Discovery of Nonthermal X-Ray Emission from the Embedded Massive Star-forming Region RCW 38

Wolk, S. J.; Bourke, Tyler L.; Smith, Randall K.; Spitzbart, B.; Alves, J.

doi:10.1086/345611

Cited by 58 publications

(62 citation statements)

References 18 publications

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“…The uncommon hard diffuse synchrotron emission has also been reported (e.g., Wolk et al 2002). In some cases the observed X-ray diffuse emission can be completely explained by the unresolved stellar population (e.g., Getman et al 2006).…”

Section: The Diffuse X-ray Emissionmentioning

confidence: 86%

ACHANDRAOBSERVATION OF THE OBSCURED STAR-FORMING COMPLEX W40

Kuhn

Feigelson

Reipurth

et al. 2010

ApJ

137

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The young stellar cluster illuminating the W40 H ii region, one of the nearest massive star-forming regions, has been observed with the ACIS detector on board the Chandra X-ray Observatory. Due to its high obscuration, this is a poorly studied stellar cluster with only a handful of bright stars visible in the optical band, including three OB stars identified as primary excitation sources. We detect 225 X-ray sources, of which 85% are confidently identified as young stellar members of the region. Two potential distances of the cluster, 260 pc and 600 pc, are used in the paper. Supposing the X-ray luminosity function to be universal, it supports a 600 pc distance as a lower limit for W40 and a total population of at least 600 stars down to 0.1 M under the assumption of a coeval population with a uniform obscuration. In fact, there is strong spatial variation in K s -band-excess disk fraction and non-uniform obscuration due to a dust lane that is identified in absorption in optical, infrared, and X-ray. The dust lane is likely part of a ring of material which includes the molecular core within W40. In contrast to the likely ongoing star formation in the dust lane, the molecular core is inactive. The star cluster has a spherical morphology, an isothermal sphere density profile, and mass segregation down to 1.5 M . However, other cluster properties, including a 1 Myr age estimate and ongoing star formation, indicate that the cluster is not dynamically relaxed. X-ray diffuse emission and a powerful flare from a young stellar object are also reported.

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Section: The Diffuse X-ray Emissionmentioning

confidence: 86%

ACHANDRAOBSERVATION OF THE OBSCURED STAR-FORMING COMPLEX W40

Kuhn

Feigelson

Reipurth

et al. 2010

ApJ

137

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“…In particular, following up on pioneering ROSAT observations, intermediate to distant clouds have been covered by Chandra: the Orion nebula (Garmire et al 2000;Feigelson et al 2002Feigelson et al , 2003Flaccomio et al 2003), part of the Rosette nebula and molecular cloud, together with M17 (Townsley et al 2003;Wang et al 2008Wang et al , 2009); Mon R2 (Kohno et al 2002); RCW38 (Wolk et al 2002); M16 (Linsky et al 2007), and by XMMNewton: M8 (Rauw et al 2002); Carina (Albacete Colombo et al 2003); Vela OB2 (Jeffries et al 2009); Orion (López-Santiago & Caballero 2008); and others. Up to thousands of point X-ray sources per cloud are detected, almost all identified with young stars, down to the brown dwarf regime.…”

