CS Studies of Dense Cores in Regions of High Mass Star Formation: A Survey of Southern Molecular Masers

Зинченко, И. И.; Lapinov, A. V.; Mattila, K.; Toriseva, M.

doi:10.1007/978-94-011-0147-9_156

Cited by 52 publications

(89 citation statements)

References 1 publication

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“…Zinchenko et al (1994) also chose this abundance ratio for the study of several CS cores. The derived H2 parameters are scaled by the abundance ratio and thus may vary by a factor of two.…”

Section: Cs Analysismentioning

confidence: 99%

ISM gas studies towards the TeV PWN HESS J1825−137 and northern region

Voisin¹,

Rowell²,

Burton³

et al. 2016

Mon. Not. R. Astron. Soc.

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HESS J1825−137 is a pulsar wind nebula (PWN) whose TeV emission extends across ∼ 1 deg. Its large asymmetric shape indicates that its progenitor supernova interacted with a molecular cloud located in the north of the PWN as detected by previous CO Galactic survey (e.g Lemiere, Terrier & Djannati-Ataï 2006).Here we provide a detailed picture of the ISM towards the region north of HESS J1825−137, with the analysis of the dense molecular gas from our 7mm and 12mm Mopra survey and the more diffuse molecular gas from the Nanten CO(1-0) and GRS 13 CO(1-0) surveys. Our focus is the possible association between HESS J1825−137 and the unidentified TeV source to the north, HESS J1826−130. We report several dense molecular regions whose kinematic distance matched the dispersion measured distance of the pulsar. Among them, the dense molecular gas located at (RA, Dec)=(18.421h,−13.282 • ) shows enhanced turbulence and we suggest that the velocity structure in this region may be explained by a cloud-cloud collision scenario.Furthermore, the presence of a Hα rim may be the first evidence of the progenitor SNR of the pulsar PSR J1826-1334 as the distance between the Hα rim and the TeV source matched with the predicted SNR radius R SNR ∼ 120 pc.From our ISM study, we identify a few plausible origins of the HESS J1826−130 emission, including the progenitor SNR of PSR J1826−1334 and the PWN G018.5−0.4 powered by PSR J1826−1256. A deeper TeV study however, is required to fully identify the origin of this mysterious TeV source.Key words: molecular data -pulsars: individual: PSR J1826−1334 -ISM: cloudscosmic-rays -gamma-rays: ISM. INTRODUCTIONHESS J1825−137 is one of the brightest and most extensive pulsar wind nebulae (PWNe) detected in TeV γ-rays (Aharonian et al. 2006). It is powered by the high spin-down power (ĖSD = 2.8 × 10 36 erg/s) pulsar PSR J1826−1334 with a dispersion measure distance of 3.9±0.4 kpc and characteristic age τc ∼ 20 kyr.PWNe represent a significant fraction of the Galactic TeV γ-ray source population. They convert a varying fraction of their pulsars' spin down energyĖSD into high energy E-mail:fabien.voisin@adelaide.edu.au (AVR); fabien.voisin@adelaide.edu.au (ANO) electrons. The electron flow is temporally randomized and re-accelerated at a termination shock resulting from pressure from the surrounding interstellar medium (ISM). InverseCompton (IC) up-scattering of soft photons then leads to TeV γ-rays, and associated synchrotron radio to X-ray emission.The morphology of PWNe can be heavily influenced by the ISM. The interaction of the progenitor supernova shock with adjacent molecular clouds can lead to a reverse shock propagating back into the PWN (Blondin, Chevalier & Frierson 2001), giving rise to an asymmetry in the radio, X-ray and γ-ray emission that can trail away from the pulsar along the pulsar-molecular cloud axis.HESS J1825−137 is an excellent example of this situa- Lemiere, Terrier & Djannati-Ataï (2006), with the bulk of the TeV γ-ray extending up to a degree south of the pulsar. In...

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“…Zinchenko et al (1994) also chose this abundance ratio for the study of several CS cores. The derived H2 parameters are scaled by the abundance ratio and thus may vary by a factor of two.…”

Section: Cs Analysismentioning

confidence: 99%

ISM gas studies towards the TeV PWN HESS J1825−137 and northern region

Voisin¹,

Rowell²,

Burton³

et al. 2016

Mon. Not. R. Astron. Soc.

