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Cosmic ray volleys from the Galactic Center and their recent impact on the Earth environment

Abstract

It is proposed that outbursts of cosmic ray electrons from the Galactic Center penetrate the Galaxy relatively undamped and are able to have a major impact on the Solar System through their ability to vaporize and inject cometary material into the interplanetary environment. It is suggested that one such ‘superwave’, passing through the Solar System toward the end of the Last Ice Age, was responsible for producing major changes in the Earth's climate and for indirectly precipitating the terminal Pleistocene extinction episode. The high concentrations of 10Be, NO3-, Ir and Ni observed in Late Wisconsin polar ice are consistent with this scenario. The intensities of the Galactic nonthermal radio background and diffuse X-ray emission ridge are shown to vary with Galactic longitude in the same manner as electron intensity along the proposed superwave ‘event horizon’. The high luminosities and unusual structural features which characterize the Crab Nebula and Cassiopeia A are shown to be attributable to the fact that these remnants happen to coincide with this event horizon and are being externally impacted by an intense volley of relativistic electrons travelling from the Galactic Center direction. The same cosmic ray volley is also shown to be able to account for the unusual structure of the extended radio source CTB 80.
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... Clarke (1981) was probably the first to propose that cosmic rays emitted by a hypothetical AGN may explain the apparent absence of complex extraterrestrial life in the Milky Way. Laviolette (1983Laviolette ( , 1987 argued, on a related note, that the Galactic center has been sporadically active on timescales of ∼10 4 yr, thus emitting high fluxes of energetic electrons (up to 10 5 times the background value) leading to abrupt changes in Earth's climate and potential mass extinctions. Gonzalez (2005) reviewed the role of AGNs in regulating habitability, and pointed out the possibility that the X-ray fluxes at the Earth arising from a hypothetical AGN in the Milky Way could be comparable to that contributed by the active Sun; this result is also consistent with the subsequent analysis by Amaro-Seoane & Chen (2014). ...
... Clarke (1981) was probably the first to propose that cosmic rays emitted by a hypothetical AGN may explain the apparent absence of complex extraterrestrial life in the Milky Way. Laviolette (1983Laviolette ( , 1987 argued, on a related note, that the Galactic center has been sporadically active on timescales of ∼10 4 yr, thus emitting high fluxes of energetic electrons (up to 10 5 times the background value) leading to abrupt changes in Earth's climate and potential mass extinctions. Gonzalez (2005) reviewed the role of AGNs in regulating habitability, and pointed out the possibility that the X-ray fluxes at the Earth arising from a hypothetical AGN in the Milky Way could be comparable to that contributed by the active Sun; this result is also consistent with the subsequent analysis by Amaro-Seoane & Chen (2014). ...
... Despite the commonality of AGN outflows, surprisingly few publications have attempted to assess their role(s) in regulating habitability. In fact, the studies in this respect date from the 1980s (Clarke 1981;Laviolette 1983Laviolette , 1987) and were of a semi-quantitative character. Furthermore, the field of AGN outflows has advanced by leaps and bounds since this period owing to a combination of empirical and theoretical breakthroughs (Krolik 1999;Kormendy & Ho 2013;Merritt 2013;Harrison et al. 2018). ...
... Despite the commonality of AGN outflows, surprisingly few publications have attempted to assess their role(s) in regulating habitability. In fact, the studies in this respect date from the 1980s (Clarke 1981;Laviolette 1983Laviolette , 1987) and were of a semi-quantitative character. Furthermore, the field of AGN outflows has advanced by leaps and bounds since this period owing to a combination of empirical and theoretical breakthroughs (Krolik 1999;Kormendy & Ho 2013;Merritt 2013;Harrison et al. 2018). ...
Preprint
It is well-known that active galactic nuclei (AGN) are accompanied by winds and outflows, some of which may reach weakly relativistic speeds of about $10$ percent the speed of light. Yet, in spite of their ubiquity, the impact of AGN outflows in modulating surface habitability of terrestrial planets on galactic scales, using the Milky Way as the basis for comparison, is poorly investigated and inadequately understood. In this work, we address this issue by focusing on two key mechanisms: AGN winds can heat atmospheres and drive atmospheric escape, as well as stimulate the formation of nitrogen oxides and thence cause ozone depletion. By developing simple models, we estimate the maximal distance up to which these deleterious effects are rendered significant for Earth-like planets in the Milky Way, and thereby demonstrate that this value may extend to $\lesssim 1$ kpc. In the case of quasars hosting larger supermassive black holes, such effects could actually influence the AGN host galaxy as a whole.
