LOS Velocity Research Articles

XookSuut: A BAYESIAN TOOL FOR MODELING CIRCULAR AND NON–CIRCULAR FLOWS ON 2D VELOCITY MAPS

We present XookSuut, a Python implementation of the DiskFit algorithm, optimized to perform robust Bayesian inference on parameters describing models of circular and noncircular rotation in galaxies. XookSuut surges as a Bayesian alternative for kinematic modeling of 2D velocity maps; it implements effcient sampling methods, specifically Markov Chain Monte Carlo (MCMC) and Nested Sampling (NS), to obtain the posteriors and marginalized distributions of kinematic models including circular motions, axisymmetric radial flows, bisymmetric flows, and harmonic decomposition of the LoS velocity. In this way, kinematic models are obtained by pure sampling methods, rather than standard minimization techniques based on the Χ2. All together, XookSuut represents a sophisticated tool for deriving rotational curves and to explore the error distribution and covariance between parameters.

TREX: Kinematic Characterization of a High-dispersion Intermediate-age Stellar Component in M33

The dwarf galaxy Triangulum (M33) presents an interesting testbed for studying stellar halo formation: it is sufficiently massive so as to have likely accreted smaller satellites, but also lies within the regime where feedback and other “in situ” formation mechanisms are expected to play a role. In this work, we analyze the line-of-sight kinematics of stars across M33 from the TREX survey, with a view to understanding the origin of its halo. We split our sample into two broad populations of varying age, comprising 2032 “old” red giant branch stars and 671 “intermediate-age” asymptotic giant branch and carbon stars. We find decisive evidence for two distinct kinematic components in both the old and intermediate-age populations: a low-dispersion (∼22 km s−1) disk-like component corotating with M33's H i gas and a significantly higher-dispersion component (∼50–60 km s−1) that does not rotate in the same plane as the gas and is thus interpreted as M33's stellar halo. While kinematically similar, the fraction of stars associated with the halo component differs significantly between the two populations: this is consistently ∼10% for the intermediate-age population, but decreases from ∼34% to ∼10% as a function of radius for the old population. We additionally find evidence that the intermediate-age halo population is systematically offset from the systemic velocity of M33 by ∼25 km s−1, with a preferred central LOS velocity of ∼ − 155 km s−1. This is the first detection and characterization of an intermediate-age halo in M33, and suggests in situ formation mechanisms, as well as potentially tidal interactions, have helped shaped it.

Multi-temporal InSAR and Sentinel-1 for assessing land surface movement of Joshimath town, India

This study deals with the spatio-temporal measurement of land movement in Joshimath town using multi-temporal SBAS-InSAR technique. A network of 424 small-baseline interferograms was generated using 111 Sentinel-1 images acquired during May 2019–April 2023. Spatial distribution of line of sight displacement (LOSD) shows south-eastern Pekamarwadi, southern Gandhinagar and central Sunil wards are majorly affected; Manoharbagh, Singhdhar, and Lowerbazar moderately affected; northern Ravigram minor affected; and Parsari ward has no sign of land movement during investigation period. The observed negative values of mean LOS velocity and acceleration in southern Gandhinagar and central Sunil indicate these patchy areas are still susceptible and riskier for land stability. The SBAS-InSAR results were validated with CORS data during January 2022–March 2023. Trends show the gradual increase in LOSD from January to November 2022, rapid increase started from November 2022 and nearly ended mid January 2023, which indicates the initiation of movement stabilization. Accuracy assessment was performed in terms of Nash–Sutcliffe efficiency coefficient (NSE), R 2 , RMSE, and MAE, and the estimated values are 0.9896, 0.9495, 1.7534 cm, and 1.4028 cm, respectively. The analysis supports that CORS and SBAS-InSAR observed LOSD are in good agreement and reveals the true story of the land movement of Joshimath.

