bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamically produced moving groups in interacting simulations
Authors: Craig Peter , Chakrabarti Sukanya , Newberg Heidi , Quillen Alice 
Published: May 2021

ABSTRACT
We show that smoothed particle hydrodynamics (SPH) simulations of dwarf galaxies interacting with a Milky Way-like disc produce moving groups in the simulated stellar disc. We analyse three different simulations: one that includes dwarf galaxies that mimic the Large Magellanic Cloud, Small Magellanic Cloud, and the Sagittarius dwarf spheroidal; another with a dwarf galaxy that orbits nearly in the plane of the Milky Way disc; and a null case that does not include a dwarf galaxy interaction. We present a new algorithm to find large moving groups in the VR, Vϕ plane in an automated fashion that allows us to compare velocity substructure in different simulations, at different locations, and at different times. We find that there are significantly more moving groups formed in the interacting simulations than in the isolated simulation. A number of dwarf galaxies are known to orbit the Milky Way, with at least one known to have had a close pericentre approach. Our analysis of simulations here indicates that dwarf galaxies like those orbiting our Galaxy produce large moving groups in the disc. Our analysis also suggests that some of the moving groups in the Milky Way may have formed due to dynamical interactions with perturbing dwarf satellites. The groups identified in the simulations by our algorithm have similar properties to those found in the Milky Way, including similar fractions of the total stellar population included in the groups, as well as similar average velocities and velocity dispersions.
Calibration of the Advanced Spectral Leakage scheme for neutron star merger simulations, and extension to smoothed-particle hydrodynamics
Authors: Gizzi D , Lundman C , O’Connor E , Rosswog S , Perego A 
Published: May 2021

ABSTRACT
We calibrate a neutrino transport approximation, called Advanced Spectral Leakage (ASL), with the purpose of modelling neutrino-driven winds in neutron star mergers. Based on a number of snapshots, we gauge the ASL parameters by comparing against both the two-moment (M1) scheme implemented in the flash code and the Monte Carlo neutrino code sedonu. The ASL scheme contains three parameters, the least robust of which results to be a blocking parameter for electron neutrinos and antineutrinos. The parameter steering the angular distribution of neutrino heating is recalibrated compared to the earlier work. We also present a new, fast and mesh-free algorithm for calculating spectral optical depths, which, when using smoothed-particle hydrodynamics (SPH), makes the neutrino transport completely particle-based. We estimate a speed-up of a factor of ≳100 in the optical depth calculation when comparing to a grid-based approach. In the suggested calibration we recover luminosities and mean energies within $25{{\ \rm per\ cent}}$. A comparison of the rates of change of internal energy and electron fraction in the neutrino-driven wind suggests comparable accuracies of ASL and M1, but a higher computational efficiency of the ASL scheme. We estimate that the ratio between the CPU hours spent on the ASL neutrino scheme and those spent on the hydrodynamics is ≲0.8 per time-step when considering the SPH code magma2 as source code for the Lagrangian hydrodynamics, to be compared with a factor of 10 from the M1 in flash.
MUSE-ALMA haloes VI: coupling atomic, ionized, and molecular gas kinematics of galaxies
Authors: Szakacs Roland , Péroux Céline , Zwaan Martin , Hamanowicz Aleksandra , Klitsch Anne , Fresco Alejandra Y , Augustin Ramona , Biggs Andrew , Kulkarni Varsha , Rahmani Hadi 
Published: May 2021

