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Explore the phenomena of high-energy emission from young and massive stellar objects. Discover gas structures, young pulsars, colliding wind binaries, and more in star-forming regions. Learn about the formation of massive stars and the interaction of stellar jets with the interstellar medium. Gain insights into the emission mechanisms and energy sources in bow shocks and high-energy environments. Join the "Relaxed Gamma-Ray Astronomy Team" as we uncover the mysteries of gamma-ray astronomy in massive star systems. Conclusions and implications for future observations are discussed.
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High-Energy Emission from Young and Massive Stellar Objects Gustavo E. Romero IAR-CONICET romero@iar-conicet.gov.ar Felix Aharonian’s Workshop November 7th, 2012
What are thecontents of star-formingregions? • Gas (Hayakawa 1952, Morrison 1958, Aharonian & Atoyan 1996). • Young, massivestarswithwindscollectiveeffects(Bykov & Fleishman 1992, Romero & Torres 2003, Torres et al. 2004, Parizot et al. 2004, Bykov: yesterday, etc). • Young pulsars. • SNRs (yesterday’stalks). • Collidingwindbinaries(Eichler & Usov 1993, Benaglia & Romero 2003, Pittard & Daugherty 2006). • Accretingsources(Paredes, Mirabel, Bosch-Ramon – thisworkshop). • FORMING MASSIVE STARS. • RUNAWAY MASSIVE STARS.
Massivestars are formed in massive and dense cores of giant molecular clouds. Thecores are theresult of thegravitationalfragmentation of thecloud Themechanism of massivestarformationisstillmatter of debate. There are twomaindifferentscenarios: accretion and coalescence .
Herbig-Haro objects HH49-50
HH 80-81: a partiallyembeddedmassiveprotostellarsystem Martí, Rodriguez & Reipurth (1993)
Polarization in the jets Carrasco-González, Rodríguez et al. 2010 B = 0.2 mG,
Interactionwiththe ISM Thewholesource (protostar + jets) isembedded in the molecular cloud Araudo, Romero, Bosch-Ramon & Paredes 2007, A&A 476, 1289
SED for HH 80-81 a=100 Bosch Ramon et al. (2010), ncloud = 103/cm3.
Themassiveprotostar IRAS 16547-4247 Southernlobe: S=ctena, a~ -0.6 d=2.9 kpc B~10-3 G Vs~1000 km/s Clear non-thermal emission Rodríguez et al. (2005) VLA
SEDs of non-thermal region at the end of the jet Araudo, Romero, Bosch-Ramon & Paredes 2007, A&A 476, 1289
Case dominatedbyprotons Araudo et al. (2007)
Westerlund 2/ RCW 49 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 PSR J1022-5746
Westerlund 2/ RCW 49 HESS Coll. Expectedsize of the PWN Size of HESS J1023-575 K&C 1984 Additionalcontributions?
RCW 49 / Westerlund 2 Benaglia et al. 2012
Stellarbow shocks • Arc-shapedfeatures of piled-up material • Samedirection as stellarvelocity • WindsconfinedbyISM rampressure • Distancetostarbymomentum balance • Radiationfromshocked gas heats • sweptdust • Dust re-radiates as MIR and FIR excess
E-BOSS v.1 28 cands(out of 283 OB runawaystarsknown) Peri, Benaglia, et al. 2012, A&A
Modelingbow-schocks and theiremission Relativisticparticles are accelerated at the reverse adiabatic shock in thestellarwind
Most of theprotons escape These p can powerthe extended source del Valle & Romero In prep.
Spectralenergydistributionsfor O4I and O9I stars del Valle & Romero 2012, A&A
Another case: Westerlund 1 HESS Coll.
Another case: Westerlund 1 Seealso poster by Martí et al. onMonoceros
AE AuriageLópez-Santiago, Miceli, del Valle, Romero, et al. ApJ Lett2012 Absorbed X-raypowerlaw ~ -2.5
AE AuriageLópez-Santiago, Miceli, del Valle, Romero, et al. ApJLett 2012 WISE + 1-8 keV EPIC mapEnergymap
VLA + MSX images of BD+43o3654 Benaglia, Romero, et al 2010, A&A C band L band
SED Benaglia, Romero, et al 2010, A&A
zOphbow-shock del Valle & Romero 2012, A&A SED and sensitivities ComputedBS & WISE image
Is HD 195592 a Fermi source?del Valle, Romero, & De Becker 2012
Conclusions • * Protostars in SFRs can be gamma-raysourceswhenembedded in the original molecular core. • * Thetypicalluminosities are ~ 1031-33 erg/s at E>100 MeV. • * Runawaymassivestars can produce relativisticparticles in theirbowshocks, and local (IC) and difusse (pp) gamma-rayemission. • * Somenearbyrunaway O stars can bedetected in gamma-raysby Fermi and in thefutureby CTA. • Gamma-rayastronomy can open a new windowtothestudy of massivestarformingprocesses.
What a world! “Relaxed gamma-rayastronomyteam” Thanks!
Some basic parameters for HH 80-81 • vj ~ 700 km/s • n ~1000 cm-3 • RHH ~ 5 1016 cm • D ~ 1.7 kpc • LX ~ 4 1031 erg/s • Beq ~ 5 mG • E max, p ~ 3 1014 eV - E max, e ~ E max, p/12 See Martí et al. (1993) and Pravdo et al. (2004) for details on the source
HH 80-81: the central source Martí, Rodriguez & Reipurth (1993)
Distributions # Number of stars vs. Spatialvelocity Tetzlaff + 2010 10 20 30 50 70 90 130 Km/s Peri, Benaglia, et al. 2012, A&A
Distributions detected BS Peri, Benaglia, et al. 2012, A&A GC
Energy losses and gains tpp ~2 1012 s >> tesc ~ 3 109 s tBremsstr ~3 1013 s tacc ~ η E/qBc, where η =(8/3)(vs/c)2 tesc = tacc 3 1014 eV (for protons)
Thestar BD+43o3654 IRAS bow shock candidates (Noriega-C. et al. 1997) Comerón & Pasquali 2007: Bow shock at MSX-D, E bands RunawayfromCyg OB2, 1.4 kpc O4 If ; 70 Mo ; 1.6 Myr; [vw = 3200 km/s] Kobulnickyet al. 2010: v~ 80km/s, dM/dt ~ 2 x 10-4 Mo/yr Ambientdensity: 6 to 100 cm-3 A non-thermalemitter?
MSX emission toward BD+430 3654 D-band image (14.65 mm)
VLA obs L-band Benaglia, Romero, et al 2010, A&A C-band
Images Is all emnission coming from the BOW SHOCK? Benaglia, Romero, et al 2010, A&A 5’ ~ 2pc
Spectralindexmap a • S(n) ~ kna • s/n (cont) ≥ 4 • s/n (a) ≥ 10 • -0.8 ≤ a ≤ 0.3. • <a> -0.4 Benaglia, Romero, et al 2010, A&A noise