Analysis of photospheric magnetic fields in AR 12546: a case study

We investigate high-resolution observations with the spectropolarimeter (SP) aboard the Hinode satellite of the Solar Optical Telescope (SOT) of a positive polarity sunspot of an active region (AR) (NOAA 12546). We present a case study for the properties of the thermal, magnetic field, and plasma flows as a function of the optical depth from the inversion of the observed Stokes profiles, covering a wide field of view area. Particular attention is paid to the examination of the net circular polarization (NCP) and area asymmetry of spectral lines in sunspots. We detect a large red-shifted velocity of 10 km sec−1 localized with the presence of a strong magnetic field corresponding to the NCP best fit of the inverted profiles. In addition, the comparison between the observed and calculated NCPs or Stokes V area asymmetries of spectral lines fitted well for most pixels in the field of view region, with a significant indication of a single-component inversion. We study the vertical gradients of temperature, magnetic strength, inclination field, and LOS velocity in the deeper and higher layers of the photosphere. The difference in the penumbral temperature between the two atmospheric layers is −130 K. The penumbral regions reveal a magnetic field gradient of Delta B sim -0.5 to −0.9 G km−1. The inclination gradient in the limb-side penumbra is between (Delta gamma /Delta z) = -9 times 10^{-3} deg km−1 to -3.5 times 10^{-2} deg km−1. In particular, we find a higher positive inclination gradient in the disk center-side penumbra (Delta gamma /Delta z)= 0.2 - 1.5 deg text{ km}^{-1}. The velocity gradient is (Delta V_{LOS}/Delta log tau )= -0.13 to −0.30 km sec−1 in the limb-side penumbra, and the disk center-side penumbra is given by (Delta V_{LOS}/Delta log tau )= 0.11 to 0.29 km sec−1.

Hazard Potential in Southern Pakistan: A Study on the Subsidence and Neotectonics of Karachi and Surrounding Areas

Coastal communities in deltaic regions worldwide are subject to subsidence through a combination of natural and anthropogenic processes. The city of Karachi in southern Pakistan is situated along the diffuse western boundary of the tectonically active Indian Plate, making it more susceptible to natural subsidence processes from plate motion-related deformational events such as earthquakes and faulting. Karachi has a dense population of over 16 million people, and determining the rate of subsidence and extent of neotectonic activity is crucial for mitigating seismic hazards. Excessive abstraction of groundwater and extensive groundwater use in irrigation are some of the anthropogenic contributions to subsidence in the area. A combination of the lack of historical data and few previous studies of the area make it difficult to determine the rate and extent of deformation in this region. We present an analysis of subsidence and neotectonic activity in Karachi and its surrounding areas using Interferometric Synthetic Aperture Radar (InSAR) timeseries techniques. The InSAR results for satellite LOS velocity change in both ascending and descending Sentinel-1 tracks indicate subsidence in key residential and industrial areas. Further decomposition into two dimensions (east–west and vertical) quantifies subsidence in these areas up to 1.7 cm per year. Furthermore, InSAR data suggest the presence of an active north–east dipping listric normal fault in North Karachi that is confirmed in the shallow subsurface by a 2D seismic line. Subsidence is known to cause the reactivation of faults, which increases the risk of damage to infrastructure.

Investigation of Ground Deformation around The Segments of Kendeng Fault in East Java 2017-2020 using Multi-Temporal InSAR Analysis with GACOS Correction Product

Multi-Temporal Interferometric SAR (MT-InSAR) analysis technique can provide spatially continuous measurements of the ground deformation and monitoring caused by the movement of four segments in the Kendeng Fault, East Java. Most ground deformation in these segments is indicated by the dominance of local thrust movements, folds, and the seismic density of earthquakes. In this study, ground deformation detection was carried out using the Small Baseline Subset Algorithm in the MT-InSAR process with the tropospheric correction from GACOS to determine ground deformation during 2017-2020. The percentage of change in the deformation velocity value resulting from applying the GACOS correction is up to 33.8% compared to without the tropospheric correction. The most significant troposphere effect correction is the area around the Cepu segments, which are dominated by high elevation thrust and folds. The results of the mean LOS velocity around the southern segments of Cepu, Waru, and Surabaya based on the Sentinel 1A SAR represent the occurrence of land subsidence in the south part of the area around segments with values ranging from 3.0 mm/yr to 6.0 mm/yr. Thus, the deformation effect causes land subsidence in the area around the delineation of the northern fault segment up to -3.0 mm/yr.