ABSTRACT
We present results of MUSE-ALMA haloes, an ongoing study of the circumgalactic medium (CGM) of galaxies (z ≤ 1.4). Using multiphase observations we probe the neutral, ionized, and molecular gas in a subsample containing six absorbers and nine associated galaxies in the redshift range z ∼ 0.3–0.75. Here, we give an in-depth analysis of the newly CO-detected galaxy Q2131−G1 (z = 0.42974), while providing stringent mass and depletion time limits for the non-detected galaxies. Q2131−G1 is associated with an absorber with column densities of log(NH i/cm−2) ∼ 19.5 and $\textrm {log}(N_{\textrm {H}_2}/\textrm {cm}^{-2}) \sim 16.5$, and has a star formation rate of SFR = 2.00 ± 0.20 M⊙yr−1, a dark matter fraction of fDM(r1/2) = 0.24–0.54, and a molecular gas mass of $M_\textrm {mol} = 3.52 ^{+3.95}_{-0.31} \times 10^9 \,\, \textrm {M}_{\odot }$ resulting in a depletion time of τdep &lt; 4.15 Gyr. Kinematic modelling of both the CO (3–2) and [O iii] λ5008 emission lines of Q2131−G1 shows that the molecular and ionized gas phases are well aligned directionally and that the maximum rotation velocities closely match. These two gas phases within the disc are strongly coupled. The metallicity, kinematics, and orientation of the atomic and molecular gas traced by a two-component absorption feature are consistent with being part of the extended rotating disc with a well-separated additional component associated with infalling gas. Compared to emission-selected samples, we find that H i-selected galaxies have high molecular gas masses given their low star formation rate. We consequently derive high depletion times for these objects.
MusE GAs FLOw and Wind (MEGAFLOW) VI. A study of C iv and Mg ii absorbing gas surrounding [O ii] emitting galaxies
Authors: Schroetter Ilane , Bouché Nicolas F , Zabl Johannes , Rahmani Hadi , Wendt Martin , Muzahid Sowgat , Contini Thierry , Schaye Joop , Schmidt Kasper B , Wisotzki Lutz 
Published: May 2021

ABSTRACT
Using the MEGAFLOW survey, which consists of a combination of MUSE and UVES observations of 22 quasar fields selected to contain strong Mg ii absorbers, we measure the covering fractions of C iv and Mg ii as a function of impact parameter b using a novel Bayesian logistic regression method on unbinned data, appropriate for small samples. We also analyse how the C iv and Mg ii covering fractions evolve with redshift. In the MUSE data, we found 215 $z = 1{-}1.5$ [O ii] emitters with fluxes ${\gt}10^{-17}$ erg s−1 cm−2 and within 250 kpc of quasar sight-lines. Over this redshift path $z = 1{-}1.5$, we have 19 (32) C iv (Mg ii) absorption systems with rest-frame equivalent width (REW) $W_r\gt $ 0.05 Å associated with at least one [O ii] emitter. The covering fractions of $z\approx 1.2$ C iv (Mg ii) absorbers with mean $W_r\approx$ 0.7 Å (1.0 Å), exceeds 50 per cent within 23$^{+62}_{-16}$ (46$^{+{18}}_{-13}$) kpc. Together with published studies, our results suggest that the covering fraction of C iv (Mg ii) becomes larger (smaller) with time, respectively. For absorption systems that have C iv but not Mg ii, we find in 73 per cent of the cases no [O ii] counterpart. This may indicate that C iv comes from the intergalactic medium (IGM), i.e. beyond 250 kpc, or that it is associated with lower mass or quiescent galaxies.
Probing the hadronic nature of the gamma-ray emission associated with Westerlund 2
Authors: Mestre Enrique , de Oña Wilhelmi Emma , Torres Diego F , Holch Tim Lukas , Schwanke Ullrich , Aharonian Felix , Parkinson Pablo Saz , Yang Ruizhi , Zanin Roberta 
Published: May 2021

ABSTRACT
Star-forming regions have been proposed as potential Galactic cosmic ray accelerators for decades. Cosmic ray acceleration can be probed through observations of gamma-rays produced in inelastic proton–proton collisions at GeV and TeV energies. In this paper, we analyse more than 11 yr of Fermi–LAT data from the direction of Westerlund 2, one of the most massive and best-studied star-forming regions in our Galaxy. In particular, we investigate the characteristics of the bright pulsar PSR J1023–5746 that dominates the gamma-ray emission below a few GeV at the position of Westerlund 2 and the underlying extended source FGES J1023.3–5747. The analysis results in a clear identification of FGES J1023.3–5747 as the GeV counterpart of the TeV source HESS J1023-575, through its morphological and spectral properties. This identification provides new clues about the origin of the HESS J1023-575 gamma-ray emission, favouring a hadronic origin of the emission, powered by Westerlund 2, rather than a leptonic origin related to either the pulsar wind nebula associated with PSR J1023–5746 or the cluster itself. This result indirectly supports the hypothesis that star-forming regions can contribute to the cosmic ray sea observed in our Galaxy.
Estimating galaxy masses from kinematics of globular cluster systems: a new method based on deep learning
Authors: Kaur Rajvir , Bekki Kenji , Hassan Ghulam Mubashar , Datta Amitava 
Published: May 2021

