Non-relativistic radiation mediated shock breakouts: I. Exact bolometric planar breakout solutions

The problem of a non-steady planar radiation mediated shock (RMS) breaking out from a surface with a power-law density profile, \rho\propto x^n, is numerically solved in the approximation of diffusion with constant opacity. For an appropriate choice of time, length and energy scales, determined by the breakout opacity, velocity and density, the solution is universal, i.e. depends only on the density power law index n. The resulting luminosity depends weakly on the value of n. An approximate analytic solution, based on the self-similar hydrodynamic solutions and on the steady RMS solutions, is constructed and shown to agree with the numerical solutions as long as the shock is far from the surface, \tau>> c/v_{sh}. Approximate analytic expressions, calibrated based on the exact solutions, are provided, that describe the escaping luminosity as a function of time. These results can be used to calculate the bolometric properties of the bursts of radiation produced during supernova (SN) shock breakouts. For completeness, we also use the exact breakout solutions to provide an analytic approximation for the maximum surface temperature for fast (v_{sh}>~0.1) non-thermal breakouts, and show that it is few times smaller than inferred based on steady-state RMS solutions

Double explosions and jet formation in GRB-supernova progenitors

Progenitors of long GRBs, and core-collapse supernovae in general, may have two separate mechanisms driving the outflows: quasi-isotropic neutrino-driven supernova explosions followed by a highly collimated relativistic outflow driven by the GRB central engine, a black hole or a magnetar. We consider the dynamics of the second GRB-driven explosion propagating through expanding envelope generated by the passage of the primary supernova shock. Beyond the central core, in the region of steep density gradient created by the SN shock breakout, the accelerating secondary quasi-spherical GRB shock become unstable to corrugation and under certain conditions may form a highly collimated jet, a "chimney", when a flow expands almost exclusively along a nearly cylindrically collimated channel. Thus, weakly non-spherical driving and/or non-spherical initial conditions of the wind cavity may produce highly non-spherical, jetted outflows. For a constant luminosity GRB central engine, this occurs for density gradient in the envelope \rho ~ r^{-\omega} steeper than \omega >4

Broad emission lines from opaque electron-scattering environment of SN 1998S

I propose that broad narrow-topped emission lines with full width at zero intensity >20000 km/s, seen in early-time spectra of SN 1998S, originate from a dense circumstellar gas and not from the supernova ejecta. The tremendous line width is the result of multiple scattering of the narrow line radiation on thermal electrons of the circumstellar shell with the Thomson optical depth of about 4 on 1998 March 6.Comment: 7 pages, 4 figures, accepted for publication in MNRA

Pengaruh Love Of Nature Pada Sustainable Consumption Behavior Yang Dimediasi Oleh Environmental Eengagement

This research aims to analyze the influence of love of nature on sustainable consumption behavior, mediated by environmental engagement. Love of nature consists of three variables: passion for nature, intimacy with nature, and commitment to nature. This survey research employs a deductive quantitative approach. The sample was randomly selected by distributing questionnaires to students at Muhammadiyah University of Surakarta and residents of Solo Raya aged 17 and above, with a total of 205 respondents. Data analysis was conducted using PLS-SEM SmartPLS v.3.2.9. The research findings indicate that love of nature and environmental engagement have a positive and significant impact on sustainable consumption behavior. Additionally, love of nature also has a positive and significant impact on sustainable consumption behavior, mediated by environmental engagement

The origin of the high velocity circumstellar gas around SN 1998S

Modelling of high resolution Balmer line profiles in the early-time spectra of SN 1998S shows that the inferred fast (roughly 400 km/s) circumstellar (CS) gas on days 23 and 42 post-explosion is confined to a narrow, negative velocity gradient shell just above the photosphere. This gas may be identified with a slow (v < 40 km/s) progenitor wind accelerated at the ejecta-wind interface. In this scenario, the photosphere coincides with a cool dense shell formed in the reverse shock. Acceleration by radiation from the supernova or by a shock-accelerated relativistic particle precursor are both possible explanations for the observed fast CS gas. An alternative, equally plausible scenario is that the fast CS gas is accelerated within shocked clouds engulfed by the outer shock, as it propagates through the intercloud wind.Comment: 9 pages, 6 figures. MNRAS, accepted. Typos added, acknowledgments correcte

The type IIn supernova 1994W: evidence for the explosive ejection of a circumstellar envelope

We present and analyse spectra of the Type IIn supernova 1994W obtained between 18 and 203 days after explosion. During the luminous phase (first 100 d) the line profiles are composed of three major components: (i) narrow P-Cygni lines with the absorption minima at -700 km/s; (ii) broad emission lines with BVZI ~4000 km/s; and (iii) broad, smooth wings, most apparent in H-alpha. These components are identified with an expanding circumstellar (CS) envelope, shocked cool gas in the forward post-shock region, and multiple Thomson scattering in the CS envelope, respectively. The absence of broad P-Cygni lines from the supernova is the result of the formation of an optically thick, cool, dense shell at the interface of the ejecta and the CS envelope. We model the supernova deceleration and Thomson scattering wings to recover the density, radial extent and Thomson optical depth of the CS envelope during the first month. We reproduce the light curve with a hydrodynamical model and find it to be powered by a combination of internal energy leakage after the explosion of an extended pre-supernova (~10^15 cm) and luminosity from circumstellar interaction. We recover the pre-explosion kinematics of the CS envelope: it is close to homologous expansion with outer velocity ~1100 km/s and a kinematic age of ~1.5 yr. The CS envelope's high mass and kinetic energy, combined with its small age, strongly suggest that the CS envelope was explosively ejected about 1.5 yr before the supernova explosion.Comment: 22 pages, 21 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Societ

