A Complete CO Survey of M31. I. Distribution and Kinematics

Dame, T. M.; Koper, E.J.R.; Israel, F.P.; Thaddeus, P.

doi:10.1086/173430

Cited by 74 publications

(91 citation statements)

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“…Although the current starformation rate in M 31 is lower than that of the Milky Way, M 31 seems to have undergone more active star-formation periods. In addition to the well-known dust ring at a radius of ∼10 kpc (Brinks & Shane 1984;Dame et al 1993) that contains enhanced star formation, Block et al (2006) found an inner dust ring with a radius of 1-1.5 kpc, which had apparently been created in an encounter with a companion galaxy, most likely M 32.…”

Section: Introductionmentioning

confidence: 89%

Supernova remnants and candidates detected in theXMM-NewtonM 31 large survey

Sasaki

Pietsch

Haberl

et al. 2012

A&A

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Context. We present the analysis of supernova remnants (SNRs) and candidates in M 31 identified in the XMM-Newton large programme survey of M 31. Supernova remnants are among the brightest X-ray sources in a galaxy. They are good indicators of the recent star-formation activities of galaxies and the interstellar environment in which they evolve. Aims. By combining the X-ray data of sources in M 31 with optical data as well as optical and radio catalogues, we aim to compile a complete, revised list of SNRs emitting X-rays in M 31 detected with XMM-Newton, study their luminosity and spatial distributions, and understand the X-ray spectra of the brightest SNRs. Methods. We analysed the X-ray spectra of the 12 brightest SNRs and candidates that have been observed with XMM-Newton. Our study of the four brightest sources allowed us to perform a more detailed spectral analysis and compare different models to describe their spectrum. For all M 31 large programme sources, we searched for their optical counterparts in the Hα, [S ii], and [O iii] images of the Local Group Galaxy Survey. Results. We confirm 21 X-ray sources as counterparts to known SNRs. In addition, we identify 5 new X-ray sources as X-ray and optically emitting SNRs. Seventeen sources are no longer considered as SNR candidates. We thus create a list of 26 X-ray SNRs and 20 X-ray SNR candidates in M 31 based on their X-ray, optical, and radio emission, which is the most recent complete list of X-ray SNRs in M 31. The brightest SNRs have X-ray luminosities of up to 8 × 10 36 erg s −1 in the 0.35-2.0 keV band.

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Section: Introductionmentioning

confidence: 89%

Supernova remnants and candidates detected in theXMM-NewtonM 31 large survey

Sasaki

Pietsch

Haberl

et al. 2012

A&A

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“…Most of the data presented here were obtained with our two telescopes in their current conÐgurations, as described in Dame et al (1993) for the northern instrument and in Cohen (1983) for the southern. Because some of the surveys were obtained as long ago as 1980, however, we review below the major changes of instrumentation that have occurred since that time.…”

Section: Observationsmentioning

confidence: 99%

“…The most heavily used Ðlterbank has 500 kHz Ðlters, which at 115 GHz yield a velocity resolution of 1.3 km s~1 and a total velocity range of 332 km s~1Èwide enough to cover the full range of Galactic CO velocities with adequate baseline except toward the Galactic center, where each position required two velocity settings. The 500 kHz Ðlterbank was used for the surveys of the southern Galactic plane (and the LMC), then transferred to Cambridge in 1988 where it was used for the M31 survey (Dame et al 1993) and most subsequent work with the northern telescope. The northern telescope is also equipped with a 250 kHz Ðlterbank which was used for all surveys prior to 1988 and since then has been run in parallel with the 500 kHz Ðlterbank, providing higher velocity resolution (0.65 km s~1) and redundancy in the central 166 km s~1 of the observed band.…”

Section: Observationsmentioning

confidence: 99%

“…No molecular cloud is free of CO emission, which is generally the most easily observed molecular line, and GMCs throughout the Milky Way can be detected in this line even with a small telescope. It has been shown by three independent methods that the velocity-integrated intensity of the 1È0 line is not only a good qualitative tracer of molecular gas, but a fairly good quantitative tracer as well, providing the column density of to a factor of 2 or better when H 2 averaged over a suitably large region (cf.°4, and reviews by Barrett 1991 andDame 1993).…”

Section: Introductionmentioning

confidence: 99%

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The Milky Way in Molecular Clouds: A New Complete CO Survey

Dame

Hartmann

Thaddeus

2001

ApJ

Self Cite

2,143

178

2,713

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New large-scale CO surveys of the Ðrst and second Galactic quadrants and the nearby molecular cloud complexes in Orion and Taurus, obtained with the CfA 1.2 m telescope, have been combined with 31 other surveys obtained over the past two decades with that instrument and a similar telescope on Cerro Tololo in Chile, to produce a new composite CO survey of the entire Milky Way. The survey consists of 488,000 spectra that Nyquist or beamwidth sample the entire Galactic plane over a (1 8 ¡) strip 4¡È10¡ wide in latitude, and beamwidth or sample nearly all large local clouds at higher lati-1 4 ¡ tudes. Compared with the previous composite CO survey of Dame et al. (1987), the new survey has 16 times more spectra, up to 3.4 times higher angular resolution, and up to 10 times higher sensitivity per unit solid angle. Each of the component surveys was integrated individually using clipping or moment masking to produce composite spatial and longitude-velocity maps of the Galaxy that display nearly all of the statistically signiÐcant emission in each survey but little noise.The composite maps provide detailed information on individual molecular clouds, suggest relationships between clouds and regions widely separated on the sky, and clearly display the main structural features of the molecular Galaxy. In addition, since the gas, dust, and Population I objects associated with molecular clouds contribute to the Galactic emission in every major wavelength band, the precise kinematic information provided by the present survey will form the foundation for many large-scale Galactic studies.A map of molecular column density predicted from complete and unbiased far-infrared and 21 cm surveys of the Galaxy was used both to determine the completeness of the present survey and to extrapolate it to the entire sky at o b o \ 32¡. The close agreement of the observed and predicted maps implies that only D2% of the total CO emission at o b o \ 32¡ lies outside our current sampling, mainly in the regions of Chamaeleon and the Gum Nebula. Taking into account this small amount of unobserved emission, the mean molecular column density decreases from D3 ] 1020 cm~2 at o b o \ 5¡ to D0.1 ] 1020 cm~2 at o b o \ 30¡ ; this drop is D6 times steeper than would be expected from a planeparallel layer, but is consistent with recent measurements of the mean molecular column density at higher latitudes.The ratio of the predicted molecular column density map to the observed CO intensity map provides a calibration of the mass conversion factor Out of the Galactic plane, X shows little systematic variation with latitude from a mean value of (1.8^0.3) ] 1020 cm~2 K~1 km~1 s. Given the large sky area and large quantity of CO data analyzed, we conclude that this is the most reliable measurement to date of the mean X value in the solar neighborhood.

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“…Dame et al 1993, and references therein). The deep CO survey of molecular clouds in the southern Milky Way by Bronfman et al (1989) covers the 300…”

Section: Molecular Clouds Energetic Stellar Winds From Cen Ob1 and mentioning

confidence: 99%