Transcript X-Rays

O
Day 7416: 2
,303 Years of
SN1987A
 ADS: ~2826 (~2.7/week) refereed papers (since 1987)
(in 45 minutes???)
Patrice Bouchet
CEA/DSM/Sap
Saclay
Heating releases a few
nucleons
 e-+ p → e + n
Escaping e carry off
energy and lepton
number
5 x 109 K
1011g/cm3
 e scatter through
charged + neutral
current (mean free path
< ~1m at the center!):
 Initially the SW has
enough energy .. BUT:
• as it travels, it heats
and melts Fe (loss of ~8
MeV/nucleon)
• neutrino emission is
accelerated  another
energy loss
3x1014g/cm3
t = 10ms
Summed losses ≡ initial
energy carried by SW
r
The energy released by further collapse is trapped
GM2/2R ~ 2.5 1053 ergs (M=1.4Mo; R=10km)
DELAYED MECHANISMS
Mezzacappa et al., 1995, 2000
Burrows et al., 1995
M
Ln
Ln
Cooling Region
Gain radius
M
Ln
Shock
Shock
Ln
M
Shock
Gain (Heating) Region
Convective/SASI
Unstable
Shock
M
• t~0.01s  the shock stalls at
R~200-300km (~equilibrium)
• t >0.5s  neutrino heating of
the nucleon “soup” left in the
wake of the shock revives the
SW (T~2 MeV + very high
entropy): Energy is IN THE
RADIATION, NOT IN THE
MATTER
• The pressure exerted by this
gas pushes the shock
outward: 99% of the 1053 ergs
released in the collapse is
radiated in υ of all flavours
• t(leak out) ~3s
Chronology
• Collapse  Core bounce  proto-NS  NS
~1 s
~10 ms
~0.5 s
• g/cm3: 1010  1011  1012  1013  1014
~100 ms ~25 ms ~5 ms ~1 ms
•
•
•
•
t ~ 1 min  shock crossed He (R~ 500 x 103 km)
Reverse shock forms
t ~ 3h: shock emerges: flash UV  ionisation
Envelope expands  cools (14000 K to 6000K)
Neutrinos
• Temperature: ~ 4±1 MeV
• Decay time: ~ 4.5 s
Just about right for neutron
star formation; results close to
modern theory
Mont Blanc (LSD) ~4.7 hours earlier?
2-stage explosion in a rapidly rotating
collapsar could explain the difference
between LSD/IMB-KII υ detections
(Imshennik & Ryazhskaya, 2003)
• Most of them ν¯e
• Fluence at Earth 5.0±2.5 x 109 cm-2
• Core radius = 30±20 km
• Total νe Energy: ~ 4±1 x 1052 ergs
¯ Energy: ~ 3±1 x 1053 ergs
• Total ν
• MBaryon = 1.45±0.15 Mo;
• MGravit.= 1.35±0.15 Mo
~1 nanogram of ν through IMB and KII and only 1 in 1015 were captured
 ~500 grams through the entire Earth ≡ 15MegaT of TNT (1 million people
experienced 1 SN1987A νe event in their body and ~300 experienced 2 events)
Light Echoes
• R310, R430; W700, S730, N980; R1170
complex (5 echoes); SE3140, N3240
• 3-dimensional structure (Xu et al., 1995).
l.yr
Distant echoes: interstellar clouds
(P. Tisserand: ~1200 real EROS2
images from july 1996 to feb. 2002)
Rings are not matter but a geometrical
effect
10 Ly
Nearby echoes: Napoleon’s Hat etc.
 few solar masses ejected by progenitor
The Progenitor Star ?
•
Sk -69°202: B3 Ia; Teff = 16300 K; R = 46.8Ro
Why blue giant, not red giant?
1.
2.
3.
Low metallicity (Shklovskii, 1984; Arnett, 1987; Hillebrandt et al., 1987): Ni rich shell?
Mass loss (Maeder & Lequeux, 1982; Maeder, 1987): light curve and slow V ejecta?
