Gustavo E. Romero IAR-CONICET Felix Aharonian’s Workshop November 7 th, 2012

 Gas (Hayakawa 1952, Morrison 1958, Aharonian & Atoyan 1996).  Young, massive stars with winds collective effects (Bykov & Fleishman 1992, Romero & Torres 2003, Torres et al. 2004, Parizot et al. 2004, Bykov: yesterday, etc).  Young pulsars.  SNRs (yesterday’s talks).  Colliding wind binaries (Eichler & Usov 1993, Benaglia & Romero 2003, Pittard & Daugherty 2006).  Accreting sources (Paredes, Mirabel, Bosch-Ramon – this workshop).  FORMING MASSIVE STARS.  RUNAWAY MASSIVE STARS.

Massive stars are formed in massive and dense cores of giant molecular clouds. The cores are the result of the gravitational fragmentation of the cloud The mechanism of massive star formation is still matter of debate. There are two main different scenarios: accretion and coalescence.

Herbig-Haro objects HH49-50

Martí, Rodriguez & Reipurth (1993)

B = 0.2 mG, Carrasco-González, Rodríguez et al Polarization in the jets

The whole source (protostar + jets) is embedded in the molecular cloud Araudo, Romero, Bosch-Ramon & Paredes 2007, A&A 476, 1289

a=100 Bosch Ramon et al. (2010), n cloud = 10 3 /cm 3.

VLA Rodríguez et al. (2005) Southern lobe: S=cte n a, a~ -0.6 d=2.9 kpc B~10 -3 G V s ~1000 km/s Clear non- thermal emission

Araudo, Romero, Bosch-Ramon & Paredes 2007, A&A 476, 1289

Araudo et al. (2007)

3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red) Westerlund 2/ RCW 49

Aharonian, F.A., et al., 2006 Westerlund 2/ RCW 49

HESS Collaboration

Westerlund 2/ RCW 49 PSR J

Westerlund 2/ RCW 49 Expected size of the PWN Size of HESS J Additional contributions? HESS Coll. K&C 1984

RCW 49 / Westerlund 2 Benaglia et al. 2012

Stellar bow shocks Arc-shaped features of piled-up material Same direction as stellar velocity Winds confined by ISM ram pressure Distance to star by momentum balance Radiation from shocked gas heats swept dust Dust re-radiates as MIR and FIR excess

E-BOSS v.1 28 cands (out of 283 OB runaway stars known) Peri, Benaglia, et al. 2012, A&A

Modeling bow-schocks and their emission Relativistic particles are accelerated at the reverse adiabatic shock in the stellar wind

Modeling bow-schocks and their emission

del Valle & Romero In prep. These p can power the extended source

del Valle & Romero 2012, A&A Spectral energy distributions for O4I and O9I stars

HESS Coll.

See also poster by Martí et al. on Monoceros

Absorbed X-ray power law ~ -2.5

WISE keV EPIC map Energy map

VLA + MSX images of BD+43 o 3654 C band L band Benaglia, Romero, et al 2010, A&A

Computed BS & WISE image SED and sensitivities del Valle & Romero 2012, A&A

Conclusions Conclusions * Protostars in SFRs can be gamma-ray sources when embedded in the original molecular core. * The typical luminosities are ~ erg/s at E>100 MeV. * Runaway massive stars can produce relativistic particles in their bowshocks, and local (IC) and difusse (pp) gamma-ray emission. * Some nearby runaway O stars can be detected in gamma-rays by Fermi and in the future by CTA. Gamma-ray astronomy can open a new window to the study of massive star forming processes.

Thanks! What a world ! “Relaxed gamma-ray astronomy team”

 v j ~ 700 km/s  n ~ 1000 cm -3  R HH ~ cm  D ~ 1.7 kpc  L X ~ erg/s  B eq ~ 5 mG  E max, p ~ eV - E max, e ~ E max, p /12 See Martí et al. (1993) and Pravdo et al. (2004) for details on the source

Martí, Rodriguez & Reipurth (1993)

Number of stars vs. Spatial velocity Tetzlaff Km/s # Peri, Benaglia, et al. 2012, A&A

detected BS GC Peri, Benaglia, et al. 2012, A&A

Benaglia et al. 2012

Absorption

t pp ~ s >> t esc ~ s t Bremsstr ~ s t acc ~ η E/qBc, where η =(8/3)(v s /c) 2 t esc = t acc  eV (for protons)

IRAS bow shock candidates (Noriega-C. et al. 1997) Comerón & Pasquali 2007: o Bow shock at MSX-D, E bands o Runaway from Cyg OB2, 1.4 kpc o O4 If ; 70 M o ; 1.6 Myr; [v w = 3200 km/s] Kobulnicky et al. 2010: o v ~ 80km/s, dM/dt ~ 2 x M o /yr Ambient density: 6 to 100 cm -3 A non- thermal emitter?

D-band image (14.65  m)

L-band C-band Benaglia, Romero, et al 2010, A&A

Is all emnission coming from the BOW SHOCK? 5’ ~ 2pc Benaglia, Romero, et al 2010, A&A

Spectral index map  noise S( ) ~ k  s/n (cont) ≥ 4 s/n (  ) ≥ ≤  ≤ Benaglia, Romero, et al 2010, A&A

Ee max ~1 TeV