Relativistic Astrophysics: general overview Jean-Pierre Lasota Lecture 1

Relativistic Astrophysics: general

overview

Jean-Pierre LasotaJean-Pierre Lasota

Lecture 1Lecture 1Lecture 1Lecture 1

For a neutron star Po= 1.41 (Haensel, Lasota & Zdunik 1999)

2GM/c2)

Einstein A, On a stationary system with spherical symmetry consisting of many gravitating masses, 1939 ANNALS OF MATHEMATICS 40: 922-936 – black holes cannot formblack holes cannot form

Oppenheimer, J. R. & Snyder, H., On Continued Gravitational Contraction, Physical Review, 1939, vol. 56, Issue 5, pp. 455-459 – black holes must formblack holes must form

Salgado, Bonazzola, Gourgoulhon, Haensel (1994)

Maximum masses of neutron Maximum masses of neutron starsstars

O

2

1

3140

max M.10

4.8M

cmg

O

2

1

3140

max M.10

4.8M

cmg

.

Rhoades & Ruffini 1973)(Nauenberg & Chapline 1973;

Mmax(rot)=1.18 MmaxMmax(rot)=1.18 Mmax

Lasota, Abramowicz, Haensel (1996)

Richard Tolman

Quasars: Marteen Schmidt Quasars: Marteen Schmidt 19631963

3C 273: a star-like object 3C 273: a star-like object with large red-shift.with large red-shift.

1616%%

First Texas Symposium on Relativistic Astrophysics Quasistellar Sources and Quasistellar Sources and

Gravitational Collapse Gravitational Collapse Austin, December 15-19, 1964

The fate of a star and the release of gravitational energy under accretionDoklady Akademii Nauk SSSR 155, 67-69 (1964)

An alternative mechanism of energy emission is examined, in the present note, which is associated with an infall of the external mass in the gravitational field of a collapsing star.

Ed SalpeterEd Salpeter

(1964)

Ya. B. Ya. B. ZeldovichZeldovich

Rees 1984:

“The idea of infall in a powerful gravitational field as a source of the radiated energy of radiosources was advanced in its most general form by I.S. Shklovsky.”On the Nature of Radio Galaxies

Astronomicheskii Zhurnal, Vol. 39, p.591 (1962)

The discovery of pulsars (1967), rapidly The discovery of pulsars (1967), rapidly rotating, strongly magnetized neutron rotating, strongly magnetized neutron stars changed the attitude of stars changed the attitude of astronomersastronomers towards compact towards compact relativistic celestial bodies.relativistic celestial bodies.

Jocelyn Bell

Bohdan Paczyński

LISA sensitivity LISA sensitivity curvecurve.

M 106M 106

“...good science demands that we seek positive evidence in support of the black hole picture, and watch for credible evidence that the standard picture may not be quite right." (Peebles 2002)

M=4 1O7

MM

EVIDENCE EVIDENCE BY:BY:

Galactic Center: Sgr AGalactic Center: Sgr A**

(NAOS/Conica-(NAOS/Conica-VLT)VLT)

Schoedel et al. 2003

QPOs in BH X-ray QPOs in BH X-ray binariesbinaries

red red dwarfdwarf

““hot hot spot”spot”

neutron star neutron star oror black black holehole

Low-mass X-ray binary Low-mass X-ray binary (LMXB)(LMXB)

ADAFADAFaccretion accretion discdisc

Mass function:Mass function:

Minimum mass of the compact objectMinimum mass of the compact object

G2

KP

M(M

iMMf

3orb

2Xn

33n

X

)

sin)(

G2

KP

MM

iMMf orb

Xn

33n

X

)(

sin)(

G2

KP

MM

iMMf orb

2Xn

33n

X

)(

sin)(

1.41.4 3.03.0

Observed masses of neutron-stars and black-holes

ttburningburning > > ttfallfall

with surface

ttradiative-coolingradiative-cooling > t > tinfallinfall

(Advection Dominated Accretion Flows)(Advection Dominated Accretion Flows)

Quiescent Quiescent (Low-Mass)(Low-Mass) X-ray X-ray transienttransient

Viscous Viscous heating:heating:

Advective Advective « cooling »:« cooling »:

Radiative Radiative cooling:cooling:

FF__

= ….= …. (free-free, Compton, synchrotron)(free-free, Compton, synchrotron)

Energy conservation:Energy conservation:

= FF _

++ FF advadv FF advadv

DiscDisc

ADAFADAF

MMquiescquiesc..

Log(M

).

R(PR(Porborb))

A DIFFERENCE BETWEEN NEUTRON STARS AND A DIFFERENCE BETWEEN NEUTRON STARS AND BLACK HOLESBLACK HOLES

XMM + Chandra

(Lasota 2006)

SPIN “PARADIGM”

Radio-loudness of AGNs is Radio-loudness of AGNs is related to the (high) value of related to the (high) value of the BH spin.the BH spin.

New observational New observational evidenceevidence

Why two AGN looking the same here have different radio (and high energy) properties?

Radio-Radio-loudness:loudness:

Luminosities:Luminosities:

FRIIFRII FRIFRI

Seyfert LINER

Elliptical Elliptical galaxiesgalaxies

• At intermediate accretion luminosities, At intermediate accretion luminosities, AGNs hosted by giant elliptical galaxies and AGNs hosted by giant elliptical galaxies and located in the lower sequence are located in the lower sequence are represented in the sample only by 4 represented in the sample only by 4 objects. But recently: many radio-quiet objects. But recently: many radio-quiet galaxies with very massive BH.galaxies with very massive BH.

• At high accretion luminosities AGN hosted At high accretion luminosities AGN hosted by giant elliptical galaxies are found on by giant elliptical galaxies are found on both sequences (majority on the lower, both sequences (majority on the lower, “radio-quiet“radio-quiet” one)

• No disc-galaxy hosted AGN on the No disc-galaxy hosted AGN on the higher “radio-loud” sequencehigher “radio-loud” sequence

Two types of RQ/RL “bimodality”:Two types of RQ/RL “bimodality”:

• c c - intermittency of narrow jet - intermittency of narrow jet production (two accretion modes)production (two accretion modes)

• c c – spin (low for disc galaxies, high – spin (low for disc galaxies, high for elliptical galaxies)for elliptical galaxies)

Spin-accretion scenarioSpin-accretion scenario

Slope of the radio-loudness Slope of the radio-loudness sequence: sequence: accretion rateaccretion rate

Normalisation: spinNormalisation: spin

critcrit~ ~ 1010-3-3

It is easy to spin-up a black-It is easy to spin-up a black-hole (in an AGN) but difficult hole (in an AGN) but difficult to spin it down. That is the to spin it down. That is the problem…problem…