Blue Loops (Summa & Chiosi, 1970): must have been RSG (Woosley, 1988)
•
Mixing: 56Ni up to ~3000 kms-1, H down to ~500 kms-1?
1.
2.
3.
Convective mixing induced by rotation (Weiss et al., 1988)
semi-convection at low abundance of heavy elements (Woosley et al., 1988)
evolutionary effect in a close binary system (Podsiadlowski & Joss, 1989)
NTT / Wampler et al., 1990  new constraints!
(at least rotational effects & convective mixing)
• Menvelope = 18±1.5 Mo
• MHe = 6 ± 1 Mo, MH,Envelope = 5-10 Mo
• MFe = 1.45 ± 0.15 Mo
• MNS = 1.40 ± 0.15 Mo (2-3 1053 ergs)
• Heavy Elements ejected = 1.5 ± 0.5 Mo
(≤1500kms-1)
Mpre-SN = (19.4 ± 1.7) Mo
First Observations
• Precursor too massive for a “good” explosion mechanism
• No spherical symmetry (polarimetry)
• Strong mixing (Bochum event)
1. R-T instabilities: mix the C, O, He layers when the outgoing
shock front passes through, but cannot account for the high
velocity of Ni (~3100km/s) (Kifonidis et al., 2000), nor the
observed polarization.
2. Convection: size and scale too small to explain asymmetries
+ NO EFFECT ON NEUTRINO HEATING and shock
evolution (Bruenn & Mezzacappa, 1994)
3. Rapid & differential rotation of progenitor (Steinmetz &
Höflich, 1992): explains polarization because of blue SG
4. Rotation of the collapsing core: introduces axial symmetry
but weak effect on the explosion (Zwerger & Müller, 1997).
5. Magnetic fields + rotation  2 high-density supersonic jets
from the collapsed core  too strong B and jets must stop
after <3s (Khokhlov & Höflich, 2000)
Utrobin, 2007
• Single star models:
1. How massive? (Utrobin 2005)
2. Rotation tends to suppress the blue solution by increasing the He core mass,
but seems necessary to break spherical symmetry prior to the explosion
(Woosley et al., 1997)
3. LBV? (Smith, 2007)
• Binary star? (Podsiadlowski, 1992, Morris & Podsiadlowski, 2006)
HYDRODYNAMIC MODEL
Woosley, 1997
Utrobin, 2007
VNiMin= 900km s-1
E=1.0 x 1051 erg
No 56Ni
VNiMax= 2500km s-1
VNiMax= 4000km s-1
VNiMin= 960km s-1
ii
E=1.5 x 1051 erg
No 56Ni
VNiMax= 2500km s-1
ii
Utrobin & Chugai, 2005
Need of both photometry and spectroscopy
Light
Curve
Evolution
• Shock through the surface, 3.84h after neutrinos: T~3x10 K  UV flash
5
 ~3h, R X 10  V ~ 6.4
• As envelope expands it flows through a recombination front: Radiation
doesn’t diffuse to photosphere but photosphere moves to radiation;
energy is released BY recombination but comes from the SHOCK
• After H, He recombination releases energy (shock,
recombination itself, and radioactivity that had
diffused out while “awaiting” the recombination front.)
• Radioactive energy deposition comes from Compton
scattering of γ-ray lines (56Co 847, 1238 keV)
Radioactive
decay
Recombination wave
Radioactive tail
56Co
Dust Formation
Release of
trapped radiation
SAAO
ESO, CTIO
Envelope
transparent
(in the optical)
Freeze-out phase
Expanding + Radioactive
tail
iii
iii
Photosphere
Ring emission
He rec.
Radioactive tail
H rec.
