E2 : Impact des trous noirs sur leur environnement

Suite aux recommandations du Conseil Scientifique 2013, le projet a été arrêté.

  • Des micro-quasars des ages sombres au trous noirs supermassifs de l’univers local

    PROGRAMME SCIENTIFIQUE

    1. Le contexte scientifique

    Les trous noirs sont parmi les objets théoriques les plus fondamentaux de notre Univers. Or, seul l’astrophysique permet actuellement de les examiner expérimentalement, par le biais des effets observables qu’ils induisent sur la matière et la lumière passant au voisinage de leurs horizons. Notre objectif est d’explorer les propriétés, l’évolution et les effets des trous noirs cosmiques à travers l’étude approfondie de leurs environnements, non seulement à différentes échelles, mais également à différentes époques de l’histoire de l’Univers. Afin de mener à bien ce projet ambitieux, nous nous focaliserons sur les quatre champs de recherche suivants :

    467382main_dn12679-1_600_0.jpg

    Vision d’artiste d’un trou noir accrétant et éjectant de la matière (NASA/Dana Berry/SkyWorks Digital)

    a. Trous noirs stellaires durant l’ère de ré-ionisation

    Les soi-disant « âges sombres » de l’univers ont commencé environ 400000 ans après le Big Bang. La matière s’étant alors refroidie, l’espace était remplit d’hydrogène neutre, ce qui perdura des centaines de millions d’années. Comment l’essentiel de cette matière fut, par la suite, à nouveau ionisée (ré-ionisée) et réchauffée sur de grands volumes, en moins d’un milliard d’années, est une des questions brulantes de la cosmologie moderne. Nous avons aujourd’hui des preuves observationnelles de formations stellaires soutenues jusqu’à z ~ 8-10. Et la détection récente d’explosions d’étoiles massives à z ~ 8.2 est un signe de l’effondrement d’étoiles massives en trous noirs stellaires à ces époques reculées, ce qui a dû produire toute une population de binaires X de forte masse (abritant un trou noir). C’est pourquoi, nous pensons que l’émission thermique (en UV et rayons X mous) et non-thermique (rayons X durs, vents et jets) de ces objets a pu chauffer le milieu intergalactique sur de vaste étendue pendant l’ère de ré-ionisation de l’univers. Une rétroaction de ces trous noirs accrétants sur leur environnement pourrait avoir une importance capitale dans les modèles de masse minimale nécessaire à la formation des galaxies naines, ainsi que dans les présents ou futurs relevés en ondes radio de l’univers jeune, dans la raie de l’hydrogène atomique (HI). Nous nous proposons d’examiner cette rétroaction théoriquement, notamment via des simulations numériques approfondies.
    nature09527-f1_2_0.jpg
    Age de la reionization (from Robertson, B. E., et al., 2010, Nature, 468, 49)
    b. La rétroaction des trous noirs supermassifs sur les bulbes des galaxies à noyau actif
    Il existe une corrélation bien établie entre la masse des trous noirs supermassifs centraux des galaxies et la dispersion des vitesses des étoiles de leurs bulbes. Cela démontre une certaine rétroaction entre la croissance du trou noir et l’évolution de la galaxie hôte. La nature de cette rétroaction est néanmoins inconnue et constitue l’un des grands mystères de l’astronomie moderne. Nous avons l’intention d’étudier la nature de cette rétroaction (très certainement liée à des éjections de particules relativistes ou des écoulements divergents de plasma) au travers d’un échantillon de noyaux actifs de galaxies, qui s’appuiera sur les données de télescopes de haute énergie actuellement en orbite, comme XMM-Newton, INTEGRAL, Fermi, Hess et d’autres qui seront lancés prochainement, tel Astro-H.
    188385main_CygA-YellowOrange_med.jpg
    Image radio du noyau actif de galaxie Cygnus A (NRAO)

    c. Influence de l’activité passée intense du trou noir supermassif au centre de notre galaxie sur son environnement

