Studying pulsar formation and evolution

via the accretion induced collapse of

white dwarfs

Ali Taani

Under supervision

Prof. Y.H. Zhao & Prof. C.M. Zhang

00-00-2012

On the distribution of massive white dwarfs

and it’s implication for accretion induced

collapse

توزيعات الكتل الضخمة لنجوم االقزام البيضاء ودورها في عملية

االنكماش بسبب تراكم المادة

الدكتور علي عبد الكريم الطعاني

جامعة البلقاء التطبيقية

كلية العقبة الجامعية

ali.taani@bau.edu.jo,

ali82taani@gmail.com

Overview of talk

1. Introduction: NS, PSR & WD

2. Formation of Millisecond Pulsars

3. AIC scenarios

4. SN Ia scenarios

5. Summary

6. Future work

1. Introduction:

2. Formation of Millisecond Pulsars

3. AIC scenarios

4. SDSS Data

5. References

6. Summary

Overview of talk

Ring Nebulae (M 57)

Young White Dwarf

Stars with < 6-8 M

make 0.5-1.0 M

Carbon/Oxygen white

dwarfs with radius ~

Earth and central

densities >106 gr/cm3

that simply cool with

time.

White dwarf االقزام البيضاء(WD) stars are most common end-point of stellar

evolution.

They are very old objects: the present population of WDs contains valuable

information about evolution of individual stars and history of our Galaxy.

How to Ignite a White Dwarf !!

How to Ignite a White Dwarf

Single stellar evolution does not appear to

cause thermonuclear explosions

We need to provoke a thermonuclear runaway

that proceeds at such a rate that matter

releases an energy/gram in excess of

gravitational binding energy=> Becomes

unbound!

WDs have lots of fuel (He/C/O)&gravitational

binding energies/gram less than that of nuclear

burning

Use accretion in a Binary as the trigger

Piro „05

Accreting WDs in our Galaxy <1% of WDs are in binaries where

accretion occurs, releasing

gravitational energy

Whereas nuclear fusion of HHe or

HeC releases

This contrast is further enhanced when

the WD stores fuel and burns it rapidly,

making these binaries detectable in

distant galaxies during thermonuclear

events.

Donor star

White Dwarf

Pulsars النجوم النوابض

(Pulse+Star)

Rapidly spinning, magnetized NSs.

Lighthouse Model:

- Spinning magnetic field generates a strong

electric field.

1967

“pulse” and “star,”

When pulsars were first discovered, it thought

they might be evidence of other intelligent life

(Aliens) in Galaxy

A. Hewish and J Bell

Pulsars and NSs

الفرق بين النجوم النوابض والنجوم النيترونية • All pulsars are NSs, but all NSs are not pulsars!!

• Light is emitted by charged particles moving close to

speed of light around magnetic fields.

• Whether we see a pulsar depends on the geometry.

– if polar beam sweeps by Earth‟s direction once each

rotation, NS appears to be a pulsar

Pulsars are

lighthouses

of Galaxy!

Pulsar Origins نشأتها

• MSPs are very old (~109 years).

• Mostly binary

• They have been ‘recycled’ by accretion

from an evolving binary companion.

• This accretion spins up the neutron star to

millisecond periods.

• During the accretion phase the system may

be detectable as an X-ray binary system.

•B ~10^(8-9) G

Normal Pulsars:

• Formed in supernova

• Periods between 0.03 and 10 s

• Relatively young (< 107 years)

• Mostly single (non-binary)

•B ~10^(11-13) G

Pulsars are believed (by most people) to be

rotating NSs

Millisecond Pulsars (MSPs):

PSR-B1937+21- 0.001557=642times

B0329+54, P_spin=0.7145=1.4 times

Recycled Processes

Observational Evidences

QPO, Spin 401 Hz (emitted X-rays are pulsed)

and powered X-ray MSPJ1808.4-3658

(Wijnands & Klis 98).

