- ID:
- ivo://CDS.VizieR/J/MNRAS/462/2266
- Title:
- RCW121 stars polarimetric study
- Short Name:
- J/MNRAS/462/2266
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a polarimetric study of the RCW121 star-forming region to derive the orientation of the sky-projected magnetic field component traced by the polarization vectors, the morphology of which tends to follow the cloud's structure. Individual polarization-angle values are consistent across the different bands, having a broad distribution towards the RCW121 HII region. We estimate the corresponding magnetic field orientation in the HII region to have a mean value of -12+/-7{deg}. RCW121 shows an elongated shape in the same direction as the magnetic field orientation, which may be evidence that magnetic pressure opposes the HII region expansion. Serkowski's relation was used to determine individual values of the total-to-selective extinction ratio (RV ) distribution and a weighted mean value of RV=3.17+/-0.05. We derive a foreground component of the polarization degree that is consistent with the literature value for this Galactic region.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/409/275
- Title:
- Rotation and magnetic field in omega Ori
- Short Name:
- J/A+A/409/275
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Omega Ori is a B2IIIe star for which rotational modulation and non-radial pulsations (NRP) have been recently investigated from two independent observational campaigns in 1998 and 1999. Putting the data of these 2 campaigns together, and adding data obtained in 2001, we search for multiperiodicity in the line profile variations and evidence for outbursts. From new spectropolarimetric data obtained at the Telescope Bernard Lyot (TBL, Pic du Midi, France) in 2001 we also measure the Stokes V parameter in the polarised light. We find evidence for the presence of a weak magnetic field in Omega Ori sinusoidally varying with a period of 1.29d. The equivalent widths (EW) of the wind sensitive UV resonance lines also show a variation with the same period, which we identify as the rotational period of the star. We propose an oblique rotator model and derive B_pol_=530+/-230G to explain the observations. Moreover, we carry out an abundance analysis and find the star to be N-enriched, a property which is shared with other magnetic stars. We propose Omega Ori as the first known classical Be star hosting a magnetic field.
- ID:
- ivo://CDS.VizieR/J/ApJ/702/1230
- Title:
- Rotation measure image of the sky
- Short Name:
- J/ApJ/702/1230
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have re-analyzed the NRAO VLA Sky Survey (NVSS) data to derive rotation measures (RMs) toward 37543 polarized radio sources. The resulting catalog of RM values covers the sky area north of declination -40{deg} with an average density of more than one RM per square degree. We have identified five regions of the sky where the foreground median RM is consistently less than 1rad/m^2^ over several degrees. These holes in the foreground RM will be useful for future studies of possible small-scale fluctuations in cosmic magnetic field structures. In addition to allowing measurement of RMs toward polarized sources, the new analysis of the NVSS data removes the effects of bandwidth depolarization for |RM|>~100rad/m^2^ inherent in the original NVSS source catalog.
- ID:
- ivo://CDS.VizieR/J/ApJ/759/25
- Title:
- Rotation measures at 1.4GHz toward the LMC
- Short Name:
- J/ApJ/759/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the magnetic field of the Large Magellanic Cloud (LMC), carried out using diffuse polarized synchrotron emission data at 1.4GHz acquired at the Parkes Radio Telescope and the Australia Telescope Compact Array. The observed diffuse polarized emission is likely to originate above the LMC disk on the near side of the galaxy. Consistent negative rotation measures (RMs) derived from the diffuse emission indicate that the line-of-sight magnetic field in the LMC's near-side halo is directed coherently away from us. In combination with RMs of extragalactic sources that lie behind the galaxy, we show that the LMC's large-scale magnetic field is likely to be of quadrupolar geometry, consistent with the prediction of dynamo theory. On smaller scales, we identify two brightly polarized filaments southeast of the LMC, associated with neutral hydrogen arms. The filaments' magnetic field potentially aligns with the direction toward the Small Magellanic Cloud (SMC). We suggest that tidal interactions between the SMC and the LMC in the past 10^9^ years are likely to have shaped the magnetic field in these filaments.
- ID:
- ivo://CDS.VizieR/J/ApJ/642/868
- Title:
- Rotation measures for 223 pulsars
- Short Name:
- J/ApJ/642/868
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The large-scale magnetic field of our Galaxy can be probed in three dimensions using Faraday rotation of pulsar signals. We report on the determination of 223 rotation measures from polarization observations of relatively distant southern pulsars made using the Parkes radio telescope.
- ID:
- ivo://CDS.VizieR/J/A+A/513/A65
- Title:
- Rotation measures in the fourth Galactic quadrant
- Short Name:
- J/A+A/513/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have re-examined the published rotation measures (RMs) of extragalactic point sources and pulsars with |b|<3{deg} 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 H{alpha}-data indicate large fluctuations in n_e_ 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 n_e_-distribution.