44Ti
Ejecta emission
Snuc = M(56Ni) x [3.9 x 1010 e-t/τ(Ni) + 7.2 x 109 (e-t/τ(Co) – e-t/τ(Ni)) erg g-1 s-1
FREEZE-OUT
The recombination & cooling time scales become comparable with
the expansion time scale: conversion of energy in radiation is not
instantaneous any longer  emitted luminosity remains greater
than instantaneous radioactive power deposition (Fransson &
Kozma, 1993)
UVOIR BLC
56Co
/ 57Co = 2
X = 2 x 1037 erg s-1
P = 5 x 1037 erg s-1
57Co
44Ti
22Na
e+
56Co
Bouchet et al., 1996
Total Input
Observed Bolom.
i
luminosity
The Dust
IAUC4746
March 1, 1989
• Clumps
• Silicates?
Lucy, Danziger, Gouiffes & Bouchet, 1989, 1991
Bouchet & Danziger, 1993
Ejecta emission = “Hot” dust
• Dust still present at day 6067 (Bouchet et al., 2004)
• And at day 7241 (Bouchet et al., 2006, 2007)
• 90 K < TDust,Ejecta < 100 K
• MDust,Ejecta = 0.1-2 x 10-3 Mo
• LIR = (1.5±0.5) x 1036 ergs-1
N: 10.36μm (Δ=5.30μm)
Fν = 0.3±0.1 mJy!
Oct. 20,2003
T-ReCS/Gemini-South
Fν = 0.45±0.05 mJy!
Dec. 26, 2006
Flux increase
due to heating
by Reverse
Shock?
Inner Debris
HST, Jan. 2007 - SAINTS
• Glowing: 44Ti decay
• Interior dust clouds
• Cold! < 300 K
• Stirred, not blended
•Fe bubbles: ~1% of mass, ~50% of interior volume
Axisymmetric ejecta: Wang et al., 2002
Radioactive elements at t=250s
56Ni
He, O, Ca
Synthesized in progenitor
:
Nonrelativistic Jets-induced explosion
Red
Shifted
Blue
Shifted
Why don’t we see a compact object?
•
•
•
Optical, near IR: obscured by black cloud?
X-rays: < cooling neutron star. Debris may be opaque at 1 keV.
Absorbed luminosity should emerge as far IR.
Circumstellar Structure
Radius: R ~ 0.6 lt yr
Expanding: V ~ 10 km s-1
Density ~ 3 x 103 – 3 x 104 cm-3
Glowing mass ~ 0.1 MSun
Nitrogen-rich
(Michael et al. 2003)
“Standard” Model
Martin & Arnett, 1995
 outer envelope BSG
•Gas expulsed by slow RSG wind (550kms-1)
concentrated into dense equatorial plane
• High-velocity low-density isotropic BSG wind
for final ~20 000 yr
• Faster BSG wind overtook RSG wind
• BSG photoionizes and heats gaz from RSG
wind (Chevalier & Dwarkadas 1996)
• RSG
Triple Ring system
Why three rings?
Rotation needed for the equatorial plane, and RSG are too big
 Podsiadlowski BUT Woosley, Chevalier, Dwarkadas, etc…
• Single rotating star: hydrodynamic formation due to ionization and heating
of the cool RSG wind (Meyer, 1997, 1999)
• Binary system: impulsive mass loss from primary star, formation of a thin
dense shell, and the expansion of 2 jets (Soker, 2002)
• Binary mergers: mass loss from a rotationally distorted envelope following
rapid in-spiral of a companion inside a common envelope (Podsiadlowski,
1992; Morris & Podsiadlowski, 2006)
• LBV: unstable LBV eject and shape their nebulae when BSG (Smith, 2007)
PN: MYCN18 (HST/WFPC2)
N. Smith
LBV: HD168625
Morris & Podsiadlowski, 2006 (Document STSCI)
The Reverse Shock
McKee, 1974:
Expanding debris are
decelerated by the CSM
which causes a shock to
propagate inward
through the SN material
(+ Chevalier, 1982)
• High velocity debris cross the RS at v~ 12 x 103 kms-1
• Freely streaming H atoms in the RS ~ 8000 kms-1
• Post-shock ions = 2000 kms-1
Extinction by
 Fast atoms & Slow ions
dust in the ring
Collisional excitation of neutral H
Lyα↑
from the debris crossing the RS
Resonant
 radiative shock seen as very
broad, high-vel Lyα & Hα emission scattering:
• No cylindrical symmetry
Heng et al., 2007; Smith et al., 2005
Michael et al., 2003
Lyα↓
Emission from the Reverse Shock
The “Bleach Out” of the Reverse
Shock
•At t=18 yr, Lα from RS ~ 15Lo ≈ 2.3 x 10-3 Mo yr-1 (x 4 since 1997)
• Lα continuum from gas
shocked by the forward blast
wave ionizes neutral H in the
debris before they reach the
RS:
 when the inward flux of
ionizing photons exceeds the
flux of H approaching the RS
 Preionization shuts off
the RS emission
Smith et al., 2005
Hotspots!
