bluuebunny/crossref_metadata_2025_split huggingface dataset:
Formation of supermassive black holes in galactic nuclei – I. Delivering seed intermediate-mass black holes in massive stellar clusters
Authors: Askar Abbas , Davies Melvyn B , Church Ross P 
Published: January 2021

ABSTRACTSupermassive black holes (SMBHs) are found in most galactic nuclei. A significant fraction of these nuclei also contains a nuclear stellar cluster (NSC) surrounding the SMBH. In this paper, we consider the idea that the NSC forms first, from the merger of several stellar clusters that may contain intermediate-mass black holes (IMBHs). These IMBHs can subsequently grow in the NSC and form an SMBH. We carry out N-body simulations of the simultaneous merger of three stellar clusters to form an NSC, and investigate the outcome of simulated runs containing zero, one, two, and three IMBHs. We find that IMBHs can efficiently sink to the centre of the merged cluster. If multiple merging clusters contain an IMBH, we find that an IMBH binary is likely to form and subsequently merge by gravitational wave emission. We show that these mergers are catalyzed by dynamical interactions with surrounding stars, which systematically harden the binary and increase its orbital eccentricity. The seed SMBH will be ejected from the NSC by the recoil kick produced when two IMBHs merge, if their mass ratio q ≳ 0.15. If the seed is ejected then no SMBH will form in the NSC. This is a natural pathway to explain those galactic nuclei that contain an NSC but apparently lack an SMBH, such as M33. However, if an IMBH is retained then it can seed the growth of an SMBH through gas accretion and tidal disruption of stars.
3D magnetized jet break-out from neutron-star binary merger ejecta: afterglow emission from the jet and the ejecta
Authors: Nathanail Antonios , Gill Ramandeep , Porth Oliver , Fromm Christian M , Rezzolla Luciano 
Published: January 2021

ABSTRACT
We perform 3D general-relativistic magnetohydrodynamic simulations to model the jet break-out from the ejecta expected to be produced in a binary neutron-star merger. The structure of the relativistic outflow from the 3D simulation confirms our previous results from 2D simulations, namely, that a relativistic magnetized outflow breaking out from the merger ejecta exhibits a hollow core of θcore ≈ 4°, an opening angle of θjet ≳ 10°, and is accompanied by a wind of ejected matter that will contribute to the kilonova emission. We also compute the non-thermal afterglow emission of the relativistic outflow and fit it to the panchromatic afterglow from GRB170817A, together with the superluminal motion reported from VLBI observations. In this way, we deduce an observer angle of $\theta _{\rm obs}= 35.7^{\circ \, \, +1.8}_{\phantom{\circ \, \, }-2.2}$. We further compute the afterglow emission from the ejected matter and constrain the parameter space for a scenario in which the matter responsible for the thermal kilonova emission will also lead to a non-thermal emission yet to be observed.
Chandra and HST studies of six millisecond pulsars in the globular cluster M13
Authors: Zhao Jiaqi , Zhao Yue , Heinke Craig O 
Published: January 2021

ABSTRACT
We analyse 55 ks of Chandra X-ray observations of the Galactic globular cluster (GC) M13. Using the latest radio timing positions of six known millisecond pulsars (MSPs) in M13 from Wang et al. (2020), we detect confident X-ray counterparts to five of the six MSPs at X-ray luminosities of LX(0.3–8 keV)∼3 × 1030–1031 erg s−1, including the newly discovered PSR J1641+3627F. There are limited X-ray counts at the position of PSR J1641+3627A, for which we obtain an upper limit LX &lt; 1.3 × 1030 erg s−1. We analyse X-ray spectra of all six MSPs, which are well described by either a single blackbody (BB) or a single power-law model. We also incorporate optical/UV imaging observations from the Hubble Space Telescope (HST) and find optical counterparts to PSR J1641+3627D and J1641+3627F. Our colour–magnitude diagrams indicate the latter contains a white dwarf, consistent with the properties suggested by radio timing observations. The counterpart to J1641+3627D is only visible in the V band; however, we argue that the companion to J1641+3627D is also a white dwarf, since we see a BB-like X-ray spectrum, while MSPs with non-degenerate companions generally show non-thermal X-rays from shocks between the pulsar and companion winds. Our work increases the sample of known X-ray and optical counterparts of MSPs in GCs.
Composite bulges – II. Classical bulges and nuclear discs in barred galaxies: the contrasting cases of NGC 4608 and NGC 4643
Authors: Erwin Peter , Seth Anil , Debattista Victor P , Seidel Marja , Mehrgan Kianusch , Thomas Jens , Saglia Roberto , de Lorenzo-Cáceres Adriana , Maciejewski Witold , Fabricius Maximilian , Méndez-Abreu Jairo , Hopp Ulrich , Kluge Matthias , Beckman John E , Bender Ralf , Drory Niv , Fisher Deanne 
Published: January 2021