Bending waves in velocity space: a first look at the THINGS sample

ABSTRACT Detection of bending waves is a highly challenging task even in nearby disc galaxies due to their sub-kpc bending amplitudes. However, simulations show that the harmonic bending of a Milky Way-like disc galaxy is associated with a harmonic fluctuation in the measured line-of-sight (los) velocities as well, and can be regarded as a kinematic signature of a manifested bending wave. Here, we look for similar kinematic signatures of bending waves in H i discs, as they extend too much beyond the optical radii. We present a multipole analysis of the H i los residual velocity fields of six nearby spiral galaxies from the THINGS sample, which uncovers the bending wave-induced velocity peaks. This allows us to identify the radial positions and amplitudes of the different bending modes present in the galaxies. We find that all of our sample discs show a combined kinematic signature of superposition of a few lower order bending modes, suggesting that bending waves are a common phenomenon. The identified velocity peaks are found to be of modes m = 2, 3, and 4, not more than 15 km s−1 in amplitude and spread across the entire H i disc. Interestingly, they appear to be concentrated near the optical edge of their host galaxies. Also, m = 2 appears to be more common than the other two modes.

A multi-criteria landslide susceptibility mapping using deep multi-layer perceptron network: A case study of Srinagar-Rudraprayag region (India)

Landslide susceptibility analysis is vital for understanding precursors, associated risk, and early rescue operations. In the past, numerous attempts have been made to develop landslide susceptibility maps using various tools. This research work aims to generate landslide susceptibility maps (LSM) by developing a deep multi-layer perceptron network named as DMLP-LSM and to demonstrate it over Srinagar-Rudraprayag region, a landslide prone region recognized by the Geological Survey of India (GSI). Initially, training datasets are generated using the analytical hierarchy process (AHP) enabled multi-criteria analysis, which involves information from various landslide causative factors. In a first, one dimensional line of sight (1D LOS) velocity, one of the critical inputs and prominent indicator for landslide susceptibility, is generated by processing 60 Sentinel-1A scenes using multi-temporal interferometric synthetic aperture radar (MT-InSAR) algorithm. The 1D LOS velocity map, generally used for quantitative monitoring slow moving landslides, is used here as a thematic layer. The thematic layers and LSMs were fed to the proposed DMLP-LSM network as input and output, respectively. The developed model reached an accuracy of 91.47% with precision, specificity and ROC_AUC score as 92.11%, 95.55% and 0.9072, respectively. It further identified nearly 15 square km area as susceptible to landslide. The efficacy of the proposed model is compared with two well-known machine learning models for LSM preparation, namely support vector machine (SVM) and random forest (RF). In terms of accuracy, DMLP-LSM and RF had similar performance, but better than SVM. The velocity maps derived from MT-InSAR processing played a prominent role in the generation of LSM, supporting model training and performance. The proposed model achieved highest precision and specificity, and its performance would also improve LSM preparation when using larger datasets. The obtained results are promising, and the trained model can help in the rapid generation of LSMs.

Atmospheric phase delay correction of PS-InSAR to Monitor Land Subsidence in Surabaya

Atmospheric phase delay is one of the most significant errors limiting the accuracy of Interferometric Synthetic Aperture Radar (InSAR) results. In this research, we used the Generic Atmospheric Correction Online Service for InSAR (GACOS) data to correct the tropospheric delay modeling from the persistent scatterers’ InSAR monitoring. Eighty-one (81) Sentinel-1A images and tropospheric delay maps from GACOS monitored land subsidence in Surabaya city between 2017 and 2019. InSAR processing was carried out using the GMTSAR software, continued with StaMPS and TRAIN, which were used to correct the tropospheric delay of PSInSAR-derived deformation measurements. The results before and after the atmospheric phase delay correction using GACOS were confirmed and analyzed in the main subsidence area. The findings of the experiments reveal that the atmospheric phase affects the mean LOS velocity results to some extent. The average difference between PS-InSAR before and after tropospheric correction is 1.734 mm/year with a standard deviation of 0.550 mm/year. The significance test of the two variables, 95%, showed that the tropospheric correction with GACOS data could affect the PS-InSAR results. Furthermore, GACOS correction may increase the error at some points, which could be due to its turbulence data’s low accuracy.