ABSTRACT
We present a new method by which the total masses of galaxies including dark matter can be estimated from the kinematics of their globular cluster systems (GCSs). In the proposed method, we apply the convolutional neural networks (CNNs) to the 2D maps of line-of-sight velocities (V) and velocity dispersions (σ) of GCSs predicted from numerical simulations of disc and elliptical galaxies. In this method, we first train the CNN using either only a larger number ($\sim 200\, 000$) of the synthesized 2D maps of σ (‘one-channel’) or those of both σ and V (‘two-channel’). Then, we use the CNN to predict the total masses of galaxies (i.e. test the CNN) for the totally unknown data set that is not used in training the CNN. The principal results show that overall accuracy for one-channel and two-channel data is 97.6 per cent and 97.8 per cent, respectively, which suggests that the new method is promising. The mean absolute errors (MAEs) for one-channel and two-channel data are 0.288 and 0.275, respectively, and the value of root mean square errors (RMSEs) are 0.539 and 0.51 for one-channel and two-channel, respectively. These smaller MAEs and RMSEs for two-channel data (i.e. better performance) suggest that the new method can properly consider the global rotation of GCSs in the mass estimation. We also applied our proposed method to real data collected from observations of NGC 3115 to compare the total mass predicted by our proposed method and other popular methods from the literature.
Hydrodynamic escape of an impact-generated reduced proto-atmosphere on Earth
Authors: Yoshida Tatsuya , Kuramoto Kiyoshi 
Published: May 2021

ABSTRACT
Recent cosmochemical studies have shown that most of Earth’s building blocks were close to enstatite meteorites in isotopic compositions. This implies the formation of an impact-induced proto-atmosphere enriched in H2 and CH4 on accreting Earth. Such a reduced proto-atmosphere would have been largely lost by hydrodynamic escape, but its flux and time-scale for hydrogen depletion remain highly uncertain. Here we carry out 1D hydrodynamic escape simulations for such an H2–CH4 proto-atmosphere by incorporating expanded chemical networks and radiative cooling processes for estimation of the duration of the H2-rich surface environment on early Earth. In the escape outflow, CH4 is dissociated effectively by direct photolysis and chemical reactions with photochemically produced ion species. On the other hand, radiative cooling by photochemical products such as H$_{3}^{+}$, CH, and CH3 significantly suppresses atmospheric escape. Even though CH4 and their concentrations are small, the heating efficiency decreases to $\sim 5\, {{\ \rm per\ cent}}$ when CH4/H2 = 0.007 in the lower atmosphere and CH4 would suffer negligible escape when CH4/H2≳ 0.01. The time-scale for H2 escape consistent with the constraints of the isotopic compositions and the amount of C and N on the present Earth is possibly more than several hundred million years. Our results suggest that a long-lived hydrogen-rich reduced environment played important roles in climate warming and the generation of organic matters linked to the emergence of living organisms during the first several hundred million years of Earth.
The Rise of Digital Repression
Authors: Feldstein Steven 
Published: May 2021

Abstract
This book documents the rise of digital repression—how governments are deploying new technologies to counter dissent, maintain political control, and ensure regime survival. The emergence of varied digital technologies is bringing new dimensions to political repression. At its core, the expanding use of digital repression reflects a fairly simple motivation: states are seeking and finding new ways to control, manipulate, surveil, or disrupt real or perceived threats. This book investigates the goals, motivations, and drivers of digital repression. It presents case studies in Thailand, the Philippines, and Ethiopia, highlighting how governments pursue digital strategies based on a range of factors: ongoing levels of repression, leadership, state capacity, and technological development. But a basic political motive—how to preserve and sustain political incumbency—remains a principal explanation for their use. The international community is already seeing glimpses of what the frontiers of repression look like, such as in China, where authorities have brought together mass surveillance, online censorship, DNA collection, and artificial intelligence to enforce their rule in Xinjiang. Many of these trends are going global. This has major implications for democratic governments and civil society activists around the world. The book also presents innovative ideas and strategies for civil society and opposition movements to respond to the digital autocratic wave.
Global Patterns of Digital Repression
Authors: Feldstein Steven 
Published: May 2021