Section: Search For Young Stars Based On X-ray Datamentioning

confidence: 99%

Star formation history of Canis Major R1

Gregorio-Hetem¹,

Montmerle

Rodrigues

et al. 2009

A&A

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Aims. The CMa R1 star-forming region contains several compact clusters as well as many young early-B stars. It is associated with a well-known bright rimmed nebula, the nature of which is unclear (fossil HII region or supernova remnant). To help elucidate the nature of the nebula, our goal was to reconstruct the star-formation history of the CMa R1 region, including the previously unknown older, fainter low-mass stellar population, using X-rays. Methods. We analyzed images obtained with the ROSAT satellite, covering ∼5 sq. deg. Complementary VRI photometry was performed with the Gemini South telescope. Colour-magnitude and colour-colour diagrams were used in conjunction with pre-main sequence evolutionary tracks to derive the masses and ages of the X-ray sources.Results. The ROSAT images show two distinct clusters. One is associated with the known optical clusters near Z CMa, to which ∼40 members are added. The other, which we name the "GU CMa" cluster, is new, and contains ∼60 members. The ROSAT sources are young stars with masses down to M ∼ 0.5 M , and ages up to 10 Myr. The mass functions of the two clusters are similar, but the GU CMa cluster is older than the cluster around Z CMa by at least a few Myr. Also, the GU CMa cluster is away from any molecular cloud, implying that star formation must have ceased; on the contrary (as already known), star formation is very active in the Z CMa region.

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“…The analysis of Chandra data revealed an arc minute-scale extended diffuse X-ray emission (Muno et al 2006b) which is only seen for a few young stellar associations in the Galaxy, for example RCW 38 (Wolk et al 2002) and possibly the Arches cluster (Law & Yusef-Zadeh 2004) as well as in the Large Magellanic Cloud in 30 Doradus C (Bamba et al 2004) and DEM L192 (Cooper et al 2004). The total X-ray luminosity of the observed diffuse emission within 5 of Wd 1 is dominated by its non-thermal component and amounts to L X ≈ 3 × 10 34 erg s…”

Section: Introductionmentioning

confidence: 99%

Discovery of extended VHEγ-ray emission from the vicinity of the young massive stellar cluster Westerlund 1

Abramowski

Acero

Aharonian

et al. 2012

A&A

100

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Aims. Results obtained in very-high-energy (VHE; E ≥ 100 GeV) γ-ray observations performed with the H.E.S.S. telescope array are used to investigate particle acceleration processes in the vicinity of the young massive stellar cluster Westerlund 1 (Wd 1). Methods. Imaging of Cherenkov light from γ-ray induced particle cascades in the Earth's atmosphere is used to search for VHE γ rays from the region around Wd 1. Possible catalogued counterparts are searched for and discussed in terms of morphology and energetics of the H.E.S.S. source. Results. The detection of the degree-scale extended VHE γ-ray source HESS J1646-458 is reported based on 45 h of H.E.S.S. observations performed between 2004 and 2008. The VHE γ-ray source is centred on the nominal position of Wd 1 and detected with a total statistical significance of ∼20σ. The emission region clearly extends beyond the H.E.S.S. point-spread function (PSF). The differential energy spectrum follows a power law in energy with an index of Γ = 2.19 ± 0.08 stat ± 0.20 sys and a flux normalisation at 1 TeV of Φ 0 = (9.0 ± 1.4 stat ± 1.8 sys ) × 10 −12 TeV −1 cm −2 s −1 . The integral flux above 0.2 TeV amounts to (5.2 ± 0.9) × 10 −11 cm −2 s −1 . Conclusions. Four objects coincident with HESS J1646-458 are discussed in the search of a counterpart, namely the magnetar CXOU J164710.2−455216, the X-ray binary 4U 1642-45, the pulsar PSR J1648-4611 and the massive stellar cluster Wd 1. In a single-source scenario, Wd 1 is favoured as site of VHE particle acceleration. Here, a hadronic parent population would be accelerated within the stellar cluster. Beside this, there is evidence for a multi-source origin, where a scenario involving PSR J1648-4611 could be viable to explain parts of the VHE γ-ray emission of HESS J1646-458.

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Discovery of Nonthermal X-Ray Emission from the Embedded Massive Star-forming Region RCW 38

Cited by 58 publications

References 18 publications

ACHANDRAOBSERVATION OF THE OBSCURED STAR-FORMING COMPLEX W40

ACHANDRAOBSERVATION OF THE OBSCURED STAR-FORMING COMPLEX W40

Star formation history of Canis Major R1

Discovery of extended VHEγ-ray emission from the vicinity of the young massive stellar cluster Westerlund 1

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