J/ApJ/720/555 COLA. III. AGN in compact IR galaxies (Parra+, 2010)
COLA.
III. Radio detection of active galactic nucleus in compact moderate luminosity
infrared galaxies.
Parra R., Conway J.E., Aalto S., Appleton P.N., Norris R.P.,
Pihlstrom Y.M., Kewley L.J.
<Astrophys. J., 720, 555-568 (2010)>
=2010ApJ...720..555P 2010ApJ...720..555P
ADC_Keywords: Active gal. nuclei ; Galaxies, IR ; Morphology ; Radio continuum
Keywords: galaxies: active - galaxies: starburst - infrared: galaxies -
radio continuum: galaxies
Abstract:
We present results from 4.8GHz Very Large Array (VLA) and global very
long baseline interferometry (VLBI) observations of the northern half
of the moderate FIR luminosity (median LIR=1011.01L☉) COLA
(Compact Objects in Low-power AGNs) sample of star-forming galaxies.
VLBI sources are detected in a high fraction (20/90) of the galaxies
observed. The radio luminosities of these cores (∼1021W/Hz) are too
large to be explained by radio supernovae or supernova remnants and we
argue that they are instead powered by active galactic nuclei (AGNs).
These sub-parsec scale radio cores are preferentially detected toward
galaxies whose VLA maps show bright 100-500 parsec scale nuclear radio
components. Since these latter structures tightly follow the FIR to
radio-continuum correlation for star formation, we conclude that the
AGN-powered VLBI sources are associated with compact nuclear starburst
environments. The implications for possible starburst-AGN connections
are discussed. The detected VLBI sources have a relatively narrow
range of radio luminosity consistent with models in which intense
compact Eddington-limited starbursts regulate the gas supply onto a
central supermassive black hole. The high incidence of AGN radio cores
in compact starbursts suggests little or no delay between the
starburst phase and the onset of AGN activity.
Description:
Snapshot radio continuum observations for the COLA-N sources were
obtained using the VLA at 4.8GHz in two observing epochs (1998 Jun 23
and 2003 Jul 19) each of 24hr in length.
VLBI 4.8GHz snapshot observations at data rate 1Gbit/s per station
were conducted for the COLA North sample using the most sensitive
telescopes available in the European VLBI network (EVN). The first
epoch on 2005 February 27/28 used Eb (Effelsberg), Wb (Westerbork),
and Ar (Arecibo). The second epoch on 2005 May 6/7 used Eb, Wb, and
Jb1 (Jodrell Bank, Lovell telescope).
Optical spectroscopy observations were taken using the 60 inch CfA
telescope at Mt Hopkins, Arizona between 2001 February and October
using the FAST spectrograph. A grating of 300 lines/mm was used to
disperse light between 4000 and 7000Å and gave a spectral
resolution of 6Å.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 79 110 COLA North sample
table3.dat 65 110 Radio and optical observations and results
table4.dat 71 21 VLBI results
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See also:
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
II/156 : IRAS Faint Source Catalog, |b| > 10, Version 2.0 (Moshir+ 1989)
II/125 : IRAS catalogue of Point Sources, Version 2.0 (IPAC 1986)
J/AJ/138/1032 : Filling in the gaps in the 4.85GHz sky (Healey+, 2009)
J/ApJS/175/314 : VSOP 5GHz AGN survey V. (Dodson+, 2008)
J/A+A/416/35 : Radio Emission from VLA FIRST Survey AGN (Wadadekar, 2004)
J/A+A/409/115 : VLA imaging of IRAS 1 Jy ULIRG sample (Nagar+, 2003)
J/AJ/126/1607 : IRAS Revised Bright Galaxy Sample (Sanders+, 2003)
J/ApJ/554/803 : New VLA Sky Survey (NVSS) Cat of IRAS 2 Jy Galaxies (Yun+
2001)
J/A+A/342/378 : 6 and 20cm flux densities of radio galaxies (Gurvits+ 1999)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- IRAS IRAS name (G1)
13- 18 A6 --- OName Other name
20- 21 I2 h RAh VLA Hour of Right Ascension (J2000)
23- 24 I2 min RAm VLA Minute of Right Ascension (J2000)
26- 30 F5.2 s RAs VLA Second of Right Ascension (J2000)
32 A1 --- DE- VLA Sign of declination (J2000)
33- 34 I2 deg DEd VLA Degree of Declination (J2000)
36- 37 I2 arcmin DEm VLA Arcminute of Declination (J2000)
39- 43 F5.2 arcsec DEs VLA Arcsecond of Declination (J2000)
45 A1 --- IR [I] I: indicates an IRAS position;
not detected by VLA
47- 50 I4 km/s VHel NED Heliocentric velocity
52- 56 F5.1 Mpc DL Luminosity distance (1)
58- 62 F5.2 [Lsun] logLIR Log of IR luminosity
64- 68 F5.2 [W/Hz] logL1.4 Log of 1.4GHz luminosity (2)
70- 74 F5.2 [W/Hz] logLFIR Log of far IR spectral luminosity
76- 79 F4.2 [-] q1.4 Log ratio of far IR to 1.4GHz luminosities (3)
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Note (1): The luminosity distance DL for each source was calculated in NED
assuming the three attractor model of Mould et al. (2000ApJ...529..786M 2000ApJ...529..786M)
and the cosmological parameters derived from 5 year WMAP data
(Hinshaw et al. 2009ApJS..180..225H 2009ApJS..180..225H), i.e., Ωm=0.276,
Ων=0.726, and H0=70.5km/s.