Abstract
This chapter presents quantitative data to explain the main arguments of the book. Specifically, it provides pooled, cross-national, time-series data to describe global patterns of digital repression, and it uses that data to develop and validate two composite indexes: a latent construct of digital repression and a latent construct of digital repression capacity. It discusses overall findings from the digital repression index—the relationship between regime type and digital repression, highest- and lowest-performing countries, as well as outliers. It also compares digital repression enactment to capacity, and investigates differences between autocracies and democracies. Finally, it analyzes individual components of digital repression—social media surveillance, online censorship, social manipulation and disinformation, Internet shutdowns, and arrests of online users for political content—and provide explanations for authoritarian and democratic use.
Thailand’s Strategy of Control
Authors: Feldstein Steven 
Published: May 2021

Abstract
This chapter presents a case study of how the Thai state deploys digital repression techniques to advance its political agenda. Thailand’s situation offers insights into how an autocratic state with a tradition of censorship and political suppression has adapted to a new digital environment. The Thai government has adeptly paired new information controls with old repressive methods, giving the state potent capabilities to control dissent. Thailand also demonstrates how digital repression is born from and develops out of internal drivers; external actors exercise limited influence in shaping the state’s digital strategies.
Transformation and Setbacks in Ethiopia
Authors: Feldstein Steven 
Published: May 2021

Abstract
This chapter focuses on political changes occurring in Ethiopia and their implications for digital technology. Since the early 2000s, Ethiopia has displayed a dismal track record when it comes to digital freedom. Internet shutdowns, rising disinformation, and traditions of online censorship and surveillance characterize Ethiopia’s digital environment. New prime minister Abiy Ahmed has ushered in important shifts, many of which are still in the early stages of implementation. Digital repression in 2020 looks very differently from prior years. This chapter discusses political change in Ethiopia and the impact of Abiy’s agenda. It describes the landscape of digital repression in the country, focusing on Internet shutdowns, rising levels of social disinformation and disinformation, as well as ongoing surveillance and censorship concerns. It then explains relevant factors that have shaped Ethiopia’s digital repression environment before turning to examine China’s influence in the country.
Enacting Political Friendship in Gezi
Authors: Çidam Çiğdem 
Published: May 2021

Abstract
This chapter deploys the alternative conceptual lens developed in the book, according to which democratic action is a theatrical experience created and sustained through the intermediating practices of political friendship, to analyze the Gezi protests of 2013. What emerges from this analysis is a richer account of events that moves beyond the limiting frameworks of success/failure and spontaneity/organization by bringing to light both the on-the-ground practices of political actors and the messiness and impurity of democratic politics even in the moment of its staging. Focusing on such intermediating practices as deliberation, judging, negotiation, artistic production, common use, and the organization of the mundane aspects of everyday life, the chapter demonstrates that those who took part in Gezi borrowed from past struggles, including May ’68, re-activated political habits, and, acting in unexpected ways, created new, if imperfect and fragile, forms of commonality among diverse figures, showing that another way of doing things is possible.
The Privy Council: The Umpire of the British Empire
Authors: Calabresi Steven Gow 
Published: May 2021

Abstract
This chapter describes the history and workings of the Privy Council, which was the Supreme Court of both the First and Second British Empires from 1607 until the present day. The Judicial Committee of the Privy Council (JCPC), as it came to be called in 1833, provided vertical federalism judicial review in all British Imperial cases arising outside of England and Wales to ensure that English colonies were not adopting laws that were repugnant to English law. The British Empire from 1607 to the present day was and is a constitutional federal entity with centralized federalism judicial review vested in what is now called the JCPC. The JCPC, which still exists, does not have the power of horizontal judicial review, either over acts of the U.K. Parliament, or of the prime minister. The Privy Council between 1607 and 1776 reined in the thirteen North American British colonies when they enacted laws or decided cases in ways that were repugnant to the laws of England. The JCPC decided Canadian and Australian federalism and separation of powers case from 1867 on thereby habituating those countries to the practice of federalism and separation of powers judicial review, which both countries have followed since gaining independence.
Canada: From Privy Council to Supreme Court
Authors: Calabresi Steven Gow 
Published: May 2021

