Volcano In Alaska Impacted Roman Empire and Egypt In 43 BCE

Once again a volcano has been linked to a historically influential climate event. 

Around the time of Julius Caesar's death in 44 BCE, written sources describe a period of unusually cold climate, crop failures, famine, disease, and unrest in the Mediterranean Region -impacts that ultimately contributed to the downfall of the Roman Republic and Ptolemaic Kingdom of Egypt. Historians have long suspected a volcano to be the cause, but have been unable to pinpoint where or when such an eruption had occurred, or how severe it was. 

In a new study published this week in Proceedings of the National Academy of Sciences (PNAS), a research team led by Joe McConnell, Ph.D. of the Desert Research Institute in Reno, Nev. uses an analysis of tephra (volcanic ash) found in Arctic ice cores to link the period of unexplained extreme climate in the Mediterranean with the caldera-forming eruption of Alaska's Okmok volcano in 43 BCE.

From here. 

The paper and its abstract are as follows:

Significance 

The first century BCE fall of the Roman Republic and Ptolemaic Kingdom and subsequent rise of the Roman Empire were among the most important political transitions in the history of Western civilization. Volcanic fallout in well-dated Arctic ice core records, climate proxies, and Earth system modeling show that this transition occurred during an extreme cold period resulting from a massive eruption of Alaska’s Okmok volcano early in 43 BCE. Written sources describe unusual climate, crop failures, famine, disease, and unrest in the Mediterranean immediately following the eruption—suggesting significant vulnerability to hydroclimatic shocks in otherwise sophisticated and powerful ancient states. Such shocks must be seen as having played a role in the historical developments for which the period is famed. 

Abstract 

The assassination of Julius Caesar in 44 BCE triggered a power struggle that ultimately ended the Roman Republic and, eventually, the Ptolemaic Kingdom, leading to the rise of the Roman Empire. Climate proxies and written documents indicate that this struggle occurred during a period of unusually inclement weather, famine, and disease in the Mediterranean region; historians have previously speculated that a large volcanic eruption of unknown origin was the most likely cause. Here we show using well-dated volcanic fallout records in six Arctic ice cores that one of the largest volcanic eruptions of the past 2,500 y occurred in early 43 BCE, with distinct geochemistry of tephra deposited during the event identifying the Okmok volcano in Alaska as the source. Climate proxy records show that 43 and 42 BCE were among the coldest years of recent millennia in the Northern Hemisphere at the start of one of the coldest decades. Earth system modeling suggests that radiative forcing from this massive, high-latitude eruption led to pronounced changes in hydroclimate, including seasonal temperatures in specific Mediterranean regions as much as 7 °C below normal during the 2 y period following the eruption and unusually wet conditions. While it is difficult to establish direct causal linkages to thinly documented historical events, the wet and very cold conditions from this massive eruption on the opposite side of Earth probably resulted in crop failures, famine, and disease, exacerbating social unrest and contributing to political realignments throughout the Mediterranean region at this critical juncture of Western civilization.

Joseph R. McConnell et al., "Extreme climate after massive eruption of Alaska’s Okmok volcano in 43 BCE and effects on the late Roman Republic and Ptolemaic Kingdom." PNAS (2020). DOI: 10.1073/pnas.2002722117

New Discoveries At Stonehenge

There is more to Stonehenge than was previously known. "The discovery makes up for the cancellation of this year’s summer solstice celebrations at Stonehenge – on 20 June – due to the ban on mass gatherings prompted by Covid-19." They were probably built by the same Neolithic/Megalithic (pre-Bell Beaker) people who built Stonehenge itself. 

The mystery near and around Stonehenge keeps growing. 

The latest revelation is the discovery of a ring of at least 20 prehistoric shafts about 2 miles from the famous Neolithic site of immense upright stones, according to an announcement from the University of Bradford. 

Archaeologists say the "astonishing" shafts in Durrington Walls date back to 2500 B.C. and form a circle more than 2 kilometers (1.2 miles) in diameter. Each one measures up to 10 meters (33 feet) in diameter and 5 meters (16 feet) deep. 

Researchers say there may have been more than 30 of the shafts at one time. . . . 

The exact purpose of the shafts is unclear, but one prominent theory is that they may have acted as a boundary to a sacred area connected to Stonehenge. 

Via National Public Radio (press release here).

Standard Model Neutrino Properties Recapped

There are seven experimentally determined parameters related to neutrinos in the Standard Model: four parameters of the PMNS matrix, and three neutrino mass eigenstates (for background see here). A new preprint has updated the latest state of the measurement of the PMNS matrix parameters and neutrino masses as of 2020.

The results for the parameters whose values aren't expressly recited in the abstract are set forth in Table III of the paper:

Taking the square roots and referring to the normal ordering that is strongly preferred by the data, the m(21) mass difference is 8.66 meV (one sigma error about 2.8%). The m(31) mass difference is 50.60 meV (one sigma error about 1.4%).