Coseismic slip gradient at the western terminus of the 1920 Haiyuan Mw 7.9 earthquake

Stepovers in strike-slip fault systems play important roles in controlling the propagation of earthquake ruptures, depending partially on the competition between the stepover width and the coseismic slip gradient approaching the step. The 1920 Mw 7.9 Haiyuan earthquake is the most recent major earthquake that has occurred along the Haiyuan fault. The earthquake rupture broke through multiple stepovers along the fault and finally ended at the 4 km-wide Jingtai pull-apart basin (releasing stepover) at the western end. To understand the process of this termination of the Haiyuan earthquake rupture, we conducted detailed mapping of the surface rupture geometry, coseismic slip measurement and slip gradient calculation in the vicinity of the endpoint based on the 0.2 m-resolution SfM-derived DEM along the 20 km section east of the Jingtai pull-apart basin. Combining coseismic slip measurements from this study and published slip data from fieldwork in the 1980s, we calculated slip gradients of 84–160 cm/km as the rupture approached the Jingtai releasing stepover. These values are high for the 4 km-wide Jingtai releasing stepover compared to those from a dataset of worldwide historical earthquakes compiled by Elliott et al. (2009). The high values imply that the rupture could have a relatively high likelihood of breaching through the Jingtai releasing stepover. Alternatively, the slip gradient may be overestimated. Detailed mapping and field investigation, however, show that the rupture may extend ~1.86 km farther west of the end location indicated in previous studies. We acquired the new slip gradient with lower value of 50–82 cm/km, which is still considerably high compared to dataset of Elliott et al. (2009). We speculate that the slip gradient could be larger variation along the stepover boundary to stop fault slip in different geologic setting. Another factor control slip termination is related to fault properties. Creep along the southern boundary fault of the Jingtai stepover, a velocity-strengthening region, may also have played a role in stopping the rupture at this location. Our observations further indicate that the increasing LOS velocity of InSAR data within the Jingtai stepover is probably related to fault behavior rather than a nontectonic signal of subsidence.

Temporal fluctuations of siachen glacier velocity: a repeat pass sar interferometry based approach

Glacier velocity, the glacier's health indicator, is an emerging research interest in global warming among the scientific community over the current decade. As per scientific reports, due to their stable and advanced nature, the glaciers of Karakoram are exclusive. The present study focuses on understanding the temporal velocity variability of the Siachen Glacier, Shyok Basin, Karakoram using SAR datasets, in the perspective of the difficulties in estimating the glacier velocity over the inaccessible Karakoram Mountain. For the hydrological year 2017-18, 30 sentinel-1 derived interferograms using the DInSAR technique were analyzed to obtain Line Of Sight velocity. The transient velocity of the glacier reflects separate patterns within the glacier for different seasons due to the thermodynamic and orographic system over the glacier surface. In azimuth and range direction, the projected annual LOS velocity to a two-dimensional surface velocity is estimated to be around 103.8 ± 3.1 m/year.

A study of land subsidence in west of Tehran using Sentinel-1 data and permanent scatterer interferometric technique

In recent years, subsidence is considered one of the major environmental challenges in semiarid and arid regions of Iran. The main reason of land subsidence in Iran is injudicious groundwater extraction for agricultural and industrial activities. This study focuses on monitoring the displacement level of the ground in the west of Tehran which is highly affected by subsidence of Shahriar and Tehran plains. To support this study, Sentinel-1 images in both ascending (28) and descending (35) paths were used. The maximum subsidence rates of 16 cm/year and 15 cm/year were estimated in the southwest of Tehran and Shahriar Plain, respectively. Three subsidence centers were discovered in Shahriar Plain which is located in an urban area. The maximum LOS velocity was calculated about 5 cm/year in Fath Highway. The maximum rate of subsidence was estimated approximately 20-70 mm/year in the vicinity of Qods City. In Shahriar Plain, accuracy of InSAR results was assessed using cross-comparison analysis of the ascending and descending paths. However, in the southwest of Tehran, the vertical velocity obtained from Sentinel-1 data is validated using the GPS observations. The validations confirmed the accuracy of the PSInSAR algorithm and the InSAR results.