Abstract
This chapter assesses the emergence of judicial review in Canada. Canadian judicial review emerged as a direct result of federalism and separation of powers umpiring by the Judicial Committee of the Privy Council (JCPC), which was Canada’s highest court from the adoption of the British North America Act in 1867 until Canada ended appeals to the JCPC in 1949. There was also, as Ran Hirschl would argue, an element of elite hegemonic entrenchment by imperial British colonial elites in the retention of the JCPC as the highest court of appeals in Canada from the creation of the Supreme Court of Canada in 1875 until Canada abolished appeals to the JCPC in 1949. Some Canadian elites tried and failed to end JCPC judicial review in Canadian cases in 1875. Canadian judicial review from 1867 to 1982 was exclusively concerned with federalism and separation of powers judicial umpiring because Canada had no constitutional Bill of Rights until 1982. There are thus two founding moments in the judicial review of legislation in Canadian history: firstly, the period from 1867 to 1982 when Canadian federalism and separation of powers law took shape as a result of federalism and separation of powers umpiring; and, secondly, the period from 1982 to the present, when the Supreme Court of Canada began vigorously enforcing the Canadian Charter of Rights and Freedoms. The emergence of judicial review from 1982 down to the present day is partly a rights from wrongs phenomenon, and it is partly the result of constitutional borrowing from the United States’s Warren Court.
The State of Israel
Authors: Calabresi Steven Gow 
Published: May 2021

Abstract
This chapter studies the emergence of judicial review in Israel, which is a rights from wrongs reaction to the Holocaust, Nazism, and Fascism. Israeli judicial review did not arise to fulfill a need for a federalism or separation of powers umpire, since Israel is a unitary nation-state without a separation of powers system. Israeli judicial review emerged in weakened form as a consequence of the Zionist mass mobilization, which led to the creation of Israel and to the issuance of Israel’s Declaration of Independence, as is explained by Professor Ackerman. Israeli adoption of written constitutionalism and of judicial review was probably, in part, a function of borrowing. I consider, and reject, Professor Ran Hirschl’s argument that Israeli judicial review originated as a power grab by a fading Ashkenazi Israeli elite. I think that proportional representation has resulted in so many political parties holding seats in the Knesset that the Supreme Court has much more power relative to the legislature than is the case in a G-20 nation with a parliamentary, unitary with an electoral system like Japan’s. I also think Israel’s common law heritage contributed to its adoption of judicial review.
Conclusion The American and Westminster Models
Authors: Calabresi Steven Gow 
Published: May 2021

Abstract
This concluding chapter identifies the four major causes of the growth and origin of judicial review in the G-20 common law countries and in Israel. First, the need for a federalism umpire, and occasionally a separation of powers umpire, played a major role in the development of judicial review of the constitutionality of legislation in the United States, in Canada, in Australia, in India, and most recently in the United Kingdom. Second, there is a rights from wrongs phenomenon at work in the growth of judicial review in the United States, after the Civil War; in Canada, with the 1982 adoption of the Canadian Charter of Rights and Freedoms; in India, after the Indira Gandhi State of Emergency led to a massive trampling on human rights; in Israel, after the Holocaust; in South Africa, after racist apartheid misrule; and in the United Kingdom, after that country accumulated an embarrassing record before the European Court of Human Rights prior to 1998. This proves that judicial review of the constitutionality of legislation often occurs in response to a deprivation of human rights. Third, the seven common law countries all borrowed a lot from one another, and from civil law countries, in writing their constitutions. Fourth, and finally, the common law countries all create multiple democratic institutions or political parties, which renders any political attempt to strike back at the Supreme Court impossible to maintain.