BANDO AAE TEORIA

Fondi 300 kEu / anno

Circa 10 programmi finanziati ogni anno selezionati da referee stranieri (16 richiesti)

Risultati scientifici dopo il secondo anno

Laura Maraschi

Modeling the properties of baryon gas in the large scale structure of the universe

•  Univ. Bologna: Lauro Moscardini

•  Univ. Roma Tre: Enzo Branchini

•  Oss. Astr. Torino: Giuseppe Murante

•  Oss. Astr. Trieste: Matteo Viel

Tool: High-resolution hydrodynamical simulations with a detailed description of the physical processes acting on ICM and WHIM.

Main goal: Characterization of the baryon gas in galaxy clusters and in the cosmic web for a realistic comparison with present and future X-ray observations.

SCIENTIFIC JUSTIFICATION To characterize the thermodynamic of

the X-ray emitting plasma at the virial radius

  Which ngas, T and Sb values do we expect at Rvir ?

  Are simulated X-ray clusters consistent with the observed ones in the outskirts ?

Implications   To calibrate the masses (gas and dark matter) in local galaxy clusters to use them as cosmological probes

  To study the accretion of primordial gas in cluster DM halos

ICM at Rvir: Simulated clusters

4 massive objects (Mvir : 1.9-3.4e15, Tvir : 5.5-9.9 keV) simulated using 4 different physical models: gravitational heating plus

artificial viscosity, cooling, star formation, feedback, thermal conduction Tgas ngas Roncarelli, Ettori et al 06

ICM at Rvir: Simulated clusters

Tgas ngas Sb [0.5-2 keV]

Unresolved CXB w. CXO (Hickox & Markevitch 05)

 Independently from the physics, just gravity

 We know what we’d observe at R200 (Tgas, Sb): X-ray observations & simulations provide a consistent picture with ngas~r-2.6 & Tgas~r-0.4 & Sb~1e-16erg/s/cm2/arcmin2

Intergalactic filaments at z~3 & clusters and groups at z~0

The goal: to have a pre-heating model able to reproduce at the same time the entropy profiles of clusters and groups and the properties of intergalactic medium

Borgani & Viel 2009, MNRAS, 392, L26

Intergalactic medium @ z=3 Standard model (left) Model with pre-heating (right)

Intracluster medium @ z=0 Standard model (left) Model with pre-heating (right)

The entropy level in galaxy groups at z~0

Sun et al. ‘08: Chandra archival data of 40 nearby groups.

No pre-heating:

Correct entropy level at r500

Too low entropy at r2500

Need Kfl>100 keV cm2 consistency with data to reach.

Combined with Ly-a data:

Either prevent heating low-δ regions at high z

Or heat at relatively low z

R500

R2500

Borgani & Viel 2009, MNRAS, 392, L26

OzLens - Sydney, 30 Sep 2008

Acceleration of high energy particles in galaxy clusters PI: Gianfranco Brunetti (INAF-IRA, Bologna) Pasquale Blasi (INAF- Oss Arcetri, Firenze) Giancarlo Setti (Univ. Bologna) Claudio Gheller (CINECA, Bologna) Rossella Cassano (INAF-IRA, Bologna) Franco Vazza (INAF-IRA, Bologna) Roberto Fusco-Femiano (INAF- IASF, Roma) Matteo Murgia (INAF- Oss Cagliari) Daniele Dallacasa (Univ. Bologna)

Aims: Particle acceleration mechanisms in galaxy clusters, shocks & turbulence in galaxy clusters, non thermal emission from galaxy clusters (gamma, X, radio)

Methods: teoretical models & numerical simulations

OzLens - Sydney, 30 Sep 2008

Simulations : Shocks in Galaxy Clusters

Vazza, Brunetti, Gheller 2008

OzLens - Sydney, 30 Sep 2008

Shocks in Galaxy Clusters

Vazza, Brunetti, Gheller 2008

OzLens - Sydney, 30 Sep 2008

Rad

io P

ower

Frequency

Turbulent acceleration in GC (Brunetti +al. 2008, Nature 455,944)‏

Acc

loss

Low frequency High frequency

OzLens - Sydney, 30 Sep 2008

Alfvenic acceleration in GC

πo

IC

Syn

Fermi

EGRET

Veritas

Brunetti, Blasi, Cassano, Gabici 2008,09

High Energy Emission from Accreting Massive Black Holes along the Cosmic

History Coordinatore: Francesco Haardt!

RU1: Universita’ dell’Insubria@Como (P.I.: F. Haardt)!RU2: Universita’ di Milano/Bicocca (P.I.: M. Colpi) !

Gas disk! Star bulge!

Density wake behind !at pericenter!