    Le trou noir supermassif au centre de notre propre galaxie, associé à la source Sgr A*, est extrêmement silencieux actuellement, et caractérise ainsi la phase de repos des trous noirs dans les noyaux galactiques de l’univers local. Cependant, nos récentes observations en rayons X et gamma (avec XMM et INTEGRAL) des nuages moléculaires de la zone centrale ont montré que Sgr A* a été le siège d’une puissante éruption, il y a quelques centaines d’années, au cours de laquelle sa luminosité X a été multipliée par un facteur de plus d’un million. Cette phase d’activité a duré environ 400 ans et a laissé son empreinte dans les nuages moléculaires de la région, qui reflètent ce rayonnement vers nous avec un retard dépendant de leur distribution spatiale autour du centre. Aussi, les variations des émissions en provenance des nuages nous permettent d’explorer, à la fois, le comportement passé du trou noir et la distribution de matière très complexe dans la région centrale. Une phase si active du trou noir central doit également avoir induit des modifications dans le milieu interstellaire très complexe qui l’entoure. Des signatures d’un effet sur la chimie des nuages ont d’ailleurs déjà été décelées au moyen d’observations en radio de raies moléculaires du SiO et du HCO. Nous proposons d’ouvrir un nouveau champ d’investigation dans nos laboratoires, mené en parallèle de notre vaste programme d’observation du Centre Galactique en rayons X et gamma, afin d’étudier les changements d’ionisation, de chauffage et de la chimie du milieu interstellaire (MIS) environnant induits par l’activité passée du trou noir supermassif. Les résultats de cette étude permettront également une meilleure compréhension des conditions physiques qui règnent dans la région centrale, et ainsi mieux modéliser la propagation et l’interaction des rayons cosmiques dans cette zone.
    6a00d8341bf7f753ef010535e9c49b970c-800wi.jpg
    Image composite (radio/infrarouge) de la zone moléculaire centrale au cœur de notre Galaxie

    d. Influence des jets et écoulements provenant des trous noirs de masse stellaire sur leur environnement et interaction entre objets compacts et étoiles compagnons au sein des systèmes binaires

    Cette partie du programme se penchera sur l’impact des trous noirs de masse stellaire des binaires X, à la fois sur le milieu environnant, et sur l’étoile compagnon du système.
    Non seulement les jets relativistes ont une influence sur l’environnement des micro-quasars, mais l’objet compact lui-même a également une influence sur son étoile compagnon, qui lui est gravitationnellement liée au sein du système binaire. Ce programme comprendra :

    1. l’étude de la nature et des caractéristiques de l’objet compact du système binaire, qui sont modifiées par accrétion et éjection de matière ;

    2. l’étude des propriétés de l’étoile compagnon, qui sont modifiées par l’objet compact : perte de masse et de moment angulaire, composition, rotation, structure du vent stellaire, etc ;

    3. L’étude de l’impact des micro-quasars sur le MIS via le rayonnement intense, les jets relativistes et autres écoulements (comme par exemple les bulles de MIS choquées par les éjections relativistes).

    cyg.png
    Les abords du trou noir stellaire de la source binaire de forte masse Cygnus X-1 (d’après Gallo et al. 2005 et Russel et al. 2007)

    2. Programme

    Nous proposons de réaliser ce travail en collaboration avec des experts reconnus mondialement, qui seront invités pour des séjours de longue durée (généralement un an) et de jeunes chercheurs de niveau post-doc, qui seront également sélectionnés en fonction de l’expertise complémentaire qu’ils pourront apporter à l’équipe actuelle (simulations, chimie du MIS, analyse de données radio). Ces experts scientifiques fourniront une partie de l’expertise initiale qui fait défaut dans nos laboratoires, pour développer l’étude de l’ère de ré-ionisation, l’impact des trous noirs extragalactiques et l’environnement du Centre Galactique. La première année sera consacrée à une description théorique détaillée des problèmes. Des investigations plus profondes seront ensuite menées grâce à des simulations étendues des processus physiques. Un dialogue continu entre la théorie, les simulations et les données disponibles conduira à une vision plus claire de l’impact des trous noirs sur leur environnement. Des quantités observables bien précises seront prédites afin de tester nos résultats avec les générations de télescopes présentes et à venir. Et ceci nous permettra de nous préparer efficacement à ces générations futures de télescopes radio, infrarouge et X dont nos laboratoires auront la responsabilité.

    Ce projet ouvrira un tout nouveau champ d’études interdisciplinaires en astrophysique des hautes énergies, mais s’appuiera sur la forte expertise des équipes d’APC et d’AIM dans le domaine des micro-quasars, des jets, des noyaux actifs de galaxies, du Centre Galactique et sur leurs programmes de recherche déjà existants. Par ailleurs, ce projet permettra d’optimiser le retour scientifique des missions X et gamma (présentes et futures) dans lesquelles nos deux laboratoires sont impliqués.

    Deux années d’étude exploratoire prises en charge par la visite de scientifiques de haut niveau permettront de concentrer le projet sur deux des éléments mentionnés ci-dessus. Par la suite, le relais sera pris par les post-doctorants lors de trois ans de travail intensif sur les simulations et les analyses de données.