- ID:
- ivo://CDS.VizieR/J/ApJS/145/213
- Title:
- Rotation measures of compact sources in CGPS
- Short Name:
- J/ApJS/145/213
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Canadian Galactic Plane Survey is providing new rotation measures (RMs) for compact extragalactic sources in the Galactic plane at a solid-angle density of roughly 1 source per square degree. To date, we have derived reliable RM values for 380 sources along lines of sight through the disk of the Galaxy in the first and second quadrants. The purpose is to provide a data set useful for studies of the magneto-ionic component of the Galactic interstellar medium (ISM). We present the method used to obtain the measurements and the resulting RMs.
- ID:
- ivo://CDS.VizieR/J/ApJ/755/21
- Title:
- Rotation measures of extragalactic radio sources
- Short Name:
- J/ApJ/755/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the Milky Way disk and halo magnetic field, determined from observations of Faraday rotation measure (RM) toward 641 polarized extragalactic radio sources in the Galactic longitude range 100{deg}-117{deg}, within 30{deg} of the Galactic plane. For |b|<15{deg}, we observe a symmetric RM distribution about the Galactic plane. This is consistent with a disk field in the Perseus arm of even parity across the Galactic mid-plane. In the range 15{deg}<|b|<30{deg}, we find median RMs of -15+/-4rad/m2 and -62+/-5rad/m2 in the northern and southern Galactic hemispheres, respectively. If the RM distribution is a signature of the large-scale field parallel to the Galactic plane, then this suggests that the halo magnetic field toward the outer Galaxy does not reverse direction across the mid-plane. The variation of RM as a function of Galactic latitude in this longitude range is such that RMs become more negative at larger |b|. This is consistent with an azimuthal magnetic field of strength 2{mu}G (7{mu}G) at a height 0.8-2kpc above (below) the Galactic plane between the local and the Perseus spiral arm. We propose that the Milky Way could possess spiral-like halo magnetic fields similar to those observed in M51.
- ID:
- ivo://CDS.VizieR/J/MNRAS/429/2934
- Title:
- SDSS magnetic white dwarf stars
- Short Name:
- J/MNRAS/429/2934
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To obtain better statistics on the occurrence of magnetism among white dwarfs, we searched the spectra of the hydrogen atmosphere white dwarf stars (DAs) in the Data Release 7 of the Sloan Digital Sky Survey (SDSS) for Zeeman splittings and estimated the magnetic fields. We found 521 DAs with detectable Zeeman splittings, with fields in the range from around 1 to 733MG, which amounts to 4% of all DAs observed. As the SDSS spectra have low signal-to-noise ratios, we carefully investigated by simulations with theoretical spectra how reliable our detection of magnetic field was.
- ID:
- ivo://CDS.VizieR/J/ApJ/836/185
- Title:
- SEDs of the radio continuum from KINGFISHER
- Short Name:
- J/ApJ/836/185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the spectral energy distribution (SED) of the radio continuum (RC) emission from the Key Insight in Nearby Galaxies Emitting in Radio (KINGFISHER) sample of nearby galaxies to understand the energetics and origin of this emission. Effelsberg multi-wavelength observations at 1.4, 4.8, 8.4, and 10.5GHz combined with archive data allow us, for the first time, to determine the mid-RC (1-10GHz, MRC) bolometric luminosities and further present calibration relations versus the monochromatic radio luminosities. The 1-10GHz radio SED is fitted using a Bayesian Markov Chain Monte Carlo technique leading to measurements for the nonthermal spectral index (S_{nu}_~{nu}^-{alpha}_nt_^) and the thermal fraction (f_th_) with mean values of {alpha}_nt_=0.97+/-0.16 (0.79+/-0.15 for the total spectral index) and f_th_=(10+/-9)% at 1.4GHz. The MRC luminosity changes over ~3 orders of magnitude in the sample, 4.3x10^2^L_{sun}_<MRC<3.9x10^5^L_{sun}_. The thermal emission is responsible for ~23% of the MRC on average. We also compare the extinction-corrected diagnostics of the star-formation rate (SFR) with the thermal and nonthermal radio tracers and derive the first star-formation calibration relations using the MRC radio luminosity. The nonthermal spectral index flattens with increasing SFR surface density, indicating the effect of the star-formation feedback on the cosmic-ray electron population in galaxies. Comparing the radio and IR SEDs, we find that the FIR-to-MRC ratio could decrease with SFR, due to the amplification of the magnetic fields in star-forming regions. This particularly implies a decrease in the ratio at high redshifts, where mostly luminous/star-forming galaxies are detected.
