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J/A+A/513/A65    Rotation measures in the fourth Galactic quadrant (Nota+, 2010)

The large-scale magnetic field in the fourth Galactic quadrant. Nota T., Katgert P. <Astron. Astrophys., 513, A65-65 (2010)> =2010A&A...513A..65N
ADC_Keywords: Magnetic fields ; Interstellar medium ; Pulsars Keywords: Galaxy: structure - ISM: magnetic fields Abstract: We have re-examined the published rotation measures (RMs) of extragalactic point sources and pulsars with |b|<3° to study the magnetic field in the fourth Galactic quadrant. We reduced the influence of structure in electron density as much as possible by excluding objects for which Hα-data indicate large fluctuations in ne somewhere along the line of sight. We also excluded objects for which the RM may have been significantly "corrupted" by an intervening supernova remnant. We modelled RM(l), the longitude dependence of RM of the unaffected extragalactic sources and pulsars. We assumed several geometries for the large-scale field. All but one of those are based on logarithmic spiral arms (with various pitch angles and widths), while one has circular symmetry. We also made different assumptions about the large-scale ne-distribution. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 47 55 The rejected extragalactic sources table4.dat 47 107 The extragalactic sources with reliable rotation measure (RM) estimates table3.dat 93 47 The rejected pulsars (PSR) table5.dat 93 132 The pulsars with reliable RM estimates notes.dat 80 31 Individual notes
See also: VII/216 : H-alpha emission regions in Southern Milky Way (Rodgers+ 1960) Byte-by-byte Description of file: table[24].dat
Bytes Format Units Label Explanations
1- 6 F6.2 deg GLON Galactic longitude 8- 12 F5.2 deg GLAT Galactic latitude 14- 18 I5 rad/m2 RM Rotation measure 20- 21 I2 rad/m2 e_RM rms uncertainty on RM 23- 26 I4 --- IHa Hα intensity (undefined unit "R") 28 I1 --- stepHa [1/3]? Rejection reason (1) (G1) 30- 34 A5 --- HII HII region RCW number(s) (1) 36- 45 A10 --- SNR SNR name (1) 47 A1 --- n_SNR [*] * indicates source rejected by Haverkorn (2008ApJ...680..362H), confirmed with 2.4GHz survey
Note (1): Only in table2.dat (rejected extragalactic sources).
Byte-by-byte Description of file: table[35].dat
Bytes Format Units Label Explanations
1- 10 A10 --- PSR PSR name (JHHMM-DDMM or BHHMM-DD) 12- 17 F6.2 deg GLON Galactic longitude 19- 23 F5.2 deg GLAT Galactic latitude 25- 28 I4 pc/cm3 DM Dispersion measure 30- 34 F5.2 kpc Dist Physical distance 36- 40 I5 rad/m2 RM Rotation measure 42- 43 I2 rad/m2 e_RM rms uncertainty on RM 45- 47 I3 --- IHa Hα intensity 49 I1 --- stepHa [1/3]? Rejection reason (G1) (1) 50 A1 --- n_stepHa [ns] Note on Hastep, in notes.dat file (1) 52- 59 A8 --- HII HII region name (RCW number) (1) 61- 63 F3.1 --- DHII ? Distance of the HII region (1) 64- 66 A3 --- n_DHII Note on DHII, in notes.dat file (1) 67 A1 --- --- [;,] 68- 70 F3.1 --- DHII2 ? Second distance of the HII region (1) 71 A1 --- n_DHII2 Note on DHII2, in notes.dat file (1) 73- 84 A12 --- SNR SNR name (1) 86 A1 --- l_DSNR Limit flag on DSNR (1) 87- 90 F4.2 kpc DSNR ? Distance of the SNR (1) 91- 93 A3 --- n_DSNR Note on DSNR, in notes.dat file (1)
Note (1): Only for table3.dat (rejected PSR).
Byte-by-byte Description of file: notes.dat
Bytes Format Units Label Explanations
1 A1 --- Note Note code 3- 80 A78 --- Text Text of the note
Globla notes: Note (G1): Rejection Hα step as follows: 1 = We guarded against Hα intensities that are exceptional on a small but not on a larger angular scale by rescinding the verdict "unreliable" if the Hα intensity towards the object was exceeded by more than 10% of the Hα intensities in (one of) the larger square(s). Clearly, the verdict "unreliable" cannot be rescinded when based on the data in the largest square. This procedure finds sources that are at a significant local maximum within a rather uniform Hα intensity, or near mostly (but not exclusively) small HII regions (step 1). 2 = To identify sources close to a local maximum on a strong Hα-intensity gradient (say, towards the edge of an HII region), we divided each of the 3 rectangular areas centered on the object in 4 quadrants and applied the above test to the 4 subareas. If this showed the object to be at a local maximum on an Hα-intensity gradient, we checked that the gradient was likely to be caused by a nearby (<0.5°) HII region (step 2). 3 = Finally, we also checked whether the object was in the direction of a known large HII region (e.g., from the RCW catalogue, Rodgers et al., 1960, Cat. VII/216), which might not have been evident from either of the above tests (step 3).
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 20-Jun-2011
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