2007
Challis, 2007
2006 – 2003 difference
Pun et al., 2002
• Ring
has brightened by factor ~ 3
• Hotspots still unresolved
• Have not fully merged
• Are the last spots in denser regions
than the ones where the first spots
appeared?
1994
Unfolding the ring!
(Garnevich, 2006)
What caused fingers?
Why so regularly spaced?
ACIS Images 2000–2007
Ring-like
Asymmetric intensity
Developments of X-ray spots
becoming a complete ring
as the blast wave crosses the
inner ring
Surface brightness increases
 Now ~x18 brighter than
2000
Lx (0.5-2keV) = 2.1x1036 ergs/s
No point source at center
N
E
1 arcsec
Park, 2007
X-ray Imaging
N
E
1991
ROSAT/HRI
ACIS (1999-10): Burrows et al. 2000
(5” pixels)
HEASARC/SkyView
Green-Blue: ACIS
Red: HST
Contour: ATCA
1 arcsecond
Park, 2007
Prompt Phase
RADIO EMISSION
• Burst of emission seen by MOST on day 2;
peaked on day 4 (Turtle et al. 1987)
• Power law decay, faded by day 150
• Synchrotron in BSG wind (ρ  r –2)
(Storey & Manchester 1987; Chevalier &
Fransson 1987)
Late Phase (Gaensler, 2007)
• after ~3 yr: impact with dense RSG wind
• α ~ -0.9  optically thin synchrotron
emission, steep electron density and small
compression ratio in the shock (vs. ~ -0.5)
• Consistent multi-wavelength picture of
reverse-shock emitting region: interaction
is with dense gas in equatorial plane
• Radio-source same size as optical ring
Ball et al. 1995
Manchester et al., 2002
Radio Imaging
• Limb brightened
• Bright lobes to
east and west
• Eastern lobe
brighter than
western lobe,
& brightening
Gaensler, faster
2007  Same as X-rays
super-resolved
(0.5(0.9
arcsec)
ATCA 9 GHz diffraction
limited
arcsec)
ROSAT
(Hasinger et al. 1996)
X-ray Flux (10-13 ergs/cm2/s)
0.5-2 keV
3-10 keV
d ~ 6200
X-ray Flux (10-13 ergs/cm2/s)
X-Ray Light Curves
Chandra
(0.5 – 2 keV)
ATCA
ROSAT
Chandra
(3 – 10 keV)
Similar rates of hard X-ray and radio
X-ray (2005-7) vs. Optical (2005-4)
The same origin for them?
X-rays: (Park et due to softening of X-ray spectrum?
Forward shock enters a “wall”?
al., 2004, 2006)
Radio: Gaensler &
Staveley-Smith
Image: ACIS 0.5-2 keV
Contours: HST (Peter Challis)
Image: ACIS 3-8 keV Image: ACIS 0.4-0.5 keV
Contours: ATCA 9GHz
PHYSICAL INTERPRETATION
Park et al., 2002, 2004; Zhekov et al., 2005  2-shocks model
At t = 18 yr:
1. Soft X-Ray = Decelerated, slow (300-1700 kms-1); kT=0.51keV; ne~6300 cm-3
2. Hard X-Ray = High-speed (3700±900 kms-1); kT= 2.7 keV; ne ~ 280 cm-3
Low speed
oblique radiative
shock: optical/UV
Slower shock in
high-density knot:
soft X-rays
Eli Michael/Colorado
High speed
shock: radio,
hard X-ray
MID-IR Emission Bouchet et al., 2006
11.7μm
18.3μm
T-ReCS (day 6526)
Graphite
Carbon
Silicates
Temperature
Optical Depth
Spitzer (day 6190)
Thermal emission from
shock-heated silicate dust
T6067 = (180±15) K
M6067= (0.1-1) x 10-5 Mo
T6526 = (160±15) K
M6526 = (3 ±1) x 10-6 Mo
Dust Heating Mechanism
T-ReCS/HST
ACIS/11.7 mm
ATNF/11.7 mm
ACIS/18.3 mm
ATNF/18.3 mm
Where is the dust?
