ns, magnetar, grb astrophysics with...

NS, Magnetar, GRB astrophysics with GWsNS, Magnetar, GRB astrophysics with GWs

Rencontres de Moriond – La Thuile, 2015, March 21-28Rencontres de Moriond – La Thuile, 2015, March 21-28

Simone Dall'OssoTAT- Tübingen University

Advanced deectors and GW astronomyAdvanced deectors and GW astronomy

Outline of the TalkOutline of the Talk

GW bursts from SGRs: magnetar oscillations excited at Giant Flares;

GWs from newly born magnetars: long-lasting GW signals due tomagnetically-induced deformations/secular bar-instability

Continuous Waves (CW): isolated radio pulsars and accreting NSs inLow Mass X-ray Binaries

GWs from (short) GRBs: role of the EOS and magnetic felds in themerger outcome; event rates; GW astronomy with aLIGO/Virgo

NS physics and GWsNS physics and GWs

- interior magnetic feld: strength, geometry and location

- NS structure: moment of inertia, sources of deformation and viscosity

- origin of NS magnetic felds; stellar progenitors of different NS classes

NS physics and GWsNS physics and GWs

Continuous Waves from NSsContinuous Waves from NSs

h0∼QD

Ω2

Q≈ϵ I

Radio pulsars: i) maximum deformation sustained by the crust ε ~10-5 -10-6 (EOS dependent)ii) current nondetection LIGO beats spindown limit for Crab/Vela (ε =10-4 )


h0∼QD

Ω2

Q≈ϵ I

Superconductivity: increases magnetic stresses by a factor H c1

B∼ 102−103

Radio pulsars: i) maximum deformation sustained by the crust ε ~10-5 -10-6 (EOS dependent)ii) current nondetection LIGO beats spindown limit for Crab/Vela (ε =10-4 )


h0∼QD

Ω2

Q≈ϵ I

LMXBs: i) accretion-induced “mountains” or r-modes can excite GW emissionii) X-ray obs. suggest spin equilibrium due to accretion physics (Patruno 2011)

iii) strain upper limits for Sco X-1 are ~ 6 times larger than maximumexpected at spin equilibrium in best case (Aasi et al. 2014).


h0∼QD

Ω2

Q≈ϵ I

LMXBs: iv) can be improved by at least 2 orders with longer observations (months vs.days) and improved sensitivity of aLIGO/Virgov) r-mode coupling to B-feld can amplify the feld and induce ε~10-9 (Cuofano

et al. 2012; cf. Rezzolla et al. 2001) consistent with observational limits.

MagnetarsMagnetars

Galactic X-ray Pulsators with:

- slow spins (5-12 s)

- spindown dP/dt ~ 10-10-10-12

Anomalous X-ray Pulsars/Soft Gamma Repeaters

Bdip∼1013÷15G

Magnetic energy best candidate

- 3 Giant Flares observed in ~30 yrs from 5 SGRs (+9 AXPs)

- Energy of 1979 and 1998 events ~ few ×1044 ergs

MagnetarsMagnetars

Similar phenomenology and frequencies

same basic mechanism?Association: either internal (Alfven) modesor crustal oscillations (Israel et al. 2005)(Watts & Strohmeyer06)

Detailed models to understand the physics Effect of strong B on frequencies?(Colaiuda & Kokkotas 2009, 20011, 2012Gabler et al. 2011)

SGR1806-20: 18 – 30.4 - 61 - 92.5 - 150 - 625 - 1840 Hz

SGR1900+14: 28.5 - 52.5 – 84 - 155.5 Hz

QPO's & NS asteroseismologyQPO's & NS asteroseismology

Magnetar oscillations and GW “bursts”Magnetar oscillations and GW “bursts”

GW Bursts: LIGO upper limits rule out by one order of magnitude optimistcpredictions (Ioka 2003, Owen & Corsi 2009). E<1048 erg vs. 1048- 1049 erg

f-mode: semi-analytical calculations (Levin & van Hoven 2011), and fullyrelativistic numerical simulations (Zink, Lasky & Kokkotas 2011) show thatf-mode excitation depends strongly on B-feld and remains always low.