ABSTRACT
We present detailed morphological, photometric, and stellar-kinematic analyses of the central regions of two massive, early-type barred galaxies with nearly identical large-scale morphologies. Both have large, strong bars with prominent inner photometric excesses that we associate with boxy/peanut-shaped (B/P) bulges; the latter constitute ∼30 per cent of the galaxy light. Inside its B/P bulge, NGC 4608 has a compact, almost circular structure (half-light radius Re ≈ 310 pc, Sérsic n = 2.2) we identify as a classical bulge, amounting to 12.1 per cent of the total light, along with a nuclear star cluster (Re ∼ 4 pc). NGC 4643, in contrast, has a nuclear disc with an unusual broken-exponential surface-brightness profile (13.2 per cent of the light), and a very small spheroidal component (Re ≈ 35 pc, n = 1.6; 0.5 per cent of the light). IFU stellar kinematics support this picture, with NGC 4608’s classical bulge slowly rotating and dominated by high velocity dispersion, while NGC 4643’s nuclear disc shows a drop to lower dispersion, rapid rotation, V–h3 anticorrelation, and elevated h4. Both galaxies show at least some evidence for V–h3correlation in the bar (outside the respective classical bulge and nuclear disc), in agreement with model predictions. Standard two-component (bulge/disc) decompositions yield B/T ∼ 0.5–0.7 (and bulge n &gt; 2) for both galaxies. This overestimates the true ‘spheroid’ components by factors of 4 (NGC 4608) and over 100 (NGC 4643), illustrating the perils of naive bulge-disc decompositions applied to massive barred galaxies.
Periastron shift of compact stellar orbits from general relativistic and tidal distortion effects near Sgr A*
Authors: Lalremruati P C , Kalita Sanjeev 
Published: January 2021

ABSTRACT
The Galactic Centre (Sgr A*), hosting a supermassive black hole, carries sufficient potential for testing gravitational theories. Existing astrometric facilities on Very Large Telescope (VLT) and the Keck Telescope have enabled astronomers to study stellar orbits near Sgr A* and perform new astronomical tests of gravitational theories. These observations have provided strong field tests of gravity (ϕ/c2 ∼ 10−3, which is much greater than ϕ/c2 for the Solar system). In this work, we have estimated magnitudes of various contributions to the periastron shift of compact stellar orbits near Sgr A* for pericentre distance in the range rp = (0.3 – 50)au at a fixed orbital inclination, i = 90°. We take the spin of the black hole as χ = 0.1, 0.44, and 0.9 and eccentricities of the orbit as e = 0.9. The relativistic effects including orders beyond 1PN and spin induced effects are incorporated in the contributions. Effect of tidal distortion on periastron shift has also been added into the estimation by considering gravitational Love numbers for polytropic models of the stars. For the tidal effect, we have considered updated mass–radii relations for low-mass stars and high-mass stars. It has been found that the tidal effect on periastron shift arising from stars represented by polytropes of indices n = 1 and n = 3 terminate above rp ∼ 2 au and rp ∼ 1 au, respectively. The periastron shift angle for the stars has been compared with the astrometric capabilities of existing large telescopes and upcoming extremely large telescopes. Challenges and prospects associated with the estimations are highlighted.
Immune Status and Mortality in Smokers, Ex-smokers, and Never-Smokers: The Ludwigshafen Risk and Cardiovascular Health Study
Authors: Delgado Graciela E , Krämer Bernhard K , März Winfried , Hellstern Peter , Kleber Marcus E , Leipe Jan 
Published: January 2021

