Introduc+On Conclusions JVLA Dataset & Data Reduc+On
Total Page：16
File Type：pdf, Size：1020Kb
The low radio frequency view of the Perseus cluster 1 (1) Université de Montréal (5) Leiden Observatory Marie-Lou Gendron-Marsolais , third year Ph.D. student (2) Harvard-Smithsonian Center (6) University of New-Mexico J. Hlavacek-Larrondo1, R. V. Weeren2, T. Clarke3, A.C. Fabian5, for Astrophysics (7) University of Oxford 4 6 7 8 (3) Naval Research Laboratory (8) Max-Planck-Instut für H.T. Intema , G.B. Taylor , K.M. Blundell , J.S. Sanders (4) University of Cambridge extraterrestrische Physik Introduc)on Conclusions New, ultra deep 230-470 MHz Karl G. Jansky Very Large Array (JVLA) data of the • Several new, previously unknown structures have been idenfied (see Fig. 2). The Perseus cluster1 (X-ray brightest cluster in the sky2, z = 0.0183, ~70 Mpc): a low- general shape of the mini-halo is curving counterclockwise and is elongated in the frequency view probing the old radio-emiUng electron populaon (see direcon of the cavity system. Mysterious filamentary spurs of emission are found Gendron-M. et al. 2017 for more details, and the recent NRAO press release). to the east, similar to radio relics, but no shocks corresponding with the posion Accreon onto supermassive black holes creates powerful jets, which strongly of the filaments are known. The large-scale and fine structure show a correlaon perturb their environment, projecng relavisc parcles on tens to hundreds of of the mini-halo emission with both the sloshing moon and the relavisc jets of kpcs that produce synchrotron emission at ~ GHz frequencies. When located in the AGN. Mini-halos are therefore not simply diffuse, uniform radio sources, but the center of a brightest cluster galaxy (BCG), they are believed to compensate rather have a rich variety of complex structures. the radiave losses of the intracluster medium (mechanical AGN feedback). • The depth and resoluon of 4’= 90 kpc Apart from jets, other forms of diffuse non-thermal radio sources in galaxy these observaons allow us to Beam clusters includes: conduct for the first me a Northern extension 1. Relics - diffuse extended sources found at the cluster’s outskirt (e.g. detailed comparison of the « toothbrush », van Weeren et al. 2016) mini-halo structure with the X- Eastern spurs 2. Halo - Mpc scale diffuse emission found found in disturbed/non cool core ray structure as seen in the NGC 1272 clusters (e.g. A 1758, Giovannini et al. 2006) Chandra X-ray images9,10 (see 3. Mini-halo - kpc scale diffuse emission detected so far in about thirty relaxed/ Fig. 3). This comparison shows cool core clusters (Giacintucci et al. 2017) that the mini-halo is enclosed We present new JVLA observaons of the mini-halo3 in the Perseus cluster at mostly behind the western 230-470 MHz. The resoluon and sensivity of these data provide a detailed and sloshing cold front, which extended view of the mini-halo structure, on which we focus our analysis. The qualitavely supports the South-western edge recent update of the facilies with the EVLA project offer new abilies to study hypothesis of reacceleraon of Southern edge Plume this structure. pre-exisng electrons by ! turbulence11. However, fainter Figure 2 - A Zoom on the emission surrounding NGC JVLA Dataset & Data reducon emission is also seen beyond, 1275 from the 270-430 MHz radio map seen in Fig. 1. 5 h in B configuraon from 2013 P-band 230 - 470 MHz shared-risk proposal as if parcles are leaking out, The main structures of the mini-halo are idenfied. (tested and commissioned observing mode, PI Hlavacek-L.) with the following and sll being reaccelerated. challenges: • The 230-470 MHz emission avoid the southern bay (see Fig. 3), an intriguing • new broadband low frequency receivers feature behaving like a cold fronts but with the opposite curvature. According to • High Dynamic range (AGN peak intensity of 9 Jy/beam at 235 MHz) simulaons of gas sloshing, this structure might be resulng from Kelvin- • Low frequency = ~60% of the dataset is radio frequency interferences (RFI) Helmholtz instabilies (see Walker, Hlavacek-L., Gendron-M. et al. for more A pipeline as been specifically developed to reduce the dataset with CASA details, and the recent NASA press release). (Common Astronomy Soware Applicaons): • These results illustrate the high-quality images that can be obtained with the new 4 • Manual and automac idenficaon of RFI (flagdata and Aoflagger ) JVLA at low radio-frequencies, as well as the necessity to obtain deeper, higher- • Imaging with Clean : use of mul-scale mul-frequency synthesis-imaging fidelity radio images of mini-halos in clusters to further understand their origin. algorithm5, number of Taylor coefficients greater than one, W-projecon algorithm with a grid mode widefield6, mul-scale cleaning algorithm7 and 8 mask liming regions where emission was expected 2’= 45 kpc Northern filament • Imaging self-calibraon: use of amplitudes and phases gain correcons from Beam data to refine calibraon Inner cavities 18’= 400 kpc Beam 59:59.9 NGC 1265 47:59.9 Southern bay Outer cavities NGC 1275 Figure 3. Le - Chandra final composite fraconal residual image ( 0.5-7 keV band, 1.4 Ms exposure, Fabian et al. 2011) with 270-430 MHz contours from 5σ = 1.75 mJy/beam to 1 Jy/ 35:59.9 beam overlaid from JVLA B-configuraon. Right - GGM filtered image of the merged X-ray CR 15 observaons with Gaussian width σ = 4 pixels (Sanders et al. 2016) with the same 270-430 MHz JVLA contours. The posion of the western cold front is indicated with white arrows. IC 310 41:23:59.9 References: (1) Gendron-Marsolais et al. MNRAS 2017 (4) Offringa et al. 2012 (8) Mohan & Rafferty 2015 (2) Forman et al. 1972 Apj 178 309 (5) Rau & Cornwell 2011 (9) Fabian et al. 2000, 2003, Figure 1 - JVLA 230-470 MHz radio map obtained (3) Soboleva et al. 1983; Pedlar et al. 1990; (6) Cornwell et al. 2008 2006, 2011 in B-configuraon (2°× 1.5°). The BCG NGC 1275 Burns et al. 1992; Sijbring 1993 (10) Sanders et al. 2016 11:59.9 (7) Cornwell 2008 is the bright source in the middle of the image ! (11) Gi et al. 2002, 2004 (rms =0.35mJy/beam, beam=22.1’’×11.3’’, peak=10.63Jy/beam, dynamic range of 30000). 23:12.0 22:24.0 21:36.0 48.0 3:20:00.0 19:12.0 18:24.0 17:36.0 48.0 16:00.0.