Zink, Lasky & Kokkotas 2011

f-mode: semi-analytical calculations (Levin & van Hoven 2011), and fullyrelativistic numerical simulations (Zink, Lasky & Kokkotas 2011) show thatf-mode excitation depends strongly on B-feld and remains always low.



f-mode: semi-analytical calculations (Levin & van Hoven 2011), and fullyrelativistic numerical simulations (Zink, Lasky & Kokkotas 2011) show thatf-mode excitation has low amplitude and depends strongly on B-feld.

lower-frequency modes: crustal torsional modes are found to reach muchlarger amplitudes (Levin & van Hoven 2011); these might even couple to Alfvenmodes in the core thus leading to global oscillations.

Numerical simulations (Zink, Lasky & Kokkotas 2011) also fnd signifcant powerat ~ 50-200 Hz, associated to Alfven modes in the core.

Long-GRBsLong-GRBs

Relativistic outfow Γ ~ 102 -103

Shock converts Ekin

to radiation (Sari&Piran 1997, Piran 1999)

i) collapsar that forms a BH (Woosley & MacFadyen 1999);

ii) ultramagnetized, ms spinning NS (Usov 1992)

Long-GRBsLong-GRBs


Shock converts Ekin




iii) a ms spinning, ultramagnetized NS might form in the collapsing core of amassive star (Metzger et al. 2006, Bucciantini et al. 2006, Metzger et al. 2011)

Long-GRBsLong-GRBs


Shock converts Ekin




iii) a ms spinning, ultramagnetized NS might form in the collapsing core of amassive star (Metzger et al. 2006, Bucciantini et al. 2006, Metzger et al. 2011)

GW signature of the collapse phase? (cf. Ando et al. 2013; Piro & Ott 2011).

GW signature from jet acceleration? (Piran & Birnholtz 2013)

ms-spinning proto-NS, differential rotation converted to toroidal magnetic feld B~1016 G → magnetic energy dissipation powers high-energy emission from here on (Duncan & Thompson 1992 → 2001 )

The magnetar-GRB connectionThe magnetar-GRB connection


E spin∼3×1052( Pms )

2

erg s−1

Bd∼1014−1015 G

Bcore∼1016 G



E spin∼3×1052( Pms )

2

erg s−1

Bd∼1014−1015 G

Bcore∼1016 G


Magnetic dipole spindown ~102 -104 s

GW emission in ~103 -105 s

ms-spinning proto-NS, differential rotation converted to twisted magnetic feld B~1016 G → magnetic energy dissipation powers high-energy emission from here on (Duncan & Thompson 1992 → 2001 )

Magnetar formation scenarioMagnetar formation scenario

0 ~1 day~ 1 hr

103-104 yrs

Dynamo/fipping

- GW “reversed-chirp”- EM spindown/GRB plateau

SGRs/AXPsGiant Flares, Magneticdecay and X-ray emission


Nousek et al. (2006)

The magnetar-GRB connectionThe magnetar-GRB connectionThe magnetar-GRB connectionThe magnetar-GRB connection

Dall'Osso et al. 2011

Cf. Zhang & Meszaros (2001)


Dall'Osso et al. 2011

Cf. Zhang & Meszaros (2001)


Bernardini et al. 2012


TOROIDAL B → PROLATE DISTORTION

Ω Bt

χ

χ≠0 excites freebody precession

Ωpre= εBΩcosχ (Mestel & Takhar72)

cf. Cutler (2002)Stella et al. (@005); Dall'Osso et al. (2009)

GW emissionmaximised !

