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EWASS 2012 – Symposium 4

EWASS 2012 – Symposium 4 The Galactic Plane reloaded : a brand new Multiwavelength Milky Way from TeV to MHz The INTEGRAL Galactic Plane Program M. Fiocchi on behalf of the INTEGRAL GPS Team Galactic hard X-ray Sky The new IGR sources in the GP HMXB systems in the INTEGRAL era

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EWASS 2012 – Symposium 4

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  1. EWASS 2012 – Symposium 4 • The GalacticPlanereloaded: a brand new MultiwavelengthMilky Way from TeV to MHz • The INTEGRAL GalacticPlaneProgram • M. Fiocchi on behalf of the INTEGRAL GPS Team • Galactic hard X-ray Sky • The new IGR sources in the GP • HMXB systems in the INTEGRAL era • The keV to TeV connection • Long monitoring of the LMXB and CV

  2. Past hard X-raysurveys HEAO 1/ A-41977-1979 Phoswich scintillator detectors covering 15-2000 keVband, wide filed of view (0.013 Crab sensitivity in the 13-80 keV) Scientific highlights: • First survey of the sky with 70 sources below 80 keV and 14 above 80 keV. • First hard X-ray spectra of galactic and extragalctic objects • Time variability GRANAT/SIGMA1989-1998 First Coded-mask X-raytelescopecovering 30-1300 keV band with a 5°x5° FOV Scientifichighlights: • A verydeep (>8 Ms) imaging of the galactic center region. • Discovery of broad electron-positronannihilationlines from the Galactic "micro-quasar" 1E1740-294 and the X-ray Nova Muscae. • Study of spectra and time variability of blackholecandidates. • Catalogconsist of a total of 37 sources of which 8 were X-ray NOVAE Telescopes such as CGRO did not have sufficient imaging capability, others like BeppoSAX, RXTE, Suzakuwere/are devoted to pointed observations

  3. INTEGRAL IBIS SPI IBIS and SPI are the main instruments • SPI optimised for spectra: 20keV-MeV • IBIS optimised for imaging: 17keV-10MeV, angular resolution 12’ IBIS is the primary survey instrument • Wide FOV (30x30 degrees) • Energy range 17-1000 keV • Sensitivity ~0.1mCrab for deep exposures (>10Ms) • JEM-X and OMC are the Monitors IBIS: healthy detector is 96% and changes in sensitivity is 2% compared to launch X

  4. The hard X-ray sky 18-60 keV • Galacticsources account for 36 % • Extragalacticsources 35% • Unidentifiedsources 29% • At the IBIS sensitivity and energyrange, the galacticemergingpopulationconsist of HMXB systems Krivonos et al. 2012 > 700 sources in the IBIS Sky (Bird et al. 2010) today more than 1000…

  5. The INTEGRAL GalacticPlane Program One of the major results of INTEGRAL was the discovery of new sources, and new source type, mostlyhighlytransientstarting from the first observations in 2003 Thesediscoverieswereobtained from mainlyScientific Core Programme, including the regular scans of the GalacticPlane and Bulgealong the first 5 years of INTEGRAL operation. From AO-5 (2007) scans of the GalacticPlanehavebeendiscontinued with a significantdrop in the discovery rate of new systems in ourGalaxy. With AO8 (2011) up to AO10 (nextyear) a multiyearsproposalhasbeenapproved and thisprogramiscollecting data for a totalexposure time of 7 Msecto be added to the existingone for a total of ~135Msec

  6. The IGRs/unknown in the Galactic Plane, example Atel 3816: Dec. 21, 2011 The transient ROSAT source 1RXS J194211.9+255552 isdetected by JEM-X with the averagedfluxes of 10±2 mCrab(3-10 keV) and 16±5 mCrab(10-25 keV). The source isnotdetected by the IBIS/ISGRI Atel 4209: 25 June, 2012 Observstion with the 1.5m "Cassini" telescope of the AstronomicalObservatory of Bologna in Loiano: the opticalspectrumistypical of an absorbedGalacticHMXB Atel 3818: Dec. 21, 2011 A soft X-ray counterpart: NH~x1.3x1022 cm-2 Γ~0.7 F1-10keV~8x10-11erg cm-2 s-1 a possiblecounterpart in the 2MASS a single star i the USNO-B1.0 catalog Optical band Hard X-ray band Soft X-ray band

  7. The IGRs/unknown in the Galactic Plane New identifications Cat4 identifications • 40 NEW IGR on GP • (Krivonos et al. 2012) Soft X-ray follow-up campaignis in progress …..