AbstractIntroductionElevated leukocyte counts are associated with cardiovascular disease. Smoking induces inflammation and alters levels of leukocyte subtypes.Aims and MethodsOur aim was to investigate the effect of smoking on circulating immune cells and their association with mortality. Lymphocyte subtypes were identified by flow cytometry of fluorescent-labeled cells. We analyzed the association of leukocytes with mortality using Cox regression and assessed their effect on risk prediction based on principle components (PCs) using area under the receiver operating characteristic curve and net-reclassification in 2173 participants from the Ludwigshafen Risk and Cardiovascular Health Study, a prospective case–control study in patients who underwent coronary angiography.ResultsThe numbers of T cells, monocytes, and neutrophils were higher and natural killer cells were lower in smokers compared with never-smokers. In never-smokers, lymphocyte counts were inversely associated with mortality while a positive association was observed for neutrophils. The neutrophil-to-lymphocyte ratio (NLR) had the strongest association in never-smokers with a hazard ratio (95% confidence interval) of 1.43 (1.26–1.61). No associations were found in smokers. Adding the first five PCs or the NLR to a risk prediction model based on conventional risk factors did not improve risk prediction in smokers, but significantly increased the area under the curve from 0.777 to 0.801 and 0.791, respectively, in never-smokers.ConclusionsLymphocyte counts were inversely associated with mortality in never-smokers but not in active smokers. Markers of innate immunity, namely total neutrophils and CD11b+/CD18+ and CD31+/CD40− granulocytes, were directly associated with mortality. Adding markers of immune function like PCs or the NLR to basic risk models improved risk prediction in never-smokers only.ImplicationsTotal leukocyte counts were higher in active smokers as compared to never-smokers due to elevated counts of neutrophils and monocytes but declined in ex-smokers with increasing time since quitting. In the never-smokers but not in smokers, lymphocyte counts were inversely associated with mortality while there was a direct association with neutrophils, even after adjustment for conventional cardiovascular risk factors. Adding markers of immune function to basic risk models improved risk prediction in never-smokers only. Our data indicate that smoking status has an important impact on the ability of leukocyte counts to predict long-term cardiovascular outcomes.
The Many Faces of Zionism
Authors: Pappé Ilan 
Published: January 2021

Abstract
This chapter examines the evolvement of the Zionist idea and movement over the years. It traces the etymology of the concept and its early adoption by evangelical Christianity. This is followed by an analysis of the origins of political Zionism in Europe. Both the official Israeli narrative, viewing Zionism as the Jewish national movement, and the counternarrative that depicts it as a settler-colonial phenomenon are presented. The settler-colonial paradigm explains the achievement of Zionism of building the infrastructure for a modern Jewish state, on the one hand, and the catastrophic effect it had on the indigenous people of Palestine, on the other. The depiction of the movement as a settler-colonial movement explains the ethnic cleansing it perpetrated against the Palestinian people in 1948. This paradigm also explains how Zionism informed Israel’s strategy toward the Palestinians ever since 1948. The chapter also discusses the appearance of post-Zionism and assesses its future trends.
“When Women Change, Everything Changes”
Authors: Batmanghelichi Kristin Soraya 
Published: January 2021

Abstract
Discourses of marriage, sexual violence, and wilaya (male guardianship system) in the Middle East and North Africa (MENA) region have been transformed in part through women’s activism in the domain of sexuality and health. Local and global actors have labored to address gender-discriminatory policies, thinking, and behavior through international conventions, regional collaboration, and, more recently, mobile technologies and social media. When popular revolts shook the region’s status quo from 2009 to 2012, shifting practices and attitudes about gender and sexuality became more distinct, recalibrating discussions on sexual harassment, the necessity of wilaya, and a woman’s decision not to marry. Meanwhile, MENA women’s advocates have pushed back against conservative norms and policies that regularly dismiss or shame their quest for gender justice and equality. This chapter offers a glimpse into the ongoing debates and struggles among these women and their allies, who challenge traditions, stigmatization, and taboos on issues related to sexuality, in particular.
A Cognitive Arab Uprising?
Authors: Hanafi Sari 
Published: January 2021

