X-ray binaries and microquasars as radio and gamma-ray sources X

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X-ray binaries and microquasars as radio and gamma-ray sources X Powered By Docstoc
					                                 Josep M. Paredes
                                  Josep M. Paredes




X-ray binaries and microquasars
 X-ray binaries and microquasars
    as radio and gamma-ray
     as radio and gamma-ray
             sources
              sources

 AGILE's FIRST YEAR OF GAMMA-RAY ASTROPHYSICS
             5th Science AGILE Worksop
                                                     1
            ESRIN, Frascati, June 13, 2008
        Microquasars: X-ray binaries with relativistic jets


                                      XB: A binary system containing a compact object (NS or
                                      a stellar-mass BH) accreting matter from the companion
                                      star. The accreted matter forms an accretion disc,
                                      responsible for the X-ray emission. A total of 299 XB in
                                      the Galaxy (Catalogue of HMXB, 4th edition Liu et al.
                                      2006, A&A 455,1165 and LMXB 2007, A&A 469, 807).

                                      HMXBs: (114) Optical companion with spectral type O
                                      or B. Mass transfer via decretion disc (Be stars) or via
                                      strong wind or Roche-lobe overflow.

                                       LMXBs: (185) Optical companion with spectral type
                                      later than B. Mass transfer via Roche-lobe overflow.



                                                               9 HMXBs
             299 XB                65 (22%) REXBs
                                                              56 LMXBs
Maybe the majority of RXBs are microquasars
                                              At least 15 microquasars
                                                                   2
                              MICROQUASARS IN OUR GALAXY
 Name               System          D      Porb     Mcomp Activity           βapp     θ       Jet Size                 Remarks
                      type        (kpc)    (d)      (M )   radio                               (AU)


                                            High Mass X-ray Binaries
LS I +61 303        B0V+NS?        2.0     26.5        −        p            ≥ 0.4     −      10 − 700             Precession ? MAGIC
V4641 Sgr          B9III+ BH       ~10      2.8       9.6       t            ≥ 9.5     −             −
LS 5039            O6.5V+NS?       2.9      4.4      1−3        p            ≥ 0.15 < 81º 10 − 1000                 Precession? HESS
SS 433           evolved A?+BH?    4.8     13.1     11± 5?      p            0.26     79º ~10 − 10
                                                                                                 4       6
                                                                                                             Precession,Hadronic, X-ray je
Cygnus X-1          O9.7I+ BH      2.5      5.6      10.1       p               −      40º      ~ 40                             MAGIC
Cygnus X-3           WNe+BH?       9        0.2       −         p            0.69     73º       ~ 104                 Radio outbursts

                                            Low Mass X-ray Binaries
Circinus X-1     Subgiant+NS      ~ 6.5    16.6        −            t         > 15    < 5º           >104
XTE J1550-564         G8+BH        5.3      1.5       9.4           t         ≥2       −         ~ 103                    X-ray jet
Scorpius X-1      Subgiant+NS       2.8     0.8       1.4           p         0.68     44º       ~ 40
GRO J1655-40         F5IV+BH        3.2     2.6       7.02          t         1.1     72º−85º        8000                 Precession ?
GX 339-4               ?+ BH       ~4       1.76    5.8 ± 0.5       t          −          −      < 4000
1E 1740.7-2942         ?+BH ?       8.5?    12.5?      −            p          −          −          ~ 106
XTE J1748-288          ?+BH ?     ≥8         ?       > 4.5?             t      1.3        −          > 104
GRS 1758-258           ?+ BH ?      8.5?    18.5?      −            p          −          −          ~106
GRS 1915+105      K-MIII+BH        12.5     33.5    14 ± 4              t   1.2 − 1.7 66º−70º ~10 − 104                    Precession?
                                                                                                                                 3
 BLACK HOLE STATES
 BLACK HOLE STATES
Black holes display different X-ray spectral states:
- Low/hard state (a.k.a. power-law state). Compact radio jet.
- High/soft state (a.k.a. steep power-law state). No radio emission.
- Intermediate and very high states           transitions. Transient radio
emission.

