LOFAR and the low frequency universe. Probing the formation and evolution of massive galaxies, AGN and clusters. Huub Röttgering Leiden Observatory

Transcription

1 LOFAR and the low frequency universe Probing the formation and evolution of massive galaxies, AGN and clusters Huub Röttgering Leiden Observatory

2 LOFAR is a natural survey instrument Green: HBA mosaic at 130 MHz Magenta: LBA mosaic at 50 Mhz/per pointing ~3 Abell clusters ~3 NGC galaxies (courtesy: Rafferty and Mohan)

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4 50 million sources at key frequencies 15,30, 60, 120, 150, 200 MHz APERTIF will play a crucial role

5 Reduction - talk de Bruyn Current Steps RFI rejection initial calibration many rounds of self calibration accurate model target bright sources widefield imaging Software speed: BBS fine-tuning: AIPS, CASA,MIRIAD,DIFMAP Next: calibrate station beamformer use full data set (images shown use only ~10 % of subbands) widefield imaging taking the varying beam into account apply ionospheric corrections

6 Ionospheric correction on Cygnus A - Bas vd Tol, Huib Intema

7 Significant datasets 3C196 - Olaf Wucknitz M51 - George Heald Cygnus A ( MHz, 8 core, 4 remote)- McKean, Ker 3C61.1: de Bruyn, Yattawatta, Shulevski, van Loo, Tjibaria NGC Rafferty, Birzan, Tasse,Morganti Clusters: Abell 2256, van Weeren, Ferrari, Macario, Pizzo, Orru, Bonafede, Shulevski Virgo A - Busy week 7 (Sept 13-17) 3 target beam observation - Bw-7 10 minute observations of a section of 3C sources -Bw-7

8 Data:12 core -, 4 remote stations, MHz, 4 hours Image: rms 6 mjy, DR *53 arcsec Cygnus A, MHz 9*5 arcsec, 0.3 mjy DR 1000

9 3C hours, 8core, 4 remote, 14MHz BW, noise ~0.6 mjy, DR~15000, 2160 sources

10 3C61.1 alpha^130_ tekst van Loo Shulevski

11 NG NGC 6251 Rafferty, Birzan, Tasse

12 LOFAR and (proto-)clusters Low-z AGN feedback and studies of cavities on long time scales (>10^8) yrs Magnetic field strength and configuration Cluster weather through morphologies of extremely old tailed radio sources Inventory of shocks traced by radio emission in (merging) clusters and even the cosmic web z~1 Sample of clusters with diffuse emission Location of radio sources wrt to LSS z>2 through the study of high RM sources in combination with Herschel z>6 associated with high radio galaxies

13 Shocks and clusters Do cluster wide shocks enable diffuse shock acceleration? form a central steep spectrum turbulent region? with a very steep radio spectrum?

14 Sausage cluster at z=0.2 van Weeren, HR, Bruggen, Hoeft

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16 GMRT at 610 MHz

17 2 Mpc * 50 kpc!

18 The spectral index alpha = from fit to matched GMRT and WSRT observations at 2.3, 1.7, 1.4, 1.2, and 0.61 GHz Resolution: 16.7 * 12.7 arcsec.

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20 Shock properties Mach number 4.6 +/- 1 Downstream velocity ~1000 km/s B = 5 microgauss Van Weeren, HR, Bruggen, Hoeft, in press

21 Shocks and clusters Can cluster wide shocks enable diffuse shock acceleration? : YES form a central spectrum turbulent region? with a very steep radio spectrum?

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23 0406: Tooth brush cluster GMRT 610 MHz ROSAT X-ray contours van Weeren etal. in prep

24 LOFAR MHz van Weeren

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27 Shocks and clusters Can cluster wide shocks enable diffuse shock acceleration? : YES form a central spectrum turbulent region? YES with a very steep radio spectrum?

28 A2256: Where is the steep spectrum halo? Intema et al. submitted, see also Kale and Dwarakanath 2010

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30 Data:10 core -, 5 remote stations, MHz, 8 hours Image: 4 MHz, rms 5 mjy, 31*19 arcsec

31 Shocks and clusters Can cluster wide shocks enable diffuse shock acceleration? : YES form a central spectrum turbulent region? YES with a very steep radio spectrum? YES LOFAR will be instrumental in mapping out the entire shock system in clusters

32 Conclusion LOFAR works! The planned surveys will be important for our understanding on the formation and evolution of galaxies, clusters and AGN More information: Heald et al. Progress with the LOFAR Imaging Pipeline in proceedings of ISKAF2010 Science Meeting A.R. Offringa et al., A LOFAR RFI detection pipeline and its first results, in proceedings of RFI mitigation workshop, PoS(RFI2010)036. O. Wucknitz, Long baseline experiments with LOFAR, in proceedings of ISKAF2010 Science Meeting H.J.A. Rottgering et al, LOFAR and the low frequency Universe, in proceedings of ISKAF2010 Science Meeting, PoS(ISKAF2010)050.