For example, the best fit values for a 1 meV first neutrino mass eigenvalue would be:

1 meV
9.66 meV
51.60 meV
Sum of neutrino masses:  62.26 meV.

Cosmology bounds the sum of the three neutrino masses to about 130 meV, which implies a mass of about 0 to 23.58 meV for the lightest neutrino mass eigenstates.

The preference for normal v. inverted mass ordering of the absolute neutrino masses is shown in Table II (in which OSC means oscillation data, and Cosmo refers to cosmology data).

In my view, the balance of the evidence also strongly disfavors the sterile neutrino hypothesis (not considered in this paper) and disfavors less strongly, but still disfavors, the existence of neutrinoless double beta decay.

As of last year, the constants were as follows (per the Particle Data Group):

The data below are in the form in which the actual values are directly measured (sine squared values of real valued mixing angles and squared values of mass differences) rather than the underlying parameter values which are easily derived from them with a scientific calculator.

in^2(theta23):

The full data for the parameters shown as ". . . " in the chart above are as follows:

sin^2(theta23) theta23 could be either side of a 45 degree angle based upon existing measurements and assuming a "normal" mass hierarchy for the neutrino masses. But existing experiments, while capable of determining that theta23 is not 45 degrees, but can't determine if it is greater or smaller than those values, which is why there is both an octant I and an octant II value.

$\mathbf{0.512}{}_{\mathbf{-}\mathbf{0.022}}^{\mathbf{+}\mathbf{0.019}}$	OUR FIT  Normal ordering, octant I
$\mathbf{0.542}{}_{\mathbf{-}\mathbf{0.022}}^{\mathbf{+}\mathbf{0.019}}$	OUR FIT  Normal ordering, octant II
−0.028$\mathbf{0.536}{}_{\mathbf{-}\mathbf{0.028}}^{\mathbf{+}\mathbf{0.023}}$	OUR FIT  Inverted ordering

Delta m32^2 with normal ordering is 2.444 ± 0.034 (the number shown in chart is inverse mass hierarchy).

Sum of neutrino masses Σmν < 0.12 eV (95%, CMB + BAO); ≥ 0.06 eV (mixing).

Directly measured neutrino mass limits:

Neutrino Flavors

The number of neutrino flavors in the Standard Model is a theoretically determined, rather than experimentally measured value, but the experimental measurements are consistent at the two sigma level with the Standard Model value of 3:

Effective number of neutrino flavors Neff 2.99 ± 0.17 (cosmology measurements) (the expected value of this measured physical constant with exactly three types of neutrinos is 3.045 rather than zero for technical reasons related to the way that radiation impacts the relevant observables). This measurement includes all light neutrinos (up to the order of roughly 1-10 eV in mass) that oscillate with each other, and is independent of whether or not they interact via the weak force.

Number of light (i.e. less than 45 GeV) neutrino flavors from Z boson decays Nν = 2.984 ± 0.008. The Standard Model theoretical value is 3.

The paper and its abstract are as follows:

[Submitted on 19 Jun 2020]

2020 Global reassessment of the neutrino oscillation picture

P. F. de Salas, D. V. Forero, S. Gariazzo, P. Martínez-Miravé, O. Mena, C. A. Ternes, M. Tórtola, J. W. F. Valle

We present an updated global fit of neutrino oscillation data in the simplest three-neutrino framework. In the present study we include up-to-date analyses from a number of experiments. Namely, we have included all T2K measurements as of December 2019, the most recent NOνA antineutrino statistics, and data collected by the Daya Bay and RENO reactor experiments. Concerning the atmospheric and solar sectors, we have also updated our analyses of DeepCore and SNO data, respectively. 

All in all, these new analyses result in more accurate measurements of θ13, θ12, Δm221 and |Δm231|. The best fit value for the atmospheric angle θ23 lies in the second octant, but first octant solutions remain allowed at ∼2σ. Regarding CP violation measurements, the preferred value of δ we obtain is 1.20π (1.54π) for normal (inverted) neutrino mass ordering. 

These new results should be regarded as extremely robust due to the excellent agreement found between our Bayesian and frequentist approaches. 

Taking into account only oscillation data, there is a preference for the normal neutrino mass ordering at the 2.7σ level. While adding neutrinoless double beta decay from the latest Gerda, CUORE and KamLAND-Zen results barely modifies this picture, cosmological measurements raise the significance to 3.1σ within a conservative approach. A more aggressive data set combination of cosmological observations leads to a stronger preference for normal with respect to inverted mass ordering, at the 3.3σ level.

This cosmological data set provides 2σ upper limits on the total neutrino mass corresponding to ∑mν<0.13 (0.15)~eV in the normal (inverted) neutrino mass ordering scenario.

These bounds are among the most complete ones in the literature, as they include all currently available neutrino physics inputs.

Comments:	34 pages, 15 figures, 3 tables
Subjects:	High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Experiment (hep-ex)
Cite as:	arXiv:2006.11237 [hep-ph]
	(or arXiv:2006.11237v1 [hep-ph] for this version)