             High/Soft



                            Low/Hard




                                                                      4
 Black body from a geometrically thin optically thick accretion disk
 (Shakura & Sunyaev 1973).




                                                                  Fender 2001, ApSSS 276, 6
Power-law from a geometrically thick optically thin plasma of electrons
      that comptonizes soft X-rays to higher energies: corona                       5
             (Sunyaev & Titarchuck 1985, Titarchuk & Lyubarskij 1995).
GRS 1915+105
         ● 1992: LMXB detected as very variable in X-rays Castro-Tirado et al. 1992
         ● 1994: first superluminal galactic source Mirabel & Rodríguez 1994, Nature 371, 4
      VARIABILITY: accretion / ejection coupling




               Mirabel et al. (1998)

  • cycles of 30 minutes in GRS 1915+105 :                    Marscher et al. (2002)
          ejections after an X-ray dip
          disappearance / refilling of the internal part of the disc ?
          transient ejections during changes of states
    same phenomenon in the quasar 3C 120 ?
                                                                                       6
         ⇒ far slower !
            Synchrotron self Compton model
     IC scattering or maybe even direct synchrotron emission from the
     jets could dominate the high-energy emission above an MeV or so
                                                Atoyan & Aharonian (1999, MNRAS 302, 253; 2001)
 GRS 1915+105
                                                         BATSE        0.05 G

                                                                      0.1 G
                                           IR
                                                                      0.2 G
                                  sub-mm
                          radio




TeV observations:
Questionable detections during flares by HEGRA CT2 and Whipple
       ● 0.25 Crab (May-June 1996), marginal                Aharonian&Heinzelmann (1998)

       ● 3.1σ, marginal, Whipple (April 1998)             Rovero et al. 2002, BAAA 45, 66

Upper limit to steady emission by Whipple
       ● 35% Crab above 400 GeV (April 2003) or < 3.5x10-11 photons/cm2/s
                                                                        7
                                                                              Horan&Weekes (2003)
  SS 433
        Precession of the jets
 Moving lines in relativistic jets (0.26c) with precession
 movement. Jets precession observed in radio.                    MERLIN, 5 GHz

   Image of SS 433 and the predicted jet
 precession cycle (twin-corkscrew pattern)
                          Stirling et al. 2002, MNRAS 337, 657

   The surrounding W50 radio nebula. Clear
 traces of the interaction of the jets of SS 433
 with the surrounding gas are shown.                              VLA, 1465 MH
                            Dubner et al. 1998, AJ 116, 1842


                     X-ray image
    Doppler-shifted iron emission lines
    from spatially resolved regions
    Particle re-acceleration in a relativistic
    jet can act also on atomic nuclei.
                       Migliari et al. 2002, Science 297, 1673
                                                                 Chandra ACIS-S
LSI+61303, V4641 Sgr, GRO J1655-40, GRS 1915+105?                        8
                      Strong radio outbursts
Cygnus X-3
  Exhibits flaring to levels of 20 Jy or more
  In 1972 was first “caught” flaring above 20 Jy. These
events are amongst the best-known examples of
observed expanding synchrotron-emitting sources (21
papers in Nature Phys. Sci. 239, No. 95 (1972))                                      VLBA
  Modelling Cyg X-3 radio outbursts: particle injection
into twin jets Martí et al. 1992, A&A 258, 309

                           VLA, 5 GHz




                                                                            β= 0.48
                                                                            θ = 73°


                                                                                         9
  Martí et al. 2001, A&A 375, 476                         Miller-Jones et al. 2004, ApJ 600, 368
                  Canadian Galactic Plane Survey (CGPS).                Spectral image of
                                                           The deepest radio index map Cygnus X-3
                                                                       CGPS at 1.4 GHz and
VLA DnC+D+B, 6c
  CAHA 3.5m, Ks                                             (rms noise 9.5 µJy beam-1)
                                                           Green Bank 4.85 GHz northern sky survey (GB6).



                                     1”



                     1.4 GHz
                                                              Cygnus X-3




                         FR II

   1’


                                                                                                       10
                                                                   Sánchez-Sutil et al. 2008, A&A 479, 523
Cygnus X-3
                TeV observations:
● Suggested to emit TeV       γ-rays
  Chadwick et al. 1985, Nature 318, 642
● Other groups have failed to detect       it
 O’Flaherty et al.1992, ApJ 396, 674
● SHALON (4.20±0.70) x10-13 photons/cm2/s above 0.8 TeV
  Sinitsyna et al. 2001, Nuc. Phys. B (Proc. Suppl.) 97, 219

                                                               , 5 GHz
   NOT YET DETECTED WITH THE NEW
GENERATION OF CHERENKOV TELESCOPES




                                                               11
                 Circinus X-1 X-ray structures
ATCA & CHANDRA
                   ● LMXB, Subgiant+NS,       ● HMXB, B+NS?
                     16.6 d, superluminal
                                           LSI+61303 Paredes et al. 2007, ApJ 664, L3




