2013 multi-messenger transient astrophysics …kiaa.pku.edu.cn/activities/xuefeng_wu.pdfhow...

Bright broad-band afterglows of gravitational wave bursts from mergers of binary neutron stars

Xuefeng Wu Purple Mountain Observatory

Chinese Center for Antarctic Astronomy Chinese Academy of Sciences

May 8, 2013

Collaborators: He Gao, Xuan Ding, Bing Zhang & Zi-Gao Dai

2013 Multi-Messenger Transient Astrophysics Workshop

KIAA, Beijing, China; May 6 - 10, 2013

How WUniverse Expands (I)

2001.9, Nanjing University

Xue-Feng

Wu

Yong-Feng

Huang

Xiang-Yu

Wang

Yi-Zhong

Fan

Bi-Ping

Gong

Zi-Gao

Dai

Tan

Lu

Da-Ming

Wei

Pawan

Kumar

Zhuo

Li

How WUniverse Expands (II)

2009.6, Penn State University

Xue-Feng

Wu

Kenji

Toma

Peter

Meszaros Alessandra

Corsi

Derek

Fox Nino

Cucchiara

How WUniverse Expands (III)

Xue-Feng

Wu

Bing

Zhang

Bin-Bin

Zhang Wei-Hua

Lei

Bo

Zhang

Wei

Deng

He

Gao Qiang

Yuan

2010.1.2, Las Vegas

~ 300 ( 0.1)Mpc z

Credit on David Shoemaker

Motivation

Adv VIRGO & LIGO

2015? 2020?

NS+NS

10.2 ~ 2000 yrEvent Rate

Zhang 2013 ApJL

http://physics.aps.org/articles/v3/29

NS-NS coalescence

Gravitational

Wave

Electromagnetic (EM) emission signal accompany with

a GWB is essential for GW identification.


NS-NS coalescence

Gravitational

Wave



The brand new channel of GW signals combining with

old channel of EM emission would lead us better

understand our universe.


NS-NS coalescence






Remnant?


NS-NS coalescence






Remnant? EOS


NS-NS coalescence






Remnant? EOS

BH


NS-NS coalescence






Remnant? EOS

BH

NS

Metzger & Berger, 2012

SGRB

Multi-band transient ~hours, days, weeks,

or even years

Li-Paczyński Nova

Opical flare ~ 1 day

Ejecta-ISM shock

Radio ~years

Li & Paczyński, 1998

Nakar& Piran, 2011

EM signals

for a BH post-merger product

Short GRBs

γ-ray Light curve

Short GRBs

X-ray afterglow plateaus: hints of magnetar?

Rowlinson et al. (2010) Rowlinson et al. (2013)

Li-Paczynski Nova / Kilonova

Metzger et al. (2010)

Radio Afterglows

Rosswog, Piran & Nakar (2012)

What if the central product is

magnetar rather than a black hole?

Why Magnetar ?

Theoretical reason Stiff EoS

Why Magnetar ?


Lattimer (2012)

Stiff equation-of-state: maximum NS mass close to 2.5 M

Why Magnetar ?


Observational reason

Zhang, 2013 (Ref therein)

Lattimer & Prakash (2010)

NS with mass > 2 Msun has been discovered

(e.g., PSR J0348+0432, M=2.01+/-0.04 Msun)

NS-NS systems: total mass can be ~ 2.6 Msun

Why Magnetar ?



Zhang, 2013 (Ref therein) Based on the observations

of the SGRB X-ray afterglows.

Rowlinson et al. 2013 Rowlinson et al. 2010

GRB 090515


(e.g., PSR J0348+0432, M=2.01+/-0.04 Msun)


Why Magnetar ?



Zhang, 2013 (Ref therein) Based on the observations

of the SGRB X-ray afterglows.

Rowlinson et al. 2013 Rowlinson et al. 2010

GRB 090515

A postmerger magnetar would

be initially rotating near the

Keplerian velocity

P~1ms.

52 2

45 0, 32 10rotE erg I P

49 1 2 6 4

,0 ,15 6 0, 310sd pL erg s B R P

3 2 6 2

45 ,15 6 0, 3

0,

~ 10rot

sd p

sd

ET s I B R P

L


(e.g., PSR J0348+0432, M=2.01+/-0.04 Msun)


Hotokezaka,et al., arXiv:1212.0905

Mass Ejection during NS-NS Merger

Initial velocity: 0.1 – 0.3 c

Ejected mass: 0.0001 – 0.01 Msun

Jet-ISM shock (Afterglow)

Shocked ISM

Ejecta

SGRB

Radio

Optical

X-ray

X-ray

X-

ray

Poynting

flux

MNS

Magnetar as the central product

SGRB

Late central engine activity ~Plateau & X-ray flare

Magnetic Dissipation

X-ray Afterglow

1000 ~10000 s

8 1 210 ergs cm

Ejecta-ISM shock with

Energy Injection (EI)


or even years

Gao, Ding, Wu, Zhang & Dai, 2013

Zhang, 2013


Shocked ISM

Ejecta

SGRB

Radio

Optical

X-ray

X-ray

X-

ray

Poynting

flux

MNS


SGRB



X-ray Afterglow

1000 ~10000 s

8 1 210 ergs cm




or even years

Zhang, 2013



Shocked ISM

Ejecta

SGRB

Radio

Optical

X-ray

X-ray

X-

ray

Poynting

flux

MNS


SGRB



X-ray Afterglow

1000 ~10000 s

8 1 210 ergs cm




or even years

Gao et al, 2013

Zhang, 2013

Rowlinson et al. 2013


Shocked ISM

Ejecta

SGRB

Radio

Optical

X-ray

X-ray

X-

ray

Poynting

flux

MNS


SGRB



X-ray Afterglow

1000 ~10000 s

8 1 210 ergs cm




or even years

Gao et al, 2013

Zhang, 2013

Magnetic Dissipation X-ray Afterglow

Flu

x (

erg

cm

-2s

-1)

t sdT

8 2 110 erg cm s

Zhang, B., 2013, ApJL, 763,22

1/3F With , one can

roughly estimate that the

optical flux could be as

bright as 17th magnitude

in R band.

