectral observations of SN 1987A; and (3) for given explosion energy the efficiency of outward radioactive Ni-56 mixing depends mainly on high growth factors of Rayleigh-Taylor instabilities at the (C+O)/He and He/H composition interfaces and a weak interaction of fast plumes with the reverse shock occurring below the He/H interface. All binary-merger models possess presupernova radii matching the photometric radius of Sanduleak -69 202 and a structure of the outer layers allowing them to reproduce the observed initial luminosity peak in the first about 7 days. Models that mix about 0.5 Msun of hydrogen into the He-shell and exhibit strong outward mixing of Ni-56 with maximum velocities exceeding the 3000 km/s observed for the bulk of ejected Ni-56 have light-curve shapes in good agreement with the dome of the SN 1987A light curve. A comparative analysis of the best representatives of our 3D neutrino-driven explosion models of SN 1987A based on single-star and binary-merger progenitors reveals that only one binary model fulfills all observational constraints, except one.

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arXiv2019

Resolving the puzzle of type IIP SN 2016X

The enigmatic type IIP SN 2016X demonstrates the unprecedented asphericity in the nebular H-alpha line profile, the absence of nebular [O I] emission, and the unusual occultation effect due to the internal dust. The hydrodynamic modelling of the bolometric light curve and expansion velocities suggests that the event is an outcome of the massive star explosion that ejected 28 Msun with the kinetic energy of 1.7x10^51 erg and 0.03 Msun of radioactive Ni-56. We recover the bipolar distribution of Ni-56 from the H-alpha profile via the simulation of the emissivity produced by non-spherical Ni-56 ejecta. The conspicuous effect of the dust absorption in the H-alpha profile rules out the occultation by the dusty sphere or dusty thick disk but turns out consistent with the thin dusty disk-like structure in the plane perpendicular to the bipolar axis. We speculate that the absence of the nebular [O I] emission might originate from the significant cooling of the oxygen-rich matter mediated by CO and SiO molecules.

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arXiv2017

Luminous type IIP SN 2013ej with high-velocity Ni-56 ejecta

We explore the well-observed type IIP SN 2013ej with peculiar luminosity evolution. It is found that the hydrodynamic model cannot reproduce in detail the bolometric luminosity at both the plateau and the radioactive tail. Yet the ejecta mass of 23-26 Msun and the kinetic energy of (1.2-1.4)x10^51 erg are determined rather confidently. We suggest that the controversy revealed in hydrodynamic simulations stems from the strong asphericity of the Ni-56 ejecta. An analysis of the asymmetric nebular H-alpha line and of the peculiar radioactive tail made it possible to recover parameters of the asymmetric bipolar Ni-56 ejecta with the heavier jet residing in the rear hemisphere. The inferred Ni-56 mass is 0.039 Msun, twice as large compared to a straightforward estimate from the bolometric luminosity at the early radioactive tail. The bulk of ejected Ni-56 has velocities in the range of 4000-6500 km/s. The linear polarization predicted by the model with the asymmetric ionization produced by bipolar Ni-56 ejecta is consistent with the observational value.

astro-ph.HE↗

arXiv2017

Light curve analysis of ordinary type IIP supernovae based on neutrino-driven explosion simulations in three dimensions

Type II-plateau supernovae (SNe IIP) are the most numerous subclass of core-collapse SNe originating from massive stars. In the framework of the neutrino-driven explosion mechanism, we study the SN outburst properties for a red supergiant progenitor model and compare the corresponding light curves with observations of the ordinary Type IIP SN 1999em. Three-dimensional (3D) simulations of (parametrically triggered) neutrino-driven explosions are performed with the (explicit, finite-volume, Eulerian, multifluid hydrodynamics) code PROMETHEUS, using a presupernova model of a 15 Msun star as initial data. At approaching homologous expansion, the hydrodynamical and composition variables of the 3D models are mapped to a spherically symmetric configuration, and the simulations are continued with the (implicit, Lagrangian radiation-hydrodynamics) code CRAB to follow the blast-wave evolution during the SN outburst. Our 3D neutrino-driven explosion model with an explosion energy of about 0.5x10^51 erg produces Ni-56 in rough agreement with the amount deduced from fitting the radioactively powered light-curve tail of SN 1999em. The considered presupernova model, 3D explosion simulations, and light-curve calculations can explain the basic observational features of SN 1999em, except for those connected to the presupernova structure of the outer stellar layers. Our 3D simulations show that the distribution of Ni-rich matter in velocity space is asymmetric with a strong dipole component that is consistent with the observations of SN 1999em. The monotonic luminosity decline from the plateau to the radioactive tail in ordinary SNe IIP is a manifestation of the intense turbulent mixing at the He/H composition interface.

