Star Formation around Active Galactic Nuclei Lessons from
- Slides: 32
Star Formation around Active Galactic Nuclei: Lessons from the mid-IR D. Alloin & E. Galliano
Embedded Young Massive Star Clusters M 82: Archetypal starburst galaxy
Embedded Young Massive Star Clusters o HST revealed Young Massive Star Clusters (YMC) in local starburst galaxies o 100 s to 1000 s in some galaxies o 0. 5 pc to 200 pc, mass~10^6 Msol o Age, few Myr to 10 Myr o Are they adolescent GC ?
Embedded Young Massive Star Clusters o On the GC time scale o YMCs are very young o On stellar formation time scale o YMCs are already evolved o Comparison with star formation o First stages of YMCs expected to be embedded
ESC…SSC…GC? o We expect the cluster to be embedded in o Dense region of ionized gas (UDHII) o Cocoon of heated dust o We can observe o o Radio cm emission IR nebular lines MIR continuum PAH
Embedded Young Massive Star Clusters o Not yet identified in observations o Giant molecular clouds o Sub-mm emission of cold gas o Future: observations with ALMA
NGC 1365, NGC 1808, visible From HST archive F 814 W D=18. 6 Mpc, 1”=90 pc F 658 N D=10. 9 Mpc, 1”=53 pc
NGC 1365, NGC 1808, visible + radio D=18. 6 Mpc, 1”=90 pc D=10. 9 Mpc, 1”=53 pc Radio data: Forbes & Norris 1998 & Collison et al. 1994
NGC 1365, NGC 1808, visible + radio =-0. 75 =-0. 4 F 814 W 3. 6 cm F 658 N 3. 6 cm =-0. 4 =-0. 3 =-0. 5 =-0. 6 D=18. 6 Mpc, 1”=90 pc D=10. 9 Mpc, 1”=53 pc Radio data: Forbes & Norris 1998 & Collison et al. 1994
NGC 1365, NGC 1808, N-band* *TIMMI 2 data
NGC 1365, NGC 1808, N-band *TIMMI 2 data
MIR templates
N-Band colors N_band colors Much redder than HII regions or PDR Deep silicate absorption Av of several 10 s Strong [Ne. II] emission
Interpretation: Embedded Star Clusters o Few objects known o Antennae, NGC 5253, SBS 0335 -052, IIZw 40 o 106 to 107 solar masses o Radio index =-0. 1 o Radio emission o =-0. 1 : thermal free-free emission from HII regions o =-0. 8 : non-thermal emission from SNR
Interpretation: Embedded Star Clusters o In NGC 1365 and NGC 1808 clusters? o negative cm indices: -0. 4 to -0. 9 o share of thermal and non-thermal emission Fν thermal ionizing photon production rate Fv non-thermal SN rate
Starburst 99 model o Model from Leitherer et al. 1999* o 106 solar masses o Instantaneous star formation o Salpeter IMF o We use: o Supernova rate o Ionizing photon production rate o Total star luminosity * www. stsci. edu/science/starburst 99
Starburst 99 model SN rate Non-thermal radio flux Ionizing photon rate Thermal radio flux Star Luminosity BB flux
Weighing and dating the clusters? Cluster age Predicted cm flux Cluster mass Predicted 12. 9µm F Av
Weighing and dating the clusters? NGC 1365 o 3 -6 Myr o 2 106 solar masses o Av=20 -40 mag NGC 1808 o 3 -5 Myr o 0. 3 106 solar masses o Av=20 -40 mag Simple model confirms that these objects are likely to be young embedded clusters: proto-globular clusters? ?
ISAAC data o Imaging in K, L and M bands o SED of the objects o LR spectroscopy in K(2. 2µm) and L(3. 5 µm) o Measure Br (K) and Br (L) o Measure extinction: deredden line fluxes o Detect PAH o Compare with more complex models
NGC 1365 K L N
K L N NGC 1808
Improved Modeling ? o GRASIL o code for spectrophotometry of evolving stellar populations taking into account the effects of dust Silva & Granato 1998
Survival of Embedded Star Clusters o Cluster lifetime dependence on mass and environmental effects (Gieles et al, Portegies et al 2002, Baumgardt & Makino 2003). o N-body simulations, Galactic center: D=34 pc, density~700 solar mass/pc 3 o 105 solar mass cluster: < 40 -120 Myr o 106 solar mass cluster: < 180 -500 Myr o Effect of molecular cloud interactions o decrease lifetime by a factor 5 -10 o hence lifetimes less than 50 Myr
NGC 1068, N band, VISIR SV: knots identification & inner spiral
NGC 1068, N band, deconvolved
NGC 1068, [Ne. II]
NGC 1068, comparison with Subaru
NGC 1068, comparison with NACO/VLT
NGC 1068, comparison with [OIII] HST
Survival of Embedded Star Clusters in strong X/UV field? o NLR clouds: high density o Ionization cone: protected cloud back-side o Dust emission o Pa. H emission o Star formation? o Jet-induced gas compression o Transient micro-bar? o Only minor flux contribution in NGC 1068, but size consistent (~14 pc)
Concluding remarks o Observational side: high-resolution imaging & MIR-NIR spectroscopy, mm/cm interferometry o Modeling side: o Codes DUSTY or GRASIL (radiation transfer) o N-body simulations for lifetime estimates o Statistical approaches o Frequency of e-clusters occurrence around AGN o Age sequence versus location?
- Reverberation
- Active galactic nuclei
- Active galactic nuclei
- Myrrh is mine its bitter perfume
- Nmr active and inactive nuclei
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- Urban realms model
- Galactic center radio transients
- Galactic habitable zone
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- Galactic cap review
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- Galactic habitable zone
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- Star formation
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- Formation initiale vs formation continue
- Formation active campaign
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