skip to main content

Explore Research Products in the NSF-PAR

Title: Thermonuclear Supernovae: Prospecting in the Age of Time-Domain and Multi-wavelength Astronomy.
We show how new and upcoming advances in the age of time-domain and multi-wavelength astronomy will open up a new venue to probe the diversity of SN Ia. We discuss this in the context of the ELT (ESO), as well as space based instrument such as James Webb Space Telescope (JWST). As examples we demonstrate how the power of very early observations, within hours to days after the explosion, and very late-time observations, such as light curves and mid-infrared spectra beyond 3 years, can be used to probe the link to progenitors and explosion scenarios. We identify the electron-capture cross sections of Cr, Mn, and Ni/Co as one of the limiting factors we will face in the future.  more » « less
Award ID(s):
1712953
NSF-PAR ID:
10160112
Author(s) / Creator(s):
Date Published:
Journal Name:
Nuclei in the Cosmos XV. Springer Proceedings in Physics, vol 219. Springer, Cham
Volume:
219
Page Range / eLocation ID:
187-194
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; ; ; ; ; et al ( , Monthly Notices of the Royal Astronomical Society)
    null (Ed.)
    ABSTRACT We present X-ray and radio observations of what may be the closest Type Iax supernova (SN) to date, SN 2014dt (d = 12.3–19.3 Mpc), and provide tight constraints on the radio and X-ray emission. We infer a specific radio luminosity $L_R\lt (1.0\!-\!2.4)\times 10^{25}\, \rm {erg\, s^{-1}\, Hz^{-1}}$ at a frequency of 7.5 GHz and a X-ray luminosity $L_X\lt 1.4\times 10^{38}\, \rm {erg\, s^{-1}}$ (0.3–10 keV) at ∼38–48 d post-explosion. We interpret these limits in the context of Inverse Compton (IC) emission and synchrotron emission from a population of electrons accelerated at the forward shock of the explosion in a power-law distribution $N_e(\gamma _e)\propto \gamma _e^{-p}$ with p = 3. Our analysis constrains the progenitor system mass-loss rate to be $\dot{M}\lt 5.0 \times 10^{-6} \rm {M_{\odot }\, yr^{-1}}$ at distances $r\lesssim 10^{16}\, \rm {cm}$ for an assumed wind velocity $v_w=100\, \rm {km\, s^{-1}}$, and a fraction of post-shock energy into magnetic fields and relativistic electrons of ϵB = 0.01 and ϵe = 0.1, respectively. This result rules out some of the parameter space of symbiotic giant star companions, and it is consistent with the low mass-loss rates expected from He-star companions. Our calculations also show that the improved sensitivity of the next-generation Very Large Array (ngVLA) is needed to probe the very low-density media characteristic of He stars that are the leading model for binary stellar companions of white dwarfs giving origin to Type Iax SNe. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; ; et al ( , Monthly Notices of the Royal Astronomical Society)
    ABSTRACT

    We present a photometric and spectroscopic analysis of the ultraluminous and slowly evolving 03fg-like Type Ia SN 2021zny. Our observational campaign starts from ∼5.3 h after explosion (making SN 2021zny one of the earliest observed members of its class), with dense multiwavelength coverage from a variety of ground- and space-based telescopes, and is concluded with a nebular spectrum ∼10 months after peak brightness. SN 2021zny displayed several characteristics of its class, such as the peak brightness (MB = −19.95 mag), the slow decline (Δm15(B) = 0.62 mag), the blue early-time colours, the low ejecta velocities, and the presence of significant unburned material above the photosphere. However, a flux excess for the first ∼1.5 d after explosion is observed in four photometric bands, making SN 2021zny the third 03fg-like event with this distinct behaviour, while its +313 d spectrum shows prominent [O i] lines, a very unusual characteristic of thermonuclear SNe. The early flux excess can be explained as the outcome of the interaction of the ejecta with $\sim 0.04\, \mathrm{M_{\odot }}$ of H/He-poor circumstellar material at a distance of ∼1012 cm, while the low ionization state of the late-time spectrum reveals low abundances of stable iron-peak elements. All our observations are in accordance with a progenitor system of two carbon/oxygen white dwarfs that undergo a merger event, with the disrupted white dwarf ejecting carbon-rich circumstellar material prior to the primary white dwarf detonation.

