# astro: black hole portraits will become more frequent

<< This year marks the fifth anniversary of the release of the first-ever image of a black hole, which revealed the glowing doughnut of the supermassive black hole called M87*. The research team that produced the image—the Event Horizon Telescope (EHT) Collaboration—recently released a second image of that same black hole, which lies 55 million light years from Earth (..). This image comes from an updated version of the EHT and confirms key features of the black hole while also revealing changes over time in the pattern of light emanating from the disk surrounding the object. Starting with this release, the collaboration expects to issue increasingly frequent updates in support of the newly developing field of black hole imaging. >>️

<< “Producing the first image of M87* was a herculean effort and involved creating, testing, and verifying many different schemes and approaches to analyzing and interpreting the data,” says Princeton University astrophysicist Andrew Chael, a member of the EHT Collaboration. “Now we are beginning to transition to a point where we understand our instrument and our analysis frameworks really well, so I think we are going to be releasing results a lot more quickly.” >>

️

Katherine Wright. Black Hole Portraits Will Become More Frequent. Physics 17, 43. Mar 15, 2024. 

https://physics.aps.org/articles/v17/43

Kazunori Akiyama, Antxon Alberdi, et al. The persistent shadow of the supermassive black hole of M 87. 

I. Observations, calibration, imaging, and analysis⋆ The Event Horizon Telescope Collaboration. Astron. Astrophys. 681, A79 (2024).

https://www.aanda.org/articles/aa/full_html/2024/01/aa47932-23/aa47932-23.html

Also: astrophysics, black hole, in https://www.inkgmr.net/kwrds.html 

Keywords: astrophysics, black hole

# gst: the fascinating possibility of two black holes masquerading as one.

<< a pair of black holes whose mutual attraction is balanced by the cosmic expansion would look the same to a distant observer as a single isolated black hole. >>

Oscar J.C. Dias and coll. << point out that when the black holes are allowed to rotate, it is possible that their spin interaction may stabilize the solutions. This raises the fascinating possibility of having an isolated pair of solar-mass black holes in our Universe, balancing happily a few hundred light years apart and impossible to distinguish from a single black hole from far away. >>

<< If these black holes are set up in precisely the correct way, they sit in an unstable equilibrium, akin to a pen balanced on its pointed end. Any disturbance will ruin this perfect balance. >>

Toby Wiseman. Two Black Holes Masquerading as One. Physics 16, 164. Sep 25, 2023. 

https://physics.aps.org/articles/v16/164

Oscar J. C. Dias, Gary W. Gibbons, et al. Static Black Binaries in de Sitter Space. Phys. Rev. Lett. 131, 131401. Sep 25, 2023.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.131401

Also: black hole, astrophysics, in: https://www.inkgmr.net/kwrds.html 

Keywords: gst, black hole, astrophysics

# phys: a quantum gravity hypothesis on infalling matter (hunting for extreme Kerr black holes)

 << Quantum gravity refers to a group of theories—string theory, for example—that aims to reconcile the microscopic world of quantum physics with the macroscopic world of general relativity. >> 

 << Now theoretical work by Grant N.  Remmen (et al) shows that celestial objects called extremal Kerr black holes are highly sensitive to quantum gravity. >> 

 

  << A Kerr black hole is a rotating, electrically neutral black hole. It is said to be extremal if it has the highest possible angular momentum that is compatible with its mass.  Extremal Kerr black holes have yet to be detected, but many theories predict their existence. >> 

 

 They << point out that quantum corrections to general relativity would provide specific contributions to a quantity called the effective action, which describes the dynamics of a gravitational field. (..) under quantum gravity, the event horizon would develop curvature singularities—regions where the gravitational field is infinitely strong. >> 

 

 << the next step is to hunt for extremal Kerr black holes and to try to detect these curvature singularities through their effect on infalling matter. >> 

Ryan Wilkinson. New Physics Magnified in Spinning Black Holes. Physics 16, s117. Aug 31, 2023.

https://physics.aps.org/articles/v16/s117 

Gary T. Horowitz, Maciej Kolanowski, Grant N. Remmen, Jorge E. Santos. Extremal Kerr Black Holes as Amplifiers of New Physics. Phys. Rev. Lett. 131, 091402. Aug 31, 2023.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.091402

Also: Ingrid Fadelli. Theoretical study shows that Kerr black holes could amplify new physics. Phys.org. Sep 22, 2023. 

https://phys.org/news/2023-09-theoretical-kerr-black-holes-amplify.html

Also: astrophysics, black hole, in: https://www.inkgmr.net/kwrds.html

Keywords: astrophysics, black holes

# gst: another way for the evaporation of a black hole

<< The quantum fluctuations that pervade empty space spontaneously give birth to pairs of particles and antiparticles. Ordinarily, these pairs annihilate so promptly that their existence is virtual. But a powerful field can pull a pair’s members apart for long enough that their existence becomes real. Now (AA) have proposed that particle pairs can be brought into existence by the immense gravitational tidal forces around a black hole (..).>>

<< If the vacuum is stable, all pairs that are created are also destroyed. But a strong field destabilizes the vacuum, makes some paths more likely than others, and leads to a deficit of pairs that recombine. The deficit is balanced by a net outflow of real particles, which, in the case of a black hole’s gravitational field, leads to the black hole’s eventual evaporation. >>️

Charles Day. Another Way for Black Holes to Evaporate. Physics 16, s77. Jun 2, 2023. 

https://physics.aps.org/articles/v16/s77

Michael F. Wondrak, Walter D. van Suijlekom, Heino Falcke. Gravitational Pair Production and Black Hole Evaporation. Phys. Rev. Lett. 130, 221502. Jun 2, 2023. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.130.221502

Also:  'black hole', in https://www.inkgmr.net/kwrds.html

Keywords: gst, black hole, astrophysics

# gst: apropos of transitions, scrambling trajectories in a radiative random unitary circuit.

AA << study quantum information scrambling in a random unitary circuit that exchanges qubits with an environment (..). As a result, initially localized quantum information  not only spreads within the system, but also spills into the environment. >>

<< The transition is also easily extended to higher dimensions, where higher-dimensional DP (directed percolation) universality classes will control the critical behavior. >>

<<  The transition in operator spreading  coincides with an information-theoretic 3 transition, which can be framed by  viewing (AA) circuit as a toy model for an evaporating black hole (..). >>️

<< Depending on the initial state of the swapped-in qubits, (AA) observe a corresponding entanglement transition in the coherent information into the environment. >>

️

Zack Weinstein, Shane P. Kelly, Jamir Marino, Ehud Altman. Scrambling Transition in a Radiative Random Unitary Circuit. arXiv:2210.14242v1 [quant-ph]. Oct 25, 2022.

https://arxiv.org/abs/2210.14242

Also: 'transition', 'random', in https://www.inkgmr.net/kwrds.html

Keywords: transition, quantum information, entanglement transition, scrambling, directed percolation

# life: a proposito di bizzarri scenari, qui un ipotetico scenario22 dipinto dal reale ...

img: Congo Square, New Orleans, Louisiana (wikipedia.org)

In definitiva qui si configurerebbe un - intrigante assai - scenario che, grosso modo, si potrebbe sinteticamente 'dipingere' in questi termini: 

(i) entità tre palle destrogire, animate aciclicamente da interazioni attrattive- repulsive a causa di già a suo tempo disvelate pulsioni neuro cognitive arcaiche, riconducibili a visioni neuro predatorie CTZ estreme, perciò ipoteticamente (si fa per dire) a-priori ad esiti immediati e in prospettiva drammaticamente lesivi- autolesivi; 

(ii) entità tre palle levogire, animate da analoghe pulsività, purtuttavia in.forme  tenui, in modalità sottotraccia, frenate da feed-back a modalità allosterica, ombreggiate, stemperate, diluite, discrete, timidamente celate, talvolta fantasmatiche perfino, quasi ma non del tutto mai silenti, perciò anch'esse a tutti gli effetti operative, sebbene a dinamiche più fluide, lente, meno dirompenti rispetto alle destrogire; 

(iii) entrambe l'Entità destrogire e levogire animat(t)rici,  generat(t)rici di dinamiche bi-multi-forcate, transeunti, con picchi di improvvisi aciclici burst ad effetti RAG-time diretti e inversi;

(iv) lo scenario al contorno e forse anche all'interno, nei vari specifici contesti, riconducibile grosso modo alla formazione aciclica di ipotetici buchi neri non inerti, caratterizzati da aciclicità in compressione e dilatazione - come fossero fisarmoniche - animati (in perpetuo?) da multi vortici in ingresso e in uscita;

Non so se basti compulsare un manuale delle funzioni speciali per formalizzare in qualche adatto topo-modo questo pulsatile multi scenario, purtuttavia assolutamente intrigante ... 

Qui una AI operativa nella formalizzazione di analogie potrebbe modellizzare, forse ... (e.g. https://flashontrack.blogspot.com/2021/08/aibot-mechanism-of-analogy-could-be.html )

Quello che appare evidente è la complessità d'insieme, un bizzarro dipinto, uno scenario dinamico che, al confronto, le storiche danze in Congo Square potrebbero sembrare semplici, ordinate coreografie ... queste, rispetto a quelle, delle topo-forme  'primitive', per dire ed anzicheforse.

In sintesi, i riferimenti (ovviamente generici) del bizzarro scenario: 

(:) buco nero con vortici 

https://flashontrack.blogspot.com/2022/09/astro-black-holes-as-q-ball-type.html

(:) scenari generati da 3 palle 

(a)

https://flashontrack.blogspot.com/2017/10/gst-more-on-three-body-problem-695.html  

(b)

https://flashontrack.blogspot.com/search?q=three-body

(:) effetti RAG-time (RAG: Ralph, Al, George) 

(a) (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=rag   

(b)

https://flashontrack.blogspot.com/search?q=rag

(:) pulsioni predatorie supportate / giustificate da visioni neuro- post- CTZ nelle modalità arcaiche oppure friendly 

https://flashontrack.blogspot.com/2019/06/brain-immagini-ctz-cicliche.html

(:) Congo Square, jazz 

(a)

https://en.m.wikipedia.org/wiki/Congo_Square   

(b)

https://flashontrack.blogspot.com/search?q=jazz   

(c) (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=jazz

(:) approccio Bertalanffy 

( https://it.m.wikipedia.org/wiki/Ludwig_von_Bertalanffy ) al reale 

https://flashontrack.blogspot.com/search?q=gst

(:) un bizzarro tracciatore 

https://flashontrack.blogspot.com/2022/10/life-proposito-di-transizioni-un.html

Anche

"Amico, qualunque cosa suonerai ... "

(a) (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=jelly+roll  

(b)

https://flashontrack.blogspot.com/search?q=jelly+roll

Keywords: life, gst, Congo Square, jazz, Jelly Roll, transition, three-body, RAG, CTZ, black hole, bizarre tracker

# life: apropos of quasi-stochastic (bizarre) landscapes in high-dimension, a case of double RAG-time inside a black hole with vortices

Here a hypotetical bizarre scenario of coexistence of double RAG-time (RAG: Ralph, Al, George) inside a black hole with vortices:

(1) 

Maurizio Belpietro.Sorprese in vista. Occhio alla strana coppia Conte D'Alema. La verità. anno vii n 258 pg 1. 19 set 2022.

https://www.laverita.info/dalema-conte-2658304063.html

(2) 

Andrea Pertici. Un soccorso centrista alla maggioranza dei due terzi?  

huffingtonpost.it. 18 Set 2022  17:08

https://www.huffingtonpost.it/blog/2022/09/18/news/un_soccorso_centrista_alla_maggioranza_dei_due_terzi-10239275/

Also

keyword 'RAG' in Notes

(quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=rag

keyword 'RAG' in FonT

https://flashontrack.blogspot.com/search?q=rag

black holes (as Q-ball-type saturons) could admit multi-vortex dynamics.

FonT. Sep 19, 2022.  

https://flashontrack.blogspot.com/2022/09/astro-black-holes-as-q-ball-type.html

PS: really intriguing the image of a black hole with vortices ...

Keywords: life, jazz, RAG-time, RAGtime, black hole, vortex, vortices, vortexes, vorticity

# astro: black holes (as Q-ball-type saturons) could admit multi-vortex dynamics

<< Theoretical physicists argue that black holes admit vortex structures >>

Img << Sketch of a black hole endowed with multiple vortices. Colors denote the orientation, with the associated trapped magnetic field lines in black. Credit: Dvali et al. >>️

<< Recently, a new quantum framework for black holes, namely in terms of Bose-Einstein condensates of gravitons (the quanta of gravity itself), has been introduced, (..) Up until our article was published, rotating black holes have not been thoroughly studied within this framework. However, they might not only exist, but also be the rule rather than the exception. >> Florian Kühnel. 

️

Ingrid Fadelli. Theoretical physicists argue that black holes admit vortex structures. Phys.org. Sep 09, 2022. 

https://phys.org/news/2022-09-theoretical-physicists-black-holes-vortex.html

AA << argue that black holes admit vortex structure. This is based both on a graviton-condensate description of a black hole as well as on a correspondence between black holes and generic objects with maximal entropy compatible with unitarity, so-called saturons. (They) show that due to vorticity, a Q-ball-type saturon of a calculable renormalizable theory obeys the same extremality bound on the spin as the black hole. Correspondingly, a black hole with extremal spin emerges as a graviton condensate with vorticity. (..) Next, (AA) show that in the presence of mobile charges, the global vortex traps a magnetic flux of the gauge field. This can have macroscopically observable consequences. >>

️

Gia Dvali, Florian Kuhnel, Michael Zantedeschi. Vortices in Black Holes. Phys. Rev. Lett. 129, 061302. Aug 3, 2022.  

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.061302

Also

keyword 'black hole' in FonT  

https://flashontrack.blogspot.com/search?q=black+hole

Keywords: astro, astrophysics, black hole, rotating black hole, vortex, vorticity

# life: a proposito di vaticini ...

a proposito di vaticini (dal lat.  vates «vate» e canĕre «cantare» )...

Mr. Mario Draghi, la simmetria rifiutata ... 

Simmetrico, purtuttavia caotico. FonT. 19 luglio 2019.

https://flashontrack.blogspot.com/2019/07/life-simmetrico-purtuttavia-caotico.html

Anche

Be careful ... by Potus Joe. FonT. 11 maggio 2022. 

https://flashontrack.blogspot.com/2022/05/life-be-careful-by-potus-joe.html

Anche

Eight new echoing black hole binaries (in Milky Way). FonT. 25 giugno 2022. 

https://flashontrack.blogspot.com/2022/06/astro-eight-new-echoing-black-hole.html

Anche

non saprei dire il perchè ma le vicende governative di Mr Mario Draghi mi hanno fatto ricordare le 'bizzarre visioni' degli Artisti Aldo, Giovanni e Giacomo nell'episodio 'Il Conte Dracula' ... 

(1)   

https://youtu.be/gZNBR4YTSLs

(2)   

https://youtu.be/m9uRj9fV-i4

Keywords: symmetry, chaos, black hole, Mario Draghi, Gov

# gst: apropos of prolate- oblate spheroid transition, the chaotic behavior of a spinless entity around a black hole.

AA << investigate the long-term orbital dynamics of spinless extended bodies in Schwarzschild geometry, and show that periodic deviations from spherical symmetry in the shape of a test body may trigger the onset of chaos. (AA) do this by applying Dixon's formalism at quadrupolar order to a nearly spherical body whose shape oscillates between a prolate and an oblate spheroid. The late-time chaotic behavior is then verified by applying Melnikov's method. >>️

Ricardo A. Mosna, Fernanda F. Rodrigues, Ronaldo S. S. Vieira. Chaotic dynamics of a spinless axisymmetric extended body around a Schwarzschild black hole. arXiv: 2207.04341v1 [gr-qc]. Jul 9, 2022. 

https://arxiv.org/abs/2207.04341

Phys. Rev. D 106, 024016 (2022). 

https://doi.org/10.1103/PhysRevD.106.024016

Also - Oblate and Prolate Spheroid.  

<< The shape of the earth is that of a round ball or sphere slightly flattened at two opposite sides. Such a body is termed a spheroid. There are two kinds of spheroids-oblate and prolate; the former as the shape of an orange, the latter that of a lemon.  >>️

Oblate and Prolate Spheroid.  

https://etc.usf.edu/clipart/30500/30587/spheroid_30587.htm

img    https://etc.usf.edu/clipart/30500/30587/spheroid_30587_sm.gif

Also

keyword 'transition' in FonT: 

https://flashontrack.blogspot.com/search?q=transition

keyword 'transizione' | 'transition' in Notes (quasi-stochastic poetry): 

https://inkpi.blogspot.com/search?q=transizione

https://inkpi.blogspot.com/search?q=transition

Keywords: gst, spheroid, behavior, chaos, transition, black hole

# astro: eight new echoing black hole binaries (in Milky Way)

<< Scattered across our Milky Way galaxy are tens of millions of black holes—immensely strong gravitational wells of spacetime, from which infalling matter, and even light, can never escape. Black holes are dark by definition, except on the rare occasions when they feed. As a black hole pulls in gas and dust from an orbiting star, it can give off spectacular bursts of X-ray light that bounce and echo off the inspiraling gas, briefly illuminating a black hole's extreme surroundings. >>

<< In a study appearing (..) in the The Astrophysical Journal, (AA) report (..) eight new echoing black hole binaries in our galaxy. Previously, only two such systems in the Milky Way were known to emit X-ray echoes. >>️

 << Kara (Erin Kara) and her colleagues are using X-ray echoes to map a black hole's vicinity, much the way that bats use sound echoes to navigate their surroundings. (..)  As a side project, Kara is working with MIT education and music scholars, Kyle Keane and Ian Condry, to convert the emission from a typical X-ray echo into audible sound waves. >>️️

Jennifer Chu. Search reveals eight new sources of black hole echoes. MIT.  May 2, 2022. 

https://phys.org/news/2022-05-reveals-sources-black-hole-echoes.html

https://youtu.be/iIeIag2Ji8k

Jingyi Wang, Erin Kara, et al. The NICER "Reverberation Machine": A Systematic Study of Time Lags in Black Hole X-Ray Binaries. ApJ. 930, 18. May 2, 2022. 

https://iopscience.iop.org/article/10.3847/1538-4357/ac6262

Also

keyword 'black hole' in FonT

https://flashontrack.blogspot.com/search?q=black+hole

keyword 'waves' in FonT

https://flashontrack.blogspot.com/search?q=waves

keyword 'onda' in Notes 

(quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=onda

Keywords: astro, black hole, echoes, waves

# gst: apropos of a immaginary transition (with a tipping point), which simulates the chaotic interactions of three black holes.

<< The interactions between three bodies such as stars or planets or black holes cannot be predicted with an elegant formula. Moerman (Arend Moerman) therefore used a computer that calculates what happens for a short period of time and then uses the result for the next period of time. >>

AA << varied the masses of the three interacting black holes. They started with one solar mass and went up to a billion times the mass of the sun. >>

<< Around ten million solar masses, there appeared to be a tipping point. In the simulations, black holes that are lighter than about ten million solar masses mostly eject each other through a gravitational slingshot. Black holes heavier than about ten million solar masses start to merge. First, two black holes merge. The third black hole will follow later. The black holes merge because they lose kinetic energy and that is because they emit gravitational waves. >>

<< Arend's work (..) has led to a new understanding of how black holes become supermassive. In the simulations, we see that heavy black holes no longer endlessly move around each other, but that, if they are heavy enough, they collide pretty much instantly. >> Simon Portegies Zwart. 

Simulating chaotic interactions of three black holes. Netherlands Research School for Astronomy. Oct 20, 2021. 

https://phys.org/news/2021-10-simulating-chaotic-interactions-black-holes.html

Tjarda C. N. Boekholt, Arend Moerman, Simon F. Portegies Zwart. Relativistic Pythagorean three-body problem. Phys. Rev. D 104, 083020. 14 Oct 14,  2021. 

https://journals.aps.org/prd/abstract/10.1103/PhysRevD.104.083020

Also

more on the three-body problem (695 families of collisionless orbits). FonT. Oct 16, 2017. 

https://flashontrack.blogspot.com/2017/10/gst-more-on-three-body-problem-695.html

keyword 'black hole' | 'astro' in FonT

https://flashontrack.blogspot.com/search?q=black+hole

https://flashontrack.blogspot.com/search?q=astro

keyword 'transition' | 'transitional' in FonT

https://flashontrack.blogspot.com/search?q=transition

https://flashontrack.blogspot.com/search?q=transitional

keyword 'transition' | 'transizion*' in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=transition

https://inkpi.blogspot.com/search?q=transizione

https://inkpi.blogspot.com/search?q=transizioni

keywords: gst, black hole, three-body problem, transition, chaos, chaotic interaction, tipping point.

# astro: aprops of horrific encounters, how to survive inside a (virtual) black hole

<< As (eight stars skirt a black hole 1m times the mass of the Sun) approach, all are stretched and deformed by the black hole's gravity. Some are completely pulled apart into a long stream of gas, a cataclysmic phenomenon called a tidal disruption event. Others are only partially disrupted, retaining some of their mass and returning to their normal shapes after their horrific encounters. >>

<< These simulations, (..) are the first to combine the physical effects of Einstein's general theory of relativity with realistic stellar density models. The virtual stars range from about one-tenth to 10 times the Sun's mass. >>

<< The division between stars that fully disrupt and those that endure isn't simply related to mass. Instead, survival depends more on the star's density. >>

Jeanette Kazmierczak. Scientists fling model stars at a virtual black hole to see who survives. NASA's Goddard Space Flight Center. Nov 26, 2021.

https://phys.org/news/2021-11-scientists-stars-virtual-black-hole.html

<< This paper introduces a series of papers presenting a quantitative theory for the tidal disruption of main-sequence stars by supermassive black holes (the pericenter-dependence of tidal disruption properties for eight stellar masses (..) and six black hole masses (..). >>

Taeho Ryu, Julian Krolik, et al. Tidal Disruptions of Main-sequence Stars. I. Observable Quantities and Their Dependence on Stellar and Black Hole Mass. ApJ 904 98. Nov 25, 2020.

https://iopscience.iop.org/article/10.3847/1538-4357/abb3cf

Also

keyword 'black hole' | 'astro' in FonT

https://flashontrack.blogspot.com/search?q=black+hole

https://flashontrack.blogspot.com/search?q=astro

keywords: astro, blackhole, tidal disruption, survival, surviving

# life: some scientists hypothesize the possibility of (A) traveling faster than light, (B) visiting the interior of a black hole, (C) being already under observation by alien entities.

(A) traveling faster than light

<< Lentz (Erik Lentz. https://iopscience.iop.org/article/10.1088/1361-6382/abe692 ) proposes one such way we might be able to do this, thanks to what he calls a new class of hyper-fast solitons – a kind of wave that maintains its shape and energy while moving at a constant velocity (and in this case, a velocity faster than light). According to Lentz's theoretical calculations, these hyper-fast soliton solutions can exist within general relativity, and are sourced purely from positive energy densities, meaning there's no need to consider exotic negative- energy- density sources that haven't yet been verified. (..) With sufficient energy, configurations of these solitons could function as 'warp bubbles', capable of superluminal motion, and theoretically enabling an object to pass through space-time while shielded from extreme tidal forces. >>

<< another recent analysis, published only this month ( David Nield.  https://www.sciencealert.com/engineers-have-proposed-the-first-model-for-a-physical-warp-drive  ;  Alexey Bobrick, Gianni Martire. https://iopscience.iop.org/article/10.1088/1361-6382/abdf6e ), which also proposes an alternative model for a physically possible warp drive that doesn't require negative energy to function. >>️️

Peter Dockrill. Faster-Than-Light Travel Is Possible Within Einstein's Physics, Astrophysicist Shows. Mar 11, 2021.

https://www.sciencealert.com/faster-than-light-travel-is-possible-within-einstein-s-physics-astrophysicist-shows

(B) visiting the interior of a black hole

<<  if a person found an isolated supermassive black hole suitable for scientific study and decided to venture in, everything observed or measured of the black hole interior would be confined within the black hole's event horizon.

Keeping in mind that nothing can escape the gravitational pull beyond the event horizon, the in-falling person would not be able to send any information about their findings back out beyond this horizon. Their journey and findings would be lost to the rest of the entire universe for all time. But they would enjoy the adventure, for as long as they survived … maybe …. >>️

Leo Rodriguez, Shanshan Rodriguez. Could a human enter a black hole to study it? A person could travel past (certain) black holes' event horizons without dying immediately — here's how. Feb 7, 2021. 

https://www.salon.com/2021/02/07/could-a-human-enter-a-black-hole-to-study-it_partner/  

(C) being already under observation by alien entities.

<< On June 25 the Pentagon and the Office of the Director of National Intelligence released their much hyped report on unidentified aerial phenomena, or UAP. (..) And while the report did not rule out an extraterrestrial origin for much of the documented UAP, it was short on details or bombshells. >> 

<<  we already know our world is easily detectable by extrasolar observers. A paper published on June 23 in Nature  

(Kaltenegger L., Faherty J.K.  https://www.nature.com/articles/s41586-021-03596-y ) shows that in the past 5,000 years, 1,715 stars have been in the right celestial position to view a populated Earth transiting the sun—with 319 more entering this sweet spot in the next 5,000 years. And seven of these far-off stars are known to have their own orbiting exoplanets that might support life. >>

<< Think of living in a room, and all the windows are open, and you do all your business, and you don’t know that all the windows are open, (..) Would you behave differently if you knew that you are being seen all your life? >>️  René Heller️

️

Tess Joosse. Aliens Might Already Be Watching Us. A new star map reveals more than 2,000 stars, some with their own planets, that have a direct view of our planetary presence. July 1, 2021

https://www.scientificamerican.com/article/aliens-might-already-be-watching-us

# gst; apropos of hair that can be combed, some perturbation fields, along the event horizon of extreme black holes, seem to evolve in time indefinitely

 <<  black holes can be fully characterized by only three physical quantities: their mass, spin and charge. Since they have no additional "hairy" attributes to distinguish them, black holes are said to have "no hair"—Black holes of the same mass, spin, and charge are exactly identical to each other. >> 

AA << discovered that a special kind of black hole violates black hole uniqueness, the so-called "no hair" theorem. Specifically, the team studied extremal black holes—holes that are "saturated" with the maximum charge or spin they can possibly carry. They found that there is a quantity that can be constructed from the spacetime curvature at the black hole horizon that is conserved, and measurable by a distant observer. Since this quantity depends on how the black hole was formed, and not just on the three classical attributes, it violates black hole uniqueness. This quantity constitutes "gravitational hair" and potentially measurable by recent and upcoming gravitational wave observatories like LIGO and LISA. >>

<< even though external perturbations of extreme black holes decay as they do also for regular black holes, along the event horizon certain perturbation fields evolve in time indefinitely. >>

<< The uniqueness theorems assume time independence. But the Aretakis phenomenon explicitly violates time independence along the event horizon. This is the loophole through which the hair can pop out and be combed at a great distance by a gravitational wave observatory, >> Lior Burko.

Extreme black holes have hair that can be combed. Theiss Research. Jan 26, 2021.

https://phys.org/news/2021-01-extreme-black-holes-hair.html

Lior M. Burko, Gaurav Khanna, Subir Sabharwal. Scalar and gravitational hair for extreme Kerr black holes. Phys. Rev. D 103, L021502. Jan 26, 2021.

https://journals.aps.org/prd/abstract/10.1103/PhysRevD.103.L021502  

# astro: runaway cooling of intracluster gas during a silent black hole

<< supermassive black holes play a fundamental role in regulating the formation of stars throughout cosmic time. This has been clearly demonstrated in the case of galaxy clusters in which powerful feedback from the central black hole is  preventing the hot intracluster gas from cooling catastrophically, thus reducing the expected star formation rates by orders of magnitude. >>

AA << present the first observational evidence for massive, runaway cooling occurring in the absence of supermassive black hole feedback in the high-redshift galaxy cluster SpARCS104922.6+564032.5 (..) The hot intracluster gas appears to be fueling a massive burst of star formation >>

<< Intracluster stars are therefore not only produced by tidal stripping and the disruption of cluster galaxies, but can also be produced by runaway cooling of hot intracluster gas at early times. Overall, these observations show the dramatic impact when supermassive black hole feedback fails to operate in clusters. They indicate that in the highest overdensities such as clusters and proto-clusters, runaway cooling may be a new and important mechanism for fueling massive bursts of star formation in the early universe. >>

J. Hlavacek-Larrondo, C.L. Rhea, et al. Evidence of runaway gas cooling in the absence of supermassive black hole feedback at the epoch of cluster formation. arXiv:2007.15660v1 [astro-ph.GA]. Jul 30, 2020.

https://arxiv.org/abs/2007.15660   

<< It reminds me of the old expression of 'when the cat's away, the mice will play,' (..) Here the cat, or black hole, is quiet and the mice, or stars, are very busy. >> Julie Hlavacek

Black hole fails to do its job. Chandra X-ray Center. Aug 3, 2020. 

https://phys.org/news/2020-08-black-hole-job.html   

# astro: apropos of elusive predators ... the mid-sized mass black hole

<< Astronomers have found the best evidence for the perpetrator of a cosmic homicide: a black hole of an elusive class known as "intermediate-mass," which betrayed its existence by tearing apart a wayward star that passed too close. >>

<< These so-called intermediate-mass black holes (..) are a long-sought "missing link" in black hole evolution. >>

Claire Andreoli. Hubble finds best evidence for elusive mid-sized black hole. NASA's Goddard Space Flight Center. Mar 31, 2020

https://m.phys.org/news/2020-03-hubble-evidence-elusive-mid-sized-black.html

Dacheng Lin, Jay Strader, et al.  Multiwavelength Follow-up of the Hyperluminous Intermediate-mass Black Hole Candidate 3XMM J215022.4−055108. ApJL 892 L25. Mar 31, 2020

https://iopscience.iop.org/article/10.3847/2041-8213/ab745b

# astro: you might find erratic massive black holes in dwarf galaxies ...

<< The new VLA (Very Large Array) observations revealed that 13 of these galaxies have strong evidence for a massive black hole that is actively consuming surrounding material. (AA) were very surprised to find that, in roughly half of those 13 galaxies, the black hole is not at the center of the galaxy, unlike the case in larger galaxies, >>  Amy Reines.

<< The scientists said this indicates that the galaxies likely have merged with others earlier in their history. This is consistent with computer simulations predicting that roughly half of the massive black holes in dwarf galaxies will be found wandering in the outskirts of their galaxies. >>

<< This work has taught us that we must broaden our searches for massive black holes in dwarf galaxies beyond their centers to get a more complete understanding of the population and learn what mechanisms helped form the first massive black holes in the early Universe, >> Amy Reines.

Astronomers find wandering massive black holes in dwarf galaxies. National Radio Astronomy Observatory. Jan 6, 2020.

https://m.phys.org/news/2020-01-astronomers-massive-black-holes-dwarf.html    

Amy Reines, James Condon, et al. A New Sample of (Wandering) Massive Black Holes in Dwarf Galaxies from High Resolution Radio Observations. arXiv:1909.04670v1 [astro-ph.GA] Sep 10, 2019.

https://arxiv.org/abs/1909.04670

Also

keyword 'astro' in FonT

https://flashontrack.blogspot.com/search?q=astro

# gst: marginally outer trapped surfaces (during a binary Black Hole merger)

<< do MOTSs (marginally outer trapped surfaces, or marginal surfaces) merge in a BBH (binary black hole ) coalescence, and if so, how, exactly? >>

<< It is an underappreciated fact that event horizons are not really very useful for studying astrophysical properties of black hole mergers, (..) What is much more useful are surfaces which go under the boring name of marginally outer trapped surfaces (..). This uninteresting name hides their importance in understanding black holes. >>

Ingrid Fadelli. Numerical evidence for the merger of MOTSs inside a binary black hole. Nov 1, 2019

https://m.phys.org/news/2019-11-numerical-evidence-merger-motss-binary.html

Daniel Pook-Kolb, Ofek Birnholtz, et al. 

Interior of a Binary Black Hole Merger. Phys. Rev. Lett. 123, 171102 Oct 21, 2019. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.171102

# astro: test the 'no-hair' hypothesis on coalescent black holes (at the ~ 10% or ~ 20% levels)

<< Agreement between the postinspiral measurements of mass and spin and those using the full waveform supports the hypothesis that the GW150914 merger produced a Kerr black hole, as predicted by general relativity, and provides a test of the no-hair theorem at the ∼10% level. An independent measurement of the frequency of the first overtone yields agreement with the no-hair hypothesis at the ∼20% level.  >>

Maximiliano Isi, Matthew Giesler, et al. Testing the No-Hair Theorem with GW150914. Phys. Rev. Lett. 123, 111102. Sep 12, 2019.    https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.111102

Synopsis: Hunting for Hair on Coalescing Black Holes. A fresh look at data from the first detected black-hole merger supports the “no hair” theorem.  Sep 12, 2019.   https://physics.aps.org/synopsis-for/10.1103/PhysRevLett.123.111102

'No-hair' theorem   https://en.m.wikipedia.org/wiki/No-hair_theorem

Kerr black hole   https://en.m.wikipedia.org/wiki/Rotating_black_hole