Utilizza questo identificativo per citare o creare un link a questo documento:
http://hdl.handle.net/20.500.12386/26312
Titolo: | Low-frequency Observations of Linearly Polarized Structures in the Interstellar Medium near the South Galactic Pole | Autori: | Lenc, E. Gaensler, B. M. Sun, X. H. Sadler, E. M. Willis, A. G. Barry, N. Beardsley, A. P. Bell, M. E. BERNARDI, GIANNI Bowman, J. D. Briggs, F. Callingham, J. R. Cappallo, R. J. Carroll, P. Corey, B. E. de Oliveira-Costa, A. Deshpande, A. A. Dillon, J. S. Dwarkanath, K. S. Emrich, D. Ewall-Wice, A. Feng, L. For, B. -Q. Goeke, R. Greenhill, L. J. Hancock, P. Hazelton, B. J. Hewitt, J. N. Hindson, L. Hurley-Walker, N. Johnston-Hollitt, M. Jacobs, D. C. Kapińska, A. D. Kaplan, D. L. Kasper, J. C. Kim, H. -S. Kratzenberg, E. Line, J. Loeb, A. Lonsdale, C. J. Lynch, M. J. McKinley, B. McWhirter, S. R. Mitchell, D. A. Morales, M. F. Morgan, E. Morgan, J. Murphy, T. Neben, A. R. Oberoi, D. Offringa, A. R. Ord, S. M. Paul, S. Pindor, B. Pober, J. C. Prabu, T. Procopio, P. Riding, J. Rogers, A. E. E. Roshi, A. Udaya Shankar, N. Sethi, S. K. Srivani, K. S. Staveley-Smith, L. Subrahmanyan, R. Sullivan, I. S. Tegmark, M. Thyagarajan, Nithyanandan Tingay, S. J. Trott, C. Waterson, M. Wayth, R. B. Webster, R. L. Whitney, A. R. Williams, A. Williams, C. L. Wu, C. Wyithe, J. S. B. Zheng, Q. |
Data pubblicazione: | 2016 | Rivista: | THE ASTROPHYSICAL JOURNAL | Numero: | 830 | Fascicolo: | 1 | Da pagina:: | 38 | Abstract: | We present deep polarimetric observations at 154 MHz with the Murchison Widefield Array (MWA), covering 625 deg<SUP>2</SUP> centered on α = 0<SUP>h</SUP>and δ = -27°. The sensitivity available in our deep observations allows an in-band, frequency-dependent analysis of polarized structure for the first time at long wavelengths. Our analysis suggests that the polarized structures are dominated by intrinsic emission but may also have a foreground Faraday screen component. At these wavelengths, the compactness of the MWA baseline distribution provides excellent snapshot sensitivity to large-scale structure. The observations are sensitive to diffuse polarized emission at ∼54′ resolution with a sensitivity of 5.9 mJy beam<SUP>-1</SUP> and compact polarized sources at ∼2.′4 resolution with a sensitivity of 2.3 mJy beam<SUP>-1</SUP> for a subset (400 deg<SUP>2</SUP>) of this field. The sensitivity allows the effect of ionospheric Faraday rotation to be spatially and temporally measured directly from the diffuse polarized background. Our observations reveal large-scale structures (∼1°-8° in extent) in linear polarization clearly detectable in ∼2 minute snapshots, which would remain undetectable by interferometers with minimum baseline lengths of >110 m at 154 MHz. The brightness temperature of these structures is on average 4 K in polarized intensity, peaking at 11 K. Rotation measure synthesis reveals that the structures have Faraday depths ranging from -2 to 10 rad m<SUP>-2</SUP> with a large fraction peaking at approximately +1 rad m<SUP>-2</SUP>. We estimate a distance of 51 ± 20 pc to the polarized emission based on measurements of the in-field pulsar J2330-2005. We detect four extragalactic linearly polarized point sources within the field in our compact source survey. Based on the known polarized source population at 1.4 GHz and non-detections at 154 MHz, we estimate an upper limit on the depolarization ratio of 0.08 from 1.4 GHz to 154 MHz. | URI: | http://hdl.handle.net/20.500.12386/26312 | URL: | https://iopscience.iop.org/article/10.3847/0004-637X/830/1/38 | ISSN: | 0004-637X | DOI: | 10.3847/0004-637X/830/1/38 | Bibcode ADS: | 2016ApJ...830...38L | Fulltext: | open |
È visualizzato nelle collezioni: | 1.01 Articoli in rivista |
File in questo documento:
File | Descrizione | Dimensioni | Formato | |
---|---|---|---|---|
Lenc2016.pdf | Pdf editoriale | 4.18 MB | Adobe PDF | Visualizza/apri |
Page view(s)
56
controllato il 19-apr-2024
Download(s)
10
controllato il 19-apr-2024
Google ScholarTM
Check
Altmetric
Altmetric
Tutti i documenti in DSpace sono pubblicati ad Accesso Aperto, salvo diversa indicazione per alcuni documenti specifici.