     
    more » « less
  3. ; ; ; ; ; ; ; ( , The Astrophysical Journal Letters)
    Abstract

    Parker Solar Probe observations reveal that the near-Sun space is almost filled with magnetic switchbacks (“switchbacks” hereinafter), which may be a major contributor to the heating and acceleration of solar wind. Here, for the first time, we develop an analytic model of an axisymmetric switchback with uniform magnetic field strength. In this model, three parameters control the geometry of the switchback: height (length along the background magnetic field), width (thickness along radial direction perpendicular to the background field), and the radial distance from the center of switchback to the central axis, which is a proxy of the size of the switchback along the third dimension. We carry out 3D magnetohydrodynamic simulations to investigate the dynamic evolution of the switchback. Comparing simulations conducted with compressible and incompressible codes, we verify that compressibility, i.e., parametric decay instability, is necessary for destabilizing the switchback. Our simulations also reveal that the geometry of the switchback significantly affects how fast the switchback destabilizes. The most stable switchbacks are 2D-like (planar) structures with large aspect ratios (length to width), consistent with the observations. We show that when plasma beta (β) is smaller than one, the switchback is more stable asβincreases. However, whenβis greater than 1, the switchback becomes very unstable as the pattern of the growing compressive fluctuations changes. Our results may explain some of the observational features of switchbacks, including the large aspect ratios and nearly constant occurrence rates in the inner heliosphere.

     
    more » « less
  4. ; ; ; ; ; ; ; ; ; ; et al ( , The Astrophysical Journal Letters)
    Abstract

    We present very early photometric and spectroscopic observations of the Type Ia supernova (SN Ia) 2023bee, starting about 8 hr after the explosion, which reveal a strong excess in the optical and nearest UV (UandUVW1) bands during the first several days of explosion. This data set allows us to probe the nature of the binary companion of the exploding white dwarf and the conditions leading to its ignition. We find a good match to the Kasen model in which a main-sequence companion star stings the ejecta with a shock as they buzz past. Models of double detonations, shells of radioactive nickel near the surface, interaction with circumstellar material, and pulsational delayed detonations do not provide good matches to our light curves. We also observe signatures of unburned material, in the form of carbon absorption, in our earliest spectra. Our radio nondetections place a limit on the mass-loss rate from the putative companion that rules out a red giant but allows a main-sequence star. We discuss our results in the context of other similar SNe Ia in the literature.

     
    more » « less
  5. ; ; ; ; ; ; ( , Monthly Notices of the Royal Astronomical Society)
    ABSTRACT

    The central star of the planetary nebula (PN) HuBi 1 has been recently proposed to have experienced a very late thermal pulse (VLTP), but the dilution of the emission of the recent ejecta by that of the surrounding H-rich old outer shell has so far hindered confirming its suspected H-poor nature. We present here an analysis of the optical properties of the ejecta in the innermost regions of HuBi 1 using MEGARA high-dispersion integral field and OSIRIS intermediate-dispersion long-slit spectroscopic observations obtained with the 10.4-m Gran Telescopio de Canarias. The unprecedented tomographic capability of MEGARA to resolve structures in velocity space allowed us to disentangle for the first time the Hα and Hβ emission of the recent ejecta from that of the outer shell. The recent ejecta is found to have much higher extinction than the outer shell, implying the presence of large amounts of dust. The spatial distribution of the emission from the ejecta and the locus of key line ratios in diagnostic diagrams probe the shock excitation of the inner ejecta in HuBi 1, in stark contrast with the photoionization nature of the H-rich outer shell. The abundances of the recent ejecta have been computed using the mappings v code under a shock scenario. They are found to be consistent with a born-again ejection scenario experienced by the progenitor star, which is thus firmly confirmed as a new ‘born-again’ star.

     
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email