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 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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 109 76 2MASS sample and measurements
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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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)
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Note (1): Objects identified as [HMC2003] JHHMMSS.ss+DDMMSS.s 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.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 26-Sep-2003