  • Position, Sujet Nom Laboratory Grade, employer Initials Photo
    Responsable, [C] Goldwurm Andrea APC Directeur Recherche, CEA AG
    Coresponsable, [A] Mirabel Felix AIM Directeur Recherche, CEA FM
    Membre, [B] Beckmann Volker APC Post-Doc CNRS VB
    Membre, [D] Chaty Sylvain AIM Professeur, Univ. Paris Diderot SC
    Membre, [C] Clavel Maica AP PhD Studen MC
    Membre, [D] Coleiro Alexis AIM PhD Student AC
    Membre, [B] De Jong Sandra APC PhD Student SDJ
    Membre, [A] Laurent Philippe APC Directeur Recherche, CEA PL
    Membre, [B,C] Soldi Simona AIM, APC Post-Doc CNES, CNRS SS
    Membre, [C] Terrier Regis APC Chargé de recherche, CNRS/IN2P3 RT
    Membre, web-page man. [C] Trap Guillaume APC Palais de la Decouverte, Collaborateur Scientif. APC et CEA

  • Summary of Reasearch Activities and Observations 2011-2013

    (in bold the activities directly financed through the E2 project)

     

    A] Stellar-Mass Black Holes in the re-ionization era (FM, PL)

    International Collaborations:

    • Dr. Mark Dijkstra, MPA-Garching, Germany
    • Prof. Lev Titarchuk, Univ. of Ferrara, Italy
    • Dr. Leonardo Pellizza, IAFE, Buenos Aires, Argentina

    Visiting Scientist Programs:

    • Mark Dijkstra, MPA-Garching, Germany, visiting scientist at AIM & APC in April 2013
    • Lev Titarchuk, Univ. of Ferrara, Italy, visiting scientist at APC & AIM in April 2013
    • Vanesa Douna, IAFE Buenos Aires, Argentina, visiting PhD student at AIM & APC, 2 -16 Sep 2013
    • [F. Mirabel, visit of IAFE Buenos Aires, Argentina, 1 month, April-May 2014]

    B] SuperMassive Black Holes in AGN (VB, SS, SDJ)

    Formation activities: Master trainings, PhDs, Thesis and Post-doctoral positions

    • March-June 2011: Master 2 research traineeship on AGN emission processes of NGC 4945 in the X-rays and gamma-rays by M.-L. Menzel (supervisor VB)
    • May-July 2012: Master 1 research traineeships on X-ray emission from the radio galaxies M87 and Cen A by Dounia Saez and Pierre Li Cavoli (supervisor VB)
    • since Oct 2010: PhD thesis of S. de Jong on « Accretion Processes in Active Galactic Nuclei at high energies » (supervisor: VB)

    Accepted Observation Proposals and Programs:

    • INTEGRAL and SWIFT simultaneous observations of NGC 7172 performed in 2011 (PI: SS)
    • INTEGRAL and SWIFT simultaneous observations of NGC 5506 performed in 2012 (PI: SS)
    • SWIFT and INTEGRAL follow-up of non-blazar Fermi AGN performed in 2012 (PI: SDJ)
    • INTEGRAL observations of M87 performed in 2011 and 2012 (PI: VB)
    • INTEGRAL and XMM-Newton simultaneous observations of NGC 2992 approved in 2011 (PI: VB) and then performed in 2013
    • INTEGRAL proposal to observe NGC 2110 submitted (PI VB) and approved in 2013

    Workshops, Conferences, Collaboration Programs:

    • « The X-ray Universe 2011 » conference in Berlin (June 2011): contributed talks (VB, SS) and poster (SDJ)
    • « The Physics of Astronomical Transients » conference in Aspen (USA, January 2012): contributed talks (SS, VB)
    • Fermi summer school in Lewes (USA, May 2012): contributed talk (SDJ)
    • COSPAR 2012, Mysore (India, July 2012), VB as main scientific organizer of escientific event (invited talk and 2 posters by VB)
    • 9th INTEGRAL Workshop (Paris, October 2012): contributed talk by SS and VB, posters by SS, VB, SDJ
    • Organisation of a session on « Outflows and Accretion from White Dwarfs to Supermassive Black Holes » (VB deputy scientific organiser) at the next COSPAR Assembly, 2014 in Moscow
    • Spring school on Cosmic Accelerators, Cargèse, France, 29 April-8 May 2013, with contributed talk (SdJ) and lecture (VB)
    • Conference The restless nature of AGNs: variability as a probe of the central engine, Naples, Italy, 20-23 May 2013, contributed talk by SS
    • Participation to the INTEGRAL Workshop, Rome, 15-18/10/2013, invited talk by VB

    International Collaborations:

    • C. Shrader, NASA/GSFC, Greenbelt, US
    • P. Lubinski, Torun, Poland
    • N. Gehrels, NASA/GSFC, Greenbelt, US
    • C. Ricci, ISDC, Geneva, Switzerland and then Kyoto Univ., Japan
    • A. Tramacere, ISDC, Geneve, CH
    • J. Tueller, NASA/GSFC, Greenbelt, US
    • J. Kennea, Penn State University, Philadelphia, US