... Not many works have explored the impact of an active Sgr A * on the habitability of the MW. Early studies identified X-rays and cosmic rays as a potential threat to lives, but they lacked a theoretical framework to quantify the damage (Clarke 1981;Laviolette 1987;Gonzalez 2005). Amaro-Seoane & Chen (2019, Paper I) adopted an empirical AGN spectral energy distribution (SED) and calculated the extinction of light in the Galactic plane. ...
Article
Sgr A∗, the supermassive black hole (SMBH) in our Galaxy, is dormant today, but it should have gone through multiple gas-accretion episodes in the past billions of years to grow to its current mass of 4 × 106 M o˙. Each episode temporarily ignites the SMBH and turns the Galactic Center into an active galactic nucleus (AGN). Recently, we showed that the AGN could produce large amounts of hard X-rays that can penetrate the dense interstellar medium in the Galactic plane. Here we further study the impact of X-rays on the molecular chemistry in our Galaxy. We use a chemical-reaction network to simulate the evolution of several molecular species, including H2O, CH3OH, and H2CO, both in the gas phase and on the surface of dust grains. We find that X-ray irradiation could significantly enhance the abundances of these species. The effect is most significant in young, high-density molecular clouds and could be prominent at a Galactic distance of 8 kpc or smaller. The imprint in the chemical abundance is visible even several million years after the AGN turns off. © 2020. The American Astronomical Society. All rights reserved..
... Not many works have explored the impact of an active Sgr A* on the habitability of the MW. Early studies identified X-ray and cosmic rays as a potential threat to lives but they lacked a theoretical framework to quantify the damage (Clarke 1981;Laviolette 1987;Gonzalez 2005). Amaro-Seoane & Chen (2019, Paper I) adopted an empirical AGN spectral energy distribution (SED) and calculated the extinction of light in the Galactic plane. ...
Preprint
Sgr A*, the supermassive black hole (SMBH) in our Galaxy, is dormant today, but it should have gone through multiple gas-accretion episodes in the past to grow to its current mass of $4\times10^6\,M_\odot$. Each episode temporarily ignites the SMBH and turns the Galactic Center into an active galactic nucleus (AGN). Recently, we showed that the AGN could produce large amount of hard X-rays that can penetrate the dense interstellar medium in the Galactic plane. Here we further study the impact of the X-rays on the molecular chemistry in our Galaxy. We use a chemical reaction network to simulate the evolution of several molecular species including $\rm{H_2O}$, $\rm{CH_3OH}$, and $\rm{H_2CO}$, both in the gas phase and on the surface of dust grains. We find that the X-ray irradiation could significantly enhance the abundances of these species. The effect is the most significant in those young, high-density molecular clouds, and could be prominent at a Galactic distance of $8$ kpc or smaller. The imprint in the chemical abundance is visible even several million years after the AGN turns off. The potential impact on the origin and evolution of organic and prebiotic molecules in the Milky Way deserves further investigation.
... A body ejected from a supernova has also been suggested to have struck North America (Firestone, 2009). Other early versions speculated that, during the Late Pleistocene, the Earth was irradiated by a burst of cosmic rays from the galactic core (LaViolette, 1987(LaViolette, , 2005 and/or impacted by large solar flares in addition to coronal mass ejections from the sun (LaViolette, 2005(LaViolette, , 2011, where the solar eruptions were induced by a supernova shock wave (Firestone et al., 2006). The YD Impact Hypothesis has since evolved into several highly controversial versions, most proposing that the abrupt YD climate reversal, Pleistocene megafaunal extinctions and disappearance of the Clovis paleoindian lithic technology were coeval and caused by continent-wide catastrophic effects of one or more impact/bolide events in North America 12.9k cal a BP (e.g. ...
