Supermassive Black Holes

Keywords: Supermassive Black Holes; Large Scale Structure; Holographic Principle 1. Introduction How supermassive black holes “... form and evolve in- side galaxies is one of the most fascinating mysteries in modern astrophysics” [1]. This analysis addresses that issue with a holographic model [2] for large scale struc- ture in the universe, based on the holographic principle [3] resulting from the theory of gravitation expressed by general relativity. The internal dynamics of large scale structures is analyzed using classical Newtonian gravity to describe the motion of sub-elements within the struc- tures and general relativity to describe the supermassive black holes at their centers. Consistency of the results with test cases across the range of large scale structures and redshifts makes it difficult to ascribe those results to numerical coincidences.

Recent Hubble Space Telescope observations have revealed that a majority of active galactic nuclei (AGNs) at z ∼ 1–3 are resident in isolated disk galaxies, contrary to the usual expectation that AGNs are triggered by mergers. Here we develop a new test of the cosmic evolution of supermassive black holes (SMBHs) in disk galaxies by considering the local population of SMBHs. We show that substantial SMBH growth in spiral galaxies is required as disks assemble. SMBHs exhibit a tight relation between their mass and the velocity dispersion of the spheroid within which they reside, the M • –σ e relation. In disk galaxies the bulge is the spheroid of interest. We explore the

Cosmological simulations The physics of supermassive black holes is a key ingredient to many state of the art cosmological simulations of galaxy formation. Their feedback effects counteract radiative cooling losses of the gas in massive galaxies and thereby reduce star-formation in these systems significantly. I presented one partic- ular implementation of such a model, which uses a two-mode prescription for AGN feedback with a moderately efficient, continuos thermal injection of energy in phases of rapid accretion relative to the Eddington limit, and an efficient, pulsed, kinetic injection at comparably low accretion rates. The model is able to produce a bimodal galaxy colour distribution, similar to what is observed in galaxy surveys (see also Nelson et al., 2017), with a transition in galaxy colours at stellar masses of about 10 10.5 M. The red galaxy population has very little ongoing star formation. We showed that this is coincident with an efficient kinetic feedback which becomes active at comparably low accretion rates relative to the Eddington limit, while SMBHs in the thermal mode are responsible for the growth via gas accre- tion.

and 100% of distant galaxies contain growing supermas- sive black holes. When these results are extrapolated to the full sky, we arrive at the huge number of about 30 million supermassive black holes in the early universe [20,21]. One of the main objectives in studying super- massive black holes is to understand their formation and growth. From an observational perspective, optical tele- scopes are not the right tool to use since they are unable to penetrate the thick cloud of gas and dust that en- shrouds nearly all black holes. Only high energy X-rays can find their way through the thick veil of gas and dust which makes the Chandra X-Ray Observatory the right tool for achieving this task.

Accepted 2011 July 18. Received 2011 July 16; in original form 2011 May 30 A B S T R A C T We consider a scenario where supermassive black holes form through direct accumulation of gas at the centre of proto-galaxies. In the first stage, the accumulated gas forms a super- massive star whose core collapses when the nuclear fuel is exhausted, forming a black hole of M BH ≈ 100 M . As the black hole starts accreting, it inflates the surrounding dense gas into an almost hydrostatic self-gravitating envelope, with at least 10–100 times the mass of the hole.

Accepted 2014 December 9. Received 2014 November 27; in original form 2014 October 10 A B S T R A C T There is mounting observational evidence that most galactic nuclei host both supermassive black holes (SMBHs) and young populations of stars. With an abundance of massive stars, core-collapse supernovae are expected in SMBH spheres of influence. We develop a novel numerical method, based on the Kompaneets approximation, to trace supernova remnant (SNR) evolution in these hostile environments, where radial gas gradients and SMBH tides are present. We trace the adiabatic evolution of the SNR shock until 50 per cent of the remnant is either in the radiative phase or is slowed down below the SMBH Keplerian velocity and is sheared apart. In this way, we obtain shapes and lifetimes of SNRs as a function of the explosion distance from the SMBH, the gas density profile and the SMBH mass. As an application, we focus here exclusively on quiescent SMBHs, because their light may not hamper detections of SNRs and because we can take advantage of the unsurpassed detailed observations of our Galactic Centre. Assuming that properties such as gas and stellar content scale appropriately with the SMBH mass, we study SNR evolution around other quiescent SMBHs. We find that, for SMBH masses over ∼10 7 M , tidal disruption of SNRs can occur at less than 10 4 yr, leading to a shortened X-ray emitting adiabatic phase, and to no radiative phase. On the other hand, only modest disruption is expected in our Galactic Centre for SNRs in their X-ray stage.