    Visiting Scientist Programs:

    • Chris Shrader, visiting scientist at APC in October 2011

    C] The Galactic Center SuperMassive Black Hole (AG, RT, MC, SS, GT)

    Formation activities: Master training, PhD Thesis and Post-doctoral positions

    • 2011: Master 1 reasearch traineeship on Limits on the past activity of the GC SMBH on the basis of the INTEGRAL data by A. Pottier (supervisor RT)
    • March-June 2011: Master 2 research traineeship (Doctoral School: A&A) on Search for past activities of close SMBH in external galaxies by M. Clavel (supervisor RT)
    • Sep 2011: Thesis defense (Doctoral School: NPAC) of G. Trap on Galactic Center High Energy emission (supervisor AG)
    • since Oct 2011: PhD thesis on the Galactic Center Black Hole of M. Clavel (supervisors: AG and RT)
    • since Dec 2012: CNES fellowship (2 yrs) for S. Soldi to work at APC on the data of the 2012 XMM Large Project survey of the Galactic Center.

    Observation Proposals and Programs:

    • Chandra Obs. of Molecular Clouds around Sgr A complex performed in July 2011 (PI: RT)
    • XMM / VLT Observations of Sgr A* in March 2012 (PI: AG), participation to a new large multi-wavelength campaign on Sgr A* (visiting observer at Paranal: MC)
    • A Large Project (700 ks) proposal for obs. with XMM of the GC region for the XMM AO11 call submitted in Oct 2011 (PI: RT) and approved
    • LP XMM Observations of the GC region (PI: RT) performed in October 2012
    • Two Proposals (1 survey, 1 ToO) for XMM Obs. in 2013 of the cloud G2 approaching Sgr A* submitted for AO12 in Oct. 2012 and approved (PI: Ponti)
    • Proposal for a 100 ks observation of Sgr C with Chandra (PI: SS) submitted in March 2013 and approved for Chandra cycle 15
    • Proposal for sub-mm Carma observations of Sgr A molecular complex, submitted May 2013 (PI: MC) approved October 2013
    • Proposal for XMM observations of Sgr B2 complex submitted in October 2013 (PI: RT)

    Workshops, Conferences, Collaboration Programs:

    • Proposal for an ISSI international team submitted in 2011 (PI: AG) and approved
    • GC ISM Heidelberg Meeting (October 2011): 2 invited talks (AG, RT), 1 poster (MC)
    • Ginzburg Conference on theoretical physics (Moscow, May 2012), invited talk on Activity of the GC SMBH by AG
    • First ISSI IT meeting on the Galactic Center held in May 2012, see the IT ISSI Web pages at http://www.issibern.ch/teams/galacticbh/
    • 2012 SF2A meeting, Nice, June 2012, contr. talk by MC (financed: Ecole Doctorale, PNHE)
    • COSPAR 2012, Mysore, India, July 2012, scientific event, invited talk by AG
    • 9th INTEGRAL Workshop, Paris, October 2012, solicited talk by RT, contributed talk by MC
    • Organization of a session on the Galactic Center Supermassive Black Hole at the next COSPAR Assembly, 2014 in Moscow (AG main scientific organiser)
    • Proposal to the Ulysses call for reasearch visits program with Ireland, for a collaboration with M. Chernyakova’s group in Dublin to develop together a simulation code of reflection processes in the GC region, submitted in Sep 2012 (PI: AG, M. Chernyakova), approved
    • Lorentz Center Workshop: A New View of Accretion onto our Galactic Center Supermassive Black Hole, Leiden, The Neetherlands, January 2013, talk by AG
    • Second ISSI IT meeting on the Galactic Center held in May 2013, see the IT ISSI Web pages
    • Spring school on Cosmic Accelerators, Cargèse, France, 29 April-8 May 2013, (MC)
    • IAU symposium 303 The Galactic Center: Feeding and Feedback in a Normal Galactic Nucleus, Santa Fe, US, October 2013, with 1 contributed talk by MC, 3 posters by SS and GT
    • Participation to the INTEGRAL Workshop 2013, Rome, 15-18/10/2013, invited talk by AG

    International Collaborations:

    • Prof. Fulvio Melia, Arizona Un.,Tucson, US
    • Dr. Gabriel Ponti, Southampton Un., UK and then MPE, Garching, Germany
    • Prof. Mark Morris, UCLA, Los Angeles, US
    • Dr. Maria Chernyakova, Dublin, Ireland
    • Dr. Maurizio Falanga, ISSI, Bern, CH
    • Prof. Vladimir Dogiel, Lebedev Institute, Moscow, Russia
    • Participation to the Chandra XVP on Sgr A* Large International collaboration (MC, AG)

