Black holes and Neutron stars in eXTP era

Zhang Shu

(on behalf of the eXTP science team) Institute of High Energy Physics

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eXTP: an ambitious mission in future

Missions crowed but short of:

large area, polarization.

eXTP: collaboration of China and Europe

Selected for Phase 0/A in 2011,

expected launch in around 2023.

eXTP satellite

XTP(2009-2014) eXTP(since 2014)

payload SFA 11 arrays：focus length 4.5m，Diameter 450 mm，SDD Energy band：0.5-20 keV FOV：12 arcmin Time resolution：10 us Energy resolution： 180eV@6keV Angular resolution：1arcmin Sensitivity：0.16uCrab（104s） Effective are：6000cm2@6keV

LAD 40 arrays SDD Energy band：2-30 keV FOV：1dg Time resolution：2us Energy resolution：200eV @ 6keV Augular resolution：1 dg Sensitivity：0.01uCrab（104s） Effective area：3m2@6keV

WFM 3 arrays，SDD Energy band：2-50 keV FOV：1.33PI Time resolution：2 us Energy resolution：300eV@6keV Angular resolution：4.5 arcmin Sensitivity：3uCrab（2x104s） Effective area：170cm2@6keV

PFA, 2 arrays：focus length 4.5m，diameter 450mm Energy band：2-10 keV FOV：12 arcmin Time resolution：500us Energy resolution： 1.8keV@6keV Angular resolution：15arcsec Sensitivity：5 uCrab（104s） Effective area：250cm2@2keV

Key properties of eXTP

Effective area ~0.6 m2 @6keV ，~0.9 m2 @0.5-2 keV（SFA) ~3 m2 @6keV (LAD) Time resolution 2-10 μs Energy resolution ~200 eV @ 6keV (LAD, SFA) Polarization MDP~1.6% (106 photons, 1 Crab under 104 s)

Powerful two eyes in energy and time domains : spectrum and timing Unique third eye in polarization domain : emission geometry and magnetism

Powers in eXTP: spectral-timing ; timing-polarimetry

Road map 2010-2030: unique and powerful eXTP

eXTP effective area and comparisons with other telescopes.

Key Sciences of eXTP:

One singularity

(Black hole)

Two stars

(Neutron star and quark star)

Three extremes

(gravity, density, magnetism)

Via observing BH and NS systems

eXTP will answer:

are the fundamental physical laws universal?

The fundamentals/pillars of modern physics: 1, General relativity theory: large scale interaction valid under extreme in gravity? 2, Quantum chromodynamics theory strong interaction, quark and gluon scale valid under extreme in matter density? 3, Quantum electrodynamics theory interaction of electron and photon valid under extreme in magnetic field?

1, what are the condition for planet formation and the emergency of life? 2, how does the solar system work? 3, what are the fundamental physical laws of the universe? (eXTP, LOFT, Nicer) 4, how did the universe originate and what is it made of? （Athena+）

Core science:

BH and strong field gravity (SFG)

The gravity potential in the vicinity of a

black hole is 4 magnitudes higher than

those used for testing GR currently.

Astronomical lab:

Measure the reflection on the

accretion disk and the

relativistically broadened Fe

line.

Core science : BH and SFG

eXTP spectral-timing：

Broadened Fe line

eXTP spectral-timing： Disk reverberation

eXTP spectral-timing： QPO

eXTP timing-polarimetry： QPO and polarization

Core science : BH and SFG

0

5E-5

1E-4

1.5E-4

3.5 4 4.5 5 5.5 6 6.5 7

Ph

oto

n/c

m2/s

/ke

V

Energy (keV)

a=0.0a=0.5a=0.9

0

0.2

0.4

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1

1E-12 1E-11

Fitted spin value (with 90% confidence rang

2-10keV Flux (ergs/s/cm2)

xtp lfa(100eV)

xmm pn(100eV)

xtp joint(100eV)xtp lfa(200eV)

xmm pn(200eV)

xtp joint(200eV)

model value

BH spin and broad Fe line in AGN led by：SFA Typical exposure :1 Ms

BH spin and broad Fe line in XRB： led by : LAD Typical exposure: a few hundred seconds.

Core science : BH and SFG

led by：LAD Typical exposure a few tens seconds. Observational target: XRB

Space-time dragging effect predicted by GR: precession of central corona and QPO.

Spectral ratio of QPO rising and fall parts.

Core science : BH and SFG

XRB hot spot and the

dynamically

broadened Fe ：

Typical exposure：a

few hundreds seconds.

led by：LAD

AGN hot spot and the dynamically broadened Fe： Typical exposure: less than 10 ks. Led by：SFA

Hot spot in inner disk

Periodical Fe line modification

Core science : BH and SFG

Reverberation mapping: AGN, typical exposure 1 Ms, led by SFA+LAD XRB, typical exposure 100 ks, led by LAD.

AGN reverberation mapping

XRB reverberation

mapping

Measure the absolute distance from BH

Core science : BH and SFG

GR predicts three

frequencies intrinsic to

accretion disk:

orbital cycle

Radial epicycle

Periastron precession

QPO measurement by eXTP： Observational target: XRB Typical exposure：10 ks Led by LAD

Core science : BH and SFG

Corona precession predicted by GR: Polarization measurement provides an independent test.

