Sylvain CHATY (Université Paris 7 / Service d’Astrophysique, France)

Sylvain CHATYSylvain CHATY(Université Paris 7 / Service

d’Astrophysique, France)F. Rahoui, P.-O. Lagage, E. Pantin, J. Rodriguez, J. F. Rahoui, P.-O. Lagage, E. Pantin, J. Rodriguez, J.

Tomsick, R. WalterTomsick, R. Walter

1st GLAST Scientific Symposium1st GLAST Scientific Symposium - February 7, 2007 - February 7, 2007

The most obscured high energy objects of our Galaxy

Or how infrared observations allow to unveil the most obscured X-ray sources of our Galaxy…

S. Chaty - GLAST - 2/02/2007S. Chaty - GLAST - 2/02/2007

PlanPlan

Discovery of new high energy sourcesDiscovery of new high energy sources Multi-wavelength optical/NIR/MIR Multi-wavelength optical/NIR/MIR observations:observations: Obscured X-ray sources: the archetype IGR J16318-Obscured X-ray sources: the archetype IGR J16318-48484848

New INTEGRAL sources: results and discussionNew INTEGRAL sources: results and discussion The futureThe future


The The -ray sky seen by INTEGRAL-ray sky seen by INTEGRAL ESA satellite ESA satellite launched on 17 launched on 17 October 2002 October 2002 by by PROTON rocket on PROTON rocket on excentric orbitexcentric orbit Imager IBIS: coded Imager IBIS: coded mask mask telescope: telescope: 10keV-4MeV10keV-4MeV

Resolution 12’, fov Resolution 12’, fov 19°19°

Highly obscured high Highly obscured high energy objects energy objects discovered by discovered by INTEGRALINTEGRAL towards the Norma arm of the

Galaxy… full of star forming regions!

How to reveal their How to reveal their nature?nature?

Lebrun et al. 2004


Discovery of new sourcesDiscovery of new sources

How to identify all these new INTEGRAL sources?

To observe in X/To observe in X/ rays is not enough: rays is not enough: ISGRI localisation not enough to identify the ISGRI localisation not enough to identify the counterpartcounterpart

To observe in optical is difficult:To observe in optical is difficult: Sources mainly in the plane (centre) of the Galaxy: too Sources mainly in the plane (centre) of the Galaxy: too

much absorption (interstellar dust and gas)much absorption (interstellar dust and gas)


Study of 20 new INTEGRAL sources at Study of 20 new INTEGRAL sources at ESO (European ESO (European Southern Observatory)Southern Observatory) Identification of counterparts, nature of systemIdentification of counterparts, nature of system Target of Opportunity & Visitor mode (2004-2006)Target of Opportunity & Visitor mode (2004-2006)

Photometry/Spectroscopy in 3 domains:Photometry/Spectroscopy in 3 domains: OpticalOptical / Near-infrared (0.4-2.5 / Near-infrared (0.4-2.5m): La Silla (3.5m-m): La Silla (3.5m-

NTT/EMMI-SOFI)NTT/EMMI-SOFI) Mid-Infrared (5-20 Mid-Infrared (5-20 m): Paranal (8m-VLT/UT3/VISIR)m): Paranal (8m-VLT/UT3/VISIR)

Multi-wavelength observationsMulti-wavelength observations


PlanPlan




The Obscured INTEGRAL source IGR J16318-4848:The Obscured INTEGRAL source IGR J16318-4848:

From INTEGRAL high energy …From INTEGRAL high energy …

… …to to Optical/MIR observations.Optical/MIR observations.

(Chaty & Rahoui, 2006; Chaty & Filliatre, Ap&SS, 2005; Filliatre & Chaty, ApJ, 2004)


Discovery of IGR J16318-4848Discovery of IGR J16318-4848

11stst source discovered source discovered by INTEGRAL by INTEGRAL (IBIS/ISGRI) on 29 (IBIS/ISGRI) on 29 January 2003January 2003

Position: Position: (l,b)~(336°, 0.5°) (l,b)~(336°, 0.5°)

2’ localisation2’ localisation 15-40 keV Flux: 50-100 15-40 keV Flux: 50-100 mCrabmCrab

ToO observations ToO observations with XMM-Newtonwith XMM-Newton

4” localisation Comptonised spectrum:

NNhh=1.84x10=1.84x1024 24 cmcm-2-2

kT = 9±0.5 keV Photon index ~ 2Photon index ~ 2

Strong photoelectric Strong photoelectric absorptionabsorption

EPIC PN, EPIC MOS2 and ISGRI spectra(Matt & Guainazzi 2003; Walter et al. 2003)(Matt & Guainazzi 2003; Walter et al. 2003)


