We present UV and/or optical observations and models of SN 2023ixf, a type II supernova (SN) located in Messier 101 at 6.9 Mpc. Early time (
This content will become publicly available on October 1, 2024
We present a series of high-resolution echelle spectra of SN 2023ixf in M101, obtained nightly during the first week or so after discovery using PEPSI on the Large Binocular Telescope. Na
- Award ID(s):
- 1813466
- NSF-PAR ID:
- 10482211
- Publisher / Repository:
- AAS Journals
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 956
- Issue:
- 1
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 46
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract flash ) spectroscopy of SN 2023ixf, obtained primarily at Lick Observatory, reveals emission lines of Hi , Hei/ii , Civ , and Niii/iv/v with a narrow core and broad, symmetric wings arising from the photoionization of dense, close-in circumstellar material (CSM) located around the progenitor star prior to shock breakout. These electron-scattering broadened line profiles persist for ∼8 days with respect to first light, at which time Doppler broadened the features from the fastest SN ejecta form, suggesting a reduction in CSM density atr ≳ 1015cm. The early time light curve of SN 2023ixf shows peak absolute magnitudes (e.g.,M u = −18.6 mag,M g = −18.4 mag) that are ≳2 mag brighter than typical type II SNe, this photometric boost also being consistent with the shock power supplied from CSM interaction. Comparison of SN 2023ixf to a grid of light-curve and multiepoch spectral models from the non-LTE radiative transfer codeCMFGEN and the radiation-hydrodynamics codeHERACLES suggests dense, solar-metallicity CSM confined tor = (0.5–1) × 1015cm, and a progenitor mass-loss rate ofv w = 50 km s−1, this corresponds to enhanced mass loss (i.e.,superwind phase) during the last ∼3–6 yr before explosion. -
more » « less
Abstract We present the optical spectroscopic evolution of SN 2023ixf seen in subnight cadence spectra from 1.18 to 15 days after explosion. We identify high-ionization emission features, signatures of interaction with material surrounding the progenitor star, that fade over the first 7 days, with rapid evolution between spectra observed within the same night. We compare the emission lines present and their relative strength to those of other supernovae with early interaction, finding a close match to SN 2020pni and SN 2017ahn in the first spectrum and SN 2014G at later epochs. To physically interpret our observations, we compare them to CMFGEN models with confined, dense circumstellar material around a red supergiant (RSG) progenitor from the literature. We find that very few models reproduce the blended N
iii (λλ 4634.0,4640.6)/Ciii (λλ 4647.5,4650.0) emission lines observed in the first few spectra and their rapid disappearance thereafter, making this a unique diagnostic. From the best models, we find a mass-loss rate of 10−3–10−2M ⊙yr−1, which far exceeds the mass-loss rate for any steady wind, especially for an RSG in the initial mass range of the detected progenitor. These mass-loss rates are, however, similar to rates inferred for other supernovae with early circumstellar interaction. Using the phase when the narrow emission features disappear, we calculate an outer dense radius of circumstellar materialR CSM,out≈ 5 × 1014cm, and a mean circumstellar material density ofρ = 5.6 × 10−14g cm−3. This is consistent with the lower limit on the outer radius of the circumstellar material we calculate from the peak Hα emission flux,R CSM,out≳ 9 × 1013cm. -
Abstract We present NuSTAR observations of the nearby SN 2023ixf in M101 ( d = 6.9 Mpc) that provide the earliest hard X-ray detection of a nonrelativistic stellar explosion to date at δ t ≈ 4 days and δ t ≈ 11 days. The spectra are well described by a hot thermal bremsstrahlung continuum with T > 25 keV shining through a thick neutral medium with a neutral hydrogen column that decreases with time (initial N Hint = 2.6 × 10 23 cm −2 ). A prominent neutral Fe K α emission line is clearly detected, similar to other strongly interacting supernovae (SNe) such as SN 2010jl. The rapidly decreasing intrinsic absorption with time suggests the presence of a dense but confined circumstellar medium (CSM). The absorbed broadband X-ray luminosity (0.3–79 keV) is L X ≈ 2.5 × 10 40 erg s −1 during both epochs, with the increase in overall X-ray flux related to the decrease in the absorbing column. Interpreting these observations in the context of thermal bremsstrahlung radiation originating from the interaction of the SN shock with a dense medium we infer large particle densities in excess of n CSM ≈ 4 × 10 8 cm −3 at r < 10 15 cm, corresponding to an enhanced progenitor mass-loss rate of M ̇ ≈ 3 × 10 − 4 M ⊙ yr −1 for an assumed wind velocity of v w = 50 km s −1 .more » « less
-
more » « less
Abstract In order to better characterize the rich supernova remnant (SNR) population of M83 (NGC 5236), we have obtained high-resolution (∼85 km s−1) spectra of 119 of the SNRs and SNR candidates in M83 with Gemini/GMOS, as well as new spectra of the young SNRs B12-174a and SN 1957D. Most of the SNRs and SNR candidates have [S
ii ]:Hα ratios that exceed 0.4. Combining these results with earlier studies we have carried out with MUSE and at lower spectroscopic resolution with GMOS, we have confirmed a total of 238 emission nebulae to be SNRs on the basis of their [Sii ]:Hα ratios, about half of which have emission lines that show velocity broadening greater than 100 km s−1, providing a kinematic confirmation that they are SNRs and not Hii regions. Looking at the entire sample, we find a strong correlation between velocity widths and the line ratios of [Oi ]λ 6300:Hα , [Nii ]λ 6584:Hα , and [Sii ]λλ 6716, 6731:Hα . The density-sensitive [Sii ]λ 6716:λ 6731 line ratio is strongly correlated with SNR diameter, but not with the velocity width. We discuss these results in the context of previously published shock models. -
more » « less
Abstract SN 2014C was originally classified as a Type Ib supernova, but at phase
ϕ = 127 days, post-explosion strong Hα emission was observed. SN 2014C has since been observed in radio, infrared, optical and X-ray bands. Here we present new optical spectroscopic and photometric data spanningϕ = 947–2494 days post-explosion. We address the evolution of the broadened Hα emission line, as well as broad [Oiii ] emission and other lines. We also conduct a parallel analysis of all publicly available multiwavelength data. From our spectra, we find a nearly constant Hα FWHM velocity width of ∼2000 km s−1that is significantly lower than that of other broadened atomic transitions (∼3000–7000 km s−1) present in our spectra ([Oi ]λ 6300; [Oiii ]λ λ 4959, 5007; Hei λ 7065; [Caii ]λ λ 7291, 7324). The late radio data demand a fast forward shock (∼10,000 km s−1atϕ = 1700 days) in rarified matter that contrasts with the modest velocity of the Hα . We propose that the infrared flux originates from a toroidal-like structure of hydrogen surrounding the progenitor system, while later emission at other wavelengths (radio, X-ray) likely originates predominantly from the reverse shock in the ejecta and the forward shock in the quasi-spherical progenitor He-wind. We propose that the Hα emission arises in the boundary layer between the ejecta and torus. We also consider the possible roles of a pulsar and a binary companion.
