Unveiling Gargantua: A new search strategy for the most massive central cluster black holes (1509.04782v1)

Abstract: We aim to unveil the most massive central cluster black holes in the universe. We present a new search strategy which is based on a black hole mass gain sensitive 'calorimeter' and which links the innermost stellar density profile of a galaxy to the adiabatic growth of its central SMBH. In a first step we convert observationally inferred feedback powers into SMBH growth rates by using reasonable energy conversion efficiency parameters, $\epsilon$. In the main part of this paper we use these black hole growth rates, sorted in logarithmically increasing steps encompassing our whole parameter space, to conduct $N$-Body computations of brightest cluster galaxies with the newly developed MUESLI software. For the initial setup of galaxies we use core-Sersic models in order to account for SMBH scouring. We find that adiabatically driven core re-growth is significant at the highest accretion rates. As a result, the most massive black holes should be located in BCGs with less pronounced cores when compared to the predictions of empirical scaling relations which are usually calibrated in less extreme environments. For efficiency parameters $\epsilon<0.1$, BCGs in the most massive, relaxed and X-ray luminous galaxy clusters might even develop steeply rising density cusps. Finally, we discuss several promising candidates for follow up investigations, among them the nuclear black hole in the Phoenix cluster. Based on our results, it might have a mass of the order of $10^{11} M_\odot$.

• The paper presents a novel calorimeter-based technique to estimate SMBH growth rates, linking stellar core profiles with black hole mass accretion.
• It employs N-body simulations with core-Sérsic models to analyze the adiabatic growth of black holes in brightest cluster galaxies.
• Findings indicate that high-accretion scenarios yield steep density cusps and potential ultramassive black holes, with the Phoenix cluster as a prime candidate.

Overview of "Unveiling Gargantua: A new search strategy for the most massive central cluster black holes"

The paper "Unveiling Gargantua: A new search strategy for the most massive central cluster black holes" by M. Brockamp and colleagues presents a novel methodology aimed at identifying the most massive supermassive black holes (SMBHs) at the centers of clusters of galaxies. The significance of discovering such massive entities lies in their potential to redefine our understanding of SMBH scaling relations and their implications for the evolution of galaxies and cosmic structures.

Methodology and Computational Approach

The research introduces a search strategy centered on a 'calorimeter' technique, which is sensitive to black hole mass accretion. This method links the stellar density profile at the core of galaxies to the adiabatic growth of their central SMBHs. The methodology is detailed as follows:

1. Energy Conversion and Growth Rates: The initial step involves converting feedback powers inferred from observations into SMBH growth rates using energy conversion efficiency parameters, denoted by ε.
2. N-Body Simulations: These growth rates are utilized to perform $N$-Body computations on brightest cluster galaxies (BCGs) using the newly developed Muesli software. The simulations employ core-Sérsic models to account for the effects of SMBH scouring.
3. Adiabatic Growth Analysis: The paper investigates the adiabatic growth of SMBHs, where changes in the core density profiles are computed numerically to observe the impact of black hole mass increase on the inner galaxy profile.

Numerical Results and Insights

The paper presents several insightful findings from its simulations:

• Core Re-Growth: It is observed that adiabatic processes and core re-growth are significant at the highest accretion rates. The simulations predict that the most massive SMBHs are found in BCGs with less pronounced cores compared to those predicted by standard empirical scaling relations typically derived in less extreme environments.
• Efficiency Parameters and Density Cusps: For scenarios where ε < 0.1 (indicative of higher accretion efficiencies), BCGs in the most massive, relaxed, and X-ray luminous galaxy clusters can develop steeply rising density cusps rather than cores.
• Candidates for Follow-up Studies: The Phoenix cluster is highlighted as a promising candidate for follow-up investigations. Based on the paper’s results, it may host a nuclear black hole of the order of $10^{11} M_⊙$.

Implications and Future Directions

The implications of these findings are profound both practically and theoretically. The identification of ultramassive black holes informs theoretical models of galaxy evolution, particularly studies focusing on the growth mechanisms of SMBHs and the role of feedback processes in shaping galaxy clusters.

Speculation on Developments Beyond Traditional Understanding

While the paper does not make direct predictions about advancements in AI, it suggests computational methodologies that could be expanded upon with more sophisticated algorithmic approaches, potentially incorporating machine learning techniques to refine the search and analysis of SMBHs.

In summary, "Unveiling Gargantua" introduces a paradigm shift in searching for massive cluster-central black holes, emphasizing the need for a more nuanced understanding of the dynamic growth processes at play within galaxy clusters. The results advocate for further detailed astrophysical investigations to confirm predictions and refine existing models governing SMBH interactions with their galactic environments.