Double pulsars: PSR J0737-3039AB-

(Lyne+04)

Accretion Induced Collapse (AIC)

Idea: Canal & Schatzman 76, & Nomoto 81

WD accretes matter from a companion 1. Avoids thermonuclear explosion and reaches

Chandrasekhar limit at density for collapse.

2. Small amount of mass is ejected & binary survives.

1- H cores always experiment thermonuclear explosion

2- CO cores can explode(SN Ia) or collapse to NS

3- ONeMg cores collapse to a NS 4- Fe cores always collapse to a NS or BH

AIC

Electron-capture collapse of

the degenerate O-Ne-Mg

M~8-12Msun

low-mass~1.25Msun

small kick velocity

Iron-core collapse

M~ >12Msun

More Massive

Received kick velocity

M ~ 1.4 Mo

R ~ 108-109 cm

Eexplosion ~ 1050 erg

MNI < 10-3 Msun

Neutron star

M ~ 1.2 Mo

R ~ 106 cm

Electron degenerate core

AIC Rate (Uncertain)

~10^-6 - 10^-4 yr-1

e−+ p+ n0 +ne. neutronization

Double Degenerate

Merge: C-OWD

56^Ni rich flow

New optical transient surveys [e.g. Palomar Transient Factory ( PTF) and Pan-STARRs, Medium Deep Survey (MDS)] are sensitive to much fainter transients

Large Synoptic SurveyTelescope LSST , which will image entire sky to limiting magnitude∼24.5 every 3-4 nights and should detect AIC events at rate ∼ 800x10^-4 yr^-1

AIC rate of ∼10^-4 yr^-1

SNe Ia i.e, SN 2008ha (Foley+09; 10), 2005E (Perets+10) and 2002bj (Poznanski+10). Low 56^Ni masses inferred from their peak luminosities (10^−3 − 0.1Msun) consistent with quantity predicted from AIC.

Deseert+06 predicted that AIC produces an optical transient with a peak luminosity ∼ 10^41 ergs s^−1

Observation

BUT…..

Optical dim

Short time scale

High Speed of ejecta v ∼ 0.1 c, (hard to detect)

Low energy 10^48-49 ergs

Low ejecta 0.2 comparison with SN Ia>1M_sun

WD must be of the O-Ne-Mg type (or merge CO-CO)

Must have a relatively large mass, 1.0 to 1.2 Msun

This is only very seldom seen in CVs type binaries.

Physics of MSP formation and physical conditions immediately after AIC remain unclear.

Data

WD: Sloan Digital Sky Survey (SDSS) 115 well-measured WDs masses

- www.sdss.org

MSP: ATNF Pulsar Catalogue (http://www.atnf.csiro.au/research/pulsar/psrcat/)

Massive WDs

M̅= 1.18 Msun

WDs

Corbet diagram

Taani et al. 2012

Reasons that make WDs attractive candidates to AIC process

Spin-Up line…

Taani, Al-Wardat & Khasawneh 2013

Pulsar： ~2267 (radio) + ~ 250 (X-ray)

PSR in Binary：~212, NS/WD/Planet

MSP: ~279， P<20ms，75% binary

Magnetic Field: 108 G - 1015 G; ~1012 G

Spin period: 1.4 ms,10s, <P>=0.5s

Bands: Radio, Optical, X-ray

References

1- Taani A., Zhang C.M., Al-Wardat M. et al., 2012a,

AN, 333, 53

2- Taani A., Zhang C.M., Al-Wardat M. et al., 2012b,

Ap&SS, 338, 295

3- Lorimer, D.R.: Living Rev. Relativ. 11, 8 (2008).

arXiv:0811.0762

4- van den Heuvel, E.P.J.: Science 303, 1143 (2004)

5- Metzger B. D., Piro A. & Quataert E. 2009, MNRAS,

396, 304

Summary Interacting binaries are interesting and important to

observe, as they allow to study accretion effect on

their ultimate evolution.

AIC is “Failed” Thermonuclear Explosion (otherwise Type Ia SN)

AIC provides missing links between MSPs and LMXBs

WDs should be significant numbers for progenitor of MSPs.

There is a strong connection between NSs and WDs via AIC.