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
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:
FileName Lrecl Records Explanations
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
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
Bytes Format Units Label Explanations
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)
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) and the cosmological parameters derived from 5 year WMAP data (Hinshaw et al. 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) 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.
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
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)
Note (4): VLA morphology class (as defined by Neff & Hutchings, 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).
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
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)
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.
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.
History: From electronic version of the journal References: Corbett et al. First results. 2002ApJ...564..650C Corbett et al. Paper II. 2003ApJ...583..670C
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 26-Jun-2012
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