2014A&A...562A..67G


C.D.S. - SIMBAD4 rel 1.7 - 2019.10.23CEST10:59:54

2014A&A...562A..67G - Astronomy and Astrophysics, volume 562A, 67-67 (2014/2-1)

ALMA reveals a warm and compact starburst around a heavily obscured supermassive black hole at z = 4.75.

GILLI R., NORMAN C., VIGNALI C., VANZELLA E., CALURA F., POZZI F., MASSARDI M., MIGNANO A., CASASOLA V., DADDI E., ELBAZ D., DICKINSON M., IWASAWA K., MAIOLINO R., BRUSA M., VITO F., FRITZ J., FELTRE A., CRESCI G., MIGNOLI M., COMASTRI A. and ZAMORANI G.

Abstract (from CDS):

We report ALMA Cycle 0 observations at 1.3mm of LESS J033229.4-275619 (XID403), an ultraluminous infrared galaxy at z=4.75 in the Chandra Deep Field South hosting a Compton-thick QSO. The source is not resolved in our data at a resolution of ∼0.75-arcsec, placing an upper-limit of 2.5kpc to the half-light radius of the continuum emission from heated-dust. After deconvolving for the beam size, however, we found a ∼3σ indication of an intrinsic source size of 0.27±0.08-arcsec (Gaussian FWHM), which would correspond to rhalf∼0.9±0.3kpc. We build the far-infrared SED of XID403 by combining datapoints from both ALMA and Herschel and fit it with a modified blackbody spectrum. For the first time, we measure the dust temperature Td=58.5±5.3K in this system, which is comparable to what has been observed in other high-z submillimeter galaxies. The measured star formation rate is SFR=1020±150M/yr, in agreement with previous estimates at lower S/N. Based on the measured SFR and source size, we constrain the SFR surface density to be ΣSFR>26M/yr/kpc2 (∼200M/yr/kpc2 for rhalf∼0.9kpc). The compactness of this starburst is comparable to what has been observed in other local and high-z starburst galaxies. If the gas mass measured from previous [CII] and CO(2-1) observations at low resolution is confined within the same dust region, assuming rhalf∼0.9±0.3kpc, this would produce a column density of NH∼0.3-1.1x1024cm–2 towards the central SMBH, similar to the column density of ≃1.4x1024cm–2 measured from the X-rays. Then, in principle, if both gas and dust were confined on sub-kpc scales, this would be sufficient to produce the observed X-ray column density without any need of a pc-scale absorber (e.g. the torus postulated by Unified Models). We speculate that the high compactness of star formation, together with the presence of a powerful AGN, likely produce an outflowing wind. This would be consistent with the ∼350km/s velocity shift observed between the Lyα emission and the submm lines ([CII], CO(2-1), [NII]) and with the highly-ionized Fe emission line at ∼6.9keV rest-frame tentatively observed in the X-ray spectrum. Finally, our observations show that, besides the mass, star formation rate and gas depletion timescale, XID403 has also the right size to be one of the progenitors of the compact quiescent massive galaxies seen at z∼3.

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: high-redshift - X-rays: galaxies - submillimeter: galaxies

Simbad objects: 12

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Number of rows : 12

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 IRAS F00183-7111 Sy2 00 20 34.7 -70 55 27     20.6     ~ 121 0
2 NAME GOODS Southern Field reg 03 32 28.0 -27 48 30           ~ 996 1
3 NAME Chandra Deep Field-South reg 03 32 28.0 -27 48 30           ~ 1750 1
4 [LBX2017] 539 QSO 03 32 29.2912 -27 56 19.465     26.76 25.82 24.922 ~ 93 0
5 NAME Extended Chandra Deep Field South reg 03 32 30.0 -27 48 20           ~ 586 0
6 QSO J0403-3605 QSO 04 03 53.7499146834 -36 05 01.914911296   17.04 17.17 16.67   ~ 228 1
7 QSO B0537-441 BLL 05 38 50.36155219 -44 05 08.9389165   15.77 16.48 16   ~ 764 2
8 NAME COSMOS Field reg 10 00 28.60 +02 12 21.0           ~ 1883 0
9 2MASX J12151913-1429422 LIN 12 15 19.134 -14 29 42.23           ~ 35 0
10 IC 4553 SyG 15 34 57.22396 +23 30 11.6084   14.76 13.88     ~ 2621 4
11 NAME Superantennae Sy2 19 31 21.4252803168 -72 39 21.448768732   17.39 16.37 14.65   ~ 275 2
12 NAME Local Group GrG ~ ~           ~ 6661 0

    Equat.    Gal    SGal    Ecl

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2019.10.23-10:59:54

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