Why ωCen and Not the Galactic Centre?

01

Step 1 · Mass & Environment

Scale the Two Objects

OC's IMBH candidate sits at ~8,200 M⊙ — roughly 500× less massive than Sgr A* (4.154 × 10⁶ M⊙). Mass alone favours the Galactic Centre for raw energy. But mass is not the whole story.

Property	ωCen IMBH	Sgr A*
Black hole mass	~8,200 M⊙	4.154 × 10⁶ M⊙
Host cluster mass	4 × 10⁶ M⊙	~1 × 10¹¹ M⊙ (galactic bulge)
Distance	5.49 kpc	8.178 kpc
Central stellar density	~10⁵ M⊙ pc⁻³	~10⁶–10⁷ M⊙ pc⁻³
Environment	Quiet GC, no star formation	Active, radiation-rich, chaotic

Open Cluster Comparator → OC: 4×10⁶ M⊙ cluster · IMBH ≥8,200 M⊙ | GC: Sgr A* 4.154×10⁶ M⊙ Debated Measured

Step payoff

Mass favours the GC by 500×. But the engineering question is not "which BH has more energy?" — it is "which BH is controllable?" OC's far lower stellar density and inactive environment make it a candidate for precision ergosphere engineering.

02

Step 2 · Energy Extraction

BZ Power: Small but Spinnable

Engineering Scenario: A near-maximal Kerr IMBH at 8,200 M⊙ with B = 10⁶ T delivers ~10²² W of BZ power. Sgr A* at the same spin and B = 10⁴ T (estimated ambient field) delivers ~10²⁵ W — 1,000× more. But OC's IMBH can in principle be spun up to a★ → 1 via controlled accretion, whereas Sgr A*'s spin state is uncertain and its accretion environment is hostile and chaotic. The engineering advantage is controllability, not raw output.

Parameter	ωCen IMBH (engineering)	Sgr A* (reference)
Mass	8,200 M⊙	4.154 × 10⁶ M⊙
Assumed spin a★	0.95 (near-maximal)	~0.5–0.9 (uncertain)
Assumed B field	10⁶ T (engineered)	~10⁴ T (ambient estimate)
Estimated P_BZ	~4.8×10³⁷ W	~1.1×10³⁹ W
Controllability	High — quiet accretion, stable field	Low — turbulent, variable

Open BZ Calculator (OC preset) → mass=8200, spin=0.95 Established GR/MHD MTH application

Step payoff

Sgr A* delivers ~23× more BZ power in absolute terms (at these parameter choices). OC's IMBH delivers a controllable, stable output from a predictable accretion environment. For a civilisation operating on geological timescales, stability matters more than peak output.

03

Step 3 · Computational Clock

ISCO Time Dilation: Why Closeness Matters

For a civilisation running computronium at the ISCO, gravitational time dilation provides a clock speedup relative to cosmic background. The ISCO radius scales with mass: r_ISCO = 6GM/c² (Schwarzschild, a=0). At near-maximal spin, r_ISCO → GM/c² (prograde). OC's IMBH has r_ISCO ≈ 1.8×10⁸ m at a=0.95 — physically tiny. The key insight: gravitational time dilation at the ISCO is the same for OC's IMBH as for Sgr A* at identical spin. It is a spin-dependent constant, not a mass-dependent one. The mass difference between OC and the GC is irrelevant for clock rate — it only affects the physical scale of the ergosphere.

ISCO property	ωCen IMBH (a=0.95)	Sgr A* (a=0.95)
r_ISCO (prograde)	~1.8 × 10⁸ m	~9.1 × 10¹⁰ m
r_ISCO / r_g	~1.94 (prograde, a=0.95)	~1.94 (same)
Time dilation γ at ISCO	~2.6 (identical to GC at same a)	~2.6 (same spin)
Physical ISCO circumference	~1.1 × 10⁹ m	~5.7 × 10¹¹ m
Tidal disruption rate	Lower (lower mass)	Higher

Open Time Dilation Calculator → Set spin a=0.95, compare ISCO redshift factor Established GR

Step payoff — the key result

The clock-rate advantage of operating at the ISCO is identical for OC's IMBH and for Sgr A* at the same spin. Mass cancels out in the ISCO redshift formula. OC's smaller ergosphere is a disadvantage in scale, not in physics. A civilisation of the right size would prefer the more manageable object.

04

Step 4 · Observational Contrast

The Distance Advantage Reverses for Observation

OC is 5.49 kpc away vs the GC at 8.178 kpc — OC is closer. For astrometric microlensing, the Einstein radius θ_E ∝ √(M/d_L), where d_L is lens distance. OC's lower IMBH mass partially offsets its proximity advantage. But for VLBI monitoring (Sgr A* has the Event Horizon Telescope), the GC wins entirely. For technosignature searches — radio beacons, neutrino fluxes — the 5.49/8.178 kpc distance ratio means OC signals arrive 2.2× stronger in flux. The final verdict: OC wins for MTH engineering (controllable spin, lower tidal disruption rate, accessible ISCO geometry, quieter environment). The GC wins for current observational access. Both are high-priority targets.

Observable	ωCen IMBH	Sgr A*
Distance	5.49 kpc (closer)	8.178 kpc
Flux ratio advantage	2.2× brighter at Earth	—
Einstein radius θ_E (IMBH lens)	~61.8 mas (at 8,200 M⊙)	N/A — direct imaging
VLBI / EHT access	Not yet observed	Direct image (2022)
Engineering environment	Quiet, controllable	Active galactic nucleus conditions

Open Microlensing Calculator → M_L=8200 M⊙ · D_L=5.49 kpc · D_S=8.00 kpc Gravitational lensing Pre-DR4

Step payoff — the synthesis

OC is closer, its IMBH is more massive than any stellar-mass BH, and its environment is the quietest of any massive BH candidate accessible from Earth. For an MTH civilisation, these properties are features, not limitations. For observational astronomers, the lack of EHT coverage is a gap Gaia DR4 (2026) and Roman (2027) will begin to close via astrometric microlensing.