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arXiv2017

Time-Dependent Ionization in theEnvelopes of Type II Supernovae at the Photospheric Phase

The importance of allowance for the time-dependent effect in the kinetics at the photospheric phase during a supernova explosion has been confirmed by several independent research groups. The time-dependent effect provides a higher degree of hydrogen ionization in comparison with the steady-state solutions and strengthens the H$α$ line in the resulting simulated spectrum, with the intensity of the effect increasing with time. However, some researchers argue that the time-dependent ionization effect is unimportant. Its allowance leads to an insignificant strengthening of H$α$ in their modeling only in the first days after explosion. We have demonstrated the importance of the time-dependent effect with the models of SN 1999em as an example using the new original LEVELS software package. The role of a number of factors that can weaken the time-dependent effect has been checked. We have confirmed that the intensity of the effect is affected by the abundance of metal admixtures in the envelope, while the addition of extra levels to themodel hydrogen atom weakens the time-dependent effect to a lesser degree and never removes it completely.

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arXiv2017

3D modelling of accretion disc in eclipsing binary system V1239 Her

We present the results of 3D-hydrodynamical simulations of accretion flow in the eclipsing dwarf nova V1239 Her in quiescence. The model includes the optical star filling its Roche lobe, a gas stream emanating from the inner Lagrangian point of the binary system, and the accretion disc structure. A cold hydrogen gas stream is initially emitted towards a point-like gravitational centre. A stationary accretion disc is formed in about 15 orbital periods after the beginning of accretion. The model takes into account partial ionization of hydrogen and uses realistic cooling function for hydrogen. The light curve of the system is calculated as the volume emission of optically thin layers along the line of sight up to the optical depth τ=2/3 calculated using Planck-averaged opacities. The calculated eclipse light curves show good agreement with observations, with the changing shape of pre-eclipse and post-eclipse light curves being explained entirely due to ~ 50% variations in the mass accretion rate through the gas stream.

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arXiv2014

Parameters of type IIP SN 2012A and clumpiness effects

The explosion energy and the ejecta mass of a type IIP supernova (SN IIP) derived from hydrodynamic simulations are principal parameters of the explosion theory. However, the number of SNe IIP studied by hydrodynamic modeling is small. Moreover, some doubts exist in regard to the reliability of derived SN IIP parameters. The well-observed type IIP SN 2012A will be studied via hydrodynamic modeling. Their early spectra will be checked for a presence of the ejecta clumpiness. Other observational effects of clumpiness will be explored. Supernova parameters are determined by means of the standard hydrodynamic modeling. The early hydrogen Halpha and Hbeta lines are used for the clumpiness diagnostics. The modified hydrodynamic code is employed to study the clumpiness effect in the light curve and expansion kinematics. We found that SN 20012A is the result of the explosion of a red supergiant with the radius of 715 Rsun. The explosion energy is 5.25x10^50 erg, the ejecta mass is 13.1 Msun, and the total Ni-56 mass is 0.012 Msun. The estimated mass of a progenitor, a main-sequence star, is 15 Msun. The Halpha and Hbeta lines in early spectra indicate that outer ejecta are clumpy. Hydrodynamic simulations show that the clumpiness modifies the early light curve and increases the maximum velocity of the outer layers. The pre-SN 2012A was a normal red supergiant with the progenitor mass of about 15 Msun. The outer layers of ejecta indicate the clumpy structure. The clumpiness of the external layers can increase the maximum expansion velocity.

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arXiv2014

Does energy of type IIP supernovae depends on stellar mass?