    Visiting Scientist Programs:

    • Fulvio Melia, visiting scientist at APC from 11/06 to 29/06/ 2012
    • Maïca Clavel, visiting PhD student at MPE Garching from 10/04 to 20/04 2013
    • Maïca Clavel, visiting PhD student at MPE Garching from 15/06 to 30/06 2013 (COST BH in the Universe)
    • Mark Morris, visiting scientist at APC from 2/9 to 18/9/ 2013
    • Michael Walls, visiting PhD student at APC, 2-7June 2013 (Ulysses Program)
    • Masha Chernyackova and M. Walls, visiting scientist and PhD student at APC, September 2013 (Ulysses Program)
    • Visit of Dublin University (DCU), Ireland by R. Terrier, M. Clavel and A. Goldwurm 18 – 22 Nov 2013 (Ulysses Program)
    • Maïca Clavel, visiting PhD student at MPE Garching from 2/12 to 4/12 2013
    • Fulvio Melia, visiting scientist at APC, 8 – 20 Dec 2013

    D] Galactic Stellar-Mass Black Hole Binaries (SC, AC)

    Formation activities: Master training, PhD Thesis and Post-doctoral positions:

    • Oct 2010 – Oct 2013: PhD thesis on Nature, formation and evolution of High Mass X-ray Binaries by Alexis Coleiro (supervisor: SC)

    Workshops, Conferences, Collaboration Programs:

    • Variable Galactic Gamma-Ray Sources, Barcelona, April 16-18, 2013 (invited review of SC)
    • XXXVIIIth Rencontres de Moriond Astrophysics « Very High Energy Phenomena in the Universe », La Thuile, 03/2013 (invited review of SC)
    • IXth INTEGRAL Workshop: Paris, 10/2012 (contributed talks of SC and AC)
    • 39th COSPAR Scientific Assembly 2012, Event 1.4 « Unveiling the properties of Supergiant Fast X-ray Transients », Mysore, India, 14-22 July 2012, (invited review of SC)

    International Collaborations:

    • Dr. Thomas Tauris (Bonn University, Max Planck fur Radio-Astronomie, Argelander Inst.).
    • Dr. John A. Tomsick (Space Sciences Laboratory, University of California, Berkeley)
    • Prof. Gustavo E. Romero (University of La Plata, Argentina)

    Visiting Scientist Programs:

    • Prof. Gustavo E. Romero, visiting scientist at AIM, Nov-Dec 2013 (PRESSPC)
    • [ Dr. Thomas Tauris, visiting scientist at AIM, planned early 2014 ]

  • PUBLICATIONS mid-2011 – 2013 (in bold publications directly supported by E2)

    Books, Monographs, Thesis:

    1. Beckmann, V. & Shrader, C.R.; Active Galactic Nuclei, 2012, ISBN-13: 978-3527410781. 350 pages. Wiley-VCH Verlag GmbH, 2012
    2. Ponti, G., Morris, M., Terrier, R., Goldwurm, A.; Traces of past activity in the Galactic Centre. 2013, In Advances in Solid State Physics, Vol. 34, « Cosmic Rays in Star-Forming Environments », eds. Olaf Reimer and Diego F. Torres, 331 (arXiv:1210.3034)
    3. Sandra De Jong, Accretion processes of radio galaxies at high energies, University: Observatoire de Paris, Ecole Doctorale Astronomie & Astrophysique d’Ile-de-France, defended 29 October 2013 at FACe/APC Paris Diderot
    4. Alexis Coleiro, Etude Multilongueur d’onde d’étoiles binaires accrétantes de grande masse, University Paris Diderot, Ecole Doctorale Astronomie & Astrophysique d’Ile-de-France, defended 25 September 2013 at SAp/IRFU/CEA Saclay

    Refereed Papers:

