STAR FORMATION IN MASSIVE CLUSTERS VIA THE WILKINSON MICROWAVE ANISOTROPY PROBE AND THE SPITZER GLIMPSE SURVEY

By N. Murray, Mubdi Rahman. 2009

135 citations recorded by the source corpus.

We use the Wilkinson Microwave Anisotropy Probe (WMAP) maximum entropy method foreground emission map combined with previously determined distances to giant H ii regions to measure the free–free flux at Earth and the free–free luminosity of the Galaxy. We find a total flux fν = 54, 211 Jy and a flux from 88 sources of fν = 36, 043 Jy. The bulk of the sources are at least marginally resolved, with mean radii ∼60 pc, electron density ne ∼ 9 cm−3, and filling factor (over the Galactic gas disk). The total dust-corrected ionizing photon luminosity is Q = 3.2 × 1053 ± 5.1 × 1052 photons s−1, in good agreement with previous estimates. We use GLIMPSE and Midcourse Space Experiment (MSX) 8 μm images to show that the bulk of the free–free luminosity is associated with bubbles having radii r ∼ 5–100 pc, with a mean of ∼20 pc. These bubbles are leaky, so that ionizing photons emitted inside the bubble escape and excite free–free emission beyond the bubble walls, producing WMAP sources that are larger than the 8 μm bubbles. We suggest that the WMAP sources are the counterparts of the extended low density H ii regions described by Mezger. The 18 most luminous WMAP sources emit half the total Galactic ionizing flux. These 18 sources have 4 × 1051 s−1 ≲ Q ≲ 1.6 × 1052 s−1, corresponding to 6 × 104 M☉ ≲ M* ≲ 2 × 105 M☉; half to two thirds of this will be in the central massive star cluster. We convert the measurement of Q to a Galactic star formation rate (SFR) , where the errors reflect only the error in free–free luminosity. We point out, however, that our inferred is highly dependent on the exponent Γ ≈ 1.35 of the high-mass end of the stellar initial mass function. For 1.21 < Γ < 1.5, we find . We also determine a SFR of 0.14 M☉ yr−1 for the Large Magellanic Cloud and 0.015 M☉ yr−1 for the Small Magellanic Cloud.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/d5ed9e21867c2467e330e46c0a6cedc012ec6e97

