We present observations at 1.2 mm with MAMBO-II of a sample of z \mathrel { \hbox { \hbox to 0.0 pt { \hbox { \lower 2.0 pt \hbox { $ \sim$ } } } \raise 2.0 pt% \hbox { $ > $ } } } 2 radio-intermediate obscured quasars , as well as CO observations of two sources with the Plateau de Bure Interferometer .
The typical rms noise achieved by the MAMBO observations is 0.55 mJy beam ^ { -1 } and 5 out of 21 sources ( 24 % ) are detected at a significance of \geq 3 \sigma .
Stacking all sources leads to a statistical detection of \langle S _ { 1.2 ~ { } mm } \rangle = 0.96 \pm 0.11 mJy and stacking only the non-detections also yields a statistical detection , with \langle S _ { 1.2 ~ { } mm } \rangle = 0.51 \pm 0.13 mJy .
At the typical redshift of the sample , z = 2 , 1 mJy corresponds to a far-infrared luminosity L _ { FIR } \sim 4 \times 10 ^ { 12 } L _ { \odot } .
If the far-infrared luminosity is powered entirely by star-formation , and not by AGN-heated dust , then the characteristic inferred star-formation rate is \sim 700 M _ { \odot } yr ^ { -1 } .
This far-infrared luminosity implies a dust mass of M _ { d } \sim 3 \times 10 ^ { 8 } M _ { \odot } , which is expected to be distributed on \sim kpc scales .
We estimate that such large dust masses on kpc scales can plausibly cause the obscuration of the quasars .
Combining our observations at 1.2 mm with mid- and far-infrared data , and additional observations for two objects at 350 \mu m using SHARC-II , we present dust SEDs for our sample and derive a mean SED for our sample .
This mean SED is not well fitted by clumpy torus models , unless additional extinction and far-infrared re-emission due to cool dust are included .
This additional extinction can be consistently achieved by the mass of cool dust responsible for the far-infrared emission , provided the bulk of the dust is within a radius \sim 2-3 kpc .
Comparison of our sample to other samples of z \sim 2 quasars suggests that obscured quasars have , on average , higher far-infrared luminosities than unobscured quasars .
There is a hint that the host galaxies of obscured quasars must have higher cool-dust masses and are therefore often found at an earlier evolutionary phase than those of unobscured quasars .
For one source at z = 2.767 , we detect the CO ( 3-2 ) transition , with S _ { CO } \Delta \nu = 630 \pm 50 mJy km s ^ { -1 } , corresponding to L _ { CO ( 3 - 2 ) } = 3.2 \times 10 ^ { 7 } L _ { \odot } , or a brightness-temperature luminosity of L ^ { \prime } _ { CO ( 3 - 2 ) } = 2.4 \times 10 ^ { 10 } K km s ^ { -1 } pc ^ { 2 } .
For another source at z = 4.17 , the lack of detection of the CO ( 4-3 ) line suggests the line to have a brightness-temperature luminosity L ^ { \prime } _ { CO ( 4 - 3 ) } < 1 \times 10 ^ { 10 } K km s ^ { -1 } pc ^ { 2 } .
Under the assumption that in these objects the high-J transitions are thermalised , we can estimate the molecular gas contents to be M _ { H _ { 2 } } = 1.9 \times 10 ^ { 10 } M _ { \odot } and < 8 \times 10 ^ { 9 } M _ { \odot } , respectively .
The estimated gas depletion timescales are \tau _ { g } = 4 Myr and < 16 Myr , and low gas-to-dust mass ratios of M _ { g } / M _ { d } = 19 and \leq 8 are inferred .
These values are at the low end but consistent with those of other high-redshift galaxies .