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arXiv 0909.2650astro-ph.CO
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z ~ 2尘埃云的红外亮度和尘埃性质

Infrared Luminosities and Dust Properties of z ~ 2 Dust-Obscured Galaxies

R. S. Bussmann, Arjun Dey, C. Borys, V. Desai, B. T. Jannuzi, E. Le Floc'h, J. Melbourne, K. Sheth, B. T. Soifer

摘要:

我们提出了SHARC-II 350微米成像的12个24微米亮(F_24微米> 0.8毫焦)的尘埃遮蔽的镓(DOG)和CARMA 1毫米成像的一个子集的2个DOG,所有选择从Bootes领域的NOAO深宽视场调查。在350微米的4个DOG的检测意味着红外光度是一致的,在2的因素内的预期的基础上,一个温暖的尘埃光谱能量分布(SED)缩放到所观察到的24微米的通量密度。8个未检测到的DOG的350 um上限与Mrk 231和M82(暖尘SED)一致,但不包括冷尘(Arp 220)SED。在我们的CARMA观测中没有检测到目标为1 mm的两个DOG,这对尘埃温度有很强的限制:T_dust > 35-60 K。假设这些尘埃性质适用于整个样本,我们发现尘埃质量约为3x10^8 M_sun。与其他z ~ 2尘埃星系群如亚毫米星系(SMG)和其他Spitzer选择的高红移源相比,DOG样品具有更高的红外光度(2 × 10^13 L_sun与其他星系群的6 × 10^12 L_sun),更温暖的尘埃温度(>35-60 K vs. ~30 K),以及较低的推断尘埃质量(3x10^8 M_sun vs. 3x10^9 M_sun)。赫歇尔和SCUBA-2调查应该能够检测到数百个这样的幂律主导的狗。我们使用HST和斯皮策/IRAC数据来估计这些源的恒星质量,并发现在我们的24 μ m明亮的DOG样本中,恒星与气体的质量比可能高于SMG和其他斯皮策选择的源。虽然需要更大的样本量来提供一个明确的结论,数据是一致的演化趋势,在z~2的大质量星系的形成涉及一个亚毫米明亮,冷尘埃和恒星形成为主的阶段,其次是24 μ m明亮,温暖的尘埃和活动星系核为主的阶段。

英文摘要:

We present SHARC-II 350um imaging of twelve 24um-bright (F_24um > 0.8 mJy) Dust-Obscured Galaxies (DOGs) and CARMA 1mm imaging of a subset of 2 DOGs, all selected from the Bootes field of the NOAO Deep Wide-Field Survey. Detections of 4 DOGs at 350um imply IR luminosities which are consistent within a factor of 2 of expectations based on a warm dust spectral energy distribution (SED) scaled to the observed 24um flux density. The 350um upper limits for the 8 non-detected DOGs are consistent with both Mrk231 and M82 (warm dust SEDs), but exclude cold dust (Arp220) SEDs. The two DOGs targeted at 1mm were not detected in our CARMA observations, placing strong constraints on the dust temperature: T_dust > 35-60 K. Assuming these dust properties apply to the entire sample, we find dust masses of ~3x10^8 M_sun. In comparison to other dusty z ~ 2 galaxy populations such as sub-millimeter galaxies (SMGs) and other Spitzer-selected high-redshift sources, this sample of DOGs has higher IR luminosities (2x10^13 L_sun vs. 6x10^12 L_sun for the other galaxy populations), warmer dust temperatures (>35-60 K vs. ~30 K), and lower inferred dust masses (3x10^8 M_sun vs. 3x10^9 M_sun). Herschel and SCUBA-2 surveys should be able to detect hundreds of these power-law dominated DOGs. We use HST and Spitzer/IRAC data to estimate stellar masses of these sources and find that the stellar to gas mass ratio may be higher in our 24um-bright sample of DOGs than in SMGs and other Spitzer-selected sources. Although larger sample sizes are needed to provide a definitive conclusion, the data are consistent with an evolutionary trend in which the formation of massive galaxies at z~2 involves a sub-millimeter bright, cold-dust and star-formation dominated phase followed by a 24um-bright, warm-dust and AGN-dominated phase.

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