Accreting Black HolesAccreting Black Holesin the Milky Way and Beyond in the Milky Way and Beyond

……

Vicky KalogeraPhysics & Astronomy Dept

withMike HenningerNatasha Ivanova

Bart Willems

In this talk :In this talk : Ultra Luminous X-ray sources (ULXs):Ultra Luminous X-ray sources (ULXs):

o what are they ? what are they ? o where are they found ?where are they found ?o their nature: their nature:

IMBH or anisotropic emission ?IMBH or anisotropic emission ?o Transient behavior: an observational diagnosticTransient behavior: an observational diagnostic

Galactic Black-Hole X-ray binaries: Galactic Black-Hole X-ray binaries: o Current measurements constrain their Current measurements constrain their

evolutionary historyevolutionary historyo Black-hole kicks and progenitors Black-hole kicks and progenitors

BH X-ray binaries in Globular Clusters: BH X-ray binaries in Globular Clusters: o Why none observed so far ? Why none observed so far ?

pre-Chandra ...

'super-Eddington''super-Eddington' sources tentativelytentatively identified (e.g., Fabbiano 1995)

some identified as X-ray pulsars (hence beaming) most often questions of source confusion (lack of variability)

ULXs: What do we know about them ?

existence of ULXs established: LX > 1039-40 erg/s

mostly found in young stellar environments (<~ 100 Myr) their nature still not well understood although many hints have been discussed … (e.g., Miller & Colbert 2003)

post-Chandra ...

if LX > 1040 erg/s and LX < Ledd = 2x1039 (M/10Msolar) erg/s

===> M

BH > 50 Msolar : accretion onto IMBH

OR

if M > Medd (e.g., because of thermal-timescale mass transfer)

===> super-Eddington mass transfer that possibly leads to beaming and anisotropic emissionLx

true = LX * (beaming fraction) < LX

ULXs: What is their nature ?

. .

ULXs: IMBH possibility

has important implications for:

• stellar dynamics (evolution of massive stars and binary black holes in clusters) and possibly Pop III stars

• seeds for super-massive black hole formation

• gravitational-wave detection

Q : Can the long-term behavior of X-ray emission be used as an observational diagnosticobservational diagnostic ? ?

VK, Henninger, Ivanova, King 2003

In the context of the thermal-viscous disk instability, an X-ray binary is transient if M is below a critical value

The development of anisotropic emission (beaming) has been connected to thermal-timescale MT and super-Eddington, i.e., high, MT rates ---> stable disk

How about accreting IMBH binaries in young stellar environments ? ---> are they stable or are they transient ?

•

Q : What is the minimum BH mass required forthe development of transient behavior ? ?

VK, Henninger, Ivanova, King 2003

Critical mass transfer rate for transient behavior:

Minimum BH mass required for transient behavior:

MT rate depends primarily on the donor mass and evolutionary stage (or orbital period)and is rather insensitive to the BH mass in the MT sequence used to calculate MT rate …

Plan:

Use numerical MT sequences to examine analytical expectations

Derive MBH,min for a wide range of stellar parameters

Does MBH,min lie consistently in the IM or stellar-mass range ?

Q : What is the minimum BH mass required forthe development of transient behavior ? ?

VK, Henninger, Ivanova, King 2003

transience: diagnostic

Minimum BH mass required for transient behavior V

K, H

enni

nger

, Iva

nova

, Kin

g 20

03

orbital period

MT rate

minimum BH mass

MBH = 1000 Msolar Mdonor = 20 Msolar

BGBZAMS

Q : Does MBH,min depend on MBH in the MT sequence ? ?

VK, Henninger, Ivanova, King 2003

Mdonor = 20 Msolar

MBH = 1000 Msolar

No !

MBH = 10 Msolar

Mdonor = 10 Msolar

MBH = 1000 MsolarMBH = 10 Msolar

Q : Can the long-term behavior of X-ray emission be used as an observational diagnosticobservational diagnostic ? ?

VK, Henninger, Ivanova, King 2003

For stellar donors more massive than ~5Msolar, MBH,min for transient behavior is in excess of 50-100Msolar for 90-100% of the MT duration.

In young stellar pops massive stars dominate the central regions due to mass segregation.

Less massive captured IMBH companions typically do not have enough time to fill their Roche lobes.

A: Yes ! in young (<~108 yr) stellar pops relevant to ULXs

Q : Can an IMBH acquire a stellar companion in a young cluster that will fill its Roche lobe ? ?

IMBH could form through successive collisions and mergers of ordinary massive stars in dense star clusters (timescale ~1-3Myr)

(Sanders 1970; Quinlan & Shapiro 1990; Portegies Zwart & McMillan 2001; Ebisuzaki et al. 2001; Gurkan et al. 2003)

After formation an IMBH could appear as an X-ray source, if an acquired stellar companion goes through Roche lobe overflow

IMBH dynamics (preliminary …)

MBH = 500 Msolar

Tev = 100 Myr

n = 104 pc-3

= 5 km/s

Ivanova, VK, Belczynski 2003

IMBH dynamics (preliminary …)

MBH = 500 Msolar

Tev = 100 Myr

n = 104 pc-3

= 5 km/s

Ivanova, VK, Belczynski 2003

initialfinal

IMBH dynamics (preliminary …)

