J/A+A/693/A202 GOODS-N field polarisation results (Berger+, 2025)
Polarisation results from the GOODS-N field with Apertif and polarised source
counts.
Berger A., Adebahr B., Wright A.H., Hildebrandt H., Dettmar R.-J.,
Adams E.A.K., Denes H., Hess K.M., Morganti R., Damstra S., Kutkin A.,
Loose G.M., Mika A., Oostrum L.C., van Leeuwen J., Ziemke J.
<Astron. Astrophys. 693, A202 (2025)>
=2025A&A...693A.202B 2025A&A...693A.202B (SIMBAD/NED BibCode)
ADC_Keywords: Radio sources ; Radio continuum ; Polarization
Keywords: magnetic fields - polarization - galaxies: active -
cosmology: observations - radio continuum: general
Abstract:
We analysed six Apertif datasets, covering the GOODS-N LOFAR deep
field region, aiming to improve our understanding of the faint radio
source composition, their polarisation behaviour, and how this affects
our interpretation of polarised source counts.
Using a semi-automatic routine, we ran rotation measure synthesis to
generate a polarised intensity mosaic for each observation. The
routine also performs source finding and cross-matching with the total
power catalogue, as well as NVSS, SDSS and allWISE, to obtain a
catalogue of 1182 polarised sources in an area of 47.4deg2. Using
the mid-infrared (MIR) radio correlation, we found no indication of
any polarised emission from star formation. To robustly estimate the
source counts, we performed an investigation of our sample's
completeness as a function of the polarised flux via synthetic source
injection.
In contrast to previous works, we find no strong dependency of
fractional polarisation on the total intensity flux density. We argue
that differences regarding previous (small-scale, deep field) analyses
can be attributed to sample variance. Relative to the findings of
previous works, here we find a steeper slope for our
Euclidean-normalised differential source counts. This is also visible
as a flattening in cumulative source counts.
We attribute the observed steeper slope in Euclidean normalised
differential source counts to a change in the source composition and
properties at low total intensities.
Description:
The sources detected in polarised intensity from 6 Apertif
observations are presented. The catalogue contains information on
their measured polarised and total intensity with Apertif (L-Band) as
well as results from crossmatches with NVSS, allWISE and SDSS.
This catalogue provides one row per component, where each component
also contains full information on the compete source. Components that
belong to the same source share the same ID. Only sources with a
fractional polarisation of at least 1% and polarised intensity
≥90muJy are catalogued.
A description of the columns can also be found in the appendix of the
paper and in Adebahr et al. (2022A&A...663A.103A 2022A&A...663A.103A).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 1200 1465 Polarised source catalogue
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See also:
J/ApJ/653/1027 : TKRS/GOODS-N Field galaxies (Weiner+, 2006)
J/ApJ/689/687 : GOODS-N spectroscopic survey (Barger+, 2008)
J/ApJ/762/46 : SHARDS: GOODS-N spectrophotometry survey
(Perez-Gonzalez+, 2013)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- ID Source ID as assigned by Aperpol
(APGN_ddd.ddd+dd.ddd)
21- 38 F18.14 deg RAdeg Right ascension of polarised source (J2000)
40- 61 E22.16 deg e_RAdeg Right ascension uncertainty (J2000)
63- 80 F18.15 deg DEdeg Declination of polarised source
82- 103 E22.16 deg e_DEdeg Declination uncertainty
105- 126 E22.16 Jy PIIsl Polarised intensity of source measured
in island
128- 149 E22.16 Jy e_PIIsl Polarised intensity uncertainty
151- 172 E22.16 Jy PIfit Polarised intensity measured by fitting
the source
174- 195 E22.16 Jy e_PIfit Polarised intensity uncertainty
197 A1 --- SCode [SEFC] S_Code (1)
199- 216 F18.14 deg RAcdeg Right ascension of polarised component
218- 233 E16.9 deg e_RAcdeg Right ascension uncertainty
235- 251 F17.14 deg DEcdeg Declination of the polarised component
253- 268 E16.9 deg e_DEcdeg Declination uncertainty
270- 285 E16.9 Jy PIcIsl Polarised intensity of the source, the
component belongs to, measured in island
287- 302 E16.9 Jy e_PIcIsl Polarised intensity uncertainty
304- 319 E16.9 Jy PIcfit Polarised intensity measured by fitting
