J/ApJ/871/215 JVLA rotation measures of Smith cloud bckg sources (Betti+, 2019)
Constraining the magnetic field of the Smith high-velocity cloud using Faraday
rotation.
Betti S.K., Hill A.S., Mao S.A., Gaensler B.M., Lockman F.J.,
McClure-Griffiths N.M., Benjamin R.A.
<Astrophys. J., 871, 215 (2019)>
=2019ApJ...871..215B 2019ApJ...871..215B
ADC_Keywords: Radio continuum; Polarization; Magnetic fields; Radio sources
Keywords: ISM: individual objects (Smith Cloud); ISM: magnetic fields;
polarization; radio continuum: general
Abstract:
The Smith Cloud is a high-velocity cloud with an orbit suggesting it
has made at least one passage through the Milky Way disk. A magnetic
field found around this cloud has been thought to provide extra
stability as it passes through the Galactic halo. We use the Karl G.
Jansky Very Large Array to measure Faraday rotation measures (RMs)
toward 1105 extragalactic background point sources behind and next to
the Smith Cloud to constrain the detailed geometry and strength of its
magnetic field. The RM pattern across the cloud gives the detailed
morphology of the magnetic field structure, which indicates a field
draped over the ionized gas and compressed at the head of the cloud.
We constrain the peak line-of-sight magnetic field strength to
≳+5µG and create a model of the magnetic field to demonstrate that
a draped configuration can qualitatively explain the morphology of the
observed RMs.
Description:
We observed 2847 extragalactic sources behind the Smith Cloud using
the upgraded Karl G. Jansky Very Large Array (JVLA) between 2012
October 19-December 8. The observations covered 1-2GHz in the A array
configuration (1.3" resolution). We detect 1105 rotation measures (RMs;
39% of observed sources) with a polarized intensity S/N≥4.
Objects:
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RA (ICRS) DE Designation(s)
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20 51.2 +01 41 Smith Cloud = NAME Smith Cloud
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 66 1105 Rotation measures
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See also:
II/249 : WHAM Northern Sky Survey, V-1.1 (Haffner+, 2003)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
J/ApJ/702/1230 : Rotation measure image of the sky (Taylor+, 2009)
J/ApJ/714/1170 : Faraday rotation at high Galactic latitude (Mao+, 2010)
J/MNRAS/467/1776 : Faraday rotation in Magellanic Bridge (Kaczmarek+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 F7.4 deg GLON [10.76/80] Galactic longitude (1)
9- 16 F8.4 deg GLAT [-44.5/-10.1] Galactic latitude
18- 25 F8.4 deg RAdeg [282.6/338.4] Right Ascension (J2000)
27- 34 F8.4 deg DEdeg [-27.4/23.7] Declination (J2000)
36- 40 F5.2 --- SN [3.05/25.8] Signal to Noise of the
Faraday depth spectrum
42- 48 F7.2 rad/m2 RM [-292.0/407.0] Raw rotation measure
50- 51 I2 rad/m2 e_RM [1/10] Uncertainty in RM
53- 59 F7.2 rad/m2 RMfit [-277.23/441.41] Milky Way foreground
subtracted rotation measure
61- 64 F4.1 rad/m2 e_RMfit [7.1/12.1] Uncertainty in RMfit
66 I1 --- T09 [0/1] Match to Taylor+ 2009, J/ApJ/702/1230
NVSS RM catalog (1=yes)
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Note (1): Data ordered by Galactic longitude.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 30-Jul-2020