J/MNRAS/430/1961 93.2GHz observations of 9C sources (Davies+, 2013)
The radio source count at 93.2GHz from observations of 9C sources using
AMI and CARMA.
Davies M.L., Stefan I.I., Bolton R.C., Carpenter J.M., Franzen T.M.O.,
Grainge K.J.B., Green D.A., Hobson M.P., Hurley-Walker N., Lasenby A.N.,
Olamaie M., Perrott Y.C., Pooley G.G., Riley J.M., Rodriguez-Gonzalvez C.,
Saunders R.D.E., Scaife A.M.M., Schammel M.P., Scott P.F., Shimwell T.W.,
Titterington D.J., Waldram E.M., Whittam I.H.
<Mon. Not. R. Astron. Soc., 430, 1961-1969 (2013)>
=2013MNRAS.430.1961D 2013MNRAS.430.1961D
ADC_Keywords: Radio sources ; Radio continuum
Keywords: surveys - galaxies: active - radio continuum: general
Abstract:
We present results from follow-up observations of a sample of 80 radio
sources, originally detected as part of the 15.2-GHz Ninth Cambridge
(9C) survey. The observations were carried out, close to
simultaneously, at two frequencies: 15.7GHz, using the Arcminute
Microkelvin Imager (AMI) Large Array, and 93.2GHz, using the Combined
Array for Research in Millimeter-wave Astronomy (CARMA). There is
currently little direct information on the 90-GHz-band source count
for S≲1Jy. However, we have used the measured 15.7-to-93.2-GHz
spectral-index distribution and 9C source count to predict the
differential source count at 93.2GHz as
26±4(S/Jy)-2.15Jy-1sr-1; our projection is estimated to be
most accurate for 10≲S≲100mJy. Our estimated differential count is
more than twice the 90-GHz prediction made by Waldram et al. (2007,
Cat. J/MNRAS/379/1442); we believe that this discrepancy is because
the measured 43-GHz flux densities used in making their prediction
were too low. Similarly, our prediction is significantly higher than
that of Sadler et al. (2008, Cat. J/MNRAS/385/1656) at 95GHz. Since
our spectral-index distribution is similar to the 20-to-95-GHz
distribution measured by Sadler et al. and used in making their
prediction, we believe that the difference is almost entirely
attributable to the dissimilarity in the lower frequency counts used
in making the estimates.
Description:
In this paper, results are presented from 93.2-GHz observations of 80
9C sources from the samples of Bolton et al. 2004, Cat. J/MNRAS/354/485.
The six 10.4-m diameter and nine 6.1-m diameter CARMA (Combined Array
for Research in Millimeter-wave Astronomy) antennas were used to make
93.2-GHz observations of the sources in the 00h field in nine days
between 2008 August 18 and 2008 October 4, and of the sources in the
15h field in nine days between 2009 June 14 and 2009 June 30.
The Arcminute Microkelvin Imager Large Array (AMI LA) was used to
carry out observations at 15.7GHz of the 00h-field sources between
2008 August 21 and 2008 August 24 and the 15h-field sources between
2009 June 16 and 2009 June 20.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 51 80 Measured 15.7-GHz and 93.2-GHz flux densities
for the 9C samples
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See also:
J/MNRAS/415/893 : AMI-LA 16 GHz sources in Perseus region (Scaife+, 2011)
J/MNRAS/404/1005 : Deep 15GHz survey (9C continued) (Waldram+, 2010)
J/MNRAS/385/1656 : Extragalactic radio-sources at 95GHz (Sadler+, 2008)
J/MNRAS/379/1442 : Multifrequency observations of 9C sources (Waldram+, 2007)
J/MNRAS/354/485 : Radio flux of 15-GHz 9C survey (Bolton+, 2004)
J/MNRAS/342/915 : 9C survey at 15GHz (Waldram+, 2003)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- 9C 9C identification (JHHMM+DDMM)
12- 16 F5.1 mJy S15.7 [11.8/381] 15.7GHz flux density
18- 21 F4.1 mJy e_S15.7 [0.7/20] S15.7 uncertainty
23 A1 --- l_S93.2 Limit flag on S93.2
25- 29 F5.1 mJy S93.2 [1.7/232] 93.2GHz flux density
31- 33 F3.1 mJy e_S93.2 [0.4/9] S93.2 thermal (Tml) uncertainty
35- 38 F4.1 mJy E_S93.2 0.5/24] S93.2 total uncertainty (1)
40 A1 --- l_alpha Limit flag on alpha
42- 46 F5.2 --- alpha [-0.6/1.5] 15.7-to-93.2-GHz spectral index
48- 51 F4.2 --- e_alpha [0.07/0.5]? alpha uncertainty (2)
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Note (1): Total error including the overall absolute calibration uncertainty.
Note (2): The estimate of the error in the spectral index uses only the thermal
error in the 93.2-GHz flux density --the error in the overall 93.2-GHz
flux scale is included in our result as a systemic error as described
in Section 6.2. We assume that the spectral index error is
(((eS15.7/S15.7)2+(eS93.2/S93.2)2)/ln(93.2/15.7))0.5. For the
three sources that were not detected at the higher frequency, limits
on the 93.2-GHz flux density and spectral index are given.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 16-Dec-2013