Bt

spin

pole-onpole-on

spin

Bt

pole-onpole-on

Internal dissipation

L = IΩ E = IΩ2


TOROIDAL B → PROLATE DISTORTION

χ≠0 excites freebody precession

Ωpre= εBΩcosχ (Mestel & Takhar72)

Mastrano et al. 2011Akgün et al. 2013

ϵB≃3.4×10−7 Bdip ,142 R12

4

M 1.42 (1−0.37

ET

E pol

)

ϵB0 ∼

E B

E grav

≃3.5×10−4 B162 R6

4 M 1.4−2

Δt ~ 105 s

Ω̇=−23

μd2

I c3 Ω3−32

5G

c5 I ϵB2 Ω5

How strong are the expected signals?How strong are the expected signals?

Ω̇=−23

μd2

I c3 Ω3−32

5G

c5 I ϵB2 Ω5


Event Rate: How many Magnetars? > 1 every 103 yrs in the Galaxy (Gaensler et al. 1999)

Have to search a nearby cluster (Virgo)

i) Distance of expected signals ~ 20 Mpc

ii) transients might imply an increase in the formation rate.

Ω̇=−23

μd2

I c3 Ω3−32

5G

c5 I ϵB2 Ω5


@D = 20 Mpc


Corsi & Meszaros (2009)

Secular bar-instability: T∣W∣

≥0.14 Growth time ~ 102-104 s

The non-axisymmetric NS emits GWs and spins down, sweeping theLIGO/Virgo range from hundreds of Hz to ≤ Hz

(cf. Doneva, Kokkotas, →azaev 2015)

Short-GRBsShort-GRBs

inspiral GW-driven, ~ point-mass+tidal @D = 200 MpcAbadie et al. 2010

Rate:0.4/40/400 per yrAbadie et al. 2010


merger

inspiral

shocks, violent dynamical transition

GW-driven, ~ point-mass+tidal


merger

inspiral GW-driven, ~ point-mass approx


Post-mergerShort GRBs

GW signals

Paczynski 1986,Narayan et al. 1992


merger

inspiral GW-driven, ~ point-mass approx


Post-mergerShort GRBs

GW signals

Paczynski 1986,Narayan et al. 1992 Strong B-feld?


Direct collapse to BH if MTOT

> Mmax

(Ω)

Formation of an unstable NS if Mmax

(Ω) > MTOT

> Mmax

Formation of an stable NS if MTOT

< Mmax

M max (Ω)=M max (1+αΩβ)

Short-GRBsShort-GRBsStrong differential rotation → strongly twisted internal feld E

B≥1050 erg

Rosswog et al. (2003), Rosswog (2005), Rezzolla et al. (2011), Giacomazzo & Perna (2013), Giacomazzo et al. (2014)


2) Event Rate: How many BNS mergers?

a) distance of expected signals ≤ 35 Mpcb) estimated rate ~ 0.1-2 event/yr (cf. Abadie et al. 2010) c) fraction of stable NSs depends on EOS

Dall'Osso et al. (2015)

data from Kiziltan et al. (2013)

M rest=M g+0.075 M g2

Timmes et al. (1996)

1) Horizon with aLIGO/Virgo ~ 35 Mpc (Dall'Osso et al. 2015)


Dall'Osso et al. (2015)

Stable PMNSD ~ 35 Mpc

Hypermassive PMNSD ~ 16 Mpc

Summary & ConclusionsSummary & Conclusions

Continuous Waves (CW): how much below the spin-down limit?Imprint of early history might be left in the crustal reference shape. Superconductivity can enhance the magnetic deformation. GW emission from LMXBs likely weaker than previously expected, butstrong input for studying the physics of Ns interiors.

GW bursts from SGRs: unlikely detection of GWs from f-mode;crustal/Alfven torsional modes much more promising, work in progress. Strength and geometry of the interior B-feld can play a signifcant role

GWs from GBRs: if ultra-magnetized, ms spinning NSs are formed incore-collapse and/or BNS mergers, and if the event rate is not belowcurrent “realistic-to-optimistic” estimates, then 1 to several newly bornmagnetars could be detected by aLIGO/Virgo in a few years of operationHigh computational costs: needs dedicated detection strategies

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