Facts about SNe and their remnants
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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”!
description
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). - PowerPoint PPT Presentation
Transcript of 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).
• Most of Type Ia SNe probably also occur in low density regions (Galactic halo and bulge).
Most of SNRs are “missing”!
Missing Supernova Remnants
Q. Daniel Wang
(Univ. of Massachusetts Amherst)
In collaboration with
Shukui Tang, Yang Chen, David Smith, Fangjun Lu, et al.
• Characteristics of SNRs in low density regions
• Accumulated X-ray emission from such SNRs
Examples of SNRs in low density evironments
Name L, b shell PWN X-ray
Crab Nebula
184.6, -5.8 NO Yes Nonthermal
G54.1+0.3 54.1, 0.3 NO Yes Nonthermal
DA 530 93.3, 6.9 D=27’in radio
NO ?
RX J1932 64, 5.3 2.4’ in X-ray
NO ?
G28.6–0.1 28.6, –0.1 10’ x 8’ in X-ray
No Nonthermal?
DA 530
1420 MHz (Landecker et al. 1999)
PSPC observation:n0 ~ 0.02-0.05 cm-3
kT ~ 10-15 keVnet ~ 8 × 1010 cm-3 s
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
G28.6–0.1
Image: Chandra ACIS-I observationsContours: VLA 20cm radio
Ueno et al. 2003
•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
T ≤107 K
SNRs in superbubbles
30 Dor C in the LMC
East half
West half
Smith & Wang 2004
100 pc
SNRs in the 3-phase ISM SNRs in the 3-phase ISM
McKee & Ostriker 1977
The interstellar space is dominated by a hot phase maintained by SNe and/or superbubbles.
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
Galactic ridge X-ray spectrum in the Chandra deep survey field
SNR thermal
Nonthermal (Valinia et al.
2000) Extragalactic
• SN rate ~ 1/(15-30)yr
• Total NH~1.51023 cm-
2
• T0 ~ 0.01 keV
• Abundance: 0.50.1
• Luminosity (0.8-10keV) ~ 91038 erg s-1
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.
~ 1055 erg, or ~ 104
Type Ia SNe over the past ~ a few x 107 years.
Snowden et al. 1997