Observational target: XRB Typical exposure：50 ks Led by：PFA and LAD

Core science : BH and SFG

The space time around

spinning BH is Kerr metric?

Strong correlation between the

estimate of the spin and

possible deviations from the

Kerr solution?

Observational target：CygX-1 exposure：100ks Led by：LAD and SFA

eXTP simulation on CygX-1: exposure 100 ks, correlation between the deformation parameter of the metric and the BH spin. (provided by Prof. Cosimo Bambi group)

Core science: NS and dense matter (DM)

Requirement to NS radius measurement: a precision of 5-10%

Core science: NS and DM

Pulse profile of hot spot on surface of NS. Measure parameters: M,R,I and θ. Input: ms pulsar: f>200 Hz Four obs. variables: flux rms, color rms, C, and ∆φ well understood emission mechanism and the light curve

NS and DM: Observational targets

1, Burst oscillation ms pulsar: 6 sources with spin frequency > 200Hz, typical exposure <a few hundreds ks to 1 Ms, led by LAD Spectrum: hot spot with black body, temperature ~ 2 keV 2, Rotational powered ms pulsar: source: PSRJ0437-4715, spin frequency: 174 Hz typical exposure: 300ks led by SFA Spectrum: hot spot with black body, temperature ~0.1-0.3 keV Mass and inclination angle: measured by radio via Shapiro delay: 1.76+-0.2 solar mass, 137.6 dg (Verbiest et al., 2008)

NS and DM: Observational targets

3, Accretion X-ray ms pulsar: 12 sources with spin frequency > 200Hz, (Patruno et al. 2013) typical exposure : depends on the strength of outburst,~ a few hundreds ks, led by LAD,SFA and PFA Spectrum: black body and thermal Comptonization (hot spot + corona)

XMM and XTE observation on the outburst of XTEJ1751-305 in 2002. Seed photons of the hot spot with both low/high temperatures can fit the spectrum.（Gierlinski et al. 2005). Polarization measurement can help to discriminate between two models.

NS and DM: Observational targets

Mass-shedding frequency to constrain NS mass and radius. target：XRB in outburst Exposure: < 1ks Led by：LAD

Core science:

magnetar and strong magnetic field

Magnetar: AXP/SGR are a special NS type. With magnetic field larger than 1014 G.

Ideal lab for testing QED predication.

QED predication of vacuum birefringence effect. Needs magnetic field > 1013 G

The largest magnetic field produced on earth: <106 G

Core science:

magnetar and strong magnetic field

0 0.5 1

Flux 10-10 erg

/cm

2/s

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0.25

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0.35

0.4

0.45

0 0.5 1

Linear Polarization (%)

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50

60

70

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90

0 0.5 1Polarization A

ngle (deg)

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100

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120

130

0 0.5 1

Flux 10-10 erg

/cm

2/s

0.2

0.25

0.3

0.35

0.4

0.45

P hase0 0.5 1

Linear Polarization (%)

20

30

40

50

60

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90

0 0.5 1Polarization Angle (deg)

90

100

110

120

130

P hase0 0.5 1

Flux 10-10 erg

/cm

2/s

0.3

0.35

0.4

0.45

P hase0 0.5 1

Linear Polariza

tion (%)

50

60

70

80

90

100

P hase0 0.5 1

Polariza

tion A

ngle (deg)

90

100

QED prediction: vacuum birefringence target：AXP 1RXS J170849.0-400910 exposure：1.3 MS Led by：PFA，SFA，LAD

Simulation on 1RXS J170849.0-400910 at 2-10 keV: X-ray flux、polarization degree, polarization angle. Input: latitude of the hot spot 30°(red), 75° (black), Inclination angle 60°, vacuum birefringence effect accounted. Theoretical model: Taverna et al., 2014.

With birefringence effect

Without birefringence effect.

More landscapes of astrophysics explored by eXTP 1, The entire outbursts of XRBs 2, accretion physics 3, Extremely violent events (bursts) : gamma-ray burst, type-I burst, AXP and SGR 4, Diffuse emission, SNR 5, X-ray polarimetry

New science window: X-ray polarimetry

Accreting black holes

• Black hole binaries: accretion geometry, BH spin

• Blazars: emission mechanism, jet composition?

• Radio quiet AGNs: corona geometry, unification model

Strong magnetism

• Rotation-powered: acceleration regions

• PWN: B-field

• accretion powered pulsars: accretion and emission geometry

• Shell-type SNRs: particle acceleration, B-field

Fundamental physics

• GR effect: space curvature, space-time frame dragging

• QED: vacuum polarization

冯骅，XTP研讨会，西峰山庄

Polar cap model Slot gap model Outer gap model

Black hole and neutron star in eXTP era

They become the messengers to us for probing the

fundamental physics.

Excellent/unprecedented three eyes of eXTP allow for working in synergy

on the tiny/fine structures residing in: the spectral domain,

the timing domain and the polarimetry domain.

Thank you !