    1. Beckmann, V., et al.; The hard X-ray emission of Centaurus A, 2011, A&A 531, 70
    2. Bower, G., …, Clavel, M. Goldwurm, A., …, Detection of Variability in the Size of Sagittarius A*, 2013, ApJL, submit.
    3. Chaty, S., Dubus, G., Raichoor, A.; Near-infrared jet emission in the microquasar XTE J1550-564, 2011, A&A, 529, A3
    4. Chaty, S., Rahoui, F., Mid-infrared spectroscopy revealing the surroundings of the obscured High Mass X-ray binary IGR J16318-4848, 2012, ApJ, 751, 150
    5. Chaty, S., Muñoz Arjonilla, A.J., Dubus, G., Infrared study of H1743-322 in outburst: a radio-quiet microquasar, 2013, A&A, submit.
    6. Clavel, M., Terrier, R., Goldwurm, A., Morris, M., Ponti, G., Soldi, S., Trap, G., Echoes of multiple outbursts of Sagittarius A* revealed by Chandra, 2013, A&A, 558, 32 (arXiv:1307.3954)
    7. Coleiro, A., Chaty, S., Distribution of High Mass X-ray Binaries in the Milky Way, 2013, ApJ, 764, 185
    8. Coleiro, A., Chaty, S., et al., Infrared identification of high-mass X-ray binaries discovered by INTEGRAL, 2013, A&A, in press (arXiv:1013.0451)
    9. Curran, P.A., Chaty, S., Zurita Heras, J.A.; Disentangling the nIR/optical emission of black hole XTE J1650-500 during outburst, 2012, A&A, 547, 41
    10. Curran, P.A., Chaty, S., Near-infrared and optical observations of the failed outbursts of black hole XTE J1550-564, 2013, A&A, 557, 45
    11. de Jong, S., Beckmann, V., Mattana, F.; The nature of the multi-wavelength emission of 3C 111, 2012, A&A 545, 90
    12. Dodds-Eden, K., .., Goldwurm, A., .., Trap, G., et al.; The Two States of Sgr A* in the Near-infrared: Bright Episodic Flares on Top of Low-level Continuous Variability, 2011, ApJ, 728, 37
    13. Dogiel, V. A., Chernyshov, D. O., Tatischeff, V., Cheng, K.-S., Terrier, R.; The Origin of the 6.4 keV Line Emission and H2 Ionization in the Diffuse Molecular Gas of the Galactic Center Region, 2013, ApJ, 771, L43
    14. Melia, F., Falanga, M., Goldwurm, A.; Polarimetric imaging of Sgr A* in its flaring state, 2012, MNRAS, 419, 2489
    15. Mirabel, I. F., Dijkstra, M., Laurent, P., Loeb, A., Pritchard, J. R.; Stellar black holes at the dawn of the universe, 2011, A&A 528, 149
    16. Soldi, S., Beckmann, S., Baumgartner, W.H., Ponti, G., Shrader, C.R., Lubinski, P., Krimm, H.A., Mattana, F., Tueller, J., Long-term variability of AGN at hard X-rays, 2013, A&A, in press (arXiv:1311.4164)
    17. Trap, G., Goldwurm, A., et al.; Concurrent X-ray, near-infrared, sub-millimeter, and GeV gamma-ray observations of Sagittarius A*, 2011, A&A, 528, 140
    18. Zurita Heras, J. A., Chaty, S., Cadolle-Bel, M., Prat, L.; Evidence of an irradiated accrétion disc in XTE J1818-245, 2011, MNRAS, 413, 235

    Conference Proceedings:

