ArticlePDF Available

# 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.
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
1987EM&P...37..241L
... 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
Full-text available
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.
Article
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.
Book
Full-text available
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.
Article
Sagittarius A* (SgrA*) lying in the Galactic Centre 8 kpc from Earth, hosts the closest supermassive black hole known to us. It is now inactive, but there is evidence indicating that about six million years ago it underwent a powerful outburst where the luminosity could have approached the Eddington limit. Motivated by the fact that in extragalaxies the supermassive black holes with similar masses and near-Eddington luminosities are usually strong X-ray emitters, we calculate here the X-ray luminosity of SgrA∗. For that, we assume that the outburst was due to accretion of gas or the tidal disruption of a star. We show that these cases could precipitate on Earth a hard X-ray (i.e. hν>2 keV) flux comparable to that from the current quiescent sun. The flux in harder energy band 20 keV<hν<100 keV, however, surpasses that from an X-class solar flare, and the irradiation timescale is also much longer, ranging from weeks to 10⁵ years depending on the outburst scenario. In the solar system gas giants will suffer the biggest impact in their atmospheres. Lower-mass planets such as Earth receive a level of radiation that might have played a role in the evolution of their primitive atmospheres, so that a detailed study of the consequences deserves further investigation. Planetary systems closer to SgrA* receive higher irradiance levels, making them more likely uninhabitable.
Article
Full-text available
Environmental changes, either expressed as periodical phenomena with moderate character or as sudden, violent, and highly dangerous events, transform the natural ecosystems, rebuild the landscapes and forge new dynamics in human societies, by influencing the demographic stability, the socioeconomic profile, the cultural trends and many investment strategies. This paper aims at : a) the filtration of various geological data / information before they reach the questionnaires of Disaster Archaeology's topics, b) the elaboration of a flexible and reciprocal methodological framework within which both parts may function separately as well as synergistically. This framework should consist of several common hermeneutic 'tools' shared by both disciplines (stratigraphies, accretion, taphonomy, destruction layers, destruction markers/indicators). Complex geological mechanisms (i.e. volcanic eruptions, earthquakes, subsidence, soil liquefaction, landslides, pedogenesis, lacustrine, fluvial and deep-sea deposits) along with hydrometeorological and hydrogeological phenomena (i.e. tsunami, storms and hurricanes, glaciations, formation of peat bogs, sapropels, loess and karst, alluvia) either function as sedimentation's formers, or as triggering factors for sediments' redistribution into extended geographical areas. Finally, the authors suggest a more thoroughly organized approach and evaluation of disaster information hidden within the formation, spatio-temporal distribution and transformation of sediments, which may be of varied origin. This information should be grouped into four main categories (geological, paleontological, biochemical-physical). The fourth (archaeological-philological and historic-artistic-mythological) deserves special mention because past disasters have been totally ignored by the majority of archaeologists and used in an uncritical way without being related to cultural change.
Article
The young planetary system {\beta} Pictoris is surrounded by a circumstellar disk of dust and gas. Because both dust and gas have a lifetime shorter than the system age, they need to be replenished continuously. The gas composition is partly known, but its location and its origin are still a puzzle. The gas source could be the exocomets (or so-called falling and evaporating bodies, FEBs), which are observed as transient features in absorption lines of refractory elements (Mg, Ca, and Fe) when they transit in front of the star at several tens of stellar radii. Nearly 1700 high-resolution spectra of {\beta} Pictoris have been obtained from 2003 to 2015 using the HARPS spectrograph. In these spectra, the circumstellar disk is always detected as a stable component among the numerous variable absorption signatures of transiting exocomets. Summing all the 1700 spectra allowed us to reach a signal-to-noise ratio higher than 1000, which is an unprecedentedly high number for a {\beta} Pictoris spectrum. It revealed many weak Fe I absorption lines of the circumstellar gas in more than ten excited states. These weak lines bring new information on the physical properties of the neutral iron gas in the circumstellar disk. The population of the first excited levels follows a Boltzmann distribution with a slope consistent with a gas temperature of about 1300 K; this temperature corresponds to a distance to the star of ~ 38 RStar and implies a turbulence of {\xi} ~ 0.8 km/s.
Article
We summarize here data on in situ nitrate ion concentrations in snow pits and firn cores over the last ∼3 250 a. Nitrate fluctuations show seasonal, 11 and 22 a periodicities, and long-term changes both at South Pole station and Vostok. High nitrate levels conform to winter darkness and solar activity peaks. Long-term lows and highs conform to solar activity minima and maxima. The data available support the hypothesis that nitrate is fixed in the upper atmosphere by some solar-mediated phenomenon causing a periodicity in East Antarctica snow. Background levels and non-periodic spikes in nitrate come from other sources.
Article
A fluid dynamical treatment of an ultra-relativistic spherical blast wave enclosed by a strong shock is presented. A simple similarity solution describing the explosion of a fixed amount of energy in a uniform medium is derived, and this is generalized to include cases in which power is supplied by a central source and the density of the external medium varies with radius. Radiative shocks, in which the escaping photons carry away momentum as well as energy, are also discussed. Formulas that interpolate between the non- and ultra-relativistic limits are proposed.
Article
A survey has been made of the intense emission regions along the galactic plane from l = 600 to 2900 at frequencies of 85 and 150 MHz with the 210 ft radio telescope at Parkes. Aerial temperatures were accurately measured, essentially in terms of thermal standards, with a known baselevel. The spectrum and "steps" of the observed emission have been investigated.
Article