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Facts about SNe and their remnants

Facts about SNe and their remnants. Evolution of an SNR sensitively depends on its environment. Observed SNRs are typically produced by SNe in relative dense environments. But most (> 80%) of core-collapsed SNe explode in superbubbles (e.g., van Dyk et al. 1996; Higdon et al. 1998).

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Facts about SNe and their remnants

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  1. Facts about SNe and their remnants • Evolution of an SNR sensitively depends on its environment. • Observed SNRs are typically produced by SNe in relative dense environments. • But most (> 80%) of core-collapsed SNe explode in superbubbles (e.g., van Dyk et al. 1996; Higdon et al. 1998). • Most of Type Ia SNe probably also occur in low density regions (Galactic halo and bulge). Most of SNRs are “missing”!

  2. Missing Supernova Remnants • Characteristics of SNRs in low density regions • Accumulated X-ray emission from such SNRs Q. Daniel Wang (Univ. of Massachusetts Amherst) In collaboration with Shukui Tang, Yang Chen, David Smith, Fangjun Lu, et al.

  3. Examples of SNRs in low density evironments

  4. DA 530 PSPC observation: n0 ~ 0.02-0.05 cm-3 kT ~ 10-15 keV net ~ 8× 1010 cm-3 s 1420 MHz (Landecker et al. 1999)

  5. RX 193214.6+300741 • Exposure: PSPC 3.3 ks • Diameter: ~7 pc (D/10kpc) vertial distance: ~ 1 kpc • L(0.1-2.4): ~1034 ergs/s • Mass: ~ 0.7Msun • n0 ~ 0.02 cm-3 • Age: ~ 7 x 103 yrs (Ve/103 km/s) • Thermal spectrum of a very high T or a Power law • No optical and radio counterparts yet. • 40 ks Chandra obs. approved

  6. G28.6–0.1 • Diameter: ~20 (D/8kpc) • L(2-10): ~3 x 1032 ergs/s • ne t~ 1011 cm-3 s • Thermal spectrum of T ~ 5.4 keV or a Power law of a photon index ~ 2 Image: Chandra ACIS-I observations Contours: VLA 20cm radio Ueno et al. 2003

  7. SNRs in superbubbles T ≤107 K

  8. East half 100 pc West half Smith & Wang 2004 30 Dor C in the LMC

  9. SNRs in the 3-phase ISM The interstellar space is dominated by a hot phase maintained by SNe and/or superbubbles. McKee & Ostriker 1977

  10. Missing SNRs and Galactic ridge X-ray emission A toy model for the GRXE: • SNRs are in a hot medium and emit thermal X-ray emission. • A GRXE spectrum samples the entire evolution of an SNR, according to the model of McKee & Ostriker (1977). • The intermixing between the X-ray emission and absorption is approximately uniform. T0 ≤106 K

  11. Galactic ridge X-ray spectrum in the Chandra deep survey field • SN rate ~ 1/(15-30)yr • Total NH~1.51023 cm-2 • T0~0.01 keV • Abundance: 0.50.1 • Luminosity (0.8-10keV) ~ 91038 erg s-1 SNR thermal Nonthermal (Valinia et al. 2000) Extragalactic

  12. Conclusions • Candidates of SNRs in low density medium have been identified and are yet to be carefully examined. • Most of such SNRs are not observed individually. • They can be detected collectively and may explain the GRXE. • They may have lasting impacts on the Galactic ecosystem.

  13. ~ 1055 erg, or ~ 104 Type Ia SNe over the past ~ a few x 107 years. Snowden et al. 1997

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