Inverse-Compton emission from clusters of galaxies: Predictions for ASTRO-H

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Table 6

Signal-to-noise results for halo.

			ASTRO-H 100 ks		500 ks		1 Ms
Cluster	s_r	ν _r		F _{20−80 keV^a}		F _{20−80 keV^a}		F _{20−80 keV^a}
	[mJy]	[MHz]	[μG]		[μG]		[μG]

Bullet	52	1340	0.84	0.42	1.18	0.18	1.37	0.13
A0520	85	325	0.26	0.40	0.39	0.17	0.46	0.12
A0521	328	153	0.61	0.28	0.83	0.12	0.94	0.08
A0665	197	327	0.25	0.72	0.38	0.31	0.45	0.22
A0697	135	153	0.25	0.85	0.35	0.37	0.40	0.26
A0754	86	1365	0.27	0.97	0.40	0.42	0.48	0.30
A1300	130	325	0.74	0.28	1.02	0.12	1.16	0.08
Coma*	640	1400	0.20	1.88	0.29	0.83	0.34	0.59
**	”	”	0.54	”	0.79	”	0.93	”
***	"	"	0.25	1.11	0.37	0.49	0.44	0.34
A1758	146	325	0.55	0.38	0.78	0.16	0.90	0.11
A1914	64	1465	1.18	0.53	1.57	0.23	1.77	0.16
A2163*	861	325	0.46	1.08	0.67	0.47	0.79	0.33
**	"	"	0.51	”	0.75	”	0.88	”
A2219	232	325	0.19	0.66	0.31	0.28	0.38	0.20
A2255	536	330	0.61	0.64	0.84	0.28	0.96	0.20
A2256*	6600	63	0.41	0.87	0.58	0.38	0.68	0.27
*	"	"	0.48	”	0.68	”	0.79	”
A2319*	1450	408	0.56	1.20	0.77	0.53	0.88	0.37
**	"	"	0.79	"	1.08	”	1.23	”
A2744	218	325	0.32	0.55	0.49	0.23	0.59	0.16
A3562	20	1400	0.26	0.55	0.38	0.24	0.44	0.17
CL0217+70^a	326	325	0.33	0.68	0.48	0.29	0.56	0.21
MACSJ0717.5+3745	493	235	0.91	0.37	1.35	0.15	1.58	0.11
MACSJ1752.0+4440^a	164	323	0.73	0.34	1.02	0.14	1.17	0.10
PLCK G171.9-40.7^a	483	235	0.98	0.26	1.33	0.11	1.52	0.08
RXCJ1514.9-1523^a	102	327	0.46	0.44	0.63	0.19	0.73	0.13
RXCJ2003.5-2323^a	360	240	0.64	0.35	0.93	0.15	1.09	0.10

Notes. For each halo, we show the radio data values s_r and ν_r used in Eq. (7) to calculate . We show the latter for 100 ks, 500 ks and, 1 Ms of ASTRO-H observations, together with the corresponding flux in the 20−80 keV energy band in units of 10^-12 erg cm^-2 s^-1. Within a few percent error, the fluxes and magnetic fields scale with observation time according to Eq. (9).

^(*)

In this case, the source is larger than the HXI FoV of 9 × 9 = 81 arcmin². In our work, for simplicity, we assumed a uniform surface brightness, therefore, s_r was scaled by a factor 81 /x where x arcmin² is the size that a source covers in the sky (see Tables 1 and 2). This estimate results in slightly conservative predictions since halos and relics are non-uniform sources.

^(**)

This gives results that assume all radio emission is coming from an area equal to the HXI FoV, so s_r was not scaled. This can be considered an optimistic estimate for the detectable magnetic field.

^(***)

Additional analysis for Coma. Since the Coma radio halo is extremely large in the sky, we estimated the thermal ICM emission only in the HXI FoV, integrating Eq. (4) out to ~ 180 kpc, which roughly corresponds to the HXI FoV, rather than over the full halo size.

^(a)

Thermal ICM emission computed using the model by Zandanel et al. (2014) for the gas density.

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