Groundwater‐level changes after earthquakes provide insight into changes in hydrogeological properties such as permeability and pore pressure. Quantifying such changes, both their location and ...magnitude, is usually hindered by limited data. Using extensive high‐resolution water‐level monitoring records, we provide direct evidence of significant groundwater drawdown (4.74‐m maximum) over a 160‐km2 area along crustal ruptures after the Mw 7.0, 2016, Kumamoto earthquake. Approximately 106 m3 of water disappeared within 35 min after the main shock. The loss of water was not caused by static‐strain driven pore‐pressure decrease nor by releasing of water through structural pathways, but most likely by water transfer downwards through open cracks. Such changes may impact the security of water resources, the safety of underground waste repositories, and contaminant transport in seismically active areas.
Key Points
Groundwater levels changed immediately after the 2016 Mw 7.0 Kumamoto earthquake
Surface and aquifer waters were transferred into the deeper crust through rupture systems
Proposed water drawdown model may be transferrable globally to other aquifer systems
We present Suzaku observations of the Centaurus cluster out to 0.95r
200, taken along a strip to the north-west. We have also used congruent Chandra observations of the outskirts to resolve point ...sources down to a threshold flux around seven times lower than that achievable with just Suzaku data, considerably reducing the systematic uncertainties in the cosmic X-ray background emission in the outskirts. We find that the temperature decreases by a factor of 2 from the peak temperature to the outskirts. The entropy profile demonstrates a central excess (within 0.5r
200) over the baseline entropy profile predicted by simulations of purely gravitational hierarchical structure formation. In the outskirts, the entropy profile is in reasonable agreement with the baseline entropy profile from Voit et al. but lies slightly below it. We find that the pressure profile agrees with the universal pressure profile of Arnaud et al. but lies slightly above it in the outskirts. The excess pressure and decrement in entropy in the outskirts appear to be the result of an excess in the measured gas density, possible due to gas clumping biasing the density measurements high. The gas mass fraction rises and reaches the mean cosmic baryon fraction at the largest radius studied. The clumping-corrected gas mass fraction agrees with the expected hot gas fraction and with the simulations of Young et al. We further the analysis of Walker et al. which studied the shapes of the entropy profiles of the clusters so far explored in the outskirts with Suzaku. When scaled by the self-similar entropy, the Suzaku entropy profiles demonstrate a central excess over the baseline entropy profile, and are consistent with it at around r
500. However, outside r
500 the entropy profiles tend to lie below the baseline entropy profile.
We present Suzaku observations of the galaxy cluster Abell 2029, which exploit Suzaku's low particle background to probe the intracluster medium at radii beyond that which is possible with previous ...observations, and with better azimuthal coverage. We find significant anisotropies in the temperature and entropy profiles, with a region of lower temperature and entropy occurring to the south-east, possibly the result of accretion activity in this direction. Away from this cold feature, the thermodynamic properties are consistent with an entropy profile which rises, but less steeply than the predictions of purely gravitational hierarchical structure formation. Excess emission in the northern direction can be explained due to the overlap of the emission from the outskirts of Abell 2029 and nearby Abell 2033 (which is at slightly higher redshift). These observations suggest that the assumptions of spherical symmetry and hydrostatic equilibrium break down in the outskirts of galaxy clusters, which poses challenges for modelling cluster masses at large radii and presents opportunities for studying the formation and accretion history of clusters.
ABSTRACT
We report on the Imaging X-ray Polarimetry Explorer (IXPE) observation of the closest and X-ray brightest Compton-thick active galactic nucleus (AGN), the Circinus galaxy. We find the source ...to be significantly polarized in the 2–6 keV band. From previous studies, the X-ray spectrum is known to be dominated by reflection components, both neutral (torus) and ionized (ionization cones). Our analysis indicates that the polarization degree is 28 ± 7 per cent (at 68 per cent confidence level) for the neutral reflector, with a polarization angle of 18° ± 5°, roughly perpendicular to the radio jet. The polarization of the ionized reflection is unconstrained. A comparison with Monte Carlo simulations of the polarization expected from the torus shows that the neutral reflector is consistent with being an equatorial torus with a half-opening angle of 45°–55°. This is the first X-ray polarization detection in a Seyfert galaxy, demonstrating the power of X-ray polarimetry in probing the geometry of the circumnuclear regions of AGNs, and confirming the basic predictions of standard Unification Models.