What heats the dust?
1. In the X-ray emitting gas?
1. Collisional heating?
2. In the denser UVO emitting knots?
2. Radiative heating?
IR-to-X ray flux ratio IRX ≈ 1!
Dust severely depleted in the shocked gas:
7
(Tgas ≈ 2x10 K  IRX ≈ 100)
1. Grain destruction by the SN shock wave?
(Dwek, 1987)
2. Inefficient production in the progenitor?
SPITZER, 2007:
ATCA / Chandra / HST (day 6300)
HST/11.7μm (day 6526)
HST/18.6μm (day 6526)
Physical Picture
11.7μm (Bouchet et al., 2006)
and HST (Challis, 2006)
EQUATORIAL RING
HOT FINGERS
SHOCK WAVE
HOT GAS
REVERSE SW
COOL EJECTA
McCray, 2007
Optical/Soft X-rays
IR??
?
NS/BH
Hard X-rays
Radio
Cf. Michael et al. 1998
SAINTS (F250W)
SN 1987A at 20 Years
• Explosion
mechanism and progenitor??
- HST images: optical spots dominate entire inner ring; blast wave crosses ER
- Inner ring detected in the mid-IR at day 6067: shock-heated silicate dust
- Dust still present in the ejecta at day 7241: heated by RS?  Reverse
shock approaches the central debris (?)
- Soft X-ray, mid-IR & radio images resemble optical image: origin mid-IR?
- Ratio [hard (> 3keV) X-rays/radio] ~ Cst.
- Soft (~0.5 – 2 keV) X-rays increased rapidly after hotspots appeared;
dominated by the decelerated shock since day ~6000; l.c. makes a turn-up at
day ~6200 as ring mid-IR flux at day ~6000
- X-ray radial expansion rate reduces since day ~6200, shock velocity reduces
to 1400 km/s; radio expansion constant at ~ 4700 km/s (Rradio = Roptical)
Hα=red; OIII=green; F250W=blue
HST - SAINTS
(Bouchet et al. 2006).
mid-IR vs HST (2005-1)
Why No Pulsar Detection NOW?
• Possible that neutron star has accreted matter and turned into a
black hole?: 56Co which powered the l.c. shows that very little
mass could have fallen back + BH truncates a gradually decreasing
flux of neutrinos + doesn’t produce bursts (Woosley, 1988)
• Maybe not beamed toward us - if slowish pulsar, expected
beaming fraction
. ~ 0.2 (Manchester, 2006)
• Possibly obscured by dust
• Pulsar magnetic field may take time to develop
• A slow, low E pulsar would not pulse at optical or X-ray
wavelengths (except maybe thermal emission from NS surface)
• Although outer parts of nebula probably have low optical depth,
we really know very little about conditions right in centre - could
be absorption/scattering of radio pulses
Keep searching for a radio pulsar and point X-ray source!
“New” Pulsar Detection ?
