Survey of Micro Quasars
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Survey of Micro Quasars. Outline. Reminder: what is a microquasar? Established and Candidate microquasars Gamma ray candidates: LSI +615, LS 5039 As seen in DC2 Models for gamma ray spectra. What and Where. High Mass XRB live near galactic plane Low Mass XRB live in the bulge.

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Presentation Transcript

Outline
Outline

  • Reminder: what is a microquasar?

  • Established and Candidate microquasars

  • Gamma ray candidates:

    • LSI +615, LS 5039

    • As seen in DC2

  • Models for gamma ray spectra


What and where
What and Where

High Mass XRB live near galactic plane

Low Mass XRB live in the bulge

microQuasar ≡ X-ray binary with jets


Candidate microquasars
Candidate Microquasars

*

*

*

*

* - g-ray candidates


Ls 5039 ls i 613
LS 5039 & LS I +613

  • 2EG J0431+6119 (aka 3EG J0435+6137)

  • = 9.2±0.6 x 10-7 cm-2s-1 E>100 MeV

  • = 2.46

    Not visible by HESS

  •  = 35.2 x 10-8 cm-2s-1 E>100 MeV

  • = 2.2

    HESS: G=2.12


Hess detected again this year
HESS: Detected again this year

H.E.S.S. preliminary

LS 5039


H e s s lightcurve 2004
H.E.S.S. lightcurve (2004)

LS 5039

Aharonian et al., Science 309(746 ), 2005

No significant variations


H e s s spectrum hard
H.E.S.S. spectrum: hard

O6V star

LS 5039

Aharonian et al., Science 309(746 ), 2005


Ls 5039 ls i 615 friends candidates in dc2
LS 5039, LS I +615 & Friends Candidates in DC2

Toby’s HEALPIX map + Saclay sources

SS 433

GRS 1915+105

Circinus X1

XTE J1550-564

GGRO J1655-40

V 4641 Sgr

GRS 1758-258

Cyg X1

GX 339-4

1E 1740.7-294.2

Cyg X3

LS5039

G = -2.42

LS I +615

G = -2.75


Models for g ray emission
Models for g-ray Emission

log eL e(erg s -1)


Standard disk model star disk corona
Standard Disk Model: Star, Disk, Corona

  • Star

    • blackbody – T ~ 104K – peak @ kT – E ~ 10 eV

  • Accretion Disk

    • Energy emission due to angular momentum transport

    • Inner radius ~3rs≈ 9 Mx km (eg 18 km for 2 solar masses)

      • Tin ~ 2 107 K

      • 1 solar mass  10M K  ~ 1 keV

      • Integrate radial temp spectrum


Standard disk model hard x rays
Standard Disk Model: Hard X-rays

  • Observations show hard x-ray spectra

    • Requires 109 K

    • Hence postulate corona


Dynamics in disk jet system
Dynamics in Disk-Jet System

High luminosity from inner disk;

Soft x-rays

GRS 1915+105

Low luminosity from corona;

Hard x-rays

T (hrs)


Jet observations
Jet Observations

  • mQ jets too small to image anytime soon

  • complicated MHD calculations!

  • practical models of jets used in calcs:

    • inject blobs of plasma at some height above the disk, bulk Lorentz G (eg 5)

    • isotropic lepton spectrum in blob, power law (-2) with min, max g corresponding to inferred max E in TeV range




Leptonic jet models
Leptonic Jet Models

Dermer

G=2; p=2.25

Includes gg annihilation with stellar field

Parades

G=1.1; p=2.2

  • Inverse compton from star dominates at high energy

  • ignores variability and non-contemporaneous measurements


Recall from m q ii ls 5039 spectral fit assuming it is a pulsar
Recall from mQ II: LS 5039 Spectral fitassuming it is a pulsar

G.Dubus

Pulsar wind parameters:

1036 erg/s, gw=106 and s=0.001

no absorption

nebular emission

But TeV and star photons create e+e- pairs !

Dubus, in prep.


Additional variability
Additional Variability

  • Two potential sources:

    • Precession of jet by drag of star gravity on disk

    • Assumed to transmit to jet

For “LS5039”; q~100 

T~ 100 days

Huge variation depending on angle of jet to disk

GRO J1655-40, V 4641 Sgr show significant misalignments

SS 433 shows 162 day period


Variability 2
Variability 2

  • Orbital effects on accretion (“two-peak” accretion model) and extinction of g’s by stellar field

Lower density wind

Lower compact obj speed

High density wind

High compact speed

Colours represent 3 epochs

Dubus

From mQ II:

Extinction at high E due to gg interactions vs orbital phase


What will glast contribute
What will GLAST Contribute?

  • There is only statistics of TWO for observations in GLAST energy range (LS 5039, LS I +613)

    • And LS 5039 might not even be a microquasar!

  • Need more candidates

    • Survey mode should allow us to examine known candidates

    • Hopefully ACTs will see more (eg LS I +613 from some northern telescope?) before we go up

      • Definitive IDs from precise positions, variability

  • Keep an eye out for variability

    • MW observations with x-ray, radio

    • Correlate gamma ray variability with disk-jet variations?

    • Untangle precession, orbital effects

    • Hopefully more understanding of disk-jet variations by then


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