Determining the dynamics and magnetic fields in He I 10830 Å during a solar filament eruption

Aims. We investigate the dynamics and magnetic properties of the plasma, including the line-of-sight velocity (LOS) and optical depth, as well as the vertical and horizontal magnetic fields, belonging to an erupted solar filament. Methods. The filament eruption was observed with the GREGOR Infrared Spectrograph at the 1.5-meter GREGOR telescope on July 3, 2016. We acquired three consecutive full-Stokes slit-spectropolarimetric scans in the He I 10830 Å spectral range. The Stokes I profiles were classified using the machine learning k-means algorithm and then inverted with different initial conditions using the HAZEL code. Results. The erupting-filament material presents the following physical conditions: (1) ubiquitous upward motions with peak LOS velocities of ∼73 km s−1; (2) predominant large horizontal components of the magnetic field, on average, in the range of 173−254 G, whereas the vertical components of the fields are much lower, on average between 39 and 58 G; (3) optical depths in the range of 0.7−1.1. The average azimuth orientation of the field lines between two consecutive raster scans (<2.5 min) remained constant. Conclusions. The analyzed filament eruption belongs to the fast rising phase, with total velocities of about 124 km s−1. The orientation of the magnetic field lines does not change from one raster scan to the other, indicating that the untwisting phase has not yet started. The untwisting appears to start about 15 min after the beginning of the filament eruption.

Observationally Based Models of Penumbral Microjets

Abstract We study the polarization signals and physical parameters of penumbral microjets (PMJs) by using high spatial resolution data taken in the Fe i 630 nm pair, Ca ii 854.2 nm, and Ca ii K lines with the CRISP and CHROMIS instruments at the Swedish 1 m Solar Telescope. We infer their physical parameters, such as physical observables in the photosphere and chromospheric velocity diagnostics, by different methods, including inversions of the observed Stokes profiles with the STiC code. PMJs harbor overall brighter Ca ii K line profiles and conspicuous polarization signals in Ca ii 854.2 nm, specifically in circular polarization that often shows multiple lobes mainly due to the shape of Stokes I. They usually overlap photospheric regions with a sheared magnetic field configuration, suggesting that magnetic reconnections could play an important role in the origin of PMJs. The discrepancy between their low LOS velocities and the high apparent speeds reported on earlier, as well as the existence of different vertical velocity gradients in the chromosphere, indicate that PMJs might not be entirely related to mass motions. Instead, PMJs could be due to perturbation fronts induced by magnetic reconnections occurring in the deep photosphere that propagate through the chromosphere. This reconnection may be associated with current heating that produces temperature enhancements from the temperature minimum region. Furthermore, enhanced collisions with electrons could also increase the coupling to the local conditions at higher layers during the PMJ phase, giving a possible explanation for the enhanced emission in the overall Ca ii K profiles emerging from these transients.

Application of Persistent Scatterer Interferometry (PSI) in monitoring slope movements in Nainital, Uttarakhand Lesser Himalaya, India