the component
321- 336 E16.9 Jy e_PIcfit Polarised intensity uncertainty
338- 353 E16.9 Jy PIcPeak Peak polarised intensity from fitting
355- 370 E16.9 Jy e_PIcPeak Peak polarised intensity uncertainty
372- 393 E22.16 Jy PIrms rms of the polarised intensity of
the island
395- 397 I3 --- IslId Island ID
399- 421 F23.18 deg RMc Rotation measure of the component
423- 443 F21.17 deg e_RMc Rotation measure uncertainty
445- 461 A17 --- TP ID of the associated Apertif total
intensity source (TP_ddd.ddd+dd.ddd)
463- 483 F21.19 Jy TPTI Total intensity of the source
485- 506 E22.16 Jy e_TPTI Total intensity uncertainty
508- 525 F18.14 deg RATdeg Right ascension of the total intensity
source
527- 548 E22.16 deg e_RATdeg Right ascension uncertainty
550- 567 F18.15 deg DETdeg Declination ot the total intensity source
569- 590 E22.16 deg e_DETdeg Declination uncertainty
592- 611 F20.18 --- FPIsl Fractional polarisation of the source
calculated using PIIsl
613- 634 F22.20 --- e_FPIsl Fractional polarisation uncertainty
636- 656 F21.19 --- FPfit Fractional polarisation of the source
calculated using PIfit
658- 679 F22.20 --- e_FPfit Fractional polarisation uncertainty
681- 700 F20.18 Jy NVSS-I ?=- Total intensity from the NVSS
702- 722 F21.19 Jy e_NVSS-I ?=- NVSS total intensity uncertainty
724- 744 F21.19 Jy NVSS-PI ?=- Polarised intensity from the NVSS
746- 767 F22.20 Jy e_NVSS-PI ?=- NVSS polarised intensity uncertainty
769- 788 F20.18 --- NVSS-FP ?=- Fractional polarisation from the NVSS
790- 810 F21.19 --- e_NVSS-FP ?=- NVSS fractional polarisation
uncertainty
812- 816 F5.1 --- NVSS-RM ?=- Rotation measure from the NVSS
818- 821 F4.1 --- e_NVSS-RM ?=- NVSS rotation measure uncertainty
823- 840 F18.14 deg RANdeg ?=- Right ascension of the NVSS source
842- 845 F4.2 s e_RANdeg ?=- Right ascension uncertainty
847- 864 F18.15 deg DENdeg ?=- Declination of the NVSS source
866- 868 F3.1 arcsec e_DENdeg ?=- Declination uncertainty
870- 888 A19 --- WISE ID of the crossmatched allWISE source
890- 907 F18.14 deg RAWdeg ?=- Right ascension of the allWISE source
909- 914 F6.4 arcsec e_RAWdeg ?=- Right ascension uncertainty
916- 925 F10.7 deg DEWdeg ?=- Declination of the allWISE source
927- 932 F6.4 arcsec e_DEWdeg ?=- Declination uncertainty
934- 939 F6.3 mag [3.4] ?=- allWISE magnitude in W1
941- 945 F5.3 mag e_[3.4] ?=- W1 uncertainty
947- 950 F4.1 --- SNRW3.4 ?=- W1 signal to noise ratio
952- 957 F6.3 mag [4.6] ?=- allWISE magnitude in W2
959- 963 F5.3 mag e_[4.6] ?=- W2 uncertainty
965- 968 F4.1 --- SNRW4.6 ?=- W2 signal to noise ratio
970- 975 F6.3 mag [12] ?=- allWISE magnitude in W3
977- 981 F5.3 mag e_[12] ?=- W3 uncertainty
983- 986 F4.1 --- SNRW12 ?=- W3 signal to noise ratio
988- 992 F5.3 mag [22] ?=- allWISE magnitude in W4
994- 998 F5.3 mag e_[22] ?=- W4 uncertainty
1000-1003 F4.1 --- SNRW22 ?=- W4 signal to noise ratio
1005-1026 A22 --- SDSS ID of the crossmatched SDSS source
1028-1043 F16.12 deg RASdeg ?=- Right ascension of the SDSS source
1045-1060 F16.13 deg DESdeg ?=- Declination of the SDSS source
1062-1069 F8.5 mag umag ?=- Magnitude in u-filter from SDSS
1071-1081 F11.9 mag e_umag ?=- u-filter magnitude uncertainty
1083-1090 F8.5 mag gmag ?=- Magnitude in g-filter from SDSS
1092-1102 F11.9 mag e_gmag ?=- g-filter magnitude uncertainty
1104-1111 F8.5 mag rmag ?=- Magnitude in r-filter from SDSS
1113-1123 F11.9 mag e_rmag ?=- r-filter magnitude uncertainty
1125-1132 F8.5 mag imag ?=- Magnitude in i-filter from SDSS
1134-1144 F11.9 mag e_imag ?=- i-filter magnitude uncertainty
1146-1157 F12.6 mag zmag ?=- Magnitude in z-filter from SDSS
1159-1173 F15.9 mag e_zmag ?=- z-filter magnitude uncertainty
1175-1184 F10.8 --- zSDSS ?=- Spectroscopic redshift from SDSS
1186-1197 E12.6 --- e_zSDSS ?=- Redshift uncertainty
1199-1200 I2 --- GN Original image the source was taken
from (see paper Sect. 2.3 for details)
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Note (1): S-code as follows:
S = for unresolved sources
E = for resolved sources
F = if an island got split
C = for manually flagged sources
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Acknowledgements:
Anna Berger, aberger(at)physik.uni-bielefeld.de
(End) Patricia Vannier [CDS] 19-Dec-2024