Multimessenger astronomy driven by high-energy neutrinos

The possible connection between high energy neutrinos in the energy region above 100 TeV and ultrahigh energy cosmic rays (UHECRs) at energies above $10^{19}$ eV motivates multi-messenger observation approaches involving neutrinos and the multi-wavelength electro-magnetic (EMG) signals. We have constructed a generic unification scheme to model the neutrino and UHECR common sources. Finding the allowed space of the parameters on the source characteristics allows a case study to evaluate the likelihood of each of the known source classes being such unified sources. The likely source candidates are transient or flaring objects mainly in optical and X-ray bands. We propose the two feasible strategies to identify these sources. One is to introduce a sub-threshold triggering in a wide field of view X-ray observatory for following up neutrino detections, and the other is to search for EMG counterparts associated with detections of multiple neutrino events coming from the same direction within a time scale of $\lesssim 30$ days. Sources with a total neutrino emission energy greater than $\sim 10^{51}$ erg are accessible with the present or near-future high energy neutrino observation facilities collaborating with X-rays and optical telescopes currently in operation. The neutrino-driven multi-messenger observations provide a smoking gun to probe the hadronic emission sources we would not be able to find otherwise.Comment: 16 pages, 4 figures. Presented as a highlight talk at the 38th International Cosmic Ray Conference (ICRC 2023), 202

A Search for Water Masers in the Saturnian System

We searched for H2O 6(1,6)-5(2,3) maser emission at 22.235 GHz from several Saturnian satellites with the Nobeyama 45m radio telescope in May 2009. Observations were made for Titan, Hyperion, Enceladus and Atlas, for which Pogrebenko et al. (2009) had reported detections of water masers at 22.235 GHz, and in addition for Iapetus and other inner satellites. We detected no emission of the water maser line for all the satellites observed, although sensitivities of our observations were comparable or even better than those of Pogrebenko et al.. We infer that the water maser emission from the Saturnian system is extremely weak, or sporadic in nature. Monitoring over a long period and obtaining statistical results must be made for the further understanding of the water maser emission in the Saturnian system.Comment: 8 pages, 2 figures, accepted for publication in PASJ (Letter

Extremely High Energy Neutrinos and their Detection

We discuss in some detail the production of extremely high energy (EHE) neutrinos with energies above 10^18 eV. The most certain process for producing such neutrinos results from photopion production by EHE cosmic rays in the cosmic background photon field. However, using assumptions for the EHE cosmic ray source evolution which are consistent with results from the deep QSO survey in the radio and X-ray range, the resultant flux of neutrinos from this process is not strong enough for plausible detection. A measurable flux of EHE neutrinos may be present, however, if the highest energy cosmic rays which have recently been detected well beyond 10^20 eV are the result of the annihilation of topological defects which formed in the early universe. Neutrinos resulting from such decays reach energies of the grand unification (GUT) scale, and collisions of superhigh energy neutrinos with the cosmic background neutrinos initiate neutrino cascading which enhances the EHE neutrino flux at Earth. We have calculated the neutrino flux including this cascading effect for either massless or massive neutrinos and we find that these fluxes are conceivably detectable by air fluorescence detectors now in development. The neutrino-induced showers would be recognized by their starting deep in the atmosphere. We evaluate the feasibility of detecting EHE neutrinos this way using air fluorescence air shower detectors and derive the expected event rate. Other processes for producing deeply penetrating air showers constitute a negligible background.Comment: 33 pages, including 12 eps figures, LaTe

Constraints on the origin of the ultra-high energy cosmic-rays using cosmic diffuse neutrino flux limits: An analytical approach

Astrophysical neutrinos are expected to be produced in the interactions of ultra-high energy cosmic-rays with surrounding photons. The fluxes of the astrophysical neutrinos are highly dependent on the characteristics of the cosmic-ray sources, such as their cosmological distributions. We study possible constraints on the properties of cosmic-ray sources in a model-independent way using experimentally obtained diffuse neutrino flux above 100 PeV. The semi-analytic formula is derived to estimate the cosmogenic neutrino fluxes as functions of source evolution parameter and source extension in redshift. The obtained formula converts the upper-limits on the neutrino fluxes into the constraints on the cosmic-ray sources. It is found that the recently obtained upper-limit on the cosmogenic neutrinos by IceCube constrains the scenarios with strongly evolving ultra-high energy cosmic-ray sources, and the future limits from an 1 km^3 scale detector are able to further constrain the ultra-high energy cosmic-rays sources with evolutions comparable to the cosmic star formation rate.Comment: 9 pages, 3 figures and 1 table. Accepted by Phys. Rev.