We stress again that the masses of our black-hole seeds continuously grow as a result of constant IDM accretion from filaments on top of the standard CDM/baryon accre- tion, in line with the growth of the parent halos. As halos with mass in the range 10 10 – 11 h 1 M are expected to grow by as much as 2 orders of magnitude between redshift z ¼ 15 and z ¼ 7 , a similar IDM accretion is predicted for their black holes. Consequently, the CDM/baryon accretion discussed above does not have to explain the black hole growth alone and can be possibly modeled more conservatively. Moreover, we would expect the low angular momentum of these supermassive black holes to increase the accretion rate as it ensures a lower mass- radiation conversion efficiency [62]. In conclusion, the model presented in this paper succeeds in predicting the observed supermassive black holes.

4 C O N C L U S I O N S We have examined the evolution of supermassive black holes (SMBHs) across cosmic time predicted by the EAGLE simulations (S15, C15). The EAGLE project consists of a suite of hydrody- namical simulations with state-of-the-art subgrid models of galaxy formation including radiative cooling, star formation, reionization, abundance evolution, stellar evolution and mass-loss, feedback from star formation, and SMBH growth and AGN feedback. The param- eters of these subgrid models were calibrated to reproduce the ob- served galaxy mass function and sizes at z = 0.1. In particular, the efficiency of AGN accretion and feedback were set to reproduce the break in the stellar mass function at z = 0.1 and the normalization of the SMBH mass-stellar mass relation at z = 0. It is important to emphasize that the subgrid models of SMBH growth and AGN feedback do not make any explicit distinction between quasar and radio modes, and that we only distinguish sources with high and low Eddington ratios during the analysis. The main findings are summarized as follows:

3 S U P E R M A S S I V E B L AC K H O L E B U I L D U P Because the overwhelming majority of supermassive black holes larger than a billion solar masses are associated with quasars at redshifts lower than 7, the small high redshift subgroup requires a plausible yet low probability explanation. Our goal in this section is to identify a scenario within the gap paradigm that satisfies these requirements. Whereas we will argue that the low probability aspect of our explanation emerges naturally, its plausibility is less obvious and much of our work will be to motivate it. The tools at our disposal will be standard, thin-disc accretion, in both prograde and retrograde configurations, mergers that double the black hole mass, and tilted discs for the initial post-merger accretion phase. We will explore simple scenarios taking into account self-gravity and disc- breakup, including estimates of timescales during and in-between the various physical processes. And, we will explore these paths in the context of the constraints imposed by the AGN feedback outlined in Section 2. We are well aware of not doing justice to the entirety of physical processes thought to influence the growth of black holes and that even within the confines of the processes that we do employ, the scenarios that we explore are contrived.

Stars in the immediate vicinity of supermassive black holes (SMBHs) can be ripped apart by the tidal forces of the black hole. The subsequent accretion of the stellar material causes a spectacular flare of electromagnetic radiation. Here, we provide a review of the observations of tidal disruption events (TDEs), with an emphasis on the important contributions of Swift to this field. TDEs represent a new probe of matter under strong gravity, and have opened up a new window into studying accretion physics under extreme conditions. The events probe relativistic effects, provide a new means of measuring black hole spin, and represent signposts of intermediate-mass BHs, binary BHs and recoiling BHs. Luminous, high-amplitude X-ray flares, matching key predictions of the tidal disruption scenario, have first been discovered with ROSAT, and more recently with other missions and in other wavebands. The Swift discovery of two γ -ray emitting, jetted TDEs, never seen before, has provided us with a unique probe of the early phases of jet formation and evolution, and Swift J1644+75 has the best covered lightcurve of any TDE to date. Further, Swift has made important contributions in providing well-covered lightcurves of TDEs discovered with other instruments, setting constraints on the physics that govern the TDE evolution, and including the discovery of the first candidate binary SMBH identified from a TDE lightcurve.

Max-Planck-Institut f ¨ur Radioastronomie, Auf dem H ¨ugel 69, 53121 Bonn, Germany Abstract. The tidal disruption of stars by supermassive black holes produces luminous soft X-ray accretion flares in otherwise inactive galaxies. First events have been discovered in X-rays with the ROSAT observatory, and have more recently been detected with XMM-Newton, Chandra and Swift, and at other wavelengths. In X-rays, they typically appear as very soft, exceptionally luminous outbursts of radiation, which decline consistent with L ∝ t − 5 / 3 on the timescale of months to years. They reach total amplitudes of decline up to factors 1000–6000 more than a decade after their initial high-states, and in low-state, their host galaxies are essentially X-ray inactive, optically inactive, and radio inactive. X-ray luminous tidal disruption events (TDEs) represent a powerful new probe of accretion physics near the event horizon, and of relativistic effects. TDEs offer a new way of estimating black hole spin, and they are signposts of supermassive binary black holes and recoiling black holes. Once discovered in the thousands in upcoming sky surveys, their rates will probe stellar dynamics in distant galaxies, and they will uncover the – so far elusive – population of intermediate mass black holes in the universe, if they do exist. Further, the reprocessing of the flare into IR, optical and UV emission lines provides us with multiple new diagnostics of the properties of any gaseous material in the vicinity of the black hole (including the disrupted star itself) and in the host galaxy. First candidate events of this kind have been reported recently.

1.1. Supermassive black holes and active galactic nuclei 20 sight, implying a de-projected jet size of ≈ 5 kpc. Whilst accretion discs produce relatively little radio emission, the radio synchro- tron emission from jets is very strong. Historically, the radio loudness parameter R = F 5GHz /F B 8 has been used to divide radio-loud (R > 10), jetted sources from radio quiet, non-jetted ones. A minority of AGN are radio-loud (∼ 15–20 per cent, Kellermann et al. 1989). Nearby radio galaxies were divided into two types by Fan- aroff & Riley (1974). Low radio luminosity Fanaroff-Riley type-I sources (FR-Is) such as M87 are edge-darkened, with the brightest emission coming from the jet core, beyond which the jet fizzles out into low-power lobes. High radio luminosity Fanaroff-Riley type-II sources (FR-IIs) are edge-brightened, with fainter jets ending in giant, bright lobes (see Figure 1.7 for a comparison). FR-Is have been found to commonly reside in clusters and are often the first ranked galaxy; FR-IIs on the other hand are more isolated (e.g. Owen & Laing 1989). Differences in their radio morphology may be understood in this context: the weaker and less well-collimated jets of FR-Is interact with a richer environment as they emerge, so they are more easily slowed by entrainment and suffer radiative losses of energy. The greater power and collimation of FR-II jets enables them to carry their energy out to greater dis- tances, eventually dumping their energy when they collide with external gas clouds, creating the hot spots and bow shocks seen in Figure 1.7.

Background: Binary supermassive black holes and gravitational recoil can thus be identified as active galactic nuclei (AGN). Galaxy mergers are thought to play a major role in galaxy and SMBH evolution. Following a major merger, the two SMBHs first form a binary at the center of the merged galaxy. If, through dynamical processes (which pre- dominantly include interactions with stars), the binary orbit becomes small enough, the resulting SMBH binary tightens and then eventually coalesces through isotropic emission of gravitational waves (Campanelli et al., 2007) causing the merged SMBH to receive a kick (up to ∼ 1000kms −1 for cer- tain spin configurations). Simulations of the post recoil trajectory suggest that following the initial large amplitude short lived oscillations, there is a prolonged period (∼ 1 Gyr) when the kicked SMBH oscillates within the galaxy core (∼ 100 pc) (Gualandris and Merritt, 2008). In principle, these post recoil oscillations can be observed either through emission line doppler shifts or as spatially offset AGN, assuming that the recoiling SMBH remains visible as an AGN. Thus, we expect to find such recoiling SMBHs in nearby galaxies that have undergone mergers within the past few Gyr.

Recent discoveries of tight correlations between the masses of supermassive black holes (BHs) in the cen- ters of nearby galaxies and either the luminosity (e.g., Kormendy & Richston[r]

Introduction 21 the next section. 1.3 Supermassive Black Holes The idea of an object so dense that light could not escape its surface was Þrst sug- gested by John Michell in his 1783 letter to the royal society (Michell 1784). This idea of a Ôdark starÕ was largely ignored until it was reinvented in the early 20th cen- tury as a black hole. Black holes were Þrst predicted as an artifact of spacetime in EinsteinÕs general theory of relativity at the strong Þeld limit, as a solution to the Ein- stein Þeld equation under the assumption of a point particle and spherical mass by Karl Schwarzschild (Schwarzschild 1916). These objects were not taken seriously astrophysically for some time, until the pioneering work of Chandrasekhar. Chan- drasekhar computed that the electron degeneracy pressure of white dwarf stars would not be able to withstand masses greater than 1.44 solar masses, and thus these objects should collapse further, possibly forming black holes (Chandrasekhar 1931, 1935). We now know that there is an intermediary state of ZwickyÕs neutron star, where elec- trons are effectively forced inside protons at this mass limit, to form stars held apart by the degeneracy pressure of neutrons (Baade & Zwicky 1934). However, work by Oppenheimer, Tolman and Volkoff concluded that stars above approximately three so- lar masses would inevitably collapse into black holes, as neutron degeneracy pressure would be unable to withstand the intense gravitational forces on such massive and compact bodies (Tolman 1939, Oppenheimer & Volkoff 1939).

We analyse the largest EAGLE simulation to understand how the baryonic content of MW-mass galaxy haloes react to the growth of their central supermassive black holes and how the resulting evolution transforms the galaxies. We argue that it is necessary to observe the circumgalactic medium to attempt to understand the roles of BH growth and AGN feedback in galaxy transformation. Our investigation leverages the high-cadence tracking of a large sample of simulated galaxies to catch the act of ‘baryon lifting’, where the BH feedback energy can eject most of the circumgalactic baryons from the halo and transform the galaxy across the green valley to the red sequence. We argue that a key physical quantity is the time integral of the total energy released by the BH divided by an analytical estimate of the binding energy of the gaseous halo (E BH/  E b

By combining previous estimates of the evolution of the halo mass function with halo occupation models and our esti- mates for merger timescales, we infer the statistics of mergers that excite quasar activity. We then graft onto this our mod- eling of quasar lightcurves and lifetimes, obtained from our simulations of galaxy mergers that include star formation and black hole growth to deduce, in an ab initio manner, the red- shift dependent birthrate of quasars as a function of their peak luminosities and the corresponding formation rate of black holes as a function of mass. Because our merger simulations relate starbursts, quasars, and red galaxies as different phases of the same events, we can then determine the cosmological formation rate of these various populations and their evolu- tion with redshift. In particular, as we demonstrate in what follows, the observed abundance of all these objects is well- matched to our estimates, unlike for other theoretical mod- els, supporting our interpretation that mergers between gas- rich galaxies represent the dominant production mechanism for quasars, intense starbursts, supermassive black holes, and

Kenneth Dalton Independent Researcher, Bang Saphan, Thailand Abstract In the following black hole model, electrons and positrons form a neutral gas which is confined by gravitation. The smaller masses are supported against gravity by electron degeneracy pressure. Larger masses are supported by ideal gas and radiation pressure. In each case, the gas is a polytrope which satisfies the Lane-Emden equation. Solutions are found that yield the physical proper- ties of black holes, for the range 1000 to 100 billion solar masses.

• Nature, 17 october 2002, p.694, a star in a 15.3-year orbit around the supermassive black hole at the centre of the milky way • Nature, 10 february 2005, p.604, Energy input from quasars regulates the growth and activity of black holes and their host galaxies • http://64.233.183.104/search?q=cache:FOizrt- • www.physics.ucsb.edu/~blaes/amaldi.ps+SMBH+alternatives&hl=nl

Additionally, observations during this period showed that quasars are more numerous at higher redshifts compared to the nearby universe. That supported the idea that after the mass accretion has ended these massive objects should be still there in the center of many nearby galaxies. Scientists estimated that the energy output measured in the nuclei of active galaxies is generated through gas accretion into the black hole and since the black hole can only increase their mass with time, they believed that some inactive galaxies of the nearby galaxies should still host a a very massive black hole. However before Hubble Space Telescope was launched, ground based observations were not sufficient to evaluate the form of that mass.