                                                                                          Chandra
                                                    SS 433




                                                                                    Chandra ACIS-S

                  Heinz et al. 2007, ApJ 663, L93
                                                                                             12
                                                       Migliari et al. 2002, Science 297, 1673
Microquasars as HE/VHE gamma-ray sources from the theoretical point of view.
                                   Leptonic models: Inverse Compton

                                   Synchrotron Self Compton (SSC)
                                   Atoyan & Aharonian 1999, MNRAS 302, 253
                                   Latham et al. 2005, AIP CP745, 323
                                   External Compton (EC)
                                   Kaufman Bernadó et al. 2002, A&A 385, L10
                                   Georganopoulos et al. 2002, A&A 388, L25

                                   SSC+EC
                                   Bosch-Ramon et al. 2004 A&A 417, 1075
                                   Dermer & Böttcher 2006

                                   Synchrotron jet emission
                                   Markoff et al. 2003, A&A 397, 645

                                   Hadronic models: Pion decay
           Wind of the companion. Romero et al. 2003, A&A 410, L1
                                                                      13
              Interstellar medium. Bosch-Ramon et al. 2005, A&A 432, 609
              The VHE gamma-ray Sky Map




LS I+61 303

         Cygnus X-1

                      LS 5039   PSR B1259-63

                                               14
  Parameters              PSR         LS I +61 303     LS 5039     Cygnus X-1
                        B1259-63
   System Type           B2Ve+NS       B0Ve+NS?       O6.5V+BH?     O9.7I+ BH
   Distance (kpc)           1.5         2.0±0.2          2.5         2 ±0.2
 Orbital Period (d)        1237           26.5           3.9           5.6

    Eccentricity           0.87           0.72           0.35          ~0

   Inclination (º)          36           30 ± 20         20?         33 ± 5

Periastron-apastron       0.7 - 10      0.1 - 0.7      0.1 - 0.2       0.2
        (AU)
   Activity Radio       Periodic (48 Periodic (26.5   Persistent    Persistent
                       ms and 3.4 yr) d and 4 yr)
Radio Structure (AU)      <2000         ~Jet-like        Jet           Jet
                                         10-700        10 -103      40 + ring
 Jet P.A. (few mas)                      0 -180        116 -128
     Remarks                             3EG             3EG
                                      J0241+6103      J1824-1514         15
       PSR B1259-63
HESS
                       The first variable galactic source of VHE
       PSR B1259-63 / SS 2883 is a binary system containing a B2Ve donor and a 47.7 ms radio
       pulsar orbiting it every 3.4 years, in a very eccentric orbit with e=0.87. No radio pulses are
       observed when the NS is behind the circumstellar disk (free-free absorption). VHE gamma-
       rays are detected when the NS is close to periastron or crosses de disk (Aharonian et al.
       2005, A&A 442, 1).




                                                                                             16
LS I +61 303
                    Historical association with a γ-ray source


                                      The radio emitting X-ray binary LS I+61 303, since its
                                      discovery, has been proposed to be associated with
                                      the γ-ray source 2CG 135+01 (= 3EG J0241+6103)
                                      Gregory&Taylor 1978, Nature 272, 704



Hartman et al. 1999, ApJS 123, 79
                                                                             EVN at 5 GHz




                  might be a black hole if i<25°
                            (Casares et al. 2005)
                                                                    Massi et al. 2001 A&A 376, 217
                                                                                          17
   INTEGRAL
                          Periodic emission
Hermsen et al. 2006     26.5 days periodicity
                      Radio (P=26.496 d)
                      Taylor&Gregory 1982, ApJ 255, 210

                      Optical and IR
                      Mendelson&Mazeh 1989, MNRAS 239, 733;
                      Paredes et al. 1994 A&A 288, 519

                      X-rays
                      Paredes et al. 1997 A&A 320, L25


                                 VHE γ-rays
                       Albert et al. 2008, ApJ (astro-ph:0806.1865)




                                EGRET observations of
                                3EG J0241+6103 shows
                                variability on short (days)
                                and long (months)
                                timescales


                                                                                               18
                                                                 Massi et al. 2005 (astro-ph/0410504)
MAGIC



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        Albert et al. 2006, Science 312, 1771


  ● Point-like source (E>200GeV) detected with ~9σ significance
  ● Excess (RA=2h40m34s, DEC=61°15’ 25”) in agreement with LS I +61303 position
  ● Source is QUIET at periastron and at relatively HIGH emission level at later orbital phases
  ● Strong orbital modulation
                                                                                                       19
MAGIC
                                                               Set 2006