Orogenic movements and sub-tropical climate have rendered the slopes of the Himalayan region intensely deformed and weathered. As a result, the incidences of slope failure are quite common all along the Himalayan region. The Lesser Himalayan terrane is particularly vulnerable to mass-movements owing to geological fragility, and many parts of it are bearing a high-risk of associated disaster owing to the high population density. An important step towards mitigation of such disasters is the monitoring of slope movement. Towards this, the Persistent Scatterer Interferometry (PSI) technique can be applied. In the present study, the PSI technique is employed in Lesser Himalayan town of Nainital in Uttarakhand state of India to decipher and monitor slope movements. A total of 15 multi-date ENVISAT ASAR satellite images, acquired during August 2008 to August 2010 period, were subjected to PSI, which revealed a continuous creep movement along the hillslopes located towards the eastern side of the Nainital lake. The higher reaches of the hill seem to be experiencing accelerated creep of \({\sim }21\) mm/year, which decreases downslope to \({\sim }5\) mm/year. Based on spatial pattern of varying PSI Mean LOS Velocity (MLV) values, high (H), moderate (M), low (L) and very low (S) creeping zones have been delineated in the hillslopes. Given the long history of mass movements and continuously increasing anthropogenic activities in Nainital, these results call for immediate measures to avert any future disaster in the town.

Deformation monitoring of dam infrastructures via spaceborne MT-InSAR. The case of La Viñuela (Málaga, southern Spain)

Dams require continuous security and monitoring programs, integrated with visual inspection and testing in dam surveillance programs. New approaches for dam monitoring focus on multi-sensor integration, taking into account emerging technologies such as GNSS, optic fiber, TLS, InSAR techniques, GBInSAR, GPR, that can be used as complementary data in dam monitoring, eliciting causes of dam deformation that cannot be assessed with traditional techniques. This paper presents a Multi-temporal InSAR (MT-InSAR) monitoring of La Viñuela dam (Málaga, Spain), a 96 m height earth-fill dam built from 1982 to 1989. The presented MT-InSAR monitoring system comprises three C-band radar (~5,7 cm wavelength) datasets from the European satellites ERS-1/2 (1992-2000), Envisat (2003-2008), and Sentinel-1A/B (2014-2018). ERS-1/2 and Envisat datasets were processed using StaMPS. In the case of Sentinel-1A/B, two different algorithms were applied, SARPROZ and ISCE-SALSIT, allowing the comparison of the estimated LOS velocity pattern. The obtained results confirm that LaViñuela dam is deforming since its construction, as an earth-fill dam. Maximum deformation rates were measured in the initial period (1992-2000), being around -7 mm/yr (LOS direction) on the coronation of the dam. In the period covered by the Envisat dataset (2003-2008), the average deforming pattern was lower, of the order of -4 mm/yr. Sentinel-1A/B monitoring confirms that the deformation is still active in the period 2014-2018 in the central-upper part of the dam, with maximums of velocity reaching -6 mm/yr. SARPROZ and ISCE-SALSIT algorithms provide similar results. It was concluded that MT-InSAR techniques can support the development of new and more effective means of monitoring and analyzing the health of dams complementing actual dam surveillance systems.

The Small-scale Structure of Photospheric Convection Retrieved by a Deconvolution Technique Applied to Hinode/SP Data

Abstract Solar granules are bright patterns surrounded by dark channels, called intergranular lanes, in the solar photosphere and are a manifestation of overshooting convection. Observational studies generally find stronger upflows in granules and weaker downflows in intergranular lanes. This trend is, however, inconsistent with the results of numerical simulations in which downflows are stronger than upflows through the joint action of gravitational acceleration/deceleration and pressure gradients. One cause of this discrepancy is the image degradation caused by optical distortion and light diffraction and scattering that takes place in an imaging instrument. We apply a deconvolution technique to Hinode/SP data in an attempt to recover the original solar scene. Our results show a significant enhancement in both the convective upflows and downflows but particularly for the latter. After deconvolution, the up- and downflows reach maximum amplitudes of −3.0 km s−1 and +3.0 km s−1 at an average geometrical height of roughly 50 km, respectively. We found that the velocity distributions after deconvolution match those derived from numerical simulations. After deconvolution, the net LOS velocity averaged over the whole field of view lies close to zero as expected in a rough sense from mass balance.

