2009ApJ...706..184M

Query : 2009ApJ...706..184M

2009ApJ...706..184M - Astrophys. J., 706, 184-202 (2009/November-3)

Millimeter observations of a sample of high-redshift obscured quasars.

MARTINEZ-SANSIGRE A., KARIM A., SCHINNERER E., OMONT A., SMITH D.J.B., WU J., HILL G.J., KLOCKNER H.-R., LACY M., RAWLINGS S. and WILLOTT C.J.

Abstract (from CDS):

We present observations at 1.2 mm with Max-Planck Millimetre Bolometer Array (MAMBO-II) of a sample of z ≳ 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 and five out of 21 sources (24%) are detected at a significance of ≥3σ. Stacking all sources leads to a statistical detection of = 0.96±0.11 mJy and stacking only the non-detections also yields a statistical detection, with = 0.51±0.13 mJy. At the typical redshift of the sample, z = 2, 1 mJy corresponds to a far-infrared luminosity LFIR∼4 x1012 L☉. If the far-infrared luminosity is powered entirely by star formation, and not by active galactic nucleus heated dust, then the characteristic inferred star formation rate is ∼700 M☉/yr. This far-infrared luminosity implies a dust mass of Md∼3x108 M☉, which is expected to be distributed on ∼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 µm using SHARC-II, we present dust spectral energy distributions (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 ∼2-3 kpc. Comparison of our sample to other samples of z ∼ 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 SCOΔν = 630±50 mJy km/s, corresponding to LCO(3–2)= 3.2 x107 L☉, or a brightness-temperature luminosity of L'CO(3–2)= 2.4x1010 K km/s pc2. 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'CO(4–3)< 1x1010 K km/s pc2. Under the assumption that in these objects the high-J transitions are thermalized, we can estimate the molecular gas contents to be M☉ and <8x109 M☉, respectively. The estimated gas depletion timescales are τg = 4 Myr and <16 Myr, and low gas-to-dust mass ratios of Mg/Md= 19 and <20 are inferred. These values are at the low end but consistent with those of other high-redshift galaxies.

Abstract Copyright: ∼

Journal keyword(s): galaxies: active - galaxies: high-redshift - galaxies: nuclei - galaxies: starburst - infrared: galaxies - quasars: general

Simbad objects: 31

goto Full paper

goto View the references in ADS

Number of rows : 31
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 12317 1
2 4C 39.25 Bla 09 27 03.01394144 +39 02 20.8518067   17.17 17.00 16.486   ~ 1036 1
3 IRAS 12514+1027 Sy2 12 54 00.8097492312 +10 11 12.237857124   19.03 18.27     ~ 57 0
4 Z 294-4 Sy1 12 56 14.2341182928 +56 52 25.238373852   14.68 13.84     ~ 2096 3
5 Z 271-60 Sy2 13 44 42.1883001099 +55 53 13.596220922   15.68 14.91     ~ 958 3
6 IC 1127 SyG 15 34 57.22396 +23 30 11.6084   14.76 13.88     ~ 3090 4
7 6C 163718+572618 Bla 16 38 13.45629995 +57 20 23.9789828     16.90 16.94   ~ 381 1
8 3C 345 Bla 16 42 58.80997043 +39 48 36.9939552   16.81 16.59 16.84   ~ 1808 3
9 [MGC2004] J171311.078+595552.13 QSO 17 13 11.158 +59 55 51.53           ~ 9 0
10 AMS 2 QSO 17 13 15.9 +60 02 34           ~ 18 0
11 AMS 3 Sy1 17 13 40.193 +59 27 45.96           ~ 11 1
12 AMS 4 Sy1 17 13 40.481 +59 49 16.89       22.84   ~ 12 0
13 AMS 5 Sy1 17 13 42.7125 +59 39 20.323       24.90   ~ 18 1
14 AMS 6 Sy1 17 13 43.9 +59 57 15           ~ 20 0
15 [MGC2004] J171402.218+594829.22 QSO 17 14 02.243 +59 48 28.75           ~ 8 0
16 AMS 8 QSO 17 14 29.63016 +59 32 33.6516           ~ 14 0
17 AMS 9 Sy2 17 14 35.6379701904 +58 56 52.447436880           ~ 11 0
18 [MGC2004] J171620.080+594026.88 QSO 17 16 19.9980 +59 40 26.840           ~ 10 0
19 AMS 11 QSO 17 18 21.3 +59 40 27           ~ 12 0
20 AMS 12 Sy1 17 18 22.6 +59 01 55           ~ 17 0
21 SDSS J171844.39+592000.8 Sy1 17 18 44.380 +59 20 00.73       22.48   ~ 27 0
22 AMS 14 Sy1 17 18 45.5 +58 51 22       23.33   ~ 14 0
23 AMS 15 QSO 17 18 56.9 +59 03 24           ~ 10 0
24 AMS 16 QSO 17 19 42.1 +58 47 09           ~ 10 0
25 [YSF2007] MIPS 22558 QSO 17 20 45.17 +58 52 21.4       23.90   ~ 21 0
26 AMS 18 Sy1 17 20 46.3 +60 02 30           ~ 12 0
27 AMS 19 Sy1 17 20 48.0 +59 43 21           ~ 17 0
28 AMS 20 QSO 17 20 59.1190 +59 17 50.940           ~ 8 0
29 AMS 21 QSO 17 21 20.1 +59 03 48           ~ 11 0
30 EM* MWC 349 ** 20 32 45.499080 +40 39 36.74124   15.88 13.15 12.13   Bep 837 0
31 4C 06.69 Bla 21 48 05.45866779 +06 57 38.6041877   16.85 16.47 15.06   ~ 703 1

To bookmark this query, right click on this link: simbad:objects in 2009ApJ...706..184M and select 'bookmark this link' or equivalent in the popup menu