Middleditch et al., 2000:
• Several detections during 1992 – 1996 at different frequencies
• Power faded after 1993; last detected 1996
• Emission with a complex period modulation near 2.14 ms
• Frequency of the signals followed a consistent and predictable
spin-down [~(2-3) x 10-10 Hz s-1] over the several year
• Modulation of the 2.14 ms period with a ~1000 s period, which
complicates its detection
• Precession due to deformation or crustal density distribution
not symmetric about the axis of rotation
Santostasi, Johnson, & Frank, 2003:
• possible asymmetric deformation that causes the precession
• main mechanism for the loss of rotational energy due to
emission of gravitational radiation
 Continuous source of gravitational wave detectable
with LIGO II in a few days (106 years for LIGO I): 2013
Forecasting SN1987A
NACO 2007
2017 celebration:
• X-ray,
optical ring: ~ 10 x brighter than today
• Hotspots will merge
• Reverse shock emission will vanish
• Interior debris will begin to brighten
• Circumstellar matter will begin to glow
• Spectacular images of NT radio emission
from ALMA
• Compact Object: JWST?, ALMA?
• Gravitational waves from LIGO II?
( based on McCray, 2007)
Forecasting SN1987A
2027 celebration:
•X-rays, optical: ~ 100 x brighter than today
•Will clearly see interior debris and circumstellar matter
•Newly synthesized elements will begin to cross reverse shock
• + ????
ARE WE REALLY
MADE FROM
THE ASHES OF
STELLAR
DEATH?
How/Why Could a Star Explode?
• Direct
Hydrodynamic: always fails? (works for <15Mo + soft EOS)
• Nuclear-burning aided? (Mezzacappa et al. 2006)
• Neutrino-Driven Wind, spherical 1D (Burrows 1987): Lowestmass massive stars (O/Ne/Mg cores; 8.8 Mo, Kitaura et al. 2006)
• Convective/SASI (Spherical Accretion Shock Instability)
Neutrino-Driven Wind 2D (Blondin et al. 2003) might work for 11.2
Mo of WHW2002, (Buras et al. 2006): other progenitor problematic
• Acoustic Power Mechanism: after delay, all progenitors explode
(Burrows et al. 2006,2007); High entropies favor r-process
• Magnetic fields, neutrino mixing and realistic neutrino transport
(Mezzacappa et al. 2006)
• MHD Jet Explosions: Rapid rotation necessary (e.g., Burrows et
al. 2007b) works for Hypernovae and GRB
The Key feature of almost all mechanisms is
the Breaking of Spherical Symmetry  3D
Radial Expansion
X-Rays
4700 ± 100 kms-1
Radio
t<5000d: 3600km/s
~ 35 000 kms-1
Racusin et al. 2007
t>5000d: 4700km/s
Gaensler et al., 2007
rapid deceleration in X whilst ~ constant in radio
+ Discrepancy in radius between radio and X-rays
 ???
MAGNETIC FIELD
 Radio and hard X-rays come from relatively low
density gas between blast wave and reverse shock
How (where) are relativistic electrons accelerated?
Non linear kinetic theory of Cosmic Ray:
shock modification and strong magnetic field
amplification in ALL the young SNR
(Berezhko, 2005; Berezhko & Ksenofontov,
2000, 2006 )
Radioemission spectrum
• Considerable synchrotron cooling of high
energy e- which reduces their X-ray
synchrotron flux
• Expected γ-ray energy flux at TeV-energies
~ 2 x 10-13 erg cm-2s-1
G-SNRs source population of the G-CR
Limits on Properties of a Central Pulsar
• No evidence for central source (PWN or pulsar) at any wavelength:
optical luminosity limit ~8 x 1033 erg s-1 (Graves et al. 2005), X-ray
limit (2-10 keV) ~5 x 1034 erg s-1 (Shtykovskiy et al. 2005)
• Radio limit of central source from 8 GHz image ~ 1 mJy
.
• Assume flat spectrum  20 GHz,
LPWN ~ 3 x1031 erg s-1
.
• For the most conservative
limit on E of central pulsar, assume PWN
.
only emits at radio frequencies and LPWN = EPSR
• For Po = 200 ms, EPSR = 3 x1031 erg s-1, then Bo ~ 6 x 1010 G
Manchester, 2007
Well within the range of possible pulsar birth parameters
PWN limits do not rule out a perfectly plausible
20-year old pulsar at the centre of SN 1987A