Numerical simulations of super-luminous supernovae of type IIn

We present numerical simulations that include 1-D Eulerian multi-group radiation-hydrodynamics, 1-D non-LTE radiative transfer, and 2-D polarised radiative transfer for super-luminous interacting supernovae (SNe). Our reference model is a ~10Msun inner shell with 10^51erg ramming into a ~3Msun cold outer shell (the circumstellar-medium, or CSM) that extends from 10^15cm to 2x10^16cm and moves at 100km/s. We discuss the light curve evolution, which cannot be captured adequately with a grey approach. In these interactions, the shock-crossing time through the optically-thick CSM is much longer than the photon diffusion time. Radiation is thus continuously leaking from the shock through the CSM, in disagreement with the shell-shocked model that is often invoked. Our spectra redden with time, with a peak distribution in the near-UV during the first month gradually shifting to the optical range over the following year. Initially Balmer lines exhibit a narrow line core and the broad line wings that are characteristic of electron scattering in the SNe IIn atmospheres (CSM). At later times they also exhibit a broad blue shifted component which arises from the cold dense shell. Our model results are broadly consistent with the bolometric light curve and spectral evolution observed for SN2010jl. Invoking a prolate pole-to-equator density ratio in the CSM, we can also reproduce the ~2% continuum polarisation, and line depolarisation, observed in SN2010jl. By varying the inner shell kinetic energy and the mass and extent of the outer shell, a large range of peak luminosities and durations, broadly compatible with super-luminous SNe IIn like 2010jl or 2006gy, can be produced.Comment: paper accepted to MNRA

Evidence for Asphericity in the Type IIn Supernova 1998S

We present optical spectropolarimetry obtained at the Keck-II 10-m telescope on 1998 March 7 UT along with total flux spectra spanning the first 494 days after discovery (1998 March 2 UT) of the peculiar type IIn supernova (SN) 1998S. The SN is found to exhibit a high degree of linear polarization, implying significant asphericity for its continuum-scattering environment. Prior to removal of the interstellar polarization, the polarization spectrum is characterized by a flat continuum (at p ~ 2%) with distinct changes in polarization associated with both the broad (FWZI >= 20,000 km/s) and narrow (unresolved, FWHM < 300 km/s) line emission seen in the total flux spectrum. When analyzed in terms of a polarized continuum with unpolarized broad-line recombination emission, an intrinsic continuum polarization of p ~ 3% results (the highest yet found for a SN), suggesting a global asphericity of >= 45% from the oblate, electron-scattering dominated models of Hoflich (1991). The smooth, blue continuum evident at early times is shown to be inconsistent with a reddened, single-temperature blackbody, instead having a color temperature that increases with decreasing wavelength. Broad emission-line profiles with distinct blue and red peaks are seen in the total flux spectra at later times, perhaps suggesting a disk-like or ring-like morphology for the dense (n_e ~ 10^7 cm^{-3}) circumstellar medium. Implications of the circumstellar scattering environment for the spectropolarimetry are discussed, as are the effects of uncertain removal of interstellar polarization.Comment: 25 pages + 2 tables + 14 figures, Submitted to The Astrophysical Journa

A very low mass of Ni-56 in the ejecta of SN 1994W

We present spectroscopic and photometric observations of the luminous narrow- line Type IIP (plateau) supernova 1994W. After the plateau phase (t >120 days), the light curve dropped by 3.5 mag in V in only 12 days. Between 125 and 197 days after explosion the supernova faded substantially faster than the decay rate of Co-56, and by day 197 it was 3.6 magnitudes less luminous in R compared to SN 1987A. The low R-luminosity could indicate less than 0.0026 {+0.0017}/ {-0.0011} Msun of Ni-56 ejected at the explosion, but the emission between 125 and 197 days must then have been dominated by an additional power source, pre- sumably circumstellar interaction. Alternatively, the late light curve was dominated by Co-56 decay. In this case, the mass of the ejected Ni-56 was 0.015 {+0.012}/{-0.008} Msun, and the rapid fading between 125 and 197 days was most likely due to dust formation. Though this value of the mass is higher than in the case with the additional power source, it is still lower than estimated for any previous Type II supernova. Only progenitors with M(ZAMS) = 8-10 Msun and M(ZAMS) > 25 Msun are expected to eject such low masses of Ni-56. If M(ZAMS) = 8-10 Msun, the plateau phase indicates a low explosion energy, while for a progenitor with M(ZAMS) > 25 Msun the energy can be the canonical 1.0E{51} ergs. As SN 1994W was unusually luminous, the low-mass explosion may require an uncomfortably high efficiency in converting explosion energy into radiation. This favors a M(ZAMS) > 25 Msun progenitor. The supernova's narrow (roughly 1000 km s^{-1}) emission lines were excited by the hot supernova spectrum, rather than a circumstellar shock. The thin shell from which the lines origi- nated was most likely accelerated by the radiation from the supernova.Comment: 19 pages AASTeX v.4.0, including 5 Postscript figures; ApJ, in pres

Circumstellar Na I and Ca II lines in type IIP supernovae and SN 1998S

We study a possibility of detection of circumstellar absorption lines of Na I D$_{1,2}$ and Ca II H,K in spectra of type IIP supernovae at the photospheric epoch. The modelling shows that the circumstellar lines of Na I doublet will not be seen in type IIP supernovae for moderate wind density, e.g., characteristic of SN 1999em, whereas rather pronounced Ca II lines with P Cygni profile should be detectable. A similar model is used to describe Na I and Ca II circumstellar lines seen in SN 1998S, type IIL with a dense wind. We show that line intensities in this supernova are reproduced, if one assumes an ultraviolet excess, which is caused primarily by the comptonization of supernova radiation in the shock wave.Comment: To be published in Astronomy Letter