Evolutionary Status of SNR 1987A at the Age of Eighteen

Abstract

$\sim$18 yr after the supernova explosion, the blast wave of SNR 1987A is entering the main body of the equatorial circumstellar material, which is causing a dramatic brightening of the remnant. We recently reported the observational evidence for this event from our {\it Chandra} data (Park et al. 2005b; P05 hereafter). We present here the temporal evolution of the X-ray emitting shock parameters and the detailed description of the spectral and image analysis of SNR 1987A, on which P05 was based. While the remnant becomes brighter, the softening of the overall X-ray spectrum continues and is enhanced on around day $\sim$6200 (since the explosion). The two-component shock model indicates that the electron temperatures have been changing for the last $\sim$6 yr. The X-ray spectrum is now described by $kT$ $\sim$ 0.3 keV and 2.3 keV thermal plasmas which are believed to characteristically represent the shock-heated density gradient along the boundary between the H{\small II} region and the dense inner ring. As the blast wave sweeps through the inner circumstellar ring shining in X-rays, we expect that the shock parameters continue to change, revealing the density and abundance structure of the inner ring. Follow-up {\it Chandra} observations will thus uncover the past history of the progenitor's stellar evolution. The origin of the relatively faint hard X-ray emission ($E$ $>$ 3 keV) from SNR 1987A is still unclear (thermal vs. nonthermal). Considering the continuous brightening of the hard band intensity, as well as the soft band flux, follow-up monitoring observations will also be essential to reveal the origin of the hard X-ray emission of SNR 1987A.

21 pages including 9 figures, Accepted by ApJ

References in corpus (1)

• Chandra LETG Observations of Supernova Remnant 1987A

Cited by in corpus (19)

• Chandra Observes the End of an Era SN 1987A
• Supernova 1996cr: SN 1987A's Wild Cousin?
• Spectral and morphological analysis of the remnant of Supernova 1987A with ALMA & ATCA
• Collisionless shock heating of heavy ions in SN 1987A
• Chandra HETG Spectra of SN 1987A at 20 years
• Indication of a Pulsar Wind Nebula in the hard X-ray emission from SN 1987A
• Thermal Emission and Radioactive Lines, but No Pulsar, in the Broadband X-Ray Spectrum of Supernova 1987A
• Probing Elemental Abundances in SNR 1987A Using XMM-Newton
• Additional evidence for a pulsar wind nebula in the heart of SN 1987A from multi-epoch X-ray data and MHD modeling
• Quantitative Age Estimation of Supernova Remnants and Associated Pulsars
• Mach Number Dependence of Electron Heating in High Mach Number Quasiperpendicular Shocks
• Spectral Evolution of the X-Ray Remnant of SN 1987A: A High-Resolution $Chandra$ HETG Study
• The Post-impact Evolution of the X-ray Emitting Gas in SNR 1987A Viewed by XMM-Newton
• SN 1987A : Tracing the flux decline and spectral evolution through a comparison of SRG/eROSITA and XMM-Newton observations
• High-cadence Dispersed Spectral Analysis of Supernova Remnant 1987A
• Latest Evolution of the X-Ray Remnant of SN 1987A: Beyond the Inner Ring
• Tracing the ejecta structure of SN 1987A: Insights and diagnostics from 3D MHD simulations
• Investigating Time Evolution of Thermal Emission from the Putative Neutron Star in SN 1987A for 50+ Years
• Unusual X-ray Oxygen Line Ratios of SN 1987A Arising From the Absorption of Galactic Hot Interstellar Medium