Density wake in front !at apocenter!

Net effects: orbital decay and circularization!

100 pc!

...and linking accretion to dynamics.!

Orbital separation !

M1! M2!

At pericenter passages, the secondary hole collects gas that can be accreted.!

As the orbit shrinks and circularizes accretion is more stable, and variability reduced.!

L/LEddxt!

Self-Consistent Modelling of the Photo-Ionized Environment of Astrophysical Sources

•  Elaborazione codice per la produzione di spettri (In banda UV e X) da plasma ionizzato in equilibrio, in regime otticamente sottile e per ioni nelo stato fondamentale

•  Estensione del codice ai casi (a) otticamente spesso (trasferimento radiativo), e (b) ioni su livelli accitati (calcolo della popolazione dei livelli)

•  Estensione del codice ai casi (a) di non equilibrio e (b) dipendente dal tempo

PI: Fabrizio Nicastro (INAF-OAR) Co-Is: D. Guetta (INAF-OAR), G. Matt, S. Bianchi (RomaTre)

Collab.: Y. krongold (UNAM, Mexico), N. Brickhouse (CfA, USA), M. Elvis (CfA, USA), S. Mathur (OSU, USA) Personale: M. van Adelsberg (INAF-OAR)

PHASE (PHotoionized Absorber Spectral Engine)

NGC 3783 Chandra MEG

900 ksec exposure

•  Most up-to-date atomic data-base (for H to Zn) •  Covers O-X-rays: more than 3000 resonant transitions •  Solves for Ionization and Level Population Balance (C & P) •  Computes proper line profile (Voigt) + Radiative Transfer •  Interfaces with public fitting packages (e.g. Sherpa, XSPEC)

Warm Absorbers = AGN Outflows Cosmologically important: Feedback

PHASE+TEPHOT (Time-Evolving PHOToionization) FeII Level Population Evolution in Time: General GRB light-curve

Ground n=2 n=3

D ~ pc

D ~ kpc

OVI-VIII Ionization Balance Evolution in Time: Typical AGN X-ray Ligh-curve (NGC 4051)

Excellent Distance diagnostics! Excellent Density diagnostics!

Simulazioni MHD di plasmi relativistici e della loro emissione ad alte energie

Responsabile: R.Bandiera Istituto: Oss. Astrof. Arcetri Partecipanti: E.Amato, L.Del Zanna, F.Pacini, D.Volpi

PULSAR WIND NEBULAE

I venti relativistici e magnetizzati prodotti da pulsar sono rallentati in uno shock terminale, dove ha luogo accelerazione di particelle. Dopo lo shock si forma una nebulosa non termica, che mostra nei raggi X una tipica morfologia getto – toro. Simulazioni MHD basate su modelli di vento magnetizzato con un flusso di energia maggiore all’equatore che al polo (e.g. Del Zanna et al. 2004, 2006) riproducono bene quanto osservato.

Crab

Raggi X

Vela

Raggi X

Modelli dello spettro integrato dell’emissione di una Pulsar Wind Nebula, su un’ampia gamma spettrale, dal radio ai raggi gamma. In figura il caso della Crab Nebula.

Alcuni Recenti Risultati

Variazioni multiple di indice spettrale, anche se con una distribuzione delle particelle iniettate a legge di potenza, è un risultato che si ottiene soltanto usando trattazioni multi-dimensionali.

Mappe simulate dell’emissione in raggi gamma (Compton inverso). Le dimensioni sono superiori a quelle in banda X ma decrescono con l’energia (eccetto che nella regione equatoriale). (Volpi et al. 2008)

La diminuzione delle dimensioni con l’energia è in accordo con le mappe in raggi gamma (risolte solo marginalmente), ottenute con MAGIC.

NON-LINEAR PARTICLE ACCELERATION AT SHOCK

WAVES: IMPLICATIONS FOR X/GAMMA RAY ASTRONOMY AND THE ORIGIN OF COSMIC RAYS

PI: Pasquale Blasi

StaffMembers:E.Amato,R.Bandiera,P.Lipari,M.Vietri

Postdocandstudents:D.Caprioli,G.Cassam‐Chennai,G.Morlino

Main Goals

1. Complete the development of a non-linear theory of diffusive particle acceleration at non-relativistic shocks

2. Application of the theory to the case of individual Supernova remnants which show non-thermal Activity

3. Application of the theory to the origin of galactic Cosmic rays

4. Investigation of the implications of the theory for the Transition from Galactic to extragalactic Cosmic Rays

MAIN RESULTS!WE DID COMPLETE THE THEORY WITH ! AMPLIFICATION OF MAGNETIC FIELD!BY THE ACCELERATED PARTICLES…!

