STAR FORMATION IN MASSIVE CLUSTERS VIA THE WILKINSON MICROWAVE ANISOTROPY PROBE AND THE SPITZER GLIMPSE SURVEY
STAR FORMATION IN MASSIVE CLUSTERS VIA THE WILKINSON MICROWAVE ANISOTROPY PROBE AND THE SPITZER GLIMPSE SURVEY
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通过威尔金森微波各向异性探测器和斯皮策掠影巡天观察大质量星团中的恒星形成
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发表时间：
2009
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通讯作者：
Mubdi Rahman
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作者：
N. Murray;Mubdi Rahman
我们使用威尔金森微波各向异性探测器的最大熵方法前景发射图，结合预先确定的到巨型H II区的距离来测量地球的自由-自由通量和银河系的自由-自由光度。我们得到了总通量fν=54,211 Jy和88个源的通量fν=36,043 Jy。大多数源至少是边缘分辨的，平均半径∼60 pc，电子密度Ne∼9 cm−3，填充因子(在银河系气体盘上)。经尘埃校正后的总电离光子光度为Q=3.2x1053±5.1x1052 光子数 S−1，与以前的估算结果一致。我们使用掠过和中途空间实验(MSX)8 μm图像显示，大部分自由光度与半径为∼5-100 PC的气泡有关，平均半径为∼20 PC。这些气泡是泄漏的，因此气泡内发射的电离光子逃逸并激发气泡壁外的自由发射，产生比8 μm气泡更大的wmap源。我们认为WMAP源相当于Mezger所描述的扩展的低密度H II区。18个最亮的WMAP源发射的电离通量占银河系总电离通量的一半。这18个源有4×1051 S−1≲Q≲1.6×1052 S−1，相当于6×10~4 M☉≲M*≲2×10~5 M☉；其中一半到三分之二将位于中心大质量星团。我们将Q的测量转换为银河系恒星形成率(SFR)，其中误差仅反映自由光度的误差。然而，我们指出，我们的推论高度依赖于恒星初始质量函数高质量端的指数Γ≈1.35。对于1.21；Γ<；1.5，我们发现。我们还确定大麦哲伦星云的SFR值为0.14 M☉ yr−1，小麦哲伦星云的SFR值为0.015 M☉ yr−1。
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.