Abstract
This chapter is a synthetical one, drawing on previous work on knowledge production in the Arab world in the last decade. It contributes to the debate about how scholarship in the Arab region has struggled with some dichotomies before being able to partially transcend them. The author presents different research trends that have evolved from mainstream critical “glocal” (global/local) trends to the more polarized ones of postcolonial and Islamic perspectives. When analyzing the latter, the author also highlights differences between the trends that existed or evolved previous to and immediately following the 2011 Arab uprisings—cognitively inspired movements that were induced by paradigm shifts in the Arab social sciences.
Critical Theories and Change in International Relations
Authors: Freyberg-Inan Annette 
Published: January 2021

Abstract
Critical theories advocate fundamental change in world politics. They attack the structural inequalities of power that maintain the status quo and are, in turn, maintained by it. Ideational power is seen to work in tandem with material power, which calls for a strategy of radical resistance that incorporates a battle for hearts and minds. One of those battlefields is the discipline of International Relations (IR) itself. This chapter begins by clarifying what critical theories in IR are and then explains why and how they problematize the notion of “peaceful change.” The changes desired by critical theories are fundamental and urgent, which imbues those theories with a level of radicalism that can justify violent means. At the same time, critical theories spotlight dimensions of power beyond the material on which material power vitally depends. This reveals possibilities for transformation by peaceful means.
Nubia, a Brief Introduction
Authors: Williams Bruce Beyer , Emberling Geoff 
Published: January 2021

Abstract
Nubia has emerged as an independent field of study partly because of dam projects that flooded long reaches of the Nile valley and adjacent deserts. The region itself includes the Nile Valley in Egypt and Sudan, from the First Cataract at Aswan to the confluence of the Blue and White Niles at Khartoum, as well as adjacent deserts. This vast area incorporates many regions, peoples, and languages, notably Nubian and Eastern Desert Bedja. Historically, the volume presents three Nubias: Islamic Nubia from the 15th century, Christian Nubia from the 6th century CE, and ancient Nubia, which centered for almost three millennia on Kush, but always encompassing diverse languages and cultures. From early times, relations with Egypt were important and sometimes decisive. Beginning with the geological and physical environment, the volume presents both narrative and topical chapters that reflect the complex developments in Nubian history and culture.
The Eastern Cemetery of Kerma
Authors: Bonnet Charles , Honegger Matthieu 
Published: January 2021

Abstract
The Eastern Cemetery of Kerma is located south of the Third Cataract, close to the ancient city that was likely the center of the Kingdom of Kerma. It extends over 70 hectares and contains about 40,000 graves. Its development from north to south covers the whole duration of the Kerma civilization (2500–1500 bce) and gives a general idea of the richness of funerary rituals and of the process of social stratification. At its beginning, the graves, small with few objects, express a relative equality of treatment in the face of death. Stratification is first perceptible during the Kerma Ancien II phase (2300–2100 bce) with larger graves of archers containing more objects, sacrificed animals, and sometimes accompanying people buried next to the main burial. A few decades later appear the first large tumuli of 20 m in diameter, which contain the graves of the rulers. During the next period which starts about 2050 bce (Kerma Moyen), the development of the cemetery is spectacular, with the multiplication of great tumuli following its central ridge. This trend culminates during the Kerma Classique (1750–1500 bce) with the royal graves excavated by George Reisner a century ago. Some of them can reach 90 m in diameter and contain hundreds of subsidiary burials; two funerary temples were erected in their proximity. The cemetery was abandoned just before the Egyptian conquest and a last royal grave was built close to the ancient city.
Egyptian Fortresses and the Colonization of Lower Nubia in the Middle Kingdom
Authors: Bestock Laurel 
Published: January 2021

