On the Far-Infrared Emission of Quasars
On the Far-Infrared Emission of Quasars
复制标题
关于类星体的远红外发射
DOI：
--
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
E. Kreysa
中科院分区：
文献类型：
--
作者：
M. Haas;R. Chini;K. Meisenheimer;M. Stickel;D. Lemke;U. Klaas;E. Kreysa
用红外空间天文台观测了欧洲中央类星体计划的10个类星体和射电星系的子样本，得到了4.8 ~ 200 μm的红外光谱能量分布。对于其中三个源，这代表了第一次远红外探测。光谱能量分布（SEDs）显示了热尘埃和同步辐射的特征。在大多数情况下，两种成分中的一种占据主导地位，而另一种则被隐藏起来。射电安静型和陡峭谱类星体的SEDs在60 μm左右有一个凸起，在100 μm左右有一个下降，这是热发射的有力证据。它可以被描述为几个改进的黑体的叠加，显示出这些物体中存在的从热（≈600 K）到冷（≈30 K）尘埃的广泛温度变化。平谱射电类星体的红外发射是在射电光谱的平滑延续，支持同步辐射的解释。对于其中一个源（3C 279），在同步加速器光谱上方有一个凸起，我们将其解释为热辐射。为了在统一方案的框架内进行比较，我们观测了射电星系Cyg A （3C 405）和3C 20。虽然3C 20还没有被探测到，但Cyg A显示的红外光谱与3C 48和无线电安静类星体惊人地相似，这有力地支持了Cyg A是一个隐藏类星体的解释。
Infrared spectral energy distributions between 4.8 and 200 μm are presented for a subsample of 10 quasars and radio galaxies from the European Central Quasar Programme observed with the Infrared Space Observatory. For three of the sources, this represents the first far-infrared detection. The spectral energy distributions (SEDs) reveal signatures of thermal dust as well as synchrotron emission. In most cases, one of the two components is so dominant that the other remains hidden. The SEDs of the radio-quiet and steep-spectrum quasars show a bump around 60 μm and a decline longward of 100 μm—strong evidence for thermal emission. It can be described as a superposition of several modified blackbodies, showing the broad variety of temperatures from hot (≈ 600 K) to cool (≈ 30 K) dust present in these objects. The infrared emission of the flat-spectrum radio quasars is in smooth continuation of the radio spectrum, supporting the interpretation as synchrotron emission. For one of these sources (3C 279), a bump is prying above the synchrotron spectrum, and we interpret it as thermal emission. For comparison within the framework of unified schemes, the radio galaxies Cyg A (3C 405) and 3C 20 are observed. While 3C 20 has not been detected, Cyg A reveals an infrared spectrum surprisingly similar to that of 3C 48 and the radio-quiet quasars, which strongly supports the interpretation of the radio galaxy Cyg A as a hidden quasar.