Note (2): Calculated from the NVSS catalog (Condon et al. 1998, Cat. VIII/65).
Note (3): Infrared total flux densities were taken from the IRAS Point Source
Catalog (Beichman et al., Cat. II/125). In order to calculate
source infrared to radio (1.4GHz) ratios (q1.4) as defined by Helou et
al. (1985ApJ...298L...7H 1985ApJ...298L...7H) we calculated for each source an equivalent
FIR flux density from
SFIR=1.26x10-14(2.58f60+f100)/3.75x1012W/m2/Hz, where
f60 and f100 are the cataloged 60 and 100um IRAS flux densities.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- IRAS IRAS name (G1)
13- 17 A5 --- Array VLA array used
19- 21 A3 --- Morph VLA morphology class of 4.8GHz image (4)
23- 30 F8.2 mJy S4.8t ? Recovered 4.8GHz flux density
32- 36 F5.2 [-] q4.8 ? Log ratio of S4.8t to FIR flux densities
38- 42 F5.2 mJy S4.8c ? Total gaussian fitted 4.8GHz flux density (5)
44- 47 F4.2 arcsec amaj ? Fitted gaussian major axis (6)
49- 52 F4.2 arcsec bmin ? Fitted gaussian minor axis (6)
54- 57 F4.2 [K] logTb ? Log Peak 4.8GHz brightness temperature (7)
59- 61 A3 --- Epoch VLBI epoch(s) observed
62 A1 --- V [*] *: VLBI detection
64- 65 A2 --- Cl Optical class (G2)
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Note (4): VLA morphology class (as defined by Neff & Hutchings,
1992AJ....103.1746N 1992AJ....103.1746N) as follows:
C = Compact;
E = Extended;
CE = Compact plus Extended;
CER = Compact plus extended with ring;
U = Undetected.
Note (5): Fitted to brightest feature in VLA image (after removing VLBI
component, hence zero indicates that brightest feature was dominated
by the VLBI component).
Note (6): To peak VLA feature (FWHM), Note for IRAS15327+2340 (Arp 220) these
are for the western nucleus as taken from the literature (see Section 4.5).
Note (7): Of gaussian component (see Section 4.5).
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- IRAS IRAS name (G1)
13- 19 A7 --- OName Other name
21 A1 --- l_Eb-Wb Limit flag on Eb-Wb (1)
22- 25 F4.2 mJy Eb-Wb ? VLBI 4.8GHz flux obtained from the peak in the
Delay-Rate map (Effelsberg telescope)
27- 30 F4.2 mJy e_Eb-Wb ? 1σ uncertainty on Eb-Wb
32 A1 --- l_Eb-Jb1 Limit flag on Eb-Jb1 (1)
33- 36 F4.2 mJy Eb-Jb1 ? VLBI 4.8GHz flux obtained from the peak in the
Delay-Rate map (Jodrell Bank, Lovell telescope)
38- 41 F4.2 mJy e_Eb-Jb1 ? 1σ uncertainty on Eb-Jb1
43 A1 --- l_Eb-Ar Limit flag on Eb-Ar (1)
44- 51 F8.2 mJy Eb-Ar ? VLBI 4.8GHz flux obtained from the peak in the
Delay-Rate map (Arecibo)
53- 56 F4.2 mJy e_Eb-Ar ? 1σ uncertainty on Eb-Ar
57 A1 --- f_Eb-Ar [n] Flag on Arp 220 (2)
59 A1 --- l_ASize Limit flag on ASize
60- 63 F4.2 mas ASize ? Angular size (3)
65 A1 --- l_LSize Limit flag on LSize
66- 69 F4.2 pc LSize ? Corresponding fitted Gaussian FWHM linear size
71 A1 --- Cl Optical class (G2)
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Note (1): Upper limits for the non-detections are indicated at 5σ.
Note (2):
n = For IRAS15327+2340 (Arp 220) on the longer baselines the two rows give
results for the west and east nuclei, respectively.
Note (3): FWHM of a circular Gaussian source fitting the flux ratio between the
Eb-Wb and Eb-Ar baselines (see Section 4.3). Sources with flux upper
limits on the Eb-Ar have consequently size lower limits.
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Global notes:
Note (G1): IRAS Name (from Point Source Calalog (Cat. II/125), excepting
F07258+3357 which is taken from the Faint Source Catalog,
Cat. II/156).
Note (G2): Optical class as follows:
H = HII;
S = Seyfert;
L = LINER;
C = Composite
- = no optical line data
See Section 4.6 for further details.
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History:
From electronic version of the journal
References:
Corbett et al. First results. 2002ApJ...564..650C 2002ApJ...564..650C
Corbett et al. Paper II. 2003ApJ...583..670C 2003ApJ...583..670C
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 26-Jun-2012