J/A+A/472/805 Radio-X-ray sources in the HDF(N) region. (Richards+, 2007)
Using VO tools to investigate distant radio starbursts hosting obscured AGN in
the HDF(N) region.
Richards A.M.S., Muxlow T.W.B., Beswick R., Allen M.G., Benson K.,
Dickson R.C., Garrett M.A., Garrington S.T., Gonzalez-Solarez E.,
Harrison P.A., Holloway A.J., Kettenis M.M., Laing R.A., Richards E.A.,
Thrall H., van Langevelde H.J., Walton N.A., Wilkinson P.N., Winstanley N.
<Astron. Astrophys. 472, 805 (2007)>
=2007A&A...472..805R 2007A&A...472..805R
ADC_Keywords: Radio sources ; X-ray sources ; Active gal. nuclei
Keywords: astronomical data bases: miscellaneous - X-rays: galaxies -
radio continuum: galaxies -- galaxies: active -- galaxies: starburst -
galaxies: evolution
Description:
This catalogue lists the properties of 62 radio sources in the Hubble
Deep Field (North) and Flanking Fields (HDFN) which were also detected
by the Chandra X-ray satellite (see Alexander et al., 2003, Cat.
J/AJ/126/539, file cdfn). This includes 55/92 sources brighter than
40uJy detected by MERLIN+VLA at 1.4GHz (see Muxlow et al., 2005, Cat.
J/MNRAS/358/1159, Richards, 2000, Cat. J/ApJ/533/611); some were
also detected by the VLA at 8.4GHz (Richards et al.,
1998AJ....116.1039R 1998AJ....116.1039R) including 7 selected at this frequency. The
cross-matching, derivation of properties and analysis are described
fully in the paper. The radio data have a positional accuracy of 15
mas with respect to the ICRS (Muxlow et al., 2005, Cat.
J/MNRAS/358/1159) but data using the GOODS HST ACS (Giavalisco et
al., 2004, Cat. II/261) positions requires a shift of -342mas in
Declination for alignment with the ICRS.
We use measurements taken from the radio observations and from the
literature to compile the flux densities, sizes and spectral/photon
indices of the cross-matched radio+X-ray sources and their redshifts
(where available), enabling us to derive the rest-frame luminosities.
The 1.4-GHz detections are all resolved at 0.2-2arcsec resolution.
The radio emission was classified using the source morphologies and
radio spectral indices; optical and IR information was used as
supporting evidence only. On this basis, starbursts outnumber radio
AGN 3:1. The high-redshift starbursts have typical sizes of 5-10kpc
and star formation rates of around 1000 Msun/yr, an order of magnitude
more extended and intense than in the local universe. The X-ray
sources are unresolved but their luminosity and spectral indices
allows X-ray AGN and obscured (Type II) AGN to be identified
(2004A&A...424..545P 2004A&A...424..545P). In this way, we can distinguish between the
origins of radio and X-ray emission from the same object.
