3 Radio data (VLA)

The VLA observations of NGC 4698 were performed by Ho & Ulvestad (2001) on 29 August 1999 (20 cm) and 31 October 1999 (6 cm). The source detection at 6 cm was reported by Ho & Ulvestad (2001); the flux density is 1.13 mJy and the background noise is 0.072 mJy beam^-1. The source, which appears largely unresolved at a resolution of $\sim$ $1\hbox{$^{\prime\prime}$ }$, is located at $\rm\alpha = 12^h48^m25.9^s$ and $\delta = +08^{\circ}30\hbox{$^\prime$ }21\hbox{$^{\prime\prime}$ }$(J2000); the radio position is accurate to $\sim$ $0\hbox{$.\!\!^{\prime\prime}$ }1$.

A reanalysis of the VLA data detected the source also at 20 cm. It is unresolved with the 1 $\hbox{$^{\prime\prime}$ }$ beam, and its 20 cm position is consistent with that measured at 6 cm. We find a flux density of 0.34 mJy, with a background noise of 0.032 mJy beam^-1. The spectral index, defined as $S_{\nu}\propto \nu^\alpha$, is $\alpha_{\rm r}\approx 1.0$.

Figure 2: Archival Hubble Space Telescope image of the region around XMMU J 124825.9+083020 taken in the F814W filter. North is up and East to the left.

 

 

Table 1: Results from the fit of the X-ray data. Columns: (1) Model: power law (PL), black body (BB), bremsstrahlung (BR), multicolor black body disk (MCD); (2) free parameter of the model: photon index $\Gamma$ for PL, temperature (keV) for BB and BR, temperature (keV) at the inner disk for MCD; (3) $\chi ^2$and degrees of freedom of the spectral fitting; (4) flux in the 0.5-10 keV band (10^-14 erg cm^-2 s^-1); (5) X-ray luminosity in the 0.5-10 keV band (10⁴³ erg s^-1) calculated for z=0.43, H₀=75 km s^-1 Mpc^-1 and q₀=0.5. No absorption is required in excess of the the Galactic column, $N_{\rm H} =1.87\times 10^{20}$ cm^-2. The uncertainties in the parameters are at the 90% confidence level.

Model	Parameter	$\chi ^2$/d.o.f.	FX	LX
(1)	(2)	(3)	(4)	(5)
PL	$\Gamma = 2.0\pm 0.2$	18.3/24	8.6	3.9
BB	$kT=0.35\pm 0.05$	34.5/24	4.5
BR	$kT=2\pm 1$	19.0/24	6.7
MCD	$kT_{in}= 0.6\pm 0.1$	23.7/24	5.4