MBH = 500 Msolar

Tev = 100 Myr

n = 104 pc-3

= 5 km/s

Ivanova, VK, Belczynski 2003

initialfinal

RLO at ZAMSRLO at E

MS

RLO

at R

max

hard-soft boundary

IMBH dynamics (preliminary …)

MBH = 500 Msolar

Tev = 100 Myr

n = 104 pc-3

= 5 km/s

Ivanova, VK, Belczynski 2003

initialfinal

RLO at ZAMSRLO at E

MS

RLO

at R

max

hard-soft boundary

X-ray

IMBH dynamics (preliminary …)

MBH = 500 Msolar

Tev = 100 Myr

n = 104 pc-3

= 5 km/s

Ivanova, VK, Belczynski 2003

different Monte Carlorealizations

Observed sample of BH X-ray binaries:

Growing in number New exciting measurements of proper motion

give us with radial velocity unique information on kinematic history

BH formation: some open questions …

What is the mass relation between progenitors and BHs ? Are asymmetric birth kicks imparted to BHs ? How do their magnitudes compare to NS kicks ?

courtesy Sky & TelescopeFeb 2003 issue

How do BHX-ray binaries form ?

primordial binary

X-ray binary at Roche-lobe overflow

Common Envelope:orbital contractionand mass loss

BH formation

Use ALL observational constraints and measurements:

Current: BH and donor mass donor position on the H-R diagram orbital period3-D velocity

Plan: Follow the Galactic motion backwards in time Derive Vcm as a function of time

Identify at least one MT sequence that satisfies ALL observables: obtain time of BH formation

and post-collapse properties

Analyze collapse dynamics: constrain BH XRB progenitor

Example case: GRO J1655-40

Proper motion measured by Mirabel et al. 2002

D = 3.2 kpc

orbit does not extendbeyond 70-100pcaway from the Galactic plane

Example case: GRO J1655-40

Mass transfer sequences must satisfy constraints on current H-R position of the donorand …

Initial values: MBH Mdonor Porb

(Mo) (Mo) (d)

4.4 2.45 0.564.4 2.45 1.44.4 2.45 1.85.4 2.0 1.5

current BH mass

current donor masscurrent orbital period

MBH Mdonor Porb

(Mo) (Mo) (d)

4.4 2.45 1.4 4.4 2.45 1.8

Mass transfer sequences must alsosatisfy constraints on current BH anddonor masses and most importantly orbital period

Example case: GRO J1655-40

time since BHformation: ~900Myr

Example case: GRO J1655-40

Constraint on BH-binary age ---> VCM = 87-89 km/s

Example case: GRO J1655-40 Use VCM, MBH, Mdonor, and Aorb (or Porb) at BH birth to constrain Aorb just before as well as the BH-progenitor mass and the possible BH kick magnitude

BH kick magnitude

BH

pro

geni

tor

mas

s

from core simulationsand stellar models:

the progenitor of a 4.4Msolar BH is a 4.8Msolar He-star

(Fryer & VK 1997)

BH kick magnitudeBH kick magnitudenecessary ! necessary !

most likely: most likely: 125 - 150 km/s125 - 150 km/s

Example case: GRO J1655-40

To follow:

> Several other systems to be analyzed

> Core-collapse runs and SN explosion constraints (with C. Fryer)

> Are BH kick magnitudes correlated with either BH mass or mass loss at BH formation ?

> Comparison with NS systems

Black Holes in Globular Black Holes in Globular ClustersClusters

Expect ~ 10Expect ~ 10-4 -4 - 10- 10-3-3 N BH from evolution N BH from evolution of N stars with Salpeter-like IMFof N stars with Salpeter-like IMF

N ~ 10N ~ 105 5 - 10- 106 6 in GC GC should have in GC GC should have many BH…many BH…

Where are they??Where are they?? BH XRBs, ULXs ?BH XRBs, ULXs ? Ejected, as binaries, GW sources ?Ejected, as binaries, GW sources ?

Standard Scenario:Standard Scenario: BHs quickly concentrate in GC core BHs quickly concentrate in GC core ((mass segregationmass segregation)) BHs decouple dynamically from GC BHs decouple dynamically from GC on ~ 10on ~ 108 8 yr timescale (yr timescale (Spitzer instabilitySpitzer instability))

BHs get ejected through interactions BHs get ejected through interactions on ~ 10on ~ 109 9 yr timescale (yr timescale (evaporationevaporation)) ~ 1 BH left in GC core today~ 1 BH left in GC core today Sometimes: Sometimes: growthgrowth to IMBH to IMBH through successive mergersthrough successive mergers

Observability of BH Observability of BH XRBsXRBs

Remaining ~ 1 BH is very likely to acquire a Remaining ~ 1 BH is very likely to acquire a companion through either:companion through either: Exchange interactionExchange interaction Tidal capture (?)Tidal capture (?)

Duty cycle of resulting XRB is:Duty cycle of resulting XRB is: Very low (<< 10Very low (<< 10-3-3) for post-exchange binaries (wide)) for post-exchange binaries (wide) Very high ( ~ 1) for tidal capture binaries (conflicts Very high ( ~ 1) for tidal capture binaries (conflicts

with observations for Galactic GC !)with observations for Galactic GC !)

(Kalogera, King, & Rasio 2003, ApJL, in press, astro-ph/0308485)

(O’Leary, Fregeau, Ivanova, & Rasio 2003)