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“…2) selected toward water maser positions: three sources in common ; zero sources in common (Zinchenko, Mattila, & Toriseva 1995); zero sources in common (Juvela 1996); and eight sources in common (Zinchenko, Pirogov, & Toriseva 1998). There is slightly more overlap of sources selected toward UCH ii regions or IRAS colors indicative of UCH ii regions: 24 sources in common (Bronfman, Nyman, & May 1996); six sources in common (Olmi & Cesaroni 1999); and three sources in common .…”

Section: The Samplementioning

confidence: 99%

A CS J = 5 → 4 Mapping Survey Toward High‐Mass Star‐forming Cores Associated with Water Masers

Shirley

Evans

Young

et al. 2003

ASTROPHYS J SUPPL S

201

258

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We have mapped 63 regions forming high-mass stars in CS J ¼ 5 ! 4 using the CSO. The CS peak position was observed in C 34 S J ¼ 5 ! 4 toward 57 cores and in 13 CS J ¼ 5 ! 4 toward the nine brightest cores. The sample is a subset of a sample originally selected toward water masers; the selection on maser sources should favor sources in an early stage of evolution. The cores are located in the first and second Galactic quadrants with an average distance of 5:3 AE 3:7 kpc and were well detected with a median peak signalto-noise ratio in the integrated intensity of 40. The integrated intensity of CS J ¼ 5 ! 4 correlates very well with the dust continuum emission at 350 lm. For 57 sufficiently isolated cores, a well-defined angular size (FWHM) was determined. The core radius (R CS ), aspect ratio [ða=bÞ obs ], virial mass (M vir ), surface density (AE), and the luminosity in the CS J ¼ 5 ! 4 line (LðCS54Þ) are calculated. The distributions of size, virial mass, surface density, and luminosity are all peaked with a few cores skewed toward much larger values than the mean. The median values, l 1/2 , are as follows: l 1/2 ðR CS Þ ¼ 0:32 pc, l 1/2 ðða=bÞ obs Þ ¼ 1:20, l 1/2 ðM vir Þ ¼ 920 M , l 1/2 ðAEÞ ¼ 0:60 g cm À2 , l 1/2 ðLðCS54ÞÞ ¼ 1:9 Â 10 À2 L , and l 1/2 ðL bol =M vir Þ ¼ 165 ðL=MÞ . We find a weak correlation between C 34 S line width and size, consistent with Dv $ R 0:3 . The line widths are much higher than would be predicted by the usual relations between line width and size determined from regions of lower mass. These regions are very turbulent. The derived virial mass agrees within a factor of 2-3 with mass estimates from dust emission at 350 lm after corrections for the density structure are accounted for. The resulting cumulative mass spectrum of cores above 1000 M can be approximated by a power law with a slope of about À0.9, steeper than that of clouds measured with tracers of lower density gas and close to that for the total masses of stars in OB associations. The median turbulent pressures are comparable to those in UCH ii regions, and the pressures at small radii are similar to those in hypercompact H ii regions (P=k $ 10 10 K cm À3 ). The filling factors for dense gas are substantial, and the median abundance of CS is about 10 À9 . The ratio of bolometric luminosity to virial mass is much higher than the value found for molecular clouds as a whole, and the correlation of luminosity with mass is tighter.

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“…At a distance of 1.7 kpc (Beck, Fischer, & Smith 1991), RCW 38 is one of the nearest star-forming regions containing an early O star. Dense molecular gas, as traced in CS emission J p 2 r 1 (Zinchenko, Mattila, & Toriseva 1995), surrounds a centimeter radio ring (T. L. Bourke et al 2002, in preparation) and appears to be confining the H ii region. The central region is essentially free of dust and molecular gas (Smith et al 1999;T.…”

Section: Introductionmentioning

confidence: 99%

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

Wolk

Bourke

Smith

et al. 2002

The Astrophysical Journal

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We report on results of a 96.7 ks Chandra observation of one of the youngest, most embedded and massive young stellar clusters studied to date in X-rays-RCW 38. We find a region of extended emission about 1.25 # pc. The emission is consistent with synchrotron emission. The power index of the emission steepens toward 1.75 the cluster core, implying that the magnetic field originates there. This is the first evidence of synchrotron emission filling a region of active star formation. The source of the necessary magnetic field is unclear. We measure the hydrogen column to the emission and find that N H increases from to cm , increasing from 21 22 Ϫ2

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CS Studies of Dense Cores in Regions of High Mass Star Formation: A Survey of Southern Molecular Masers

Cited by 52 publications

References 1 publication

ISM gas studies towards the TeV PWN HESS J1825−137 and northern region

ISM gas studies towards the TeV PWN HESS J1825−137 and northern region

A CS J = 5 → 4 Mapping Survey Toward High‐Mass Star‐forming Cores Associated with Water Masers

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

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