From ccarilli@aoc.nrao.edu Tue Aug 6 15:19:44 2002 Date: Thu, 01 Aug 2002 07:18:31 -0600 From: Chris Carilli To: Steve Rawlings Subject: IGM forms Luigina Feretti wrote: > Dear Chris, > below my report on the WG Intergalactic medium, > prepared with the contribution > of Gianfranco Brunetti, Carlo Burigana, Torsten Ensslin, > Doris Neumann, Gabriele Giovannini, Gianfranco De Zotti. > > Attached you find the figures. > Let me know if there is anything that needs further clarification. > > I will be mostly absent from the institute in the next days/week, > but I will read e-mails at least every couple of days. > Regards. > Luigina > > --------------------------------------------------------------- > > Level 1 goals: > 1 - Non-thermal ICM component = diffuse radio sources > (radio halos, relics, mini-halos): detailed structure, > spectra, polarization, detection on new faint objects > of this class > > 2- Thermal ICM component: SZ effect on arcsec scale, to derive > detailed structure of thermal intracluster medium, and to detect > the SZ effect arising from quasar-driven blast waves > during the preheating phase of the intracluster medium. > > ---------------------------------------------------------------------- > > Figures: > > luigina.fig1 : example of a diffuse radio halo: > extended source of very low surface brightness > and steep spectrum. Difficult to detect with > current instruments. Point-to-point spectra available > for a few sources, and only at frequencies lower than > 1.4 GHz. Only upper limits to the polarized flux available. > > > luigina.fig2 : expected flux density distribution of radio halos. > Different lines refer to slightly different model > of the Xray and radio lum function, whereas the > histogram shows the flux density distribution > of known halos. Detection of faint objects of this > class will allow to study correlations and evolution. > > > luigina.fig3 : differential expected counts per deg^2 of quasar-driven > blast waves, as a function of their brightness and > frequency. These should be detected with SZ effect > on the arcsec scale. > > --------------------------------------------------------------------- > > SKA Requirements: > > **Level 1 science program: Diffuse cluster sources > > Spec Requirement Design fail meet exceed comments > ---- ----------- ------- ---- ---- ------ -------- > A/T m^2/K 20000 X depends on freq > > FoV sq.deg 1 X at 1.4 GHz > > Multibeam > number 100 > beam sep (deg) 100 low freq only > # subarrays > > response time s > > Freq range GHz 0.3- 5GHz 0.3-20 X > > Correlator: > Bandwidth GHz 0.5+nu/5 X > # spec channels 1e4 full BW > sampling time s > > Configuration: > max baseline km 100 X > 50% area baseline 10 X > T_b sens K 1 ? at 0.1"res > > #independent IFs 2 X > max sep of IFs > > DNR: > spatial 1e6 > spectral 1e5 > polarization 1e4 > > # spatial pixels 1e8 > > ----------------- > Special requirements: to detect low brightness features, a centrally > condensed array with good coverage of the short baselines is > needed. What is of interest is the surface brightness sensitivity > of the inner array, within ~5 - 10 km. > > Referring to Fig 2, halos down to total flux of 0.1 mJy in nearby > clusters, and to 0.01 mJy in distant (z ~ 1) clusters should be > detected with SKA (with 50% collecting area within 10 km). > > Major problem(s): KARST, Europe, Australia 2, USA designs have a 50% area > baseline much longer than 10 km. > Australia 1 design has a 50% area baseline of 4 km, which is very good > for the present aim. > No indication is given for LAR and India. > > Possible Compromises: The 50% area baseline in KARST, Australia 2 and USA > is between 30 and 40 km. This could still be acceptable if the > array is very centrally condensed (but need simulations/computations) > > ------------------------------------------------------------------------------ > > SKA Requirements: > > **Level 1 science program: High resolution SZ effect > > Spec Requirement Design fail meet exceed comments > ---- ----------- ------- ---- ---- ------ -------- > A/T m^2/K 20000 X depends on freq > > FoV sq.deg 1 X at 1.4 GHz > > Multibeam > number 100 > beam sep (deg) 100 low freq only > # subarrays > > response time s > > Freq range GHz 10-36 GHz 0.3-20 X > > Correlator: > Bandwidth GHz 0.5+nu/5 X > # spec channels 1e4 full BW > sampling time s > > Configuration: > max baseline km 100 X > 50% area baseline 10 X > T_b sens K 1 X at 0.1"res > > #independent IFs 2 > max sep of IFs > > DNR: > spatial 1e6 > spectral 1e5 > polarization 1e4 > > # spatial pixels 1e8 > > ----------------- > Special requirements: High frequency (>20 GHz) is needed for SZ effect > in the clusters. For the detection of quasar-driven blast waves, > a frequency of 10 GHz could be sufficient (see Fig. 3). > > Major problem(s): > > Possible Compromises: > > ------------------------------------------------------------------------------ > > ------------------------------------------------------------------------- > Luigina Feretti phone + 39 051 6399412 > Istituto di Radioastronomia CNR fax + 39 051 6399431 > Via P. Gobetti, 101 > I-40129 Bologna lferetti@ira.cnr.it > Italy http://www.ira.bo.cnr.it/~lferetti/ > ------------------------------------------------------------------------- > > ------------------------------------------------------------------------ > Name: luigina.fig1 > luigina.fig1 Type: Postscript Document (APPLICATION/PostScript) > Encoding: BASE64 > > Name: luigina.fig2 > luigina.fig2 Type: Postscript Document (APPLICATION/PostScript) > Encoding: BASE64 > > Name: luigina.fig3 > luigina.fig3 Type: Postscript Document (APPLICATION/PostScript) > Encoding: BASE64