SN1987A: Birth of a Supernova Remnant

Supernova 1987A at 25 years

Highlights of the past 25 yearsOutstanding mysteries and surprisesWhat we can expect to learn, sooner and laterTOPICSSupernova Energy SourcesCore collapse: E ~ GM2/R ~ 0.1 Mc2 ~ 1053 ergs Neutrinos: t ~ 10sRadioactivity: 0.07 M8[56Ni g 56Co g 56Fe] ~ 1049 ergs. Light: t ~ 3 monthsKinetic energy: ~ 10 M8, Vexpansion ~ 3000 km/s ~ 1051 ergs ~ 1% core collapse. X-rays: t ~ decades - centuries.Neutrino signal (1053 ergs) a a neutron star formed (I think!)

Optical Light (1049 ergs): driven by radioactivity56Co57Co44Ti

X-rays (1051 ergs): from kinetic energy (crash)What we have learned:the interior

RADIOACTIVE DEBRIS

IR nebular spectrum:

CO bands a interior T < 3000 K @ 260 days; now < 300 K

Strong, optically thick FIR lines of [FeII], [CoII] a newly synthesized Fe must occupy ~ 50% of volume of glowing interior: nickel bubbles due to foaming action driven by radioactive heating

Fe, Co, NiDustC, O, Si, SH, HeInterior Dust Formation

400 700 d: bolometric luminosity shifted from optical to FIR;Red sides of nebular emission lines vanished Visible glow of interior comes mostly from near side. Morphology determined largely by dust distribution. Dust obscures central object.Southern extension is in equatorial plane

What we have learned:the exteriorCrash: birth of SNR1987A

Time-lapse movie of HST images 1994 - 2006

HST - OpticalMarch 2011ATCA 9 GHz 2009Chandra 0.5 2 keV2009

Light Curves of CS RingOptical (HST)

Radio, IR, X-ray

RADIOACTIVE DEBRIS

Motion of optical (HST) hotspotsExpansion of X-ray ring (Racusin et al) and radio shell (Ng et al)

Heating of debris by external X-rays

Hubble observations of the reverse shock: an adventure in spectroscopy

HaH + p g H* + pH + p g 2p + e Line emission and impact ionization at reverse shock surfaceDn/n = v;/c H* g H + hnHa, LyaLuminosities of Ha and LyaEach hydrogen atom crossing RS will produce, on average:

Rexc(2p)/Rion = 1 Lya

Rexc(Ha)/Rion = 0.2 Ha

Integrated luminosity of Ha amass flux of H atoms across RS.zDlDl/lo = v/cwhere v = H0z and H0 = 1/tSurfaces of constantDoppler shift are planar sections of the supernova debrisTo observer

STIS Ha Observations Jan 30, 2010

Doppler Mapping of Ha Emission from RS Surface

Lyman-a

Ha 2010/2004

Lya vs. HaReverse shock: photon emission ratio Lya/Ha should be 5/1Ratio should be independent of Doppler velocity

But actual ratio varies from 10/1 to 200/1 !Line profiles completely different: unlike Ha, Lya is not confined to surface; appears to come from interior

(We should have realized this in 2004): There must be another mechanism to account for most Lya emission!

Two possiblities (maybe both):1. Resonant scattering of narrow Lya from the ring by HI in debris2. Heating of HI in debris by external X-rays

Resonance Scattering of Lya by Supernova Debris Source of Lya is nearly stationary emission from hotspots in circumstellar ring

Model requires:aSufficient luminosity of Lya photons from hotspots to account for broad Lya;aSufficient optical depth of SN envelope in damping wings of Lya @ 5000 km/s.

New (March 2011) results fromCosmic Origins Spectrograph

COS compared to STIS:UV onlyMuch (60x) better sensitivity & S/NBut poor spatial resolution

Ly aNV 1240CIV1550He II 1640H (2S a 1S) continuum from hotspotsBroad NV1239,1242 Emission from Reverse ShockNVReverse shock excitation:

Ha/H = [Rexc(Ha) (12.1 eV)]/Rion(H) (13.6 eV) = 0.2

NV1240/N = [Rexc(1240) (10.1 eV)]/Rion(N+4) (98 eV) = 500!

Borkowski, Blondin, & McCray 1997Carbon/Nitrogen RatioStandard cosmic abundance ratio: C/N = 4.1

Narrow UV emission lines from ring a C/N = 0.11Broad UV emission lines from RS a C/N = 0.05

Interpretation: nuclear burning (CNO bi-cycle) converts C, O into N. This explains decreased C/N ratio in ring.

Further decrease of C/N ratio seen in RS a either: (a) stratification of C/N ratio in outer envelope of progenitor; or (b) continued nucleosynthesis subsequent to ejection of ring. The Future: what can we hope to learn?

What is the compact object? What made the triple ring system?How (where) are the relativistic electrons accelerated?What is the distribution of newly-synthesized elements in the SN interior

Compact object? not a clue!

Bolometric luminosity < few hundred L8 < 10-3 Crab pulsar

The best hope: image compact FIR source with JWST (2018?)

How (where) are the relativistic electrons accelerated? Image non-thermal radio emission.ALMA will do these things:Angular resolution