Bars and boxy/peanut bulges in thin and thick discs

We explore trends in the morphology and line-of-sight (los) velocity of stellar populations in the inner regions of disc galaxies using N-body simulations with a thin (kinematically cold) and a thick (kinematically hot) disc which form a bar and a boxy/peanut (b/p) bulge. The bar in the thin disc component is ~50% stronger than the thick disc bar and is more elongated, with an axis ratio almost half that of the thick disc bar. The thin disc b/p bulge has a pronounced X-shape, while the thick disc b/p is weaker with a rather boxy shape. This leads to the signature of the b/p bulge in the thick disc being weaker and further away from the plane than in the thin disc. Regarding the kinematics, we find that the los velocity of thick disc stars in the outer parts of the b/p bulge can be higher than that of thin disc stars, by up to 40% and 20% for side-on and Milky Way-like orientations of the bar, respectively. This is due to the different orbits followed by thin and thick disc stars in the bar-b/p region, which are affected by two factors. First, thin disc stars are trapped more efficiently in the bar-b/p instability and thus lose more angular momentum than their thick disc counterparts and second, thick disc stars have large radial excursions and therefore stars from large radii with high angular momenta can be found in the bar region. We also find that the difference between the los velocities of the thin and thick disc in the b/p bulge (Δvlos) correlates with the initial difference between the radial velocity dispersions of the two discs (Δσ). We therefore conclude that stars in the bar-b/p bulge will have considerably different morphologies and kinematics depending on the kinematic properties of the disc population they originate from.

Velocity segregation effects in galaxy clusters at 0.4 ≲z≲ 1.5

Our study is meant to extend our knowledge of the galaxy color and luminosity segregation in velocity space (VCS and VLS, resp.), to clusters at intermediate and high redshift. Our sample is a collection of 41 clusters in the 0.4<~z<~1.5 redshift range, for a total of 4172 galaxies, 1674 member galaxies within 2R200 with photometric or spectroscopic information, as taken from the literature. We pay attention to perform homogeneous procedures to select cluster members, compute global cluster properties, in particular the LOS velocity dispersion sigmaV, and separate blue from red galaxies. We find evidence of VCS in clusters out to z~0.8 (at the 97%-99.99% c.l., depending on the test), in the sense that the blue galaxy population has a 10-20% larger sigmaV than the red galaxy population. Poor or no VCS is found in the High-z sample at z>=0.8. For the first time, we detect VLS in non-local clusters and confirm that VLS only affects the very luminous galaxies, with brighter galaxies having lower velocities. The threshold magnitude of VLS is ~m3+0.5, where m3 is the magnitude of the third brightest cluster galaxy, and current data suggest that the threshold value moves to fainter magnitudes at higher redshift. We also detect (marginal) evidence of VLS for blue galaxies. We conclude that the segregation effects, when their study is extended to distant clusters, can be important tracers of the galaxy evolution and cluster assembly and discuss the poor/no evidence of VCS at high redshift.

Analysis of a spatially deconvolved solar pore

Solar pores are active regions with large magnetic field strengths and apparent simple magnetic configurations. Their properties resemble the ones found for the sunspot umbra although pores do not show penumbra. Therefore, solar pores present themselves as an intriguing phenomenon that is not completely understood. We examine in this work a solar pore observed with Hinode/SP using two state of the art techniques. The first one is the spatial deconvolution of the spectropolarimetric data that allows removing the stray light contamination induced by the spatial point spread function of the telescope. The second one is the inversion of the Stokes profiles assuming local thermodynamic equilibrium that let us to infer the atmospheric physical parameters. After applying these techniques, we found that the spatial deconvolution method does not introduce artefacts, even at the edges of the magnetic structure, where large horizontal gradients are detected on the atmospheric parameters. Moreover, we also describe the physical properties of the magnetic structure at different heights finding that, in the inner part of the solar pore, the temperature is lower than outside, the magnetic field strength is larger than 2 kG and unipolar, and the LOS velocity is almost null. At neighbouring pixels, we found low magnetic field strengths of same polarity and strong downward motions that only occur at the low photosphere, below the continuum optical depth $\log \tau=-1$. Finally, we studied the spatial relation between different atmospheric parameters at different heights corroborating the physical properties described before.