There is no obvious correlation between radio and X-ray luminosities
nor spectral indices at z>1.3. About 70% of both the radio-selected
AGN and the starburst samples were detected by Chandra. The X-ray
luminosity indicates the presence of an AGN in at least half of the 45
cross-matched radio starbursts. Eleven of these are type-II AGN, of
which 7 are at z>1.5. This distribution overlaps closely with the
X-ray detected radio sources which were also detected by SCUBA. Almost
all extended radio starbursts at z>1.3 host X-ray selected obscured
AGN. The radio emission from most of these ultra-luminous objects is
dominated by star formation although the highest redshift (z=4.424)
source has a substantial AGN contribution. Star-formation appears to
contribute less than 1/3 of their X-ray luminosity. Our results
support the inferences from SCUBA and IR data, that at z>1.5, star
formation is observably more extended and more copious, it is closely
linked to AGN activity and it is triggered differently, compared with
star formation at lower redshifts.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table12.dat 244 62 Properties of radio-X-ray sources in and around
the HDF(N) (table 1 and 2 of the paper)
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See also:
J/AJ/126/539 : The Chandra Deep Fields North and South (Alexander+, 2003)
J/MNRAS/358/1159 : Radio sources in HDF and HFF (Muxlow+, 2005)
J/ApJ/533/611 : 1.4GHz survey in HDF region (Richards+, 2000)
Byte-by-byte Description of file: table12.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name IAU-like name of radio source
16- 17 I2 h RAh Right Ascension ICRS (hr)
19- 20 I2 min RAm Right Ascension ICRS (min)
22- 28 F7.4 s RAs Right Ascension ICRS (sec)
30 A1 --- DE- Declination ICRS (sign)
31- 32 I2 deg DEd Declination ICRS (deg)
34- 35 I2 arcmin DEm Declination ICRS (arcmin)
37- 42 F6.3 arcsec DEs Declination ICRS (arcsec)
44- 56 F13.9 deg RAdeg Right Ascension ICRS (decimal degrees)
58- 70 F13.10 deg DEdeg Declination ICRS (decimal degrees)
72- 77 F6.1 uJy S1.4GHz Radio Flux Density at 1.4 GHz (VLA)
79- 82 F4.1 arcsec LAS ? Largest Angular Size (MERLIN+VLA)
84 A1 --- l_R.SI [<>e] Flag on radio spectral index if it is
a limit (<>) or an estimate (e) (see paper)
85- 89 F5.2 --- R.SI Radio spectral index between 1.4-8.4GHz
(S varies as frequency-R.SI)
91- 94 F4.2 --- e_R.SI Error in spectral index in low direction
96- 99 F4.2 --- E_R.SI Error in spectral index in high direction
101 A1 --- n_z [sp] Redshift origin is photometric (p)
or spectroscopic (s)
103-108 F6.4 --- z ? Redshift of associated optical/IR source
110-115 F6.4 --- e_z ? Error in Redshift
117-135 A19 --- r_z Redshift reference (Bibcode)
137-140 F4.2 arcsec R-Xsep Angular separation of radio and X-ray peaks
142-144 I3 --- [ABB2003] X-ray source number in J/AJ/126/539/cdfn
146-150 F5.2 aW/m2 FX Xray flux density 0.5-8.0 keV (Chandra)
152 A1 --- f_X.SI [<>e] Flag if X-ray photon index if it is
a limit (<>) or an estimate (e) (see paper)
153-157 F5.2 --- X.SI X-ray photon index between 0.5-2, 2-8keV
(F varies as Energy-X.SI)
159-162 F4.2 --- e_X.SI Error in photon index in low direction
164-167 F4.2 --- E_X.SI Error in photon index in low direction
169 A1 --- ISO [I] Detection by ISO at 7 and/or 15um (1)
171 A1 --- Spitzer [S] Detection by Spitzer at 16um (1)
173-175 A3 --- SMM Detection by SCUBA at 850um (SMM) (1)
177-184 E8.3 W/Hz L1.4GHz ? Rest frame 1.4-GHz radio luminosity
186-193 E8.3 W/Hz L1.4lo ? Lower bound to 1.4-GHz radio luminosity
195-202 E8.3 W/Hz L1.4up ? Upper bound to 1.4-GHz radio luminosity
204-210 A7 --- Rclass Radio source class: AGN, SB (Starburst),
or U (Unknown)
211-218 E8.3 W LX ? Rest frame full-band X-ray luminosity
220-227 E8.3 W LXlo ? Rest frame full-band X-ray luminosity
lower bound
229-236 E8.3 W LXup ? Rest frame full-band X-ray luminosity
upper bound
238-244 A7 --- Xclass X-ray characteristics of
AGN (AGN-X) or obscured AGN (AGN-II)
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Note (1): ISO, Spitzer and SCUBA data used did not cover the whole
radio+X-ray field.
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Acknowledgements:
Anita M. S. Richards, a.m.s.richards(at)manchester.ac.uk
(End) Patricia Vannier [CDS] 06-Sep-2007