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J/AJ/126/63      Host galaxies of 2MASS-QSOs with z≤3        (Hutchings+, 2003)

Host galaxies of 2MASS-selected QSOs to redshift 0.3. Hutchings J.B., Maddox N., Cutri R.M., Nelson B.O. <Astron. J. 126, 63 (2003)> =2003AJ....126...63H
ADC_Keywords: Active gal. nuclei ; QSOs ; Photometry ; Redshifts Keywords: galaxies: fundamental parameters - galaxies: interactions - infrared radiation - quasars: general Abstract: We present and discuss optical imaging of 76 active galactic nuclei (AGNs) that represent the selected Two Micron All Sky Survey (2MASS) sample for z<0.3, from a full list of 243. They are found to have dust-obscured nuclei, residing in host galaxies that show a high fraction (greater than 70%) of tidal interactions. The derived luminosities of the AGNs and host galaxies are similar to traditionally selected AGNs, and they may comprise some 40% of the total AGN population at low redshift. We have measured a number of host galaxy properties and discuss their distributions and interrelations. We compare the 2MASS AGNs with optically selected samples and the IRAS-selected galaxy samples and discuss the differences in terms of merger processes and initial conditions. Description: The observations were acquired as a CFHT "snapshot" proposal, during the first semester of 2002. The list of 243 QSOs was used as the target list for 200s integrations with the R-band filter and the CFHT 12K camera. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 109 76 2MASS sample and measurements
See also: II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 2 I2 h RAh Hour of right ascension (J2000) (1) 4- 5 I2 min RAm Minute of right ascension (J2000) (1) 7- 11 F5.2 s RAs Second of right ascension (J2000) (1) 13 A1 --- DE- Sign of the declination (J2000) (1) 14- 15 I2 deg DEd Degree of declination (J2000) (1) 17- 18 I2 arcmin DEm Arcminute of declination (J2000) (1) 20- 23 F4.1 arcsec DEs Arcsecond of declination (J2000) (1) 25 I1 --- NType QSO nuclear classification, from 2MASS 27- 31 F5.3 --- z Redshift 33- 36 F4.1 mag Jmag The 2MASS J-band magnitude 38- 41 F4.1 mag Kmag The 2MASS K-band magnitude 43- 46 F4.1 mag Bmag The USNOA-2.0 catalog B-band magnitude 48- 51 F4.1 mag Rmag The USNOA-2.0 catalog R-band magnitude 53- 55 F3.1 arcsec FWHM Image full width at half-maximum 57- 61 F5.2 mag QSOmag The QSO magnitude 63- 66 F4.1 mag Hostmag ? The host galaxy magnitude 68- 70 F3.1 --- HType [1/3] Host type (2) 72- 75 F4.1 mag Range ? Dynamic range (3) 77- 80 F4.1 mag/arcsec2 LSB ? Limiting surface brightness 82- 84 F3.1 --- Ellip ? Host galaxy ellipticity 86- 90 F5.1 mag RMAG ? Absolute R-band magnitude (4) 92 I1 --- Int [0/3] Interaction level index (5) 94- 98 F5.2 --- N/H ? The nuclear-to-host flux ratio 100-103 F4.2 mag/kpc Scale ? Luminosity scale length 105-108 F4.1 [W/Hz] S20cm ? The 20cm radio power (6)
Note (1): Objects identified as [HMC2003] in Simbad Note (2): The overall host galaxy "type" was quantified by measuring the best linear fit to the two types of plot. A clearly exponential profile is assigned a value 1.0, while a clearly spheroidal profile has value 2.0. In a number of cases, the profile was clearly one or the other, but had regions of poor fit. These were regarded as "disturbed" disks or spheroids and given values between 1 and 2, depending on the length of the profile lying outside the linear fit. A number of plots had different regions of good fit to the different profiles (usually resembling an inner bulge and outer disk structure), and these were given values of 1.3-1.7, depending on the relative lengths of the two regions of linear fit in the profiles. Finally, there were many host galaxies that are very irregular or asymmetrical and show no regions of linear fits in any plots. Usually, these are clearly merging or tidally disturbed galaxies, and they are given host type values of 3.0. Note (3): The dynamic range of each image is from QSO nucleus to lowest contour used Note (4): Based on H0=70km/s/Mpc, and no k-corrections have been applied. Note (5): For all host galaxies, we have assigned an "interaction level" index from 0 to 3. This is an attempt to quantify merging and tidal disturbances that have been associated with triggering of nuclear activity in many types of AGNs. Level 3 indicates large-scale and clear tidal disturbance, while level 0 indicates a symmetrical and undisturbed morphology. Other indicators in between include very asymmetrical arms, knots with connecting luminous bridges to the main galaxy, an off-centered nucleus, outer arcs, a warped disk, or nuclear jetlike features. This index was estimated independently by the two principal authors, with a high degree of agreement. Note (6): Based on positional coincidence to within 2" in the NVSS and FIRST radio surveys.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 26-Sep-2003
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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