Herschel unveils a puzzling uniformity of distant dusty galaxies-猫眼课题宝

DOI：

10.1051/0004-6361/201014687

发表时间：

2010-05

期刊：

Astronomy and Astrophysics

影响因子：

6.5

通讯作者：

中科院分区：

物理与天体物理2区

文献类型：

作者：

D. Elbaz;H. Hwang;B. Magnelli;E. Daddi;H. Aussel;B. Altieri;A. Amblard;P. Andreani;V. Arumugam;R. Auld;T. Babbedge;S. Berta;A. Blain;J. Bock;J. Bock;Á. Bongiovanni;A. Boselli;V. Buat;D. Burgarella;N. Castro-RodrÍguez;A. Cava;J. Cepa;P. Chanial;R. Chary;A. Cimatti;D. Clements;A. Conley;L. Conversi;A. Cooray;A. Cooray;M. Dickinson;H. Dominguez;C. Dowell;C. Dowell;J. Dunlop;E. Dwek;S. Eales;D. Farrah;N. F. Schreiber;M. Fox;A. Franceschini;W. Gear;R. Genzel;J. Glenn;M. Griffin;C. Gruppioni;M. Halpern;E. Hatziminaoglou;E. Ibar;K. Isaak;R. Ivison;R. Ivison;G. Lagache;D. L. Borgne;E. Floc’h;L. Levenson;L. Levenson;N. Lu;D. Lutz;S. Madden;B. Maffei;G. Magdis;G. Mainetti;R. Maiolino;L. Marchetti;A. Mortier;Hien Nguyen;Hien Nguyen;R. Nordon;B. O’Halloran;K. Okumura;S. Oliver;A. Omont;M. Page;P. Panuzzo;A. Papageorgiou;C. Pearson;C. Pearson;I. Fournón;A. P. Garćıa;A. Poglitsch;M. Pohlen;P. Popesso;F. Pozzi;J. Rawlings;D. Rigopoulou;D. Rigopoulou;L. Riguccini;D. Rizzo;G. Rodighiero;I. Roseboom;M. Rowan‐Robinson;A. Saintonge;M. S. Portal;P. Santini;M. Sauvage;B. Schulz;D. Scott;N. Seymour;Lijing Shao;D. Shupe;Anthony J. Smith;J. Stevens;E. Sturm;M. Symeonidis;L. Tacconi;M. Trichas;K. Tugwell;Mattia Vaccari;I. Valtchanov;J. Vieira;L. Vigroux;L. Wang;R. Ward;G. Wright;C. Xu;M. Zemcov;M. Zemcov

赫歇尔空间天文台使我们能够通过直接采样其远红外（IR）发射的峰值来精确测量星暴星系和活动星系核（AGN）的辐射热输出。在这里，我们检查是否光谱能量分布（SED）和尘埃温度的星系强烈演变了过去80%的宇宙年龄。我们讨论了可能的后果的恒星形成率（SFR）的测定和任何证据的重大变化，他们的恒星形成的属性。我们使用100至500 μm的赫歇尔深河外星系巡天来计算星系中的总红外光度，直至最微弱的水平，并使用GOODS-North场的PACS和SPIRE（PEP和爱马仕关键计划）。通过在24 μm之前的位置上堆叠图像来实现对较暗光度的扩展。我们表明，在SPIRE波段的测量可以使用统计混乱的限制以下，如果使用更高的空间分辨率的信息，例如，在24 μm，以确定“孤立”的星系，其通量不被明亮的邻居。在z ~ 1.5以下，中红外外推对于色散仅为40%（0.15 dex）的恒星形成星系是正确的，因此与z ~ 0星系相似，在30年内亮度低于超亮红外星系（ULIRGs，L_（IR）≥ 10^（12）L_（12））。当考虑到可能影响这些星系SED的物理过程的范围时，这种狭窄的分布令人困惑。仅从160 μm、250 μm或350 μm波段中的一个波段进行外推往往会高估总的红外光度。这可能是由于在这些模板上缺乏Herschel之前约150 μm（静止帧）的远红外限制。我们还注意到，在z ~ 1附近的亮红外星系（LIRGs，L_（IR）≥ 10^（11）L_（11））的尘埃温度比它们的本地类似物略低10-15%，而在z ~ 1.6附近的超亮红外星系的尘埃温度可达20%（采用单一修正黑体拟合的远红外峰值发射率指数β = 1.5）。在z = 1.5以上，发现遥远的星系表现出明显更大的中-远红外比，这可能是由于更强的宽发射线或被隐藏的活动星系核加热的温暖的尘埃连续体。三分之二的活动星系核在测量红移的领域中表现出与纯粹的恒星形成星系相同的行为。因此，很大一部分活动星系核在非常高的SFR和类似于纯粹的恒星形成星系的条件下形成了同时代的星星。

The Herschel Space Observatory enables us to accurately measure the bolometric output of starburst galaxies and active galactic nuclei (AGN) by directly sampling the peak of their far-infrared (IR) emission. Here we examine whether the spectral energy distribution (SED) and dust temperature of galaxies have strongly evolved over the last 80% of the age of the Universe. We discuss possible consequences for the determination of starformation rates (SFR) and any evidence for a major change in their star-formation properties. We use Herschel deep extragalactic surveys from 100 to 500 μm to compute total IR luminosities in galaxies down to the faintest levels, using PACS and SPIRE in the GOODS-North field (PEP and HerMES key programs). An extension to fainter luminosities is done by stacking images on 24 μm prior positions. We show that measurements in the SPIRE bands can be used below the statistical confusion limit if information at higher spatial resolution is used, e.g. at 24 μm, to identify “isolated” galaxies whose flux is not boosted by bright neighbors. Below z ~ 1.5, mid-IR extrapolations are correct for star-forming galaxies with a dispersion of only 40% (0.15 dex), therefore similar to z ~ 0 galaxies, over three decades in luminosity below the regime of ultra-luminous IR galaxies (ULIRGs, L_(IR) ≥ 10^(12) L_⊙). This narrow distribution is puzzling when considering the range of physical processes that could have affected the SED of these galaxies. Extrapolations from only one of the 160 μm, 250 μm or 350 μm bands alone tend to overestimate the total IR luminosity. This may be explained by the lack of far-IR constraints around and above ~150 μm (rest-frame) before Herschel on those templates. We also note that the dust temperature of luminous IR galaxies (LIRGs, L_(IR) ≥ 10^(11) L_⊙) around z ~ 1 is mildly colder by 10–15% than their local analogs and up to 20% for ULIRGs at z ~ 1.6 (using a single modified blackbody-fit to the peak far-IR emission with an emissivity index of β = 1.5). Above z = 1.5, distant galaxies are found to exhibit a substantially larger mid- over far-IR ratio, which could either result from stronger broad emission lines or warm dust continuum heated by a hidden AGN. Two thirds of the AGNs identified in the field with a measured redshift exhibit the same behavior as purely star-forming galaxies. Hence a large fraction of AGNs harbor coeval star formation at very high SFR and in conditions similar to purely star-forming galaxies.

Herschel unveils a puzzling uniformity of distant dusty galaxies

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