                                                               Oct 2006
   Albert et al. 2008, ApJ (astro-ph:0806.1865)




                                                              Nov 2006




                                                               Dec 2006



                                                                                                          Dec 2006
                                                               Averaged




                                                  ● More complete orbital coverage
                                                  ● Similar behaviour as last year           Esposito et al. 2007, A&A 474, 575
                                                  ● Maximum flux detected at phase 0.6-0.7
                                                                                                                         20
                                                  ● Exception one point at Φ~0.85
      Periodic with a period of (26.8±0.2) days




Lomb and Scargle formalism applied to the LS I +61 303 MAGIC data
                                                              21
Energy Spectrum MAGIC                                                          average cycle I

                                                                           cycle II 0.5<Φ<0.6
Energy Spectrum

                                                                           cycle II 0.6<Φ<0.7




                          The average energy spectrum from 300 GeV to 3 TeV is well fitted by a power
                        law with spectral index α = -2.6 ± 0.2 (stat) ± 0.2 (syst)
                          The luminosity above 200 GeV is ~7 x 1033 erg s-1 (if distance ~2 kpc)
                          It is more luminous at TeV energies than at X-rays
                          Spectral stability: both cycles (over 1 year) / different measured phases / days
                                                                                                   22
                                           Albert et al. 2008, ApJ (astro-ph:0806.1865)
VERITAS
          VERITAS has recently confirmed the earlier results reported by the
          MAGIC Collaboration.
                       0.8-0.5




                        0.5-0.8




                                       Acciari et al. 2008, ApJ 679, 1427
                                                                            23
VLBA       Jet-like features have been reported several times, but show a puzzling
           behavior (Massi et al. 2001, 2004). Recent VLBI observations show a rotating
           jet-like structure (Dhawan et al. 2006, VI Microquasars Workshop, Como, Setember 2006)


                            H       G        F


                                                 E
                 A

       I



                                             D


B                               C
                     J

                         NOT TO SCALE
              Observer

    3.6cm images, ~3d apart, beam 1.5x1.1mas or 3x2.2 AU.
    Semi-major axis: 0.5 AU                                                              24
VLBA       Jet-like features have been reported several times, but show a puzzling
           behavior (Massi et al. 2001, 2004). Recent VLBI observations show a rotating
           jet-like structure (Dhawan et al. 2006, VI Microquasars Workshop, Como, Setember 2006)

                                                                                     ------
                            H       G        F                                        10 AU


                                                 E
                 A

       I



                                             D


B                               C
                     J

                         NOT TO SCALE
              Observer

    3.6cm images, ~3d apart, beam 1.5x1.1mas or 3x2.2 AU.
    Semi-major axis: 0.5 AU                                                              25
                                                     A possible scenario comes from the interaction
                                                     of the relativistic wind from a young pulsar with
                                                     the wind from its stellar companion, as in PSR
                                                     B1259-63. A cometary nebula of radio emitting
                                                     particles is formed. It rotates with the orbital
                                                     period of the binary system. We see this nebula
                                                     projected (Dubus 2006, A&A 456, 801).




   Mirabel 2006, (Perspective) Science 312, 1759


  UV photons from the companion star suffer
  inverse Compton scattering by the same
  population of non-thermal particles, leading
                                                                        Dubus 2006, Vulcano Workshop
  to emission in the GeV-TeV energy range.

Dubus 2006, A&A 456, 801; Maraschi & Treves 1981).


                                                                                             26
Romero, Okazaki et al. apply a “Smoothed Particle Hydrodynamics” (SPH) code in 3D
dynamical simulations for both the pulsar-wind interaction and accretion-jet models.



                                  When orbital effects are included, even the most favorable
                                  assumptions toward a large Be/pulsar wind momentum ratio
                  Be star         do not produce the simple elongated shape inferred in the
        Pulsar                    VLBI radio image, which was previously cited as strong
                                  evidence in favor of a pulsar wind interaction scenario.
                                                          Romero et al. 2007, A&A 474, 15


                                   Wind collision interface geometry at
                                   periastron for collision between a Be-
                                   star wind with a pulsar wind of energy
                                   ĖPSR = 1036 erg.


                                                                            MAGIC
                                                                            AGILE
MULTIWAVELENGTH CAMPAIGN                                                     XMM
      September 2007                                                         VLBA
                                                                            RATAN           27
                                           Discovery of the TeV counterpart by H.E.S.S.
   LS 5039                                 (Aharonian et al. 2005 , Science 309, 746).

