Relativistic jet radio flux density from OC's spinning IMBH — compared against MeerKAT and SKA sensitivity limits.
| Instrument | 5σ limit (mJy @ ν, 1h) | S_ν / limit | Status | Hours for 5σ |
|---|---|---|---|---|
| Computing… | ||||
The "fundamental plane" of black hole activity (Merloni et al. 2003, Falcke & Biermann 1995) is an empirical correlation among radio luminosity, X-ray luminosity, and black hole mass that holds across ten decades in mass — from stellar-mass X-ray binaries to AGN. The relation used here is:
log(S_ν [mJy]) = 0.6·log(L_X [erg/s]) + 0.78·log(M [M☉]) − 2·log(D [pc]) − 14.446
where L_X is approximated by the effective jet power P_jet × η_jet converted to erg/s (1 W = 10⁷ erg/s), and D is the OC distance in parsecs (5490 pc). This approximation is robust within ~0.5 dex given the scatter in the fundamental plane.
Compact, self-absorbed synchrotron jets from AGN and X-ray binaries are observed to have nearly flat radio spectra (spectral index α ≈ 0, S_ν ∝ ν⁰) from ~1 GHz to ~30 GHz in the self-absorption regime (Blandford & Königl 1979). The flux estimate is therefore nearly frequency-independent across the slider range. At high frequencies (>30 GHz), the jet core typically steepens (α ~ −0.7 optically thin region); at <1 GHz, absorption cuts in. The fundamental plane calibration is most reliable near 5 GHz.
MeerKAT (Jonas & MeerKAT Team 2016): 64-dish array at Karoo, South Africa. 5σ point-source sensitivity at 5 GHz in 1h ≈ 3 µJy = 0.003 mJy. Integration time scales as T ∝ (S_limit)⁻². For SKA Mid (Phase 1): sensitivity improves by ~5× over MeerKAT, giving ~0.6 µJy in 1h. VLA (NRAO): 5σ at 5 GHz in 1h ≈ 5 µJy = 0.005 mJy.
The tool computes the angular size of a notional jet at 100 gravitational radii (100 r_g) from the IMBH at OC's distance of 5.49 kpc. For M = 8200 M☉, r_g ≈ 1.2×10⁷ m; 100 r_g at 5490 pc corresponds to ~3 µas — below Earth-baseline VLBI resolution (~10–20 µas). The jet will be a point source for all near-term radio instruments. The value reported is informational only.
Targeted VLA observations of OC at ~5 GHz have placed upper limits on any radio point source coincident with the cluster center. Depending on the precise astrometry and confusion from background sources, the upper limit is typically <0.05–0.1 mJy at 5 GHz. Translating via the fundamental plane, this constrains the IMBH to be either very low mass or accreting far below Eddington — consistent with Bondi accretion from the ambient intracluster medium. A high-spin BZ jet operating at L_jet ≥ 10⁻⁵ L_Edd would already be ruled out at the ~3σ level.