Recent star formation in the inner Galactic Bulge seen by ISOGAL

Schüller, F.; Omont, A.; Glass, Ian S.; Schultheis, M.; Egan, M. P.; Price, S. D.

doi:10.1051/0004-6361:20052891

Cited by 14 publications

(25 citation statements)

References 30 publications

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“…We find that 97% of the sources fulfill the minimum criteria of F E > F D , which are the flux measurements at 14.65 μm (D-band) and 21.3 μm (E-Band), and this corresponds to a rising SED towards longer wavelengths. Schuller et al (2006) use a selection criteria of F E /F D ≥ 2, and from our matches we find that 1165 fulfill this, which is 77% of the sources with reliable flux measurements in both of these bands. Lumsden et al (2002) adopts a less conservative requirement by using F E ≥ 2 × F A , and we find that 86% of our matches fulfill this, where F A corresponds to the flux in the A band of MSX (8 μm).…”

Section: Association With Msxmentioning

confidence: 70%

“…For the most complex region in the Galactic center, Schuller et al (2006) estimates 10% of the sources to be actually diffuse PDR emission rather than protostellar sources.…”

Section: Association With Msxmentioning

confidence: 99%

“…For the eventual matching between the ATLASGAL and WISE positions, we did not use any color requirements, but the above derived limiting angular offset. We then put a further constraint on the matched sources by requiring a S /N > 10 for the 22 μm band WISE measurements in order to ensure their nature as embedded sources instead of a chance alignment with a field star or evolved stars, which are not detected at 22 μm (see, e.g., Schuller et al 2006). We discuss in more detail the justification and the color properties of these matches in Sect.…”

Section: Association With Wisementioning

confidence: 99%

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The ATLASGAL survey: a catalog of dust condensations in the Galactic plane

Csengeri¹,

Urquhart²,

Schüller³

et al. 2014

A&A

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215

402

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Context. The formation processes and the evolutionary stages of high-mass stars are poorly understood compared to low-mass stars. Large-scale surveys are needed to provide an unbiased census of high column density sites that can potentially host precursors to high-mass stars. Aims. The ATLASGAL survey covers 420 sq. degree of the Galactic plane, between −80 • < < +60 • at 870 μm. Here we identify the population of embedded sources throughout the inner Galaxy. With this catalog we first investigate the general statistical properties of dust condensations in terms of their observed parameters, such as flux density and angular size. Then using mid-infrared surveys we aim to investigate their star formation activity and the Galactic distribution of star-forming and quiescent clumps. Our ultimate goal is to determine the statistical properties of quiescent and star-forming clumps within the Galaxy and to constrain the star formation processes. Methods. We optimized the source extraction method, referred to as MRE-GCL, for the ATLASGAL maps in order to generate a catalog of compact sources. This technique is based on multiscale filtering to remove extended emission from clouds to better determine the parameters corresponding to the embedded compact sources. In a second step we extracted the sources by fitting 2D Gaussians with the Gaussclumps algorithm. Results. We have identified in total 10861 compact submillimeter sources with fluxes above 5σ. Completeness tests show that this catalog is 97% complete above 5σ and >99% complete above 7σ. Correlating this sample of clumps with mid-infrared point source catalogs (MSX at 21.3 μm and WISE at 22 μm), we have determined a lower limit of 33% that is associated with embedded protostellar objects. We note that the proportion of clumps associated with mid-infrared sources increases with increasing flux density, achieving a rather constant fraction of ∼75% of all clumps with fluxes over 5 Jy/beam being associated with star formation. Examining the source counts as a function of Galactic longitude, we are able to identify the most prominent star-forming regions in the Galaxy. Conclusions. We present here the compact source catalog of the full ATLASGAL survey and investigate their characteristic properties. From the fraction of the likely massive quiescent clumps (∼25%), we estimate a formation time scale of ∼7.5 ± 2.5 × 10 4 yr for the deeply embedded phase before the emergence of luminous young stellar objects. Such a short duration for the formation of high-mass stars in massive clumps clearly proves that the earliest phases have to be dynamic with supersonic motions.

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Section: Association With Msxmentioning

confidence: 70%

“…For the most complex region in the Galactic center, Schuller et al (2006) estimates 10% of the sources to be actually diffuse PDR emission rather than protostellar sources.…”

Section: Association With Msxmentioning

confidence: 99%

Section: Association With Wisementioning

confidence: 99%

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The ATLASGAL survey: a catalog of dust condensations in the Galactic plane

Csengeri¹,

Urquhart²,

Schüller³

et al. 2014

A&A

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215

402

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“…• 089 (Omont et al 2003; Schuller et al 2006). On the other hand, quiescent giant molecular clouds such as G0.25−0.01 (Lis & Carlstrom 1994; appear to contain highly inefficient star formation.…”

Section: Introductionmentioning

confidence: 99%

Star Formation in the Central 400 Pc of the Milky Way: Evidence for a Population of Massive Young Stellar Objects

Yusef‐Zadeh

Hewitt

Arendt

et al. 2009

ApJ

204

264

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The central kpc of the Milky Way might be expected to differ significantly from the rest of the Galaxy with regard to gasdynamics and the formation of young stellar objects (YSOs). We probe this possibility with midinfrared observations obtained with Infrared Array Camera and Multiband Imaging Photometer on Spitzer and with Midcourse Space Experiment. We use color-color diagrams and spectral energy distribution (SED) fits to explore the nature of YSO candidates (including objects with 4.5 μm excesses possibly due to molecular emission). There is an asymmetry in the distribution of the candidate YSOs, which tend to be found at negative Galactic longitudes; this behavior contrasts with that of the molecular gas, approximately 2/3 of which is at positive longitudes. The small-scale height of these objects suggests that they are within the Galactic center region and are dynamically young. They lie between two layers of infrared dark clouds and may have originated from these clouds. We identify new sites for this recent star formation by comparing the mid-IR, radio, submillimeter, and methanol maser data. The methanol masers appear to be associated with young, embedded YSOs characterized by 4.5 μm excesses. We use the SEDs of these sources to estimate their physical characteristics; their masses appear to range from ∼10 to ∼20 M . Within the central 400 × 50 pc (|l| < 1.• 3 and |b| < 10 ) the star formation rate (SFR) based on the identification of Stage I evolutionary phase of YSO candidates is about 0.14 M yr −1 . Given that the majority of the sources in the population of YSOs are classified as Stage I objects, we suggest that a recent burst of star formation took place within the last 10 5 yr. This suggestion is also consistent with estimates of SFRs within the last ∼10 7 yr showing a peak around 10 5 yr ago. Lastly, we find that the Schmidt-Kennicutt Law applies well in the central 400 pc of the Galaxy. This implies that star formation does not appear to be dramatically affected by the extreme physical conditions in the Galactic center region.

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“…The MSX project is a multiwavelength infrared survey of the entire Galactic plane in four spectral bands at 8, 12, 15, and 21 μm with a spatial resolution of ∼18 . Schuller et al (2006) (hereafter: Paper I) defined selection criteria based on the [7]- [15] ISOGAL color (where [7] and [15] are the magnitudes at 7 and 15 μm, respectively, measured with ISO), as well as the magnitude uncertainty at 15 μm, σ 15 (residual between the fitted point spread function and the actual source profile, see Schuller et al 2003), which serves as a parameter for the spatial extension of the source (explained below). These criteria were established from a group of point sources from the ISOGAL point source catalog…”

Section: Introductionmentioning

confidence: 99%

Recent star formation in the inner Galactic bulge seen by ISOGAL

Immer

Schüller

Omont

et al. 2012

A&A

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122

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We present 5-38 μm spectroscopic observations of a sample of 68 ISOGAL sources with unknown natures, taken with the Spitzer Infrared Spectrograph. Based on the characteristics and the slope of their spectra, we classified the sources as young or late-type evolved objects. These sources were selected to test selection criteria based on the ISOGAL [7]-[15] color and the spatial extent parameter σ 15 . We revised these criteria until they reliably distinguished between young and late-type evolved objects and then applied them to all ISOGAL sources in the central molecular zone (CMZ), resulting in the selection of 485 sources believed to be young. Furthermore, we added 656 Midcourse Space Experiment (MSX) sources to the CMZ sample that fulfilled F E /F D > 2 with F D and F E being the flux densities in the D (15 μm) and E (21 μm) bands. After obtaining L bol F 15 conversion factors, we calculated the bolometric luminosity, L bol , values for the CMZ sample and subsequently the masses of the sources. Applying a Kroupa initial mass function, we derived the total mass in young objects that have been formed over the last 1 Myr, resulting in an average star formation rate of 0.08 solar masses per year for the CMZ.

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Recent star formation in the inner Galactic Bulge seen by ISOGAL

Cited by 14 publications

References 30 publications

The ATLASGAL survey: a catalog of dust condensations in the Galactic plane

The ATLASGAL survey: a catalog of dust condensations in the Galactic plane

Star Formation in the Central 400 Pc of the Milky Way: Evidence for a Population of Massive Young Stellar Objects

Recent star formation in the inner Galactic bulge seen by ISOGAL

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