The proto-magnetar would eject a

wide-beam wind, whose dissipation

would power an X-ray afterglow as

bright as~ (10−8–10−7) erg cm−2 s−1.

The duration is typically 103–104s.


Shocked ISM

Ejecta

SGRB

Radio

Optical

X-ray

X-ray

X-

ray

Poynting

flux

MNS


SGRB



X-ray Afterglow

1000 ~10000 s

8 1 210 ergs cm




or even years

Zhang, 2013


ISM (n) 0L

Energy conservation equation

49 2 6 4

0 ,15 6 0, 310 pL B R P

34

3sw pM nm R

Ejecta-ISM shock with Energy Injection Gao, Ding, Wu, Zhang & Dai, 2013, arXiv:1301.0439

0

2 2 2: ( 1) ( 1)

rot

sd

dec ej sw

ET

L

T M c M c when

Dynamics depends on and , namely

and

0L ejM

pBejM

Ejecta-ISM shock with Energy Injection

For given different

leads to different

Dynamic cases.

Some of them could

be even relativistic

pB

ejM

, ,2ej ej crM M

3 2

, ,2 45 0, 3~ 6 10ej crM M I P

Non-relativistic

If

14 4~10 , ~10ejB G M M

sd decT T


X-ray:

Opt:

Radio:

11 2 1~10peakF erg cm s

~10peakF mJy

7~10peakT s

~ 1peakF Jy

4~ ~10peak sdT T s

4~ ~10peak sdT T s

15 4~10 , ~10ejB G M M

~sd decT T


X-ray:

Opt:

Radio:

3~ ~10peak sdT T s


~100peakF mJy

7~10peakT s

~100peakF mJy

3~ ~10peak sdT T s

15 3~10 , ~10ejB G M M

sd decT T


X-ray:

Opt:

Radio:

3~ ~10peak sdT T s


~10peakF mJy

7~10peakT s

~ 1peakF Jy

3~ ~10peak sdT T s

SGRB

Flu

x (

erg

cm

-2s

-1)

t sdT

8 2 110 erg cm s

X-ray Emission in All Directions

Magnetic dissipation

sdT

Magnetic dissipation +

Ejecta-ISM shock w/ EI

SGRB

Flu

x (

erg

cm

-2s

-1)

t sdT

8 2 110 erg cm s

X-ray Emission in All Directions

Magnetic dissipation

Magnetic dissipation +

Ejecta-ISM shock w/ EI

sdT

3 410 ~10obsT s

Late Re-brightening in SGRB 080503


--- Li-Paczynski Model

Perley et al. 2009, ApJ, 696, 1871


--- Refreshing Shock Model

Hascoet et al. 2012, A&A, 541, A88

Ek,0 = 7 e 50 erg

Ek,inj = 30 Ek,0

ε_e = (ε_B )^0.5

ε_B = 5 e −2,

p = 2.5

n = 1 e -3 cm−3

z = 0.5


--- Gao, Ding, Wu, Zhang & Dai (2013) Model

Ding, Gao, Wu, Zhang & Dai 2013,

in preparation

Relativistic PTF Transient PTF11agg

--- Another GWB magnetar candidate?

Cenko et al. (2013)

Event Rate by VLA Bright Radio Transient Survery

Bower & Sauer. 2011, ApJL, 728, 14

• Field of 3C 286

• 23-year archival observation

• 1.4 GHz

event rate (>350 mJy ) is

< 6×10−4 degree−2 yr−1,

or < 20 yr −1

Bright GWB afterglow rate

uncertainties:

(1) NS-NS merger

(2) Fraction of forming a massive

millisecond magnetar

How to differentiate BH and Magnetar

Gravitational Wave Signal EM Counterpart

Chirp + Ring down

BH:

Magnetar:

After the standard chirp signal and merger

phase, there should be an extended GW

emission episode afterward due to a

secular bar-mode instability of the newly

formed proto-magnetar.

BH:

SGRB: No X-ray Plateau

No-SGRB:

No X-ray

Li-Paczyński Nova

Weak Radio Signal

SGRB: w/ X-ray Plateau

No-SGRB:

X-ray detection

Bright Opt Signal

Strong Radio Signal

Magnetar:

No extended GW

emission after merger

Localization Error Box

Strategy to Detect EM Counterpart of GWB

~Tens of square degree

~Tens of seconds before merger

trigger Adv-LIGO

Localization Error Box



Two kinds of strategy

1) Small field of view, with both

fast-slewing speed and high

sensitivity.

103–104s could go through

the whole Error Box


trigger Adv-LIGO

GW Localization Error Box




1) Small field of view, with both

fast-slewing speed and high

sensitivity.

If 103–104s could go through

the whole Error Box


trigger Adv-LIGO

~ sd

dec

err

slew TP

A

~ 1decP

Telescope field of view




2) Large field of view, with

fast-slewing capability and

moderate sensitivity.

GWAC

Einstein Probe


trigger Adv-LIGO

GW Localization Error Box

Telescope field of view

~ sd

dec

sky

slew TP

A

If 103–104s could go through

the whole sky ~ 1decP

Thank You

2013 multi-messenger transient astrophysics …kiaa.pku.edu.cn/activities/xuefeng_wu.pdfhow...

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