We determine the oxygen density in the central zone of nine type IIP supernovae (SN~IIP) at the nebular stage using oxygen doublet [O I] 6300, 6364 Å. Combined with two available estimates these data indicate that oxygen densities on day 300 are distributed in rather narrow range $(2.3\pm1)\times10^9$ cm$^{-3}$. The result does not depend on the distance, extinction, or model assumptions. We demonstrate that the found density distribution suggests that the explosion energy of SN~IIP increases with the stellar mass.

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arXiv2013

Disparity between Hα and Hβ in SN 2008in: inhomogeneous external layers of type IIP supernovae?

We study disparity between Hα and Hβ in early spectra of the type IIP supernova SN 2008in. The point is that these lines cannot be described simultaneously in a spherically-symmetric model with the smooth density distribution. It is shown that an assumption of a clumpy structure of external layers of the envelope resolves the problem. We obtain estimates of the velocity at the inner border of the inhomogeneous zone (\approx6100 km s^{-1}), the filing factor of inhomogeneities (\leq0.5), and the mass of the inhomogeneous layers (~ 0.03 M_{\odot}). The amplitude of flux fluctuations in the early spectrum of Hα (ΔF/F ~ 10^{-2}) imposes a constraint on the size of inhomogeneities (\leq 200 km s^{-1}). A detection of fluctuations in the early Hα of type IIP supernovae might become an observational test of the inhomogeneous structure of their envelopes. We propose also the indirect test of the clumpy structure of external layers: the study of properties of the initial radiation outburst due to the shock breakout. The inhomogeneous structure of external layers of type IIP supernovae could be an outcome of density perturbations and density inversion in outer convective layers of presupernova red supergiant.

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arXiv2013

Type IIP supernova 2008in: the explosion of a normal red supergiant

The explosion energy and the ejecta mass of a type IIP supernova make up the basis for the theory of explosion mechanism. So far, these parameters have only been determined for seven events. Type IIP supernova 2008in is another well-observed event for which a detailed hydrodynamic modeling can be used to derive the supernova parameters. Hydrodynamic modeling was employed to describe the bolometric light curve and the expansion velocities at the photosphere level. A time-dependent model for hydrogen ionization and excitation was applied to model the Halpha and Hbeta line profiles. We found an ejecta mass of 13.6 Msun, an explosion energy of 5.05x10^50 erg, a presupernova radius of 570 Rsun, and a radioactive Ni-56 mass of 0.015 Msun. The estimated progenitor mass is 15.5 Msun. We uncovered a problem of the Halpha and Hbeta description at the early phase, which cannot be resolved within a spherically symmetric model. The presupernova of SN 2008in was a normal red supergiant with the minimum mass of the progenitor among eight type IIP supernovae explored by means of the hydrodynamic modeling. The problem of the absence of type IIP supernovae with the progenitor masses <15 Msun in this sample remains open.

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arXiv2011

Supernova 2000cb: high-energy version of SN 1987A

Among type IIP supernovae there are a few events that resemble the well-studied supernova 1987A produced by the blue supergiant in the Large Magellanic Cloud. We study a peculiar supernova 2000cb and compare it with the supernova 1987A. We carried out hydrodynamic simulations of the supernova in an extended parameter space to describe its light curve and spectroscopic data. The hydrogen H-alpha and H-beta lines are modeled using a time-dependent approach. We constructed the hydrodynamic model by fitting the photometric and spectroscopic observations. We infer a presupernova radius of 35 Rsun, an ejecta mass of 22.3 Msun, an explosion energy of 4.4x10^{51} erg, and a radioactive Ni-56 mass of 0.083 Msun. The estimated progenitor mass on the main sequence lies in the range of 24-28 Msun. The early H-alpha profile on day 7 is consistent with the density distribution found from hydrodynamic modeling, while the H-alpha line on day 40 indicates an extended Ni-56 mixing up to a velocity of 8400 km/s. We emphasize that the dome-like light curves of both supernova 2000cb and supernova 1987A are entirely powered by radioactive decay. This is unlike normal type IIP supernovae, the plateau of which is dominated by the internal energy deposited after the shock wave propagation through the presupernova. We find signatures of the explosion asymmetry in the photospheric and nebular spectra. The explosion energy of supernova 2000cb is higher by a factor of three compared to supernova 1987A, which poses a serious problem for explosion mechanisms of type IIP supernovae.

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