J/MNRAS/533/4068 POSSUM RMs and galaxy group associations (Anderson+, 2024)
Probing the magnetized gas distribution in galaxy groups and the cosmic web with
POSSUM Faraday rotation measures.
Anderson C.S., McClure-Griffiths N.M., Rudnick L., Gaensler B.M.,
O'Sullivan S.P., Bradbury S., Akahori T., Baidoo L., Bruggen M.,
Carretti E., Duchesne S., Heald G., Jung S.L., Kaczmarek J., Leahy D.,
Loi F., Ma Y.K., Osinga E., Seta A., Stuardi C., Thomson A.J.M.,
Van Eck C., Vernstrom T., West J.
<Mon. Not. R. Astron. Soc. 533, 4068-4080 (2024)>
=2024MNRAS.533.4068A 2024MNRAS.533.4068A (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, group ; Galaxies, radio ; Magnetic fields ; Polarization
Keywords: magnetic fields - techniques: polarimetric -
galaxies: groups: general - intergalactic medium -
radio continuum: galaxies
Abstract:
We present initial results from the Polarisation Sky Survey of the
Universe's Magnetism (POSSUM), analyzing 22817 Faraday Rotation
Measures (RMs) with median uncertainties of 1.2rad/m2 across 1520
square degrees to study magnetized gas associated with 55 nearby
galaxy groups (z∼0.025) with halo masses between 1012.5 and
1014.0M☉. We identify two distinct gas phases: the Intragroup
Medium (IGrM) within 0-2 splashback radii and the Warm-Hot
Intergalactic Medium (WHIM) extending from 2 to 7 splashback radii.
These phases enhance the standard deviation of residual (i.e.,
Galactic foreground RM-subtracted) RMs by 6.9±1.8rad/m2 and
4.2±1.2rad/m2, respectively. Estimated magnetic field strengths
are several uG within the IGrM and 0.1-1uG in the WHIM. Our findings
indicate that 'missing baryons' in the WHIM likely extend beyond
the gravitational radii of group-mass halos to Mpc scales, consistent
with large-scale, outflow-driven 'magnetized bubbles' seen in
cosmological simulations. We demonstrate that RM grids are an
effective method for detecting magnetized thermal gas at galaxy group
interfaces and within the cosmic web. This approach complements X-ray
and Sunyaev-Zel'dovich effect methods, and when combined with Fast
Radio Burst Dispersion Measures, data from the full POSSUM survey -
comprising approximately a million RMs - will allow direct magnetic
field measurements to further our understanding of baryon circulation
in these environments and the magnetised universe.
Description:
Each row of this table is a POSSUM RM measurement, and the nearest
galaxy group association in the sense defined in the paper.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table.dat 397 22817 POSSUM Rotation Measure (RM) measurement
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table.dat
--------------------------------------------------------------------------------
Bytes Format Unit s Label Explanations
--------------------------------------------------------------------------------
1- 19 F19.15 deg RAdeg Right Ascension of RM source (J2000) (RAdeg)
21- 40 F20.16 deg DEdeg Declination of RM source (J2000) (DEdeg)
42- 46 I5 --- SBID ASKAP Telescope Scheduling Block ID (sbid)
48- 70 E23.16 rad/m2 peakRM Peak RM (peakRMradmm)
72- 91 F20.18 rad/m2 e_peakRM Error in Peak RM (peakRMerr_radmm)
93-118 F26.20 rad/m2 peakRMc Peak RM with foreground scalar correction
(peakRMforegroundcorrectedradmm)
120-142 F23.19 rad/m2 peakRMfor Peak RM with surrounding foreground scalar
(peakRMforegroundestimateradmm)
144-151 F8.3 mJy Ipeak Stokes I peak flux density
(stokesIpeakfluxdensity_mJy)
153-157 F5.3 mJy e_Ipeak Stokes I peak flux density
(stokesIpeakfluxdensityerrmJy)
159-179 F21.17 mJy PI Polarised intensity (polintmJy)
181-200 F20.18 mJy e_PI Error in polarised intensity
(polinterr_mJy)
202-221 F20.15 --- polsnr Signal-to-noise ratio of polarised intensity
(pol_snr)
223-241 F19.15 deg RAndeg Right Ascension of nearest group
(nearestgroupra_deg)
243-251 F9.5 deg DEndeg Declination of nearest group
(nearestgroupdec_deg)
253-258 I6 --- TnestID Tully NEST ID (tullynestID)
260-279 A20 --- MKnestID MK NEST ID (MKnestID)
280-309 F30.19 --- nearb Fiducial scaled impact parameter to nearest
group member
(nearestgroupscaledimpactparameter)
311-329 F19.17 deg nearr2td Angular size of splashback radius region
(nearestgroupangularr2t_degs)
331-349 F19.17 Mpc nearr2tM Physical size of splashback radius region
(nearestgroupr2tMpc)
351-368 F18.15 Mpc nearDist Distance to nearest group from Earth
(nearestgroupdistfromearth_Mpc)
370-375 F6.1 km/s nearRVcmb CMB-relative velocity of nearest group
(nearestgroupcmbrelativevelocitykmper_sec)
377-392 F16.1 Msun nearM Mass of nearest group
(nearestgroupnestmassMsol)
394-397 F4.1 --- nearNmemb Number of members in the nearest group
(nearestgroupnumberofmembers)
--------------------------------------------------------------------------------
History:
From Craig Anderson, Craig.Anderson(at)anu.edu.au
Acknowledgements:
The authors thank the reviewer, Russ Taylor, for his time and
comments, which have helped clarify the presentation of several
important aspects of our work. This scientific work uses data obtained
from Inyarrimanha Ilgari Bundara / the Murchison Radio-astronomy
Observatory. We acknowledge the Wajarri Yamaji People as the
Traditional Owners and native title holders of the Observatory site.
CSIRO's ASKAP radio telescope is part of the Australia Telescope
National Facility. Operation of ASKAP is funded by the Australian
Government with support from the National Collaborative Research
Infrastructure Strategy. ASKAP uses the resources of the Pawsey
Supercomputing Research Centre. Establishment of ASKAP, Inyarrimanha
Ilgari Bundara, the CSIRO Murchison Radio- astronomy Observatory and
the Pawsey Supercomputing Research Centre are initiatives of the
Australian Government, with support from the Government of Western
Australia and the Science and Industry Endowment Fund. The POSSUM
project has been made possible through funding from the Australian
Research Council, the Natural Sciences and Engineering Research
Council of Canada, the Canada Research Chairs Program, and the Canada
Foundation for Innovation. The Dunlap Institute is funded through an
endowment established by the David Dunlap family and the University of
Toronto. This work was partially funded by the Australian Government
through an Australian Research Council Australian Laureate Fellowship
(project number FL210100039) to N.Mc-G.. B.M.G. acknowledges the
support of the Natural Sciences and Engineering Research Council of
Canada (NSERC) through grant RGPIN-2015-05948, and of the Canada
Research Chairs program. CIRADA is funded by a grant from the Canada
Foundation for Innovation 2017 Innovation Fund (Project 35999), as
well as by the Provinces of Ontario, British Columbia, Alberta,
Manitoba and Quebec. TA was supported in part by JSPS KAKENHI Grant
Number, JP21H01135. SPO acknowledges support from the Comunidad de
Madrid Atraccion de Talento program via grant 2022-T1/TIC-23797.
(End) Patricia Vannier [CDS] 24-Jul-2024