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sabato 5 febbraio 2022
# astro: aprops of horrific encounters, how to survive inside a (virtual) black hole
venerdì 10 gennaio 2020
# astro: you might find erratic massive black holes in dwarf galaxies ...
mercoledì 5 agosto 2020
# astro: runaway cooling of intracluster gas during a silent black hole
sabato 25 giugno 2022
# astro: eight new echoing black hole binaries (in Milky Way)
mercoledì 6 aprile 2022
# astro: going beyond a performance by Frank Zappa (or a speech by – for example – a political entity), two speeds of sound found on Mars
mercoledì 28 ottobre 2020
# astro: the effect of Yarkovsky acceleration to direct the asteroid Apophis (towards us, hypothetically)
martedì 22 febbraio 2022
# gst: apropos of a immaginary transition (with a tipping point), which simulates the chaotic interactions of three black holes.
lunedì 19 settembre 2022
# astro: black holes (as Q-ball-type saturons) could admit multi-vortex dynamics
venerdì 18 maggio 2018
# astro: crazy chaotic encounters (and megamerger)
<< Binary black holes are basically like giant targets hanging out in the cluster, and as you throw other black holes or stars at them, they undergo these crazy chaotic encounters >>
<< What people had done in the past was to treat this as a purely Newtonian problem, (..) Newton’s theory of gravity works in 99.9 percent of all cases. The few cases in which it doesn’t work might be when you have two black holes whizzing by each other very closely, which normally doesn’t happen in most galaxies >> Carl Rodriguez
Jennifer Chu. Dense stellar clusters may foster black hole megamergers. MIT News Office. Apr 10, 2018.
http://news.mit.edu/2018/dense-stellar-clusters-may-foster-black-hole-megamergers-0410
Carl L. Rodriguez, Pau Amaro-Seoane, et al. Post-Newtonian Dynamics in Dense Star Clusters: Highly-Eccentric, Highly-Spinning, and Repeated Binary Black Hole Mergers.
Phys. Rev. Lett. 120, 151101 (2018). doi: 10.1103/PhysRevLett.120.151101.
arXiv:1712.04937 [astro-ph.HE]. Mar 14, 2018
mercoledì 6 marzo 2019
# gst astro: when a superbubble can generate trains of shock waves
<< Sixty-seven million light-years away, a galaxy is blowing enormous bubbles. We know what they are. Known as nuclear superbubbles, the structures are likely created by the supermassive black hole in the galaxy's centre. Now, thanks to new data, we know something incredible is occurring inside them. >>
<< Observations from NASA's Chandra X-ray Observatory of spiral galaxy NGC 3079 have revealed that the bubbles are actually a huge cosmic particle accelerator, producing energetic high-speed particles around their edges. >>
<< As the bubbles expand into the surrounding gas of the interstellar medium, they generate shock waves, which in turn produce tangled magnetic fields. (..) particles ricochet around these shock magnetic fields; when they pass through the shock front, they get an acceleration boost. >>
Michelle Starr. Astronomers Have Found 'Superbubbles' Producing Shock Waves in Another Galaxy. Mar 4, 2019.
Jiang-Tao Li, Edmund Hodges-Kluck, et al. Detection of non-thermal hard X-ray emission from the "Fermi bubble" in an external galaxy. ApJ in press. arXiv:1901.10536v1 [astro-ph.HE] Jan 31, 2019.
lunedì 4 marzo 2019
# astro: quiescent black holes abound in our Galaxy
AA << results provide new circumstantial evidences for a wandering intermediate-mass black hole in the Galactic center, suggesting also that high-velocity compact clouds can be probes of quiescent black holes abound in our Galaxy. >>
Shunya Takekawa, Tomoharu Oka, et al. Indication of Another Intermediate - mass Black Hole in the Galactic Center. arXiv: 1812.10733v1 [astro-ph.GA] doi: 10.3847/2041-8213/aafb07
https://arxiv.org/abs/1812.10733
"The Invisible Galaxy" - 100 Million Black Holes Lurking in the Milky Way (Weekend Feature). Mar 2, 2019
mercoledì 7 novembre 2018
# astro: the strange behavior of Oumuamua (Hawaiian for "scout")
<< 'Oumuamua (1I/2017 U1) is the first object of interstellar origin observed in the Solar system. >>
AA << discuss the possible origins of such an object including the possibility that it might be a lightsail of artificial origin. >>
Shmuel Bialy, Abraham Loeb. Could Solar Radiation Pressure Explain 'Oumuamua's Peculiar Acceleration? arXiv:1810.11490 [astro-ph.EP]. Oct 30, 2018.
https://arxiv.org/abs/1810.11490
Robby Berman. Harvard scientists suggest 'Oumuamua is an alien device. It's an asteroid, it's a comet, it's actually a spacecraft? Nov 6, 2018.
https://bigthink.com/surprising-science/oumuamua-spacecraft-alien-device
NASA utd about 'Oumuamua:
Calla Cofield. NASA Learns More About Interstellar Visitor 'Oumuamua. Nov. 14, 2018.
