LOFAR and the low frequency universe Probing the formation and evolution of massive galaxies, AGN and clusters Huub Röttgering Leiden Observatory
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)
50 million sources at key frequencies 15,30, 60, 120, 150, 200 MHz APERTIF will play a crucial role
Reduction - talk de Bruyn Current Steps RFI rejection initial calibration many rounds of self calibration accurate model target + 10-100 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
Ionospheric correction on Cygnus A - Bas vd Tol, Huib Intema
Significant datasets 3C196 - Olaf Wucknitz M51 - George Heald Cygnus A (210-240 MHz, 8 core, 4 remote)- McKean, Ker 3C61.1: de Bruyn, Yattawatta, Shulevski, van Loo, Tjibaria NGC 6251 - Rafferty, Birzan, Tasse,Morganti Clusters: Abell 2256, 0406 - 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
Data:12 core -, 4 remote stations, 120-155 MHz, 4 hours Image: rms 6 mjy, DR 500 59 *53 arcsec Cygnus A, 210-240 MHz 9*5 arcsec, 0.3 mjy DR 1000
3C61.1 60 hours, 8core, 4 remote, 14MHz BW, noise ~0.6 mjy, DR~15000, 2160 sources
3C61.1 alpha^130_1400-0.5 tekst -0.7-1.0 van Loo Shulevski
NG NGC 6251 Rafferty, Birzan, Tasse
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
Shocks and clusters Do cluster wide shocks enable diffuse shock acceleration? form a central steep spectrum turbulent region? with a very steep radio spectrum?
Sausage cluster at z=0.2 van Weeren, HR, Bruggen, Hoeft
GMRT at 610 MHz
2 Mpc * 50 kpc!
The spectral index alpha =-0.6-2.0 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.
Shock properties Mach number 4.6 +/- 1 Downstream velocity ~1000 km/s B = 5 microgauss Van Weeren, HR, Bruggen, Hoeft, in press
Shocks and clusters Can cluster wide shocks enable diffuse shock acceleration? : YES form a central spectrum turbulent region? with a very steep radio spectrum?
0406: Tooth brush cluster GMRT 610 MHz ROSAT X-ray contours van Weeren etal. in prep
LOFAR 120-140MHz van Weeren
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?
A2256: Where is the steep spectrum halo? Intema et al. submitted, see also Kale and Dwarakanath 2010
Data:10 core -, 5 remote stations, 115-165 MHz, 8 hours Image: 4 MHz @135 MHz, rms 5 mjy, 31*19 arcsec
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
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.