The Super DIOS project, which is an improved version of DIOS (Diffuse Intergalactic Oxygen Surveyor), is one of the candidates for Japan’s future scientific satellites, to be launched after 2030. The ...main scientific objective of the project is to unravel the flow of energy and metal cycles at various scales from galaxies, galaxy clusters to the warm-hot intergalactic medium along the Cosmic Web. The primary goal is the quantification of baryons, especially the unidentified “dark baryons”. Super DIOS will have a wide field of view of
∼
1 degree, with an angular resolution of
∼
15 arcseconds and high energy resolution (
E
/
d
E
>
1000
). The detector will be a 30 kilo-pixel array of Transition Edge sensor (TES) with a micro-wave SQUID multiplexer read-out system. In this paper, we report on the scientific concept of Super DIOS and the status of its newly developed technologies.
Fine grained nuclear emulsion with several 10nm silver halide crystals can detect submicron tracks. This detector is expected to be worked as dark matter detector with directional sensitive. Now, ...nuclear emulsion became possible to be produced at Nagoya University, and extreme fine grained nuclear emulsion with 20nm diameter was produced. Using this emulsion and new reading out technique with expansion technique, for optical selection and X-ray microscopy, recoiled tracks induced by dark matter can be detected automatically. Then, readout efficiency is larger than 80% at 120nm, and angular resolution for final confirmation with X-ray microscopy is 20°. In addition, we started to construct the R&D underground facility in Gran Sasso.
Standard galaxy formation models predict that large-scale double-lobed radio sources, known as DRAGNs, will always be hosted by elliptical galaxies. In spite of this, in recent years a small number ...of spiral galaxies have also been found to host such sources. These so-called spiral DRAGNs are still extremely rare, with only ~5 cases being widely accepted. Here we report on the serendipitous discovery of a new spiral DRAGN in data from the Giant Metrewave Radio Telescope (GMRT) at 322 MHz. The host galaxy, MCG+07-47-10, is a face-on late-type Sbc galaxy with distinctive spiral arms and prominent bulge suggesting a high black hole mass. Using WISE infra-red and GALEX UV data we show that this galaxy has a star formation rate of 0.16−0.75 M⊙ yr-1, and that the radio luminosity is dominated by star-formation. We demonstrate that this spiral DRAGN has similar environmental properties to others of this class, but has a comparatively low radio luminosity of L1.4 GHz = 1.12 × 1022 W Hz-1, two orders of magnitude smaller than other known spiral DRAGNs. We suggest that this may indicate the existence of a previously unknown low-luminosity population of spiral DRAGNS.
The supernova remnant G347.3-0.5 (J1713.7-3946) is known as one of the unique SNRs that emit TeV g-rays, as well as nonthermal X-rays. We present a detailed study of molecular gas toward this SNR ...obtained with the 4 m millimeter and submillimeter telescope NANTEN at an angular resolution of 2'.6. This study has revealed that several intensity peaks and the overall distribution of the molecular gas with radial velocities from -12 to -3 km s super(-1) show a remarkably good correlation with the X-ray features, strongly supporting the recently derived kinematic distance around 1 kpc, as opposed to the 6 kpc previously claimed. In addition, we show that absorption of X-rays is caused by local molecular gas at softer X-ray bands. Subsequent measurements of the submillimeter J = 3-2 transition of CO made with the ASTE 10 m and CSO 10.4 m submillimeter telescopes toward three of the molecular intensity peaks have revealed higher excitation conditions, most likely higher temperatures above 630 K, in contrast to the typical gas temperature, 10 K, in low-mass dark clouds. This temperature rise is most likely caused by enhanced heating by the high-energy events in the SNR, where possible mechanisms include heating by X-rays, g-rays, and/or cosmic-ray protons, although we admit that additional radiative heating by young protostars embedded may be working as well. In one of the CO peaks, we have confirmed the presence of broad molecular wings of 620 km s super(-1) velocity extent in the CO J = 3-2 transition. Two alternative interpretations for the wings are presented; one is shock acceleration by the blast wave, and the other is molecular outflow driven by an embedded protostar. The SNR evolution is well explained as the free expansion phase based on the distance of 1 kpc. The molecular data set should be valuable for making a further detailed comparison with the g-ray and X-ray distributions in order to examine the cosmic-ray acceleration quantitatively.
Nuclear emulsion is a perfect choice for a detector for directional DM search because of its high density and excellent position accuracy. The minimal detectable track length of a recoil nucleus in ...emulsion is required to be at least 100nm, making the resolution of conventional optical microscopes insufficient to resolve them. Here we report about the R&D on a super-resolution optical microscope to be used in future directional DM search experiments with nuclear emulsion as a detector media. The microscope will be fully automatic, will use novel image acquisition and analysis techniques, will achieve the spatial resolution of the order of few tens of nm and will be capable of reconstructing recoil tracks with the length of at least 100nm with high angular resolution.
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