The discovery of a molecular cavity in the Norma near arm associated to H.E.S.S r-ray source located in the direction of Westerlund 1

arXiv:1003.1734

Abraham Luna et al.

VRI from 2.2m MPG/ESO+WFI Clark et al. (2005)

A Galactic Super Star Cluster

• 150 stars with M>35 Msun

• Mass: 105 Msun

• Extent: ~6 pc across• Distance: 5 kpc• Age: 4 +/- 1 MyrThe cluster is coeval, and

old enough to have produced supernovae.

Est. rate: 1 per 10,000 years!

1 pc

Chandra Observations

VRI from 2.2m MPG/ESO+WFI

Clark et al. (2005)

Chandra ACIS1 pc

We see diffuse X-rays from the cluster wind and unresolved pre-main-sequence stars, point-like emission from colliding wind binaries, and a pulsar!

pulsar

Pulsar CXO J164710.2-455216

• Period: 10.6107(1) s• Spin-down: <2x10-10 s s-1

• LX = 3x1033 erg s-1 (not a radio pulsar)

• Spectrum: kT = 0.6 keV blackbody (not a cooling NS)

• No IR counterpart (not an X-ray binary)

Diffuse Emission from Wd 1

After removing point sources, there is 3x1034 erg s-1 of diffuse emission.

Pre-Main-Sequence Stars

• Age ~1 Myr.• 1398 optically-studied 0.3

<M<3Msun stars.• LX = 1.2x1033 erg s-1, line-

rich, thermal spectra.

• Age ~4 Myr.

• LX = 3x1034 erg s-1, <20% thermal.

• About 30,000 stars with 0.3<M<3Msun

Orion: Feigelson et al. 2005 Westerlund 1

pulsar

Stellar Winds• With 25 WR stars, the power output is 1039 erg s-1,

and the mass loss rate a few 10-4 Msun yr-1.• The entire diffuse flux from Westerlund 1 can be

explained as a freely-expanding wind.• Most clusters are ~10x more luminous than woul

d be expected from supersonic winds (Chevalier & Clegg 1985; Stevens & Hartwell 2003).– The density of the wind might be increased by entraining c

ooler material (Dorland & Montmerle 1987; Stevens & Hartwell 2003).

– The pressure could be increased if the wind is confined by the ISM (Chu et al. 1995).

3.6, 4.5, and 8.0 m: Spitzer/GLIMPSE(R. Indebetouw)

Westerlund 1

3.6, 4.5, 5.8 and 8.0 m: Spitzer/GLIMPSE

(E. Churchwell et al.)

RCW 49 (Westerlund 2)

2 pc

Westerlund 1: ISM is Gone

3.6, 4.5, and 8.0 m: Spitzer/GLIMPSE(R. Indebetouw)

Chandra

2 pcpulsar

But SNRs would be in interaction But SNRs would be in interaction with MCs at the bubble edgewith MCs at the bubble edge

SN exploding close to the MCs or :– Enter the radiative phase sooner [Chevalier ’99]

– Detection through optical lines H , SII, OIII: shock (vs ~ 100 km/s): cloud interaction (n ~10 cm-3, T ~104-5K) [Bocchino et al ’00] + X-ray radiation from less dense regions.

– NT particles expected hard X-rays & gamma-rays (IC443, Gamma Cygni) [Bykov et al ’00, ‘04]

No Supernova Shocks in a Wind-Blown Bubble

Supernova Remnants?

1 pc

• Supernova rate is one per 10,000 yr.

• At 1051 erg per SN, the power output is 3x1039 erg s-1.

• Less than 10-5 of that is X-rays.

pulsar

• Motivation: the stellar clusters are potential acceleration sites of VHE: SNRs, PWN, Winds

• Observations: extended emission off-centered from the cluster

• Data: Columbia-Calan CO survey (0.125d, 1km/s, 0.1K; [339.55d,-0.4d], 2d*2d)

Kothes et al. 2007

15m

2d

[-104, -94, -90, -84] km/s

M~10E6 Msun

Ek~10E51 erg

t~10E6 yr

Norma arm: -91 km/s; 4.9kpcScutum arm: -48 km/s; 3.5kpc

NS+BIN: GX340+0 <11kpc

Magnetar: CXO J164710.2-455216

NS: PSR J1648-4611

• RCW49:[284.3,-0.3], HII complex• D~2.3-8 kpc, 90’*70’ & 12’ core• Excited by the Westerlund 2 cluster• Stars + Optical nebulosity + Diffuse emission• A wind-blown shell resulting from W2 cluster

843 MHz by the Molonglo Observatory Synthesis Telescope

43’’

25’’

• Westerlund 2:[284.27,-0.33], tight open cluster

• 1-3 Myr, 5E3 Msun, E~3.6E51 erg

• The core of the HII region RCW49

2MASS J, H, & K

Intense SFR: numerous Pre Main Sequence objects + many early-type stars

Spitzer 3.6, 4.5, & 5.8um tri-color image

HESS TeV + MOST Radio

Triangle= WR star (82+83 Msun, ~3.7d)

Dotted blister= wind bubble of WR star

Thanks