Photometric observationsPhotometric observations

photometric observations on 23-25/02/2003photometric observations on 23-25/02/2003 Discovery of the optical counterpart, confirmation of NIR counterpart (Walter et Discovery of the optical counterpart, confirmation of NIR counterpart (Walter et

al. 2003) al. 2003) B>25.4+/-1; I=16.05+/-0.54, Ks=7.20+/-0.05

Absorption in opt/NIR:Absorption in opt/NIR: IGR source exhibits unusual 17.4mag absorption 100x stronger than interstellar absorption but 100 x lower than X-rays!!! Material absorbing in X-rays must beMaterial absorbing in X-rays must be

concentrated near the compact objectconcentrated near the compact object


NIR spectroscopy: 0.95-2.5 NIR spectroscopy: 0.95-2.5 mm

Unusual spectrum very rich in many strong emission linesUnusual spectrum very rich in many strong emission lines Strong H (Br, Pa, Pf), HeI (P-Cyg): dense, ionised windStrong H (Br, Pa, Pf), HeI (P-Cyg): dense, ionised wind• He II: highly excited regionHe II: highly excited region• [FeII]: shock heated material[FeII]: shock heated material• FeII => densities > 10FeII => densities > 1055-10-1066 cm cm-3-3

• NaI: cool/dense regionsNaI: cool/dense regions• Lines originate from different media (various densities, Lines originate from different media (various densities,

temperature)temperature)

• Highly complex, stratified circumstellar environment + Highly complex, stratified circumstellar environment + enveloppe, wind…enveloppe, wind…

• =>=> luminous post main sequence star: sgB[e] star: luminous post main sequence star: sgB[e] star:High-mass X-ray binary systemHigh-mass X-ray binary system


Spectral Energy DistributionSpectral Energy Distribution Fit parameters: Fit parameters:

L ~ 10L ~ 106 6 dd226kpc6kpcLL

T = 23 500 KT = 23 500 KM = 30 MM = 30 M

High L, T and High L, T and M: M:

Supergiant starSupergiant star Distance = 6kpcDistance = 6kpc

Av = 17.5 magAv = 17.5 mag

• Unusual absorption:cocon of dust?

Hertzprung-Russel DiagramHertzprung-Russel Diagram


IGR J16318-4848 Optical -> mid-infrared IGR J16318-4848 Optical -> mid-infrared SEDSED

•High Mass X-ray Binary system:High Mass X-ray Binary system:

•Supergiant star: sgB[e], T=23500 K,, R=20.5R = 15x106km

•+Neutron star

•+ Cocoon of Dust/cold gas: T=900K, R=11.9R** = 1a.u.= 1a.u.

•Need for extra (dust) component. Extension of this dust Need for extra (dust) component. Extension of this dust component seems to suggest that it is enshrouding the whole component seems to suggest that it is enshrouding the whole binary system.binary system.

ESO/NTTVLT/VISIR

Spitzer

MIR excessMIR excess


VLT/VISIR

Dusty or not dusty?Dusty or not dusty?

•IGR J16318-4848:•Companion star: sgB[e]

T=23500K, R=20 RSun

•+ Cocoon of Dust: T=900K, R=12R*

IGR J17544-2619:IGR J17544-2619:(Pellizza, Chaty, Negueruela, 2006, (Pellizza, Chaty, Negueruela, 2006, A&A)A&A)

Companion star: O9IbCompanion star: O9Ib

T=30000K, R=22 RT=30000K, R=22 RSunSun

No need for extra componentNo need for extra component

ESO/NTTVLT/VISIR ESO/NTT


PlanPlan




Optical to MIR resultsOptical to MIR results


Results of 2004 NTT-SOFI/EMMI and 2005/2006 Paranal UT3-VISIR Results of 2004 NTT-SOFI/EMMI and 2005/2006 Paranal UT3-VISIR observationsobservationsSourceSource Spectral Spectral

typetypeNhiNhi NhVNhV NhXNhX Star Star

Temp Temp (K)(K)

Star Star RadiuRadius s (R*)(R*)

DustDust

TempTemp

(K)(K)

DustDust

RadiRadiusus

(R*)(R*)