…AND WITH THE DYNAMICAL REACTION OF THE MAGNETIC FIELD ON THE PLASMA !

WE APPLIED THE NLDSA TO THE CASE OF RXJ1713 WHICH HAS RECENTLY BEEN DETECTED AT TeV BY HESS!

WE ESTABLISHED THAT MAGNETIC FIELD AMPLIFICATION !LEADS TO ACCELERATION OF PROTONS TO ~106 GeV (knee)!

WE DETERMINED THE CONNECTION BETWEEN SNR AND CR!THROUGH THE COMPLEX PHENOMENON OF ESCAPE!

The case of RXJ1713

Aharonian et al. 2007

The case of RXJ1713 FERMIHESS,CTA

L

H

MORLINO,AMATO&BLASI2009

Spectral and Timing Properties of Isolated Neutron Stars, Magnetars and

Related Objects

PI: R. TUROLLA

PADOVA UNIT: R, TUROLLA, L. NOBILI, A. ALBANO, L. PAVAN, L. ZAMPIERI

OAR UNIT: L. STELLA, GL. ISRAEL, E. BOZZO, M. BURGAY, S. DALL’OSSO

Magnetar Spectra

Quiescent X-ray emission (0.5-10 keV) from SGRs/AXPs modeled by a thermal component (kT ~ 0.5 keV) plus a power law tail (Γ ~ 1.5-4). A high-energy (~ 15-200 keV) tail detected by INTEGRAL in many sources

Observational evidence that the Soft Gamma Repeaters and the Anomalous X-ray Pulsars host an ultra-magnetized neutron star, a magnetar (B > BQED ~ 4.4x1013 G)

Magnetar magnetospheres are twisted, i.e.the B-field has a non-vanishing toroidal component. Large currents (j ≫ jGJ) are required to support the field

A physical emission model: thermal photons emitted by the cooling star surface undergo resonant (cyclotron) up-scattering onto magnetospheric charges

A twisted dipolar magnetoshpere

BB PL HE PL

R. Turolla, A. Albano, F. Bernardini, G.L. Israel, L. Nobili, L. Pavan, N. Rea, S. Zane

A Monte Carlo code has been developed to solve radiative transfer in the magnetosphere. Proper account for photon propagation in a strongly magnetized medium and magnetic Compton scattering

Magnetic Compton scattering Conservative (magnetic Thomson) scattering

Seed blackbody

HE cut-off due to electron recoil

Spectral model implemented in XSPEC

Resonan Cyclotron Scattering explains magnetar spectra in the soft X-ray range. Extension to the 10-200 keV band under way

OzLens - Sydney, 30 Sep 2008

Supergiant Fast X-ray Transients:

(Sakano et al. 2002)

(Sguera et al. 2005)

SAX J1818.6-1703

XTEJ1739-302

~8 ks

ISGRI Science Window image sequence

t~500s LX>2x103

Like many other HMXB:

  OB supergiant companion stars   Outburst X-ray luminosities ~1036-1037 erg s-1

At difference with many others HMXBs:

  Extremely high X-ray luminosity variations between outburst and quiescence LX~104-105

  Sporadic outbursts lasting only few hours

(for periodic SFXT see Sidoli et al. 2007)   Evidences of Pspin~1000-2000 s (>300 s) (Sguera et al. 2006; Walter et al. 2006)

Standard HMXBs with standard NSs?

OzLens - Sydney, 30 Sep 2008

SFXT: the most extreme case ever observed...

IGRJ17544-2619

~1032 erg/s

~1033 erg/s

~1036 erg/s

~1037 erg/s

Caught by Chandra from quiescence to outburst

LX~105

t~5 h

(In't Zand 2005)

OzLens - Sydney, 30 Sep 2008

The Gated accretion model for SFXT sources:

Ra

BOW SHOCK

NS

OB STAR

WIND

An interaction very similar to the Earth - Solar Wind case: matter flows away along the magnetosphere (and does not accrete..)

Supergiant Fast X-ray Transients might host MAGNETARS!!!

Requires Neutron Star magnetic field >1014 G instead of the typical 1012 G

  QUIESCENCE: Accretion is inhibited during most of the orbital motion of the NS around it supergiant companion by a MAGNETIC BARRIER ( gives LX~1032-1034 erg/s )   OUTBURST: Sporadic outbursts due to episodes of enhanced accretion due to the presence of “clumps” from the wind of the supergiant companion ( gives LX~1036-1037 erg/s )

Quest’anno abbiamo finanziato un nuovo progetto (PI S. Orlando, OA Pa)

Sviluppo di simulazioni MHD per fenomeni di accrescimento e dischi in oggetti stellari giovani