    1. Beckmann, V., Jean, P., Lubiński, P., Soldi, S., Terrier, R.; The dominant emission process of the X-ray spectrum of Cen A, 2011, Proc. of the Conf. « The X-ray Universe », Berlin 2011, id 34
    2. Beckmann, V., De Jong, S., Mattana, F., Saez, D., Soldi, S.; Gamma-ay emitting radio galaxies at hard X-rays: Seyfert core or jet emission ? ; 2013, PoS INTEGRAL 2012, id 058
    3. Beckmann, V., Shrader, C.; The AGN phenomenon: open issues; 2013, PoS INTEGRAL 2012, id69
    4. Clavel, M., Terrier, R., Goldwurm, A., Morris, M., Ponti, G., Soldi, S., Trap, G.; Chandra observations of the X-ray emission from Molecular Clouds at the Galactic Center related to Sgr A* past activity; 2013, PoS INTEGRAL 2012, id 106
    5. Clavel, M., Terrier, R., Goldwurm, A., Morris, M., Ponti, G., Soldi, S., Trap, G.; The reflection of two past outbursts of Sagittarius A* observed by Chandra during the last decade, 2013, Conf. Proc of IAU 303 Symp. « The Galactic Center: Feeding and Feedback in a Normal Galactic Nucleus », 30/9-4/10/2013, Santa Fe, NM, USA, submit.
    6. Coleiro, A., Chaty, S., Zurita Heras, J.A., Rahoui, F., Tomsick, J.A., Identification of 12 High Mass X-Ray Binaries detected by INTEGRAL through NIR photometry and spectroscopy2013, PoS INTEGRAL 2012, id
    7. de Jong, S., Beckmann, V.; The non-thermal core of 3C 111, 2011, Proc. of the Conf. « The X-ray Universe », Berlin 2011, id 309
    8. de Jong, S., Beckmann, V., Soldi, S., et al.; M87 in hard X-rays: an INTEGRAL view; 2013, PoS INTEGRAL 2012, id 070
    9. de Jong, S., Beckmann, V., Mattana, F.; The non-thermal core of 3C 111, 2012, Proceedings of Science, SISSA, PoS(Extremesky 2011) 076.
    10. Mirabel, I. F.; Stellar black holes: Cosmic history and feedback at the dawn of the universe, 2011, IAU Symp., 275, 3 (arXiv:1012.4944)
    11. Menzel, M.L., Beckmann, V., Mattana, F.; AGN emission processes of NGC 4945 in the X-rays and gamma-rays, 2012, Proceedings of Science, SISSA, PoS (Extremesky 2011) 075
    12. Soldi, S., et al.; AGN variability at hard X-rays, 2011, Proc. of the Conf. « The X-ray Universe », Berlin 2011, id 154
    13. Soldi, S., et al.; High-energy emission from NGC 5506, the brightest hard X-ray Narrow Line Seyfert 1 galaxy, 2011, Proc. of the Conf. « NLS1 Galaxies and their place in the Universe », Milan 2011
    14. Soldi, S., Baumgartner, W., Beckmann, V., et al.; AGN variability at hard X-rays; 2013, PoS INTEGRAL 2012, id 65
    15. Soldi, S., Clavel, M., Goldwurm, A., Morris, M., Ponti, G., Terrier, R., Trap, G.; An X-ray survey of the Central Molecular Zone: variability of the Fe Kalpha emission line, 2013, Conf. Proc of IAU 303 Symp. « The Galactic Center: Feeding and Feedback in a Normal Galactic Nucleus », 30/9-4/10/2013, Santa Fe, NM, USA, submit.
    16. Soldi, S., Clavel, M., Goldwurm, A., Ponti, G., Terrier, R., Trap, G., Greiner, J., Prinz, T., Rau, A., Servillat, M.; A new Very Faint X-ray Transient in the Galactic centre, 2013, Conf. Proc of IAU 303 Symp. « The Galactic Center: Feeding and Feedback in a Normal Galactic Nucleus », 30/9-4/10/2013, Santa Fe, NM, USA, submit.
    17. Trap, G., Ponti, G., Soldi, S., Clavel, G., Terrier M., Goldwurm, A., Thermonuclear bursts from AX J1745.6–‐2901, 2013, Conf. Proc of IAU 303 Symp. « The Galactic Center: Feeding and Feedback in a Normal Galactic Nucleus », 30/9-4/10/2013, Santa Fe, NM, USA, in preparation

  • 28/09/2013 – R1

    Echoes of multiple outbursts of Sagittarius A* revealed by Chandra

    Using the Chandra X-ray Observatory, a team of scientists led by researchers of the APC laboratory in Paris, and SAp/CEA Saclay, France, has been studying the diffuse X-ray emission coming from a region close to the center of our Galaxy. The rapid and complex variations they observed can only be created by an intense X-ray radiation reflected by the dense molecular clouds of the region. The required radiation can only have been produced by the central supermassive black hole undergoing multiple periods of intense activity in the past. The paper reporting these results has been published in Astronomy and Astrophysics (Clavel, M., Terrier, R., Goldwurm, A., Morris, M., Ponti, G., Soldi, S., Trap, G., 2013, A&A, 558, A32, arXiv:1307.3954) and it is one of the highlights of the A&A 2013 October volume.

    Sagittarius A* is the supermassive black hole at the Galactic center. It is located at about 26,000 light years from the sun and is one of the least luminous known supermassive black holes of the Universe. Nevertheless, there is evidence that this object has been more luminous in the past, between several decades and a few hundreds years ago. This past activity can be studied from the reflection of its X-ray component by the dense molecular clouds surrounding Sagittarius A*. Indeed, it takes longer for the emission to travel from the black hole to the cloud and then from the cloud to us than to come directly from the black hole. Thus, the reflected radiation is reaching the Earth with a delay compared to the direct emission from the illuminating object (which is already seen about 26,000 years after it is emitted) and thus it appears as a light echo of an activity that has been quenched since then. If measured in great detail this echo allows us to study the past behavior of the black hole.

    When the high energy radiation hits the cool molecular gas of the cloud it is partly absorbed by the gas and partly scattered away. A fraction of the absorbed radiation is re-emitted as fluorescence light at specific energies corresponding to the difference of the electron energy levels of the atoms involved in the absorption and re-emission processes. One characteristic fluorescent line, which is expected to be particularly intense, is the one corresponding to the first two energy levels of the iron atom at 6.4 keV in the X-ray band. This X-ray line and the associated scattered continuum emission (the so called reflection component) have been indeed observed by the large space X-ray observatories presently in operation, notably the European INTEGRAL and XMM-Newton satellites and the American Chandra observatory. It is emanating from the massive and dense clouds of molecular gas that turn around the center of the Milky Way at distances varying between few tens to thousand light years from it.