Article
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During the end of the last glacial period in the Northern Hemisphere near 12.9k cal a BP, deglacial warming of the Bølling–Ållerod interstadial ceased abruptly and the climate returned to glacial conditions for an interval of about 1300 years known as the Younger Dryas stadial. The Younger Dryas Impact Hypothesis proposes that the onset of the Younger Dryas climate reversal, Pleistocene megafaunal extinctions and disappearance of the Clovis paleoindian lithic technology were coeval and caused by continent-wide catastrophic effects of impact/bolide events in North America. While there are no known impact structures dated to the Younger Dryas onset, physical evidence of the impact/bolide events is argued to be present in sediments spanning several continents at stratigraphic levels inferred to date to the Bølling-Ållerod/Younger Dryas boundary (YDB). Reports of nanometer to submicron-sized diamonds in YDB sediments, in particular the rare 2H hexagonal polytype of diamond, lonsdaleite, have been presented as strong evidence for shock processing of crustal materials. We review the available data on diamonds in sediments and provide new data. We find no evidence for lonsdaleite in YDB sediments and find no evidence of a spike in nanodiamond concentration at the YDB layer to support the impact hypothesis.
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It is well-known that active galactic nuclei (AGN) are accompanied by winds and outflows, some of which may reach weakly relativistic speeds of about 10 per cent the speed of light. Yet, in spite of their ubiquity, the impact of AGN outflows in modulating surface habitability of terrestrial planets on galactic scales, using the Milky Way as the basis for comparison, is poorly investigated and inadequately understood. In this work, we address this issue by focusing on two key mechanisms: AGN winds can heat atmospheres and drive atmospheric escape, as well as stimulate the formation of nitrogen oxides and thence cause ozone depletion. By developing simple models, we estimate the maximal distance up to which these deleterious effects are rendered significant for Earth-like planets in the Milky Way, and thereby demonstrate that this value may extend to ≲ 1 kpc. In the case of quasars hosting larger supermassive black holes, such effects could actually influence the AGN host galaxy as a whole.
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Preview containing table of contents and sample pages. Book can be ordered at: https://www.lulu.com/en/ca/shop/marinus-anthony-van-der-sluijs/on-the-origin-of-myths-in-catastrophic-experience-vol-2-the-earths-aurora/paperback/product-zndv7q.html?page=1&pageSize=4. In this second volume, the earth’s magnetic field and aurora take centre stage. Geomagnetic reversals are rare occasions when the field dwindles, the north and south magnetic poles trade places, and minor poles come into play. This process remains incomplete in the much more frequent case of a geomagnetic excursion. Throughout human history, people have personified and mythologised the aurora. If a geomagnetic excursion had occurred within human memory, they could have observed spectacular transformations of the lights, even at low latitudes, and enshrined these in myths, monuments, images and rituals. Many elements of the primordial condition described worldwide may thus be explained – awe-inspiring luminous rings, arcs and columns, often dynamic and structured, that seemingly held up a gloomy, low-hanging sky. Evidence is cited for two excursions that could have informed age-old traditions in this way. Specialists dispute both and a way out of the controversy is proposed. The unique effects that a geomagnetic reversal or excursion must have on the aurora are further explored through possible contemporary parallels on other solar-system bodies and in experimental work on terrellae, of which a historical survey is given. A wealth of new information is provided throughout on the history of geomagnetic studies and auroral physics. With a foreword by Dr. C. J. Ransom. XXXIII + 516 pages, including 168 illustrations and index.
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Raup and Sepkoski 1 have recently reported evidence fora 26-Myr periodicity in the occurrence of mass extinctions based on a study of marine fossils. The data baseline of 250 Myr suggests events of variable amplitude, with some of the strongest peaks associated with boundaries between major geological periods which have been defined by previous palaeontological studies. In a more limited quantitative study, Fischer and Arthur 2 earlier cited evidence for a 32-Myr period of major extinction events. Hatfield and Camp 3 were among the first to suggest that mass extinctions might be correlated with periodic galactic phenomena, noting intervals of 80-90 Myr between major mass extinctions with an exceptionally strong mass extinction every 225-275 Myr. Here we point out a possible correlation between the 26-Myr extinction period and the Sun's oscillation about the galactic plane.