Romerriget, Vesteuropa og Skandinavien. Kulturkontakter og den danske historiebevidsthed i 1100-tallet

The Roman Empire, Western Europe, and Scandinavia Cultural Contacts and Danish Historical Consciousness during the 12th CenturyThe article investigates five works of Danish historiography of the 12th century with a focus on underlying cultural contacts with Western Europe: England, the Roman-German Empire, Northern France. These contacts are regarded as the decisive precondition for the development of a specifically Danish moulding of medieval historiography and thus for the shaping and sharpening of cultural self-consciousness. It is taken for a fact that the transfer and reception of ideas from foreign cultural backgrounds never result in more or less exact reproductions, but that for instance the early Danish historiographers had to merge their own cognitive horizons with those of their foreign sources and of their intended audience in order to communicate their (political) message successfully. Consequently, the way they crossed this gap and applied medieval hermeneutics to Danish history is of special interest. It is further assumed that a history of ideas cannot be written without a glance at the history of structures and events and the conditions these provide for the author; therefore, the philological analysis of the texts and their inner logic is combined with the historical reconstruction of their constitutive conditions. As 12th century Danish historiography appears to be far from homogeneous, it is important to look at the diachronic development in contents and hermeneutics of the Danish works. Changes can indicate shifts in the learned networks as well as changes in the historical preconditions and socio-political ambience. English influence was predominant during the 11th century in these networks, including the organisation of the church. Nevertheless, relations with Saxon (Northern-German) churches, especially Bremen, always existed and became more important from King Svend II Estridsen’s time on. As a result, a blending of English and German influences – with quite productive effects on 12th century Danish historiography – must be taken into consideration. These effects are apparent in the work of the Anglo-Saxon priest Ælnoth, who lived in Odense Monastery, the same locality where Knud IV (St Knud) was slain before the altar of St Alban’s. After a short Passio written in 1095/96, Ælnoth composed his long, elaborate, and artful chronicle ca. 1110-17. It is cast in the mould of a triptych, with the history of Knud’s father and his older and younger brothers as predecessors and successors on both sides of a hagiographical centre-narrative. Ælnoth thus intertwines a hagiographical and a historiographical discourse, calling into question the traditional division between genres. The hermeneutics applied in all parts of the chronicle displays three semantic layers – historical, typological, moral – analogous to Biblical exegesis. At the centre of the interpretation is Knud himself, analogous to Christ, preceded by his father Svend Estridsen who, in the extension of the analogy, holds the position of David; the other kings are compared with them implicitly by their deeds and characters. There is a strong focus on Knud as a holy rex iustus who by his perfect deeds follow the ideas of Augustine and Ps.-Cyprian. Ælnoth’s chronicle is not arranged around a »classical« martyr legend; in fact, Knud’s life is more similar to those of holy Anglo-Saxon kings from Bede’s time. At the same time, Ælnoth was familiar with German historiography. In this context, the pronounced political functionalism of his chronicle shows an interesting parallel to vitae of German bishops from the 11th and 12th centuries. Ælnoth appeals with considerable subtlety to King Niels, the contemporary ruler. By the literary celebration of St Knud, he seeks to found a reciprocal relation between the Odense Cathedral and the King: legitimation in exchange for gifts and protection. Once again, Ælnoth thus interweaves, in a most accomplished manner, documentation of own interests, guidance of the king’s conduct, and assertion of local prestige. To this effect, he freely employs both Anglo-Saxon and German traditions in a Danish context. Being the first to do so, he succeeds in mounting Danish history on an independent and worthy platform of holiness within the wider horizon of Christianity. A second step in the same direction is taken by the anonymous Danish author of the Chronicon Roskildense, written in the circle surrounding Bishop Eskil of Roskilde. It is a polemical treatise insofar as it takes sides in a struggle in 1137/38 over the Nordic archbishopric. Eskil demanded – in vain – its transfer from Lund to Roskilde, as explained in deep detail by M. Gelting. Scholars have not been nearly as irritