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Observations with PAPER at 148 MHz Centaurus A and the Galactic Centre

Observations with PAPER at 148 MHz Centaurus A and the Galactic Centre. Irina Stefan University of Cambridge (Cavendish Laboratory). Acknowledgments: Dave Green, Dan Harris. On behalf of the PAPER team:

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Observations with PAPER at 148 MHz Centaurus A and the Galactic Centre

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  1. Observations with PAPER at 148 MHzCentaurus A and the Galactic Centre Irina Stefan University of Cambridge (Cavendish Laboratory) Acknowledgments: Dave Green, Dan Harris On behalf of the PAPER team: C. Carilli, Z. Ali, J. Aguirre, R. Bradley, D. DeBoer, M. Dexter, N. Gugliucci, D. Jacobs, P. Klima, A. Liu,D. MacMahon, J. Manley, D. Moore, A. Parsons, J. Pober, W. Walbrugh

  2. the Precision Array for Probing the Epoch of Reionization

  3. PAPER antennas • expanded this year from 64 to 128 antennas • dual polarization (XX-YY) • non-steerable • 110 - 190 MHz bandwidth • 40o FWHM primary beam • smooth spectral response • integrate every 10.7 s • 2048 channels of width 48.83 kHz

  4. The imaging array 300 wavelengths • 64 antennas in minimum redundancy configuration • resolutions between ∼15’ and 25’ across the band • data sets of ∼10 min long

  5. The imaging array Karoo South Africa 300 wavelengths US ‘radio quiet zone’ ZA ‘radio quiet zone’

  6. Data calibration Stefan et al., 2013, MNRAS, 432, 1285 = AIPY (Astronomical Interferometry in Python) = AIPS (Astronomical Image Processing System)

  7. The Centaurus A field Stefan et al. (2013) 40 deg

  8. The Centaurus A field Stefan et al. (2013) • 40 deg-wide field • dynamic range of 3500 • r.m.s. of 0.5 Jy/beam Cen A PKS 1209-52 Galactic plane

  9. The Centaurus A field Stefan et al. (2013) • lower limit of 5 wavelengths → structures larger than ~12o not imaged

  10. Centaurus A Stefan et al. (2013) Contour levels are a geometric progression in √2, staring from 2 Jy/beam. • peak brightness = 1745 Jy/beam • flux density = 4100 Jy

  11. 3.8 Mpc away - the closest radio galaxy • structures on scales from parsecs to hundreds of kpc Centaurus A MRC1318–434B PKS1320–446 • 25’x23’ FWHM Gaussian restoring beam

  12. Centaurus A spectral index map Stefan et al. (2013)

  13. Centaurus A in radio and X-ray Stefan et al. (2013) • S1 & S2: • inverse Compton B-fields - 0.1 G to 1.3 G • minimum pressure B-fields - 0.5 G to 1 G • S3: • hydrodynamical interaction?

  14. The Galactic Centre field: preliminary results 40 deg NGC6357 NGC6334 20 deg o W31 M20 M8 Tornado NGC6383

  15. Conclusions • PAPER is a 128-element array in the South African Quite Zone. • Although aimed at the statistical detection of the reionization signal, PAPER is also well suited for wide-field imaging. • We used PAPER data to image the Cen A and Galactic Centre fields with a resolution of 25’. • We used the PAPER large bandwidth to obtain a spectral index map of Cen A centered on 148 MHz. • We observe a correspondence between regions rich in complex • morphological radio structure at 1.4 GHz and regions of flatter spectral index in the PAPER map. • We observed possible correlation of X-ray emission with a series of • radio knots seen in the PAPER radio image.

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