SNR 101

3rd X-ray A

stronomy school

Wallops Island M

ay 12-16 May

Ilana HA

RRUS

(USRA

/NA

SA/GSFC)

Many thanks to:

Pat Slane (Center for Astrophysics)

CXC website for their m

arvelous animations

Chandra SNR catalogue on-line (aka Fred Seward’s catalogue)

What are SN

Rs ?

SNRs: SuperN

ova Remnants are the tracers of

explosions from stars reaching the end of their lifes.

SNRs also enrich the ISM

by dispersing material

produced both during the star’s life and at them

oment of the SN

event.

How frequent? Estim

ates varies according to SNtypes, environm

ent (Galaxy type), …: About 2 per

century for Milky W

ay (all types)

Why should we (you) care?

SNRs are probes both of their progenitor star (and

of their pre-supernova life) and of the ISM.

They are also cosmic accelerators (cosm

ic rays).

Birth places of neutron stars and stellar mass black

holes.

They can also be space laboratories for study ofhigh m

agnetic fields, shock physics, jets, winds,(PW

Ne)…

is a lot darker….

•Morphology classification is a zoo

•Spectral classification is a royal mess

Now the real story….

Hughes et al. 2000, ApJ, 528, L109

Park et al. 2002, ApJ, 564, L39

Park et al. 2002, ApJ, 564, L39

Hughes &

Slane 2003, ApJ (submitted)

Is this a SN

R?

NO

YES

Shell-like?

YESN

O

NO

/?

NO

NO

Mostly Therm

al?

YES

“Mostly therm

al?

“YES”

Compact O

bject?

Mostly Therm

al?

Pulsar associated?

YESYES

Mostly Therm

al?N

OYES

YESShell-like?

NO

YES

NO

NO

Why is this such a m

ess??

SNR evolution (and their appearance now) depends on

many factors:

•Its age

•Its environment (density)

•The total energy of the explosion

and … its progenitor star (mass, type of SN

associated..)

3 phases in SNR’s life.

•Free expansion (less than 200-300 years)

•Adiabatic or “Taylor-Sedov” phase (about 20,000 years)

•Radiative or Snow-plow phase (up to 500,000 years)

and then … Merge with the ISM

Free expansion phase

•Independent of the nature of the SN explosion

•No deceleration

•Evolution only depends on Eo the initial energy.

•Velocity of ejected shell varies between (7-12) 103 km

s-1

•Mass swept-up negligible until M

su ~ Meje ~ 1 M

§

===> Rs = 250 yrs Meje 5/6 n

1 -1/3 E51 -1/2

SNR enters then its A

diabatic Phase

Sedov-Taylor phase

The key word here is SELF SIMILA

R (solutions can be scaled fromsolutions elsewhere)

===> f(r, t) becomes f(r/r

ref) *f(rref )

(skipping the equations) … Et voilà!

Rs =12.4 pc (KE

51 /n1 ) 1/5 t

4 2/5

t ==390 yr Rs T

meas -1/2

Sedov-Taylor phase

The Sedov-Taylor phase is one the most often used in

papers about SNRs (that’s because one can get actual

physical quantities from m

easurements).

In Sedov-Taylor model one expects therm

al emission

coming from

a thin shell behind the blast wave. As the

shock expends the pressure drops between the shockwave and the m

aterial ejected.

At one point, “reverse” shock starts propagating ===> will

eventually heat the ejecta (also thermal em

ission).

Radiative phase

T drops as a steep function of radius

===> at some point, T is below T

recomb ~ 1 keV

Age of SN

R when this happens depends on models for

cooling functions, explosion energy and density.

Between 17,000 and 25,000 years (assuming standard E

oand n

1 )

Then: THE EN

D… SN

R merges with surrounding m

edium

Why so com

plicated then??

•Different explosion energy, age, …

•Different angle of visions

•Am

ount of material along line of sight is not uniform

•ISM is not hom

ogenous

•Different progenitor histories

•…..

First the simplest:

• Different angle of view:

ßThen we may see the SN

R“through” a lot m

ore ofabsorption.

ISM not hom

ogenous

Several models to explain differences with

Sedov-Taylor “shell-like” predictions.

Several problems with this type of m

odels.

“Several” clouds evaporating“slowly” behind shock wave(W

hite & Long, 1991)

Different progenitors

Type Ia: thermo-

nuclear destruction of anaccreting white dwarf.Low O

/Fe ratio.

Type II:Core collapseof m

assive star. High

O/Fe ratio.

Hughes et al. 2000, ApJ, 528, L109

Park et al. 2002, ApJ, 564, L39

Pulsar Wind N

ebulae (in SNRs)

ß Recent developments (using Chandra) of PW

Ne studies

(particle acceleration, magnetic fields, jets, winds, …)

Pulsar Wind N

ebulae

Studies of PWN

can yield information on m

agneticfields, ….

With the new

data increasefrom

Chandra(and the spatialresolution), it isnow possible tostart doingstatisticalanalysis.

Gotthelf 2003

What was not m

entioned here:

ß Non-equilibrium

ionization effectsß N

on-thermal em

ission at the shock wave (SN 1006)

ßAccuracy of the spectral diagnostics

ßAssociation of PSR/SN

Rß…

For more inform

ation on SNRs:

Books and proceedings:ß“Supernovae and Stellar W

ind in the ISM” T. Lozinskaya

ß“ Supernovae and supernova remnants” K. W

eilerß“N

eutrons stars in supernova remnants” (proc)-- Slane and Gaenlser (Eds.)

ß“Exploring the X-ray U

niverse” Charles & Seward

Articles:ßTrim

ble -- Rev. Mod. Phys.1982 Vol 54, N

o 4

ßMcKee -- A

pJ 1974188 355ßChevalier -- A

pJ 1974 188 501ßH

amilton, Sarazin & Chevalier 1983 A

pJ Supp, 51 115

Conclusions

SNRs (and PW

Ne) are a com

plicated but important

field of study.

Thanks to Chandra (its spatial resolution and its ability toallow for spatially resolved spectroscopy) and X

MM

-Newton (its

large effective area and its ability to collect many m

ore photons.)

===>large rethinking of the field is happening now

Any questions?