  8. HMXBs before the INTEGRAL era • ~60 HMXBs known in our Galaxy before the launch of INTEGRAL in 2002 (Liu et al. 2000) • HMXBs classified into two groups:(depending on the evolutionary state of the donor star): • 85% Be HMXBs • 15% Supergiant HMXBs (SGXBs) • HMXBs in the INTEGRAL era • INTEGRAL doubledthe number of known • HMXB with two new classes: • highlyobscured HMXB • supergiantfast X-raytransients

  9. HMXBs in the INTEGRAL era, characteristic • highlyobscured HMXB • very high columndepths of NH > ~1024 cm-2, suchthatthesesourcescouldnot be identifiedearlier with soft X-rayinstruments • Morethanhalfhavesupergiantcompanions, where a significantfraction of the absorptionis due to the supergiant's stellar wind • Most of them show X-raypulsations, indicatingthat the compact objectis a neutronstar • supergiantfast X-raytransients • Short (a few hours) and intense (L≈1036-37erg s-1) flares, accretionpowered with X-ray pulsar likespectrum, vithvery high dynamicrange : 3-5 orders of magnitude with respect to the quiescentemission (10 32 erg/s) i.e. greater than that of classical persistent variable supergiant HMXBs (< 20) • In 4 SFXTs the X-ray pulsations are detected, indicating that the compact object is a neutron star • the X-ray variability is driven by properties of the NS compact object (gated mechanisms) or by the clumpy wind with different geometry

  10. HMXBs in the new GPS The case of the Be HMXB IGR J19294+1816 The XRT fluxes of 3x10-11erg cm-2s-1(1-10 keV) indicatinga decliningphase with respect to the INTEGRAL observation. The INTEGRAL detection (2012 may26) isconsistent with the 116 dayorbitalperiod: 18±2 mCrab(18-40 keV) 13±3 mCrab (3-10 keV) • Rodriguez et al 2009, Bozzoet al. 2010: • 12.43781 s spin period of a pulsar binary • Possible 117 day orbital period • Hard spectra • Rodriguez et al 2009: • INTEGRAL data shows short and intense flares A timing analysisclearly shows X-raypulsations with a period of P=12.457 +/- 0.006 s compatible with a Be-HMXB Swift/XRT ToO Typical of a SFXT ~20 days Are Be reminiscent of SFXT? GPS is the only opportunity to understand the evolutionarypath of the HMXB

  11. HMXBs in the new GPS The case of the Be HMXB GS 0834-43 First detection in outburst by Granat in 1990 (LapShov et al. 1992) with a peakflux of ~ 500 mCrab Detections by CGRO/BATSE atregular intervalsuntil1993 (Wilson et al. 1997) Later on no outburstsdetected with BATSE, Swift/BAT or INTEGRAL/IBIS During the GPS (2012-06-26): detectionat a fluxlevel of 109±2 mCrab in 18-40 keV and 64±4 mCrab in 3-10 keV, with a spectralindex of 3.0±0.2 (Atel 4218) This new, strong detectionsignature of a renewedperiod of activityaftera long period of quiescence. Italsoallowed for detection with FERMI/GRBM (Atel4235)

  12. The long monitoring of the SFXT IGRJ 16328-4726 Duration ~ 3.5hr For most of the time (10Ms) in quiescence Fx<10-12 erg s-1cm-2 occasionally fast -ray flares Fx~ 3.3x10-10 erg s-1cm-2 Fiocchi et al 2010

  13. The long monitoring of the SFXT IGRJ 16328-4726 IBIS observations show very short (few tens of minutes or hours) and intense flare (~2x10-10erg s-1cm-2 20-60 keV), with a dynamic range > 200 in the hard X-ray. The long term IBIS light curve allow us to discover the 10.07 day orbital period The Swift triggered ToO has shows a high dinamic range (> 200) in the soft X-ray band and refined the error position within an OB star in this error box The spectral properties during the outbursts show a constant spectral index and a strong variable Nh, correlated with the 2-10 keV flux The standard clumpywindtheoryestimated mass and the radiusof the clumpresponsible of the flare (Mcl≃ 4x1022g and Rcl ≃ 4.4x106km) in agreement with theoreticalvalues Foldedlitgh curve 20-60 keV NH vs Flux2-10 keV Γ vs Flux2-10 keV