                   LS 5039 could be related to the
  1999 May 8
                   HE γ-ray source 3EG J1824-1514




                                                                                                  HESS
  Φ: 0.12 - 0.15

                         VLBA, 5 GHz




                                                    Good extrapolation of the EGRET spectrum.




  Paredes et al. 2000, Science 288, 2340




P = 3.9060 ± 0.0002 d                                                    i = 20.3˚ ± 4.0
e = 0.35 ± 0.04                        And assuming pseudo-
                                          synchronisation
                                                                        Mcompact = 5.4 (+1.9-1.4) M
                                                                                               28
Periastron at phase 0.0                    at periastron:
HESS   3.9 day orbital modulation in the TeV gamma-ray flux
        Variable TeV emission with the orbital period of the binary system.
        Flux maximum at inferior conjunction of the compact object.
                                                   Aharonian et al. 2006, A&A 460, 743




This suggests that photon-photon absorption (e+-e- pair
production on stellar UV photons), which has an angle
dependent cross-section plays a major role but……
● the flux should be 0 at periastron and superior
conjunction, and is not!
● the spectrum shows strong variability, but not at 200
GeV as predicted by absorption models! (Dubus 2006,                                      29
Böttcher 2007)
VLBA                             NEW VLBI RESULTS REVEAL CHANGING
                                            MORPHOLOGY
          P.A. : 125
                                                           Ribó et al. 2008, A&A 481, 17
  1999 May 8     Φ=0.12 - 0.15




                                         P.A. = 116 ± 2º                P.A. = 128 ± 2º
           VLBA+VLA, 5 GHz

aredes et al. 2000, Science 288, 2340




                                                                              30
  Cygnus X-1                  Stellar Mass Black Hole
                        5 pc (8’) diameter ring-structure of bremsstrahlung emitting
                       ionized gas at the shock between (dark) jet and ISM.
    VLA
                                       WSRT                                VLBA+VLA




                                          Gallo et al. 2005, Nature

                                                                                 15 mas    30 AU
                                             Single-sided jet (microblazar?) resolved at milli-arcse
                                              scales with VLBA in hard state. Opening angle <2°
                                                              bulk velocity is β>0.6c     31
Martí et al. 1996, A&A 306, 449
MAGIC
                         New TeV source: Cygnus X-1




Albert et al. 2007, ApJ 665, L51
        ● Source location α = 19h58m17s, δ = 35°12’8”    ±1.5’ (stat) ± 2’ (syst)

        ● Compatible with the position of Cygnus X-1 and exclude radio ring
        ● 4.9σ   for the second halve of the night (at phase 0.9-1.0, when the black hole
                                                                                            32
           is behind the star)
                     Correlation with X-rays

                                               ●   MAGIC sees an excess
                                               right before the first Swift
                                               peak rise and zero flux in
                                               the decaying edge of
                                               second Swift peak

                                               ●    Hard x-rays could be
                                               produced at the base of the
                                               jet and γ-rays further away
                                               by interaction with stellar
                                               wind

                                               ●   BUT… opacities are
                                               expected to be huge (10 at
                                               1 TeV)




                                                                    33
Albert et al. 2007, ApJ 665, L51
                                   Spectrum




● Well fitted by power law with index -3.2±0.6 and ~10% Crab at 1 TeV
             Albert et al. 2007, ApJ 665, L51
                                                                        34
MAGIC   LSI+61303

                                               LS 5039




                Season I + Season II



         Cygnus X-1



                                         Flare TeV emission?
                                       If the wind has a clumpy structure,
                                       then jet-clump interactions can
                                       produce rapid flares of gamma-rays
                                                                        35
                                       Romero et al. 2007, astro-ph/0708.1525
                            Summary
Microquasars allow to gain insight into the physics of relativistic jets and
the connection between accretion disc instabilities and the formation of jets

Models predict that radio jets could be natural sites for the production of high
energy photons via Compton scattering, pion decay and direct synchrotron
emission.

Most µqs have been detected as soft γ-ray emitters. Up to now, above ~ 500
keV, a handful of µqs have been detected: Cyg X-1 and GRO J1655-40 at ~1
MeV; LS 5039 and LSI+61303 above 100 MeV; LS 5039, LSI+61303 and
Cygnus X-1 at TeV.

4 HMXB have been detected at TeV energies whereas any LMXB has. This
fact points the importance of having a bright companion (O or B star) as source
of seed photons for the IC emission and target nuclei for hadronic interactions.

     NS and BH are among these detected XRBs.
     Periodic TeV emission is present in two systems.
     Flare TeV emission might be common in all these sources.
                                                                            36

				
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