Published papers

The Next Generation Virgo Cluster Survey (NGVS) is a deep, high resolution imaging campaign that used the 1 deg$^2$ MegaCam instrument on the Canada-France-Hawaii Telescope to carry out a comprehensive optical survey of the Virgo cluster, from its core to its virial radius. The NGVS covers a contiguous area of 104 deg$^2$ (8.63 Mpc$^2$ at the 16.5 Mpc distance of Virgo) in the $u^*$-,$g$-,$i$-, and $z$-band, with additional limited coverage in $r$. In this paper, we present the final catalog of Virgo galaxies across the entire NGVS area. The catalog includes 3680 galaxies considered to be $bona~fide$ members of the cluster, spanning a factor of 2.5 million in luminosity, from $g = 8.42$ mag to $g = 24.41$ mag ($M_g = -22.67$ mag to $M_g = -6.68$ mag). With 2100 previously uncataloged galaxies, the NGVS catalog augments the number of known Virgo members by a factor 2.3. The catalog is complete down to $g = 18.6$ mag ($M_g=-12.5$ mag, corresponding to a stellar mass $M_* \sim 1.6\times10^7~M_{\odot}$ for an old stellar population) and 50% complete at $g = 22.0$ mag ($M_g=-9.1$ mag, $M_* \sim 6.2\times10^5~M_{\odot}$), three magnitudes deeper than the venerable Virgo Cluster Catalog (VCC), which for over 40 years has served as the reference standard for Virgo. Photometric and structural parameters are derived for all NGVS galaxies and presented in a series of tables, alongside nuclear and morphological classification, as well as stellar masses and, when available, radial velocities.

Because Japan’s financial system is bank-centered, understanding the structure of the loan and deposit markets is of central importance. However, prior to the mid-2000s, there was limited statistical evidence concerning competition in regional financial markets and interregional flow of funds, despite the potentially significant changes driven by financial crises and deregulation. We address this issue by proposing a methodology for estimating loans and deposits at the financial institution–prefecture level using available data. Based on these estimates, we measure the degree of concentration in the loan and deposit markets and develop indicators of interregional fund flows mediated by lending and deposit activities. Our 1990 estimates yield the following findings: First, consistent with the post-2005 period, market concentration in both the loan and deposit markets was lower in metropolitan areas than in rural areas. Second, while market concentration increased between 1990 and 2005, regions that initially exhibited high loan market concentration experienced a decline in concentration, indicating heterogeneous dynamics across regions. Third, our indicators of interregional fund flows suggest that while lending is primarily financed by deposits from the same prefecture, deposits from other prefectures are also used. This implies that inter-regional fund flows, facilitated by loans and deposits, were already active in 1990. At the same time, the extent of such flows changed substantially between 1990 and 2005, reflecting financial institution failures and mergers during the financial crisis as well as more proactive branch location policies.

Cyber risk in banking is often studied as an operational or idiosyncratic shock, but it may also matter for financial stability and long-horizon asset pricing. We show that declines in a bank intermediation-capacity index predict a lower ten-year Treasury term premium three to four quarters ahead, with stronger effects when system-wide financial stress is elevated, whereas VIX responds mainly contemporaneously. Using quarterly U.S. data from 2001Q2 to 2025Q3 and incident-level cyber records, we further show that the delayed response is more clearly concentrated in intermediation-capacity disruptions than in theft/extortion events, and that it remains visible in medium-horizon block, innovation-based, and timing-falsification checks. We interpret the evidence as consistent with a gradual intermediation channel rather than as a point-identified structural mechanism. These findings suggest that incident-based bank cyber indicators may provide useful information for financial-stability monitoring and macroprudential surveillance.

This study examines the role of energy security in poverty reduction in the 12 poorest Asian economies from 2000 to 2019. We postulated an energy security index using principal component analysis. We adopted the system generalized method of a moment technique to manage endogeneity and dynamism in the model. For robustness, we applied a panel-corrected standard error (PCSE). We found a negative relationship between energy security and poverty reduction, suggesting that energy security helps reduce poverty. We conclude that energy security promotes sustainable poverty alleviation and recommends feed-in tariffs, net metering, tax credits, and energy resource diversification away from fossil fuels.