  14. SFXTsas candidate MeVSources!!!! • Outbursts of IGR J17354-3255: • Duration 0.5-10 hours, occasionally a fewdays • 18-60 keVflux of 20-40 mCrab, rarelybrigtherthan 100mCrab • Detectionsignificance of 5-10σ • Similar X-rayspectralshape, powerlawΓ=2.4 • Outbursts of AGL J1734-3310: • Fast MeVflarelasting 1-2 day (Bulgarelli et al. in prep.) • >100MeV flux of 3.5x10-6ph cm-2 s-1 • Super AGILE 3σupper limit of 60mCrab (20-60 keV) • Detectionsignificance of 3-5σ The intermediate SFXT IGRJJ17354-3255 is the best candidate counterpart of the transientMeVAGL J1734-3310, based on spatialcorrelation and similartransientbehaviour on short timescale

  15. The GPS from keV to TeV • The GP surveyatTeVenergies (HESS, Milagro) detected ~60 sourcesmost of themidentifiedas PWN or SNR and ~25 unidentifiedsources • The GP surveyatMeV/GeVenergies (Gamma-ray satellite AGILE-Fermi) reported more than 300 sources, mainly PRS and SNR and ~onethirdunidentified • Thanks to • Very large field of view • Goodsensitivity • Arcmin location accuracy (nedeed to soft X-ray and optical and IR follow-up) • INTEGRAL GPS is so far the onlypossibility to • Identified the unknowMeV/GeV/TeVsources • Understanding the physicalprocessworking from keV to TeVenergies From radio to TeVwith AGILE data (Pellizzoni et al. 2010) From radio to TeVwithout X and Gamma data (de Jager et al. 2008) CMBR (a), FIR (b), starlight (c); thick line: total IC spectrum The lack of information in the X and gamma-ray band precludes drawing a comprehensive multiwavelength picture of the phenomenology and emission mechanism HESS data fit an IC process scattering on CMBR related to electron power-law index 2.0 with a break at 67 TeV. AGILE data are compatible with IC emission from the additional electron component, scattering on FIR and starlight photon fields

  16. The GPS from keV to TeV: the case of PWN VELA From radio to TeVwith CHANDRA, INTEGRAL and AGILE data (Fiocchi et al. COSPAR 2010) • Assuming a magnetic field of few µgauss, two electron populations are needed to fit data from radio to TeV: • the radio synchrotron is responsible for: • the IC bump in the GeV band arising from scattering on galactic and starlight photon fields • the SSC bump in the hard-X/soft Gamma ray • the very energetic X-ray synchrotron is responsible for the IC bump in the GeV band arising from scattering on the CMB photons.

  17. Long monitoring of the CVs • About 60 CVsdetectedabove 17 keV: • ~90% are intermediate polar • ~5% are polar Twoemission component: • The soft emission (Tbb∼60–120 eV) isoriginated from reprocessing of the hard-X photons in the irradiatedpoles of the whitedwarfatmosphere • The hard emission (Tbremss∼16–35 keV) isoriginated from opticallythin plasma in the post-shock regionabove the magneticpoles • Hard X-rayIPs are observed with Pspin/Porb<0.1 • No mCVisfoundbetween 0.3<Pspin/Porb<1 • Significantcorrelationispresent with hard X-rayspectralhardnessand Pspin/Porb • No consistentexplanationexistsyetdescribingall the observedpropertiesconsistently

  18. Long monitoring of the LMXBs • Spectral and timing characteristics of each sub-classes of the LMXB is in progress to investigate • the accretionphysicsprocess • Non thermalemission > 100keV • the correlationbetweenspectral state and periodicsignal • Populationstudy and theirevolutopnarypath 4U1636-53 (20-60 keV)

  19. Conclusions • New sources, new source type and long monitoring of the know sources are an unique legacy of the INTEGRAL • The on going regular and frequent scans of the Galactic Plane represent the only possibility to • systematically identify a large number of unidentified MeV/GeV/TeVsources • define the timing and spectral characteristics, spatial distributions, luminosity functions and the evolutionary paths of the separate object classes • Trigger ToO of on particular and interesting event (Be outburst, SFXT, BH/NS outburst, changes of the states ……………..) • This study represents one of the most important challenge in the field of accreting galactic compact objects

  20. For more information you can see http://gpsiasf.iasf-roma.inaf.it Thanks for your attention

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