https://www.nasa.gov/feature/jpl/nasa-learns-more-about-interstellar-visitor-oumuamua
mercoledì 7 ottobre 2020
# astro: the turbulent history of Ryugu
venerdì 21 luglio 2017
# s-astro: the “mudball” model; a terrestrial muddiness from carbonaceous asteroids
<< Scientists have long held the belief that planets – including Earth – were built from rocky asteroids, but new research challenges that view >>
Planets like earth may have had muddy origins. July 14, 2017
https://m.phys.org/news/2017-07-planets-earth-muddy.html
<< It would have been a mud, rather than a rock >>
Philip A. Bland, Bryan J. Travis. Giant convecting mud balls of the early solar system. Science Advances 14 Jul 2017: Vol. 3, no. 7, e1602514 doi: 10.1126/sciadv.1602514
lunedì 31 dicembre 2018
# astro: sources of ripples of spacetime: a brief history of black holes
<< The history of (..) hunt for these enigmatic objects traces back to the 18th century, but the crucial phase took place in a suitably dark period of human history - World War II. >>
Carla Rodrigues Almeida. A brief history of black holes. Max Planck Institute for the History of Science. Dec 27, 2018.
http://theconversation.com/a-brief-history-of-black-holes-107298
lunedì 28 agosto 2017
# astro: the binary black hole spin distribution, a sort of cosmic estension of Mr. Jelly Roll
<< The direct detection of gravitational waves from merging binary black holes opens up a window into the environments in which binary black holes form. One signature of such environments is the angular distribution of the black hole spins >>
AA << report that, if the magnitudes of the black hole spins are allowed to extend to high values, the effective spins for these systems indicate a 0.015 odds ratio against an aligned angular distribution compared to an isotropic one [isotropic spin orientation: the spins of the black holes are randomly oriented with respect to the orbit of the binary system]. When considering the effect of ten additional detections, this odds ratio decreases to 2.9 × 10−7 against alignment >>
Will M. Farr, Simon Stevenson, et al. Distinguishing spin-aligned and isotropic black hole populations with gravitational waves. Nature 548, 426–429 Aug 24, 2017 doi: 10.1038/nature23453
http://www.nature.com/nature/journal/v548/n7668/full/nature23453.html
https://arxiv.org/abs/1706.01385
<< Amico, qualunque cosa suonerai . . . suonerai Jelly Roll >>
Jelly Roll Morton (opp. Mouton, alias di Ferdinand La Menthe, opp. La Mothe, New Orleans, 20 ott ~1885 - Los Angeles, 10 luglio 1941, ~56a). Ref: Alan Lomax. "Mister Jelly Roll". Duell, Sloan & Pearce, New York (1950); cit. in: Arrigo Polillo, "JAZZ". Oscar Saggi Mondadori. (1977):315,325.
martedì 1 agosto 2017
# s-astro: cosmic nomads, transfers, impacts
a) cosmic nomads
Lee Billings. Wandering in the Void, Billions of Rogue Planets without a Home. New results suggest free-floating giant planets are less common than previously believed, but hint at vast numbers of smaller castaway worlds. July 24, 2017
b) cosmic transfers
Ashley Yeager. Half of the Milky Way comes from other galaxies
Simulations suggest that galactic winds blew the material in from elsewhere. July 26, 2017
https://www.sciencenews.org/article/half-milky-way-comes-other-galaxies
Daniel Angles-Alcazar
Claude-Andre Faucher-Giguere
et al. The cosmic baryon cycle and galaxy mass assembly in the FIRE simulations. Mon Not R Astron Soc (2017) 470 (4): 4698-4719. doi: 10.1093/mnras/stx1517
Publ. June 20, 2017
c) cosmic impacts
Jenny Wells. Evidence of impacts that structured the Milky Way galaxy. July 18, 2017
https://m.phys.org/news/2017-07-evidence-impacts-milky-galaxy.html
Deborah Ferguson, Susan Gardner, Brian Yanny. Milky Way Tomography with K and M Dwarf Stars: The Vertical Structure of the Galactic Disk. The American Astronomical Society. The Astrophysical Journal, Volume 843, Number 2 . Publ. July 14, 2017.
http://iopscience.iop.org/article/10.3847/1538-4357/aa77fd/meta
giovedì 7 marzo 2019
# gst astro: approaches to hack a black hole (to distinguish scrambled information from noise)
paper.1
Adam Mann. Physicists May Have Found a Way to 'Untangle' Information Trapped in a Black Hole. Mar 6, 2019
https://www.livescience.com/64935-black-hole-information-paradox.html
K. A. Landsman, C. Figgatt, et al. Verified quantum information scrambling. Nature. volume 567, pages 61–65 (2019) Mar 6, 2019.
https://www.nature.com/articles/s41586-019-0952-6
paper.2
Mike McRae. Physicists Want to Use Quantum Particles to Find Out What Happens Inside a Black Hole. Mar 6, 2019.
Beni Yoshida, Norman Y. Yao. Disentangling Scrambling and Decoherence via Quantum Teleportation. Phys. Rev. X 9, 011006. Jan 9, 2019
https://journals.aps.org/prx/abstract/10.1103/PhysRevX.9.011006
martedì 9 agosto 2016
# s-astro: and come out the other side
<< One of the biggest problems when studying black holes is that the laws of physics as we know them cease to apply in their deepest regions. Large quantities of matter and energy concentrate in an infinitely small space, the gravitational singularity, where space-time curves towards infinity and all matter is destroyed. Or is it? A recent study (..) suggests that matter might in fact survive its foray into these space objects and come out the other side. >>
Do black holes have a back door? R&I World. 9 Aug 2016.
http://ruvid.org/ri-world/black-holes-might-have-a-back-door/
Gonzalo J Olmo , D Rubiera-Garcia and A Sanchez-Puente. Impact of curvature divergences on physical observers in a wormhole space–time with horizons. Classical and Quantum Gravity, Volume 33, Number 11. Published 28 April 2016.