Abstract
In the early part of the 2nd millennium bce, the Egyptian state took control of Lower Nubia, building a series of monumental fortresses along the Nile that are remarkable for their sophisticated military architecture. This was Egypt’s first major expansion beyond its traditional borders. Various theoretical models of imperialism and core-periphery interactions have been brought to bear on studies of the forts and their populations, seeking to explain the military, economic, and ideological purposes behind the original construction of the monuments as well as the apparently shifting nature of their occupation, from probable rotating garrisons to more permanent settlement, and their interactions with local populations (cf. Trigger 1976:64–81; Adams 1977:183–88; Zibelius-Chen 1988:69–135; S.T. Smith 1995, 2003; Williams 1999; Flammini 2008; Török 2009:79–101; Vogel 2004; Knoblauch 2008). The resulting picture of Egyptian occupation of Nubia is a nuanced if not entirely agreed upon one. The fortresses are important to archaeology more broadly because they offer a richly documented case study for consideration of state control of foreign territory; they belong in the broader discourse about imperialism, colonization, and colonialism, how different state strategies of control can be understood in the material record, and how people live and interact in border zones. That the methods of Middle Kingdom control can be contrasted to both earlier and later Egyptian strategies of interaction with Nubia, and that the region is one of modern colonial entanglements, makes a critical approach to its occupation in the Middle Kingdom all the more vital.
Nubians in Egypt from the Early Dynastic Period to the New Kingdom
Authors: Meurer Georg K. 
Published: January 2021

AbstractNubians lived in Egypt from Predynastic times and through all periods. In the Aswan region, they were part of the indigenous population from Old to Middle Kingdom (A-Group, C-Group). From late Middle Kingdom through Second Intermediate Period, representatives of the Pan-Grave culture, presumably to be identified with the Medjay, and later the Kerma culture was present in Upper Egypt (Theban area) progressively up to the Delta at Tell el-Dab’a until the 18th Dynasty. Despite the official Egyptian dogma that regarded foreigners as elements of chaos, the reality shows that Nubians were integrated in the Egyptian society when accepting the Egyptian way of life. This is also visible in the wider range of occupations performed by native Nubians. While from time to time foreign groups also left the Egyptian Nile Valley, this Egyptianization or cultural entanglement resulted in a disappearing of foreigners in the sources.
History and the Kushite Royal Inscriptions
Authors: Pope Jeremy 
Published: January 2021

AbstractThis chapter examines ancient Kushite perceptions and uses of the past that are featured in the corpus of royal inscriptions from the Second Kingdom of Kush, also known as the Napatan era (ca. 10th–3rd centuries bce), and it compares that corpus to previously published definitions of history as a genre. While most of the Kushite texts are retrospective in outlook, they also exhibit several features that differentiate them from paradigmatic Western examples of historical writing such as the accounts of Hecataeus of Miletus, Herodotus, and Thucydides. As a result, Kush is often portrayed as a prehistoric or ahistoric society in both scholarly and more popular literature. Nevertheless, the royal inscriptions of the Second Kingdom display at least four characteristics that are commonly associated with the writing of history: (1) commemoration of abrupt change; (2) explanation of human causality; (3) investigation of source material; and (4) presentation to a broad audience.
The X-Group Period in Lower Nubia
Authors: Dann Rachael J. 
Published: January 2021

Abstract
The X-Group (or Post-Meroitic) Period in Lower Nubia is a period of cultural continuity from the previous Meroitic Period, while also being a period of significant change and innovation. X-Group culture is characterized in the elite sphere by forms of material culture that frequently combine motifs with Egyptian, Classical, and Kushitic antecedents in inventive ways, long-distance trade relationships and monumental building projects in the mortuary domain. In both elite and non-elite circles a distinctive pottery tradition endures, and ritual practices focused at sites with long genealogies continued. The introduction of the waterwheel in Lower Nubia enabled an expansion of agricultural cropping regimes and supported settlement in the region, which was frequently based at sites that had seen Meroitic Period activity, although there is frequently a gap in the chronology rather than direct temporal continuity.
Nubian Texts, Nubian Lives
Authors: Ruffini Giovanni R. 
Published: January 2021

Abstract
Nubian texts provide valuable insight into Nubian social and economic history. Accounts reveal economic priorities both secular and sacred. Documentary evidence hints at the nature of state centralization and the movement of goods and coins in and out of Nubia. Magic reveals Nubia’s deep-seated hopes and fears. Literature shows innovative theology and Nubia’s sense of its place in world history. Funerary inscriptions record the careers of the elite and their sense of their own place in the cosmos. But much is missing from the Nubian textual record as well, suggesting that major literary genres never indigenized in Nubia the way they did in Egypt or Ethiopia. Other genres ebb and flow over time, hinting at the economy of Nubian literacy and the processes through which it ultimately dies.