Investment volume in green projects, specifically in the green electricity market, suffers from limitations such as inadequate long-term financing, various risks, and a low rate of return on investment. Renewable energy power purchase agreements (PPAs), as a direct legal contract between a power provider and a power buyer, are one of the most popular instruments to increase investment. In this study, we model an adjusted PPA in the local currency framework to lower exchange rate risk and incremental tariffs by having the government pay part of the spillover tax revenues to the PPA, leading to a higher return on investment. The major conclusion of this study is that the use of tax revenue through the spillover effect of green electricity supply is a suitable source of financing for PPAs. As one policy implication, we recommend that developing countries allocate 50% of the tax revenue originating from power supply and adopt incremental PPAs to encourage private investment in green projects.

Neutrinoless double beta decay (0v2b) has been investigated as a physical process that can provide evidence for the Majorana nature of neutrinos. The theoretical predictions of the 0v2b rate are subject to significant uncertainty, primarily due to nuclear matrix elements (NME). To reduce this uncertainty, experimental measurements of the half-lives of two-neutrino double beta decay (2v2b) in various nuclei are essential as a benchmark for NME calculations. The PIKACHU (Pure Inorganic scintillator experiment in KAmioka for CHallenging Underground sciences) project searches for the previously unobserved 2v2b decay of 160Gd, employing Ce-doped Gd3Ga3Al2O12 (GAGG) single crystals. In the Phase 1 experiment, we aim to improve the current lower limit on the 2v2b half-life of 160Gd by a prior study using a Ce-doped Gd2SiO5 (GSO) crystal. Ultimately, in Phase 2, the project seeks to achieve a sensitivity surpassing the theoretical prediction of 7.4 x 10^20 years, enabling the potential discovery of the 160Gd 2v2b decay. In this paper, we describe the development of background models based on GEANT4 simulations. The modeled backgrounds are contributions from uranium and thorium decay chains, 40K present in GAGG, and 40K gamma-rays from outside of GAGG. Additionally, we developed models for both 2v2b and 0v2b decay by implementing the theoretical kinematics of two-electron emission in double beta decay in the GEANT4 simulation. As a result, our background models successfully reproduced the measured background spectrum through fitting. By generating pseudo background spectra expected in Phase 1 and analyzing them with the combined background and 2v2b models, we evaluated the 2v2b sensitivity of Phase 1 to be 2.78 x 10^19 years (90% C.L.). This paper presents the development of these simulation models and the expected sensitivities for both Phase 1 and Phase 2 based on the pseudo data analyses.

In recent years fractal Weyl laws and related quantum eigenfunction hypothesis have been studied in a plethora of numerical model systems, called quantum maps. In some models studied there one can easily prove uniform hyperbolicity. Yet, a numerically sound method for computing quantum resonance states, did not exist. To address this challenge, we recently introduced a new class of quantum maps. For these quantum maps, we showed that, quantum resonance states can numerically be computed using theoretically grounded methods such as complex scaling or weak absorbing potentials. However, proving uniform hyperbolicty for this class of quantum maps was not straight forward. Going beyond that work this article generalizes the class of scattering maps and provides mathematical proofs for their uniform hyperbolicity. In particular, we show that the suggested class of two-dimensional symplectic scattering maps satisfies the topological horseshoe condition and uniform hyperbolicity. In order to prove these properties, we follow the procedure developed in the paper by Devaney and Nitecki. Specifically, uniform hyperbolicity is shown by identifying a proper region in which the non-wandering set satisfies a sufficient condition to have the so-called sector bundle or cone field. Since no quantum map is known where both a proof of uniform hyperbolicity and a methodologically sound method for numerically computing quantum resonance states exist simultaneously, the present result should be valuable to further test fractal Weyl laws and related topics such as chaotic eigenfunction hypothesis.