IGR J16195-IGR J16195-49454945

OBOB 2.182.18 2.92.9 77 2310023100 22.622.6 950950 6.16.1

IGR J16207-IGR J16207-51295129

B0IB0I 1.731.73 22 3.73.7 3250032500 21.221.2

IGR J16318-IGR J16318-48484848

sgB[e]sgB[e] 2.062.06 3.33.3 200200 2350023500 20.520.5 900900 11.911.9

IGR J16320-IGR J16320-47514751

OBOB 2.142.14 6.66.6 2121 3260032600 22.622.6

IGR J16358-IGR J16358-47264726

sgB[e]?sgB[e]? 2.202.20 3.33.3 3333 2480024800 20.520.5 820820 1010

IGR J16393-IGR J16393-46414641

?? 2.22.2 <2.7<2.7 2424

IGR J16418-IGR J16418-45324532

OB?OB? 1.881.88 2.72.7 1010 2700027000 20.220.2

IGR J16465-IGR J16465-45074507

B0.5IB0.5I 2.122.12 1.11.1 6060 2750027500 20.120.1

IGR J16479-IGR J16479-45144514

OBOB 2.142.14 3.43.4 7.77.7 3200032000 20.320.3

IGR J17252-IGR J17252-36163616

OBOB 1.561.56 3.83.8 1515 3000030000 20.620.6

IGR J17391-IGR J17391-30213021

O8Iab(f)O8Iab(f) 1.371.37 1.71.7 3030 3210032100 22.922.9

IGR J17544-IGR J17544-26192619

O9IbO9Ib 1.441.44 1.11.1 1.41.4 3070030700 2222

IGR J17597-IGR J17597-22012201

Late?Late? 1.21.2 <2.9<2.9 55

IGR J18027-IGR J18027-20162016

sgOBsgOB 1.11.1 <2.1<2.1 99

IGR IGR J19140+0951J19140+0951

sgB0.5IsgB0.5I 1.681.68 2.92.9 66 2000020000 21.221.2


Nature of systems: Nature of systems: Corbet DiagramCorbet Diagram 80% of Norma sources are X-ray pulsars High spin periods Star Porb=10d, M=20Msol, a=50Rsol < Rdust

(Rdust=240RSunfor IGR J16318)

Underfilled Roche lobe Supergiants

•HMXBs Pspin vs Porb:•Be Binaries•supergiant Roche lobe overflow systems•super-giant wind accretors


So, what are these sources?Different geometries, different scenarii

Presence of a cocoon of dense and absorbing dust concentrated:Presence of a cocoon of dense and absorbing dust concentrated:

1) Around the whole system: obscured sources (1) Around the whole system: obscured sources (~IGR J16318) :~IGR J16318) : neutron star orbits permanently within a dense cocoon: persistent X-ray emissionneutron star orbits permanently within a dense cocoon: persistent X-ray emission density 10density 1011–1211–12 cm cm–3–3

Disc thickness 10Disc thickness 1012–1312–13 cm (10-100 R cm (10-100 RSunSun)) Disc radius 10Disc radius 1013–1413–14 cm (1-10 a.u.) cm (1-10 a.u.)

2) Only around the 2) Only around the compact object: SFXTs (~IGR J17544):: Eccentric orbit, neutron star crosses periodically inside the atmosphere/envelope of companion star, Eccentric orbit, neutron star crosses periodically inside the atmosphere/envelope of companion star,

causing transient X-ray outbursts?causing transient X-ray outbursts?

The answer will be given by orbital periods of these sources…The answer will be given by orbital periods of these sources…


Conclusions

INTEGRAL doubled the population of massive binaries with supergiant in our Galaxy, and revealed a class of highly absorbed binaries.

• These INTEGRAL sources exhibit common characteristics:• High Mass X-ray Binaries with O/B supergiant secondaries

• Compact object: mostly neutron star, high Pspin• Close to the galactic plane |b|<1°• No radio emission

• But they are not the same!• Intrinsic absorption around the neutron star (X-ray absorption)

• Cocoon of dust/cold gas enshrouding whole system (MIR excess)

• Properties, circumstellar environment due to star• X-ray transient/persistent


The future…The future…

This new population constrains our This new population constrains our view on formation and evolution of view on formation and evolution of HMXBsHMXBs:• dominant population born with two very massive components, dominant population born with two very massive components,

in rich star-forming region?in rich star-forming region?• Short living systems…Short living systems…• What will happen when the supergiant star dies?What will happen when the supergiant star dies?

• Primary progenitors of NS/NS or NS/BH mergers,Primary progenitors of NS/NS or NS/BH mergers,• Good candidates of gravitational waves emitters?Good candidates of gravitational waves emitters?• Link with short/hard gamma-ray bursts?Link with short/hard gamma-ray bursts?

GLAST will discover such new and unexpected GLAST will discover such new and unexpected objects…objects…

Sylvain CHATY (Université Paris 7 / Service d’Astrophysique, France)

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Transcript of Sylvain CHATY (Université Paris 7 / Service d’Astrophysique, France)