御幸牧場において「集団発生した低酸度二等乳」に関する研究 : (1) 低酸度二等乳中のCa及びMgについて

1970年に広島県福山市に位置する御幸牧場で低酸度二等乳の集団発生がみられ,その牧場の乳牛群の全てがこの慢性の泌乳障害である低酸度二等乳症に罹っていることが判った。御幸牧場における低酸度二等乳の集団発生は1930年代にオランダで発生した'the Utrecht abnormality of milk'と全く同じ現象であることが判った。 御幸牧場に発生した異常乳の特微は次の通りである。 1) 全ての泌乳中の乳牛がアルコール試験陽性乳を泌乳した。 2) 個乳のうちのいくつかは熱凝固性を示した。 3) 個乳のうちいくつかは鹹味を呈し,電気伝導度が高い値を示した。 4) ほとんどの個乳のイオン状Caが高い値を示した。 5) 御幸牧場の個乳のCa/Mg比はモル比で6.92であり,正常乳のそれは6.00以下であるので,御幸牧場の異常乳中のCaが高くMgが低い。 6) 夏季の牛乳はとくにMgが低くくまた蛋日含量も低くいが,冬季の牛乳はCaが高い。 以上の事から,御幸牧場の乳牛は或る代謝異常に罹っていて,その結果として体内から体外への異常なCaの流出とMg排泄の減少がみられるものと考えられる。A great deal of abnormal milk secretion had been observed in the Miyuki Dairy Farm in Japan in the year 1970, when nearly all the lactating dairy cows in the herd fell into a chronic lactation disorder. The mass outbreak of abnormal milk secretion in Miyuki Dairy Farm agreed with a phenomenon that occurred in the Netherlands and has been called 'the Utrecht abnormality of milk.' The characteristic signs of the abnormal milk in Miyuki Dairy Farm were: l) all lactation dairy cows yielded milk with alcohol test positive, 2) some of them showed heating test positive properties, 3) some of them had a salty taste and high conductivity, 4) most of them showed a high content in ionized Ca, 5) the ratio of Ca/Mg was 6.92 for chemical equivalent, this meant high Ca and low Mg in the abnormal milk, 6) low Mg and low protein milk was yielded in the summer months and high Ca milk in the winter months. So it appeared that the cows of Miyuki Dairy Farm must have been victims of some metabolic disturbance resulting in an abnormal outflow of Ca and the saving of Mg from the body into milk

御幸牧場において「集団発生した低酸度二等乳」に関する研究 : (2) 低酸度二等乳泌乳牛の血中Ca及びMgについて

1970年に御幸牧場で集団発生した低酸度二等乳はアルコール試験陽性でまた熱凝固性を示し,これは'the Utrecht abnormality of milk'と同じ特微を示した。そしてまたその異常乳はCaが高くMgが低いこととイオン状Caが高い値を示した。 御幸牧場の乳牛の血清Caが高く血清Mgが低いことと全血Caが高いと云う特微がみられた。尚,全血Mgには差がみられなかった。 表　御幸牧場の乳牛群と対称牛群の血中のMg及びCaについて (単位meq/l) 御幸牧場の乳牛群の平均値: 頭数 17, 全血中のCa 3.82, 全血中のMg 1.82, 血清中のCa 4.49, 血清中のMg 1.82 対象群の平均値: 頭数 54, 全血中のCa 3.34, 全血中のMg 1.85, 血清中のCa 4.24, 血清中のMg 2.00 以上の結果から,御幸牧場の乳牛群の血清Caが高い。血清Mgが低いと云う特微とが密接に関係していると考えられる。乳牛の血清Mgが低くく血清Caが高いと云う特微はその乳牛群がMgの代謝異常かMg欠乏をともなった慢性的な泌乳障害におち入っているにちがいないと推定される。A great deal of abnormal milk secretion has been observed in the Miyuki Dairy Farm, and the abnormal milk showed alcohol test positive and heating test positive properties that are called 'the Utrecht abnormality of milk.' The abnormal milk showed high Ca and low Mg content in its skim milk and had a high ionized Ca level. The cows in the Miyuki Dairy Farm showed a low Mg content and a high Ca content in the blood serum, and a high Ca level in the whole blood compared with that of normal groups. 1) The mean value in the blood serum of Mg is 1.82meq/l for abnormal groups and 2.00meq/l for normal ones. 2) The mean value in the blood serum of Ca is 4.49meq/l for abnormal and 4.24meq/l for normal ones. 3) The mean value in the whole blood of Mg is 1.82meq/l for abnormal and 1.85meq/l for normal groups. 4) The mean value in the whole blood of Ca is 3.82meq/l for abnormal and 3.34meq/l for normal groups. From these results, the abnormal milk in the Miyuki Dairy Farm which showed a low Mg and a high Ca content must have been yielded from cows suffering from a low Mg and a high Ca content in their blood serum. From low serum Mg and high serum Ca, the author has arrived at the conclusion that the lactating dairy cows in the Miyuki Dairy Farm must have been suffering from chronic lactation disorder accompanied by a disturbance of the Mg metabolism or by a Mg deficiency