    This emission was also already observed to vary and even to propagate with an apparent superluminal speed by the same research team back in 2010 using XMM-Newton and was then attributed to the reflection of a long outburst, about 300 years long, from Sagittarius A* (see http://www2.cnrs.fr/presse/communique/1894.htm).

    Taking advantage of Chandra exceptional high resolution the team of astrophysicists focused on the bright clouds which are less than 100 light years away from Sagittarius A* in projection towards the Galactic east in order to explore in greater details the drastic variations of the iron line fluorescent emission during the past decade. They found that the observed variations can be described essentially by two different behaviors: either a two-year peak propagating from west to east in one specific molecular structure (called the Bridge) or a linear change, either increasing or a decreasing, for the past ten years in all the other structures. Based on the density of the clouds which are reflecting the past emission of Sagittarius A*, the team concluded that these two behaviors are likely due to two distinct past events of Sagittarius A*.

     

     

    The animation above presents the main results of the publication. The first color image gives a static view of the neutral iron fluorescence line emission at 6.4 keV in the region, as seen by Chandra between 1999 and 2011. Both the position of the supermassive black hole Sagittarius A* (white cross) and the angular scale in light years (ly) are indicated on this image plotted in Galactic coordinates. Then the animation shows that the brightest regions are correlated with molecular materials which are moving at different velocities. In particular three groups of clouds are identified in the radio images of a characteristic molecular line: MC1 & MC2, G0.11-0.11 and The Bridge. The rest of the animation gives a high resolution view of the X-ray variations occurring in these clouds as seen by Chandra. First it shows an overview of the variations with three images corresponding to three different periods. This is also summarized in a composed color image where the emission detected is, between 1999 and 2003 in red, between 2004 and 2007 in green and between 2008 and 2011 in blue. Second, it zooms on the Bridge region showing the two-year peaked variation of this cloud starting in 2008 and propagating from right to left. Third, it zooms on the MC1 & MC2 clouds which have been varying linearly from 1999 to 2011 with also a clear propagation from right to left, away from Sagittarius A*.

    The figure below shows a sample of the characteristic lightcurves of the different parts of the molecular clouds, located in the composite color image of the region where the 6.4 keV iron line emission detected between 1999 and 2003 is in red, between 2004 and 2007 in green and between 2008 and 2011 in blue. The plots give the 4 to 8 keV continuum intensity, in units of 10-6 ph cm-2 s-1,measured in 15″-size square regions within the identified molecular clouds, at different years. The two behaviors mentioned above are clearly visible in the lightcurves, with the inset 1) and 2) showing the two-year peak emission propagating along the Bridge and all other plots showing the ten-year linear rises or decays.

    This is the first time that such fast variations of the reflection component from the Galactic center molecular clouds, and in particular an event as short as a couple of years seen both in its rising and decaying phase, are reported convincingly. The events at the origin of these two past outbursts are still not understood but these results shed a new light on the behavior of the Galactic supermassive black hole Sagittarius A* and indicate that these and future observations will likely lead soon to a full reconstruction of the past few hundred years history of its activity.

     

     

    These results will be presented (oral talk) at the IAU 303 Symposium « The Galactic Center: Feeding and Feedback in a Normal Galactic Nucleus », 30/9 – 4/10/2013 in Santa Fe, NM, USA, by M. Clavel (https://science.nrao.edu/science/meetings/IAU303-GC2013) and will be the subject of a Chandra News release in October 2013 (http://www.nasa.gov/mission_pages/chandra/main/index.html).

     

    Article by: M. Clavel, A. Goldwurm

     

     

    Team Documents:

    • E2 2011-2013 Activity Report submitted to Science Committee: CS 2013 – E2 – V2.pdf
    • E2 Preliminary 2013 Budget: E2-Budget2013D-p1.pdf E2-Budget2013D-p2.pdf E2-Budget2013D-p3.pdf
    • E2 2011-2013 Activity Report submitted to Science Committee revised version: CS 2013 – E2 – V4.pdf
    • Proposal to upgrade the project to AIM-APC Interface Project: InterfaceProject_AIM_APC_BH_v4
    Attachment Size
    CS 2013 – E2 – V2.pdf 353.33 KB
    E2-Budget2013D-p1.pdf 193.98 KB
    E2-Budget2013D-p2.pdf 286.15 KB
    E2-Budget2013D-p3.pdf 293.86 KB
    cs_2013_-_e2_-_v4.pdf 355.88 KB
    interfaceproject_aim_apc_bh_v4.pdf 465.2 KB