OBSERVING GALAXY CLUSTERS WITH NEXT GENERATION RADIO TELESCOPES. Melanie Johnston-Hollitt Victoria University of Wellington

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1 OBSERVING GALAXY CLUSTERS WITH NEXT GENERATION RADIO TELESCOPES Melanie Johnston-Hollitt Victoria University of Wellington

2 Radio Renaissance Radio astronomy is currently undergoing a renaissance in terms of construction of new instruments and revitalization of high impact science goals In the last decade a number of new radio telescopes have been constructed and older telescopes upgraded: International LOFAR Telescope (ILT) Jansky Very Large Array (JVLA) Australia Telescope Compact Array (ATCA) E-Merlin Australian SKA Pathfinder (ASKAP) Fiver Hundred Meter Aperture Synthesis Telescope (FAST) Westerbork Radio Synthesis Telescope (WRST) Murchison Widefield Array (MWA) At the end of this next decade this will culminate in the Square Kilometre Array

ASKAP: 36 element PAF interferometer, 700 MHz -1.8 GHz (see Johnston et al. (2008), Norris et al.

3 Next Generation Radio Telescopes Many telescopes currently in construction leading up to the SKA. We ve heard a lot about LOFAR, here I want to focus on ASKAP & MWA and then finally comment on SKA. ASKAP: 36 element PAF interferometer, 700 MHz -1.8 GHz (see Johnston et al. (2008), Norris et al. (2011)) MWA: 128 title dipole array, MHz (see Tingay et al. (2013a), Bowman et al. (2013))

4 ASKAP & MWA ASKAP 36 PAF enabled antennas, GHz range with 300 MHz band. 27 square degree FOV with up to 10 resolution. MWA 128 tiles of 16 dipoles, MHz range, ~30 MHz band. 30 square degree FoV with ~ resolution in 2015 and hopefully resolution in late 2016 after addition of a further 128 tiles Located at Murchison Radio Observatory (MRO) which is a protected radio quiet zone in Western Australia. Two surveys of interest to people working on clusters: ASKAP-EMU & MWA s GLEAM. EMU is a future survey, GLEAM is nearly completed.

5 EMU Evolutionary Map of the Universe will be a continuum radio survey on ASKAP at 1.4 GHz. The aim is to achieve 10uJy rms and 10 resolution hopefully with an option for tapered images also. First observations on a test array of 12 antennas scheduled later this year. EMU is an open collaboration. PI is Ray Norris, but if you want to join, let me know. We are soliciting early science ideas now.

6 Example of EMU-like Science The ATCA can now achieve 10 ujy/b 10 resolution images which are thus analogous to EMU. Here I show an example of the kind of thing that can be done with such an instrument. Will examine PLCK G (z=0.38) work done by Gerardo Martinez Aviles & MJH. X-ray & SZ courtesy of Gabriel Pratt & Nabila Aghanim. Collaborators Tiziana Venturi, Gianfranco Brunetti, Rossella Cassano (all present) and Chiara Ferrari To appear in Martinez Aviles et al. hopefully soon.

7 Field of PLCK G at 2.1 GHz, 11 ujy/b

9 Field of PLCK G taper applied Radio halo appears ~950 x 470 kpc

11 Clearly a merging cluster yet doesn t sit on the Cassano et al. correlation. We have investigated effects of redshift and there seems to be evidence that the correlation is evolving beyond z = EMU will fill this part of the box Full analysis in Martinez Aviles et al. (in prep)

12 GLEAM Survey GaLactic and Extragalactic All-sky MWA Survey M. Bell, J. Callingham, K.S. Dwarakanath, B-Q. For, B. Gaensler, P. Hancock, L. Hindson, N. Hurley-Walker, M. Johnston-Hollitt, A. Kapinska, E. Lenc, B. McKinley, J. Morgan, A. Offringa, P. Procopio, L. Staveley-Smith, R. Wayth, C. Wu, Q. Zheng 5 x 32 MHz frequencies of the entire sky south of +30 degrees. Covers 72 to 231 MHz down to the confusion limit (5 60 mjy) Excellent short spacing uv-coverage -> important for diffuse emission. Complementary to MSSS (Heald et al. submitted) in point source sensitivity.

13 GLEAM Sky Coverage All observations completed, phase I data processing done & phase II on going.

Clusters in GLEAM MWA 150 MHz Due to low resolution, although it is

GLEAM, you need ancillary higher resolution data to confirm it.

Selected all clusters in the MCXC with R 500 > 15 Sample of 105

15 Clusters in GLEAM MWA 150 MHz Due to low resolution, although it is possible to detect diffuse cluster emission in distant clusters in GLEAM, you need ancillary higher resolution data to confirm it. So, first look has been at larger nearby clusters. Selected all clusters in the MCXC with R 500 > 15 Sample of 105 clusters, but only 67 have been processed. ATCA 2.1 GHz CL z= Zheng et al. (in prep) SUMSS 0.8 GHz

16 Sample of nearby clusters Spans redshift up to ~0.07 and most are within 43 < Log(Lx) <45.

17 Diffuse emission Diffuse emission is detected in 12/67 clusters (18%) including several new halos and possible relics. Detection rate is similar to extended GMRT sample (Kale, Venturi et al.) Additionally, diffuse emission detected in GLEAM for unknown clusters is much larger than that in the current literature. I ll show three examples: A3667, A754and A3376.

18 Hindson, Johnston-Hollitt et al. 2014

19 Hindson, Johnston-Hollitt et al. 2014

20 Spectral Index Both relics suggest shocks of 2.4 +/- 0.4 which are consistent with the value derived from X-ray. Hindson, Johnston-Hollitt et al. 2014

21 GLEAM 150 MHz Naturally Weighted, so Galactic emission Suppressed but needs to still be separated via spectral index mapping. RMS = 11 mjy/b 2.5 beam

22 30 deg GLEAM 150 MHz 6mJy/b ~2.5 arcmin A754 Hydra A New SNR

25 1.4 GHz VLA at 70 resolution Macario et al MHz GLEAM RMS = 9 mjy/b ~2.5 resolution

26 A3376 Little known fact; double relic first noted in the honours (MSc) thesis of Tara Murphy, University of Sydney, 1999 from her search of SUMSS. Independently rediscovered by Bagchi 2002 using NVSS. z= XMM, ATCA, AAO campaign undertaken from

27 Optical Galaxy Distribution Spectroscopic observations undertaken in December 2004 to map the cluster. Right is the optical isodensity for confirmed spectroscopic cluster members Note filaments

28 GLEAM 150 MHz RMS 4 mjy/ b

29 Results GLEAM is seeing similar detection rates for diffuse emission as other dedicated studies but GLEAM is detection larger diffuse emission than all other work. We have the first detection of diffuse radio emission associated with a filament in the cosmic web. There are other examples in GLEAM which I haven t shown and am in the process of verifying spectroscopically. Next few years both GLEAM and EMU will have a huge impact on cluster science. Beyond that we have SKA1_LOW and SKA1_MID with the possible continuance of ASKAP.

CSIRO astronomy and space science (CASS) Ray Norris, CSIRO Astronomy & Space Science

ASKAP in the SKA era CSIRO astronomy and space science (CASS) Ray Norris, CSIRO Astronomy & Space Science Overview ASKAP Overview ASKAP science in SKA era ASKAP = FLASH VAST Australian Square Kilometre