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Citations in the corpus

The RMS survey : Galactic distribution of massive star formation (2013, background): “A recent study of the Wilkinson Microwave Anisotropy Probe free–free foreground emission maps (Murray & Rahman 2010) found that the 18 most luminous Galactic star-forming regions are responsible for the production of over half of the total ionizing luminosity of Galaxy.”
MODELING THE METALLICITY DISTRIBUTION OF GLOBULAR CLUSTERS (2010, background): “There may even exist young star clusters with masses ∼105 M in the Galactic disk, hidden behind tens of visual magnitudes of extinction but revealing themselves through free–free emission of their ionization bubbles (Murray & Rahman 2010).”
Galaxy and Mass Assembly (GAMA): the star formation rate dependence of the stellar initial mass function (2011, methodology): “The measured low SFRs of the Magellanic Clouds (0.14 M yr−1 for the Large Magellanic Cloud and 0.015 M yr−1 for the Small Magellanic Cloud as given by Murray & Rahman 2010) and the measured IMF slopes for their stellar clusters being Salpeter or steeper (Massey et al. 1995) also agree with our…”
The role of dwarf galaxy interactions in shaping the Magellanic System and implications for Magellanic Irregulars (2012, methodology): “The fourth column presents a lower limit, determined from the free–free flux measured by Murray & Rahman (2010) using Wilkinson Microwave Anisotropy Probe.”
DIRECT NUMERICAL SIMULATION OF RADIATION PRESSURE-DRIVEN TURBULENCE AND WINDS IN STAR CLUSTERS AND GALACTIC DISKS (2012, background): “In contrast, a cluster of ZAMS stars drawn from a fully sampled IMF will have L/M∗ ≈ 10 3L⊙/M⊙ (Murray & Rahman 2010), an order of magnitude lower.”
Variations in the Galactic star formation rate and density thresholds for star formation (2012, methodology): “Values of the SFR for the CMZ in the literature vary by factors of several, but recent measurements based on number counts of massive young stellar objects, appear to converge to a value close to 0.1M⊙yr−1 (e.g. 0.14M⊙yr−1 and 0.08M⊙yr−1: Yusef-Zadeh et al. 2009; Immer et al. 2012).”
Star formation in semi-analytic galaxy formation models with multiphase gas (2015, background): “The local UV background relative to the MW is assumed to scale in proportion with the global SFR of the galaxy in the previous time step relative to the MW SFR, UMW = SFR SFRMW , where we choose SFRMW = 1.0M⊙ yr −1 (Murray & Rahman 2010; Robitaille & Whitney 2010).”
TOWARD A UNIFICATION OF STAR FORMATION RATE DETERMINATIONS IN THE MILKY WAY AND OTHER GALAXIES (2011, methodology): “For example, to calculate a total ionizing luminosity for the Milky Way from their catalog of WMAP H II regions, Murray & Rahman (2010) had to make at least three significant assumptions, each of which increases the Galactic SFR by ∼40–100% with large uncertainty: 1) they multiply their measured N…”
WHAT DRIVES THE EXPANSION OF GIANT H ii REGIONS?: A STUDY OF STELLAR FEEDBACK IN 30 DORADUS (2010, unknown): “Lastly, ψ is the ratio of bolometric power to the ionizing power in a cluster; we set ψ = 3.2 using the 〈S〉/〈M∗〉 and the 〈L〉/〈M∗〉 relations of Murray & Rahman (2010).”
RADIATION PRESSURE FROM MASSIVE STAR CLUSTERS AS A LAUNCHING MECHANISM FOR SUPER-GALACTIC WINDS (2010, methodology): “Examination of actively star forming regions in the Milky Way shows that the bubble walls are far from uniform; multiple shells, clumps, and ’elephant trunks’ (pillars pointing toward the center of the bubble) are common (Murray & Rahman 2010).”
Star formation rates and efficiencies in the Galactic Centre (2017, methodology): “Longmore et al. (2013a) used this catalogue and the free– free-to-SFR conversion presented by Murray & Rahman (2010), to estimate a global SFR of ∼0.06 M yr−1 within the region |l| < 1◦ and |b| < 0.5◦ (the same region adopted by this work).”
The big problems in star formation: The star formation rate, stellar clustering, and the initial mass function (2014, background): “Similarly, within the Milky Way, the amount of infrared or ionizing luminosity per unit molecular mass varies by several orders of magnitude from one giant molecular cloud to another (Mooney & Solomon 1988; Murray & Rahman 2010; Vutisalchavakul & Evans 2013).”
The lifecycle of molecular clouds in nearby star-forming disc galaxies (2019, background): “…range of typical expansion velocities found in nearby HII regions in the Milky Way, LMC, NGC300, and M33 (6−30 km s−1, see e.g. Bertoldi & McKee 1990; Murray & Rahman 2010; Hygate et al. 2019a; Kruijssen et al. 2019; McLeod et al. 2019b,a) and in numerical simulations of expanding HII regions…”
Evolution of the atomic and molecular gas content of galaxies (2013, methodology): “The local UV background relative to the MW is set by relating the SFR of the galaxy in the previous time step to the MW SFR as UMW = SFR SFRMW , where we choose SFRMW = 1.0M⊙ yr −1 (Murray & Rahman 2010; Robitaille & Whitney 2010).”
ATLASGAL - properties of a complete sample of Galactic clumps (2017, background): “We also know that a large fraction of the star formation is also further concentrated in large star forming complexes that can be associated with numerous GMCs (Murray & Rahman 2010, Urquhart et al. 2014b).”
STELLAR FEEDBACK IN MOLECULAR CLOUDS AND ITS INFLUENCE ON THE MASS FUNCTION OF YOUNG STAR CLUSTERS (2009, unknown): “…fwvw = 80 km s −1 (Matzner 2007). cBased on Equation (4) of Krumholz & Matzner (2009) for the blister case, with the coefficient reduced by a factor of 2.22 to correct an error in the published paper and updated with 〈L/M∗〉 = 1140L⊙M −1 ⊙ and 〈S/M∗〉 = 6.3× 10 46 s−1 M−1 ⊙ (Murray & Rahman 2010).”
OBSERVING THE NEXT GALACTIC SUPERNOVA (2013, methodology): “This SFR is consistent with direct estimates of the SFR, which range from 1 to 4 M yr−1 (e.g., McKee & Williams 1997; Murray & Rahman 2010; Robitaille & Whitney 2010; Chomiuk & Povich 2011; Davies et al. 2011).”
What controls star formation in the central 500 pc of the Galaxy (2013, background): “…SFR in the CMZ may therefore be spurious due to an overproduction of lowmass stars with respect to the observed massive stars, whether the SFR is determined using massive YSOs (Yusef-Zadeh et al. 2009) or the ionising flux from massive stars (Murray & Rahman 2010; Lee, Murray & Rahman 2012).”
STAR FORMATION EFFICIENCIES AND LIFETIMES OF GIANT MOLECULAR CLOUDS IN THE MILKY WAY (2010, methodology): “As shown by Murray & Rahman (2010), Rahman & Murray (2010), and this paper, there is solid evidence that stellar feedback disrupts the host GMC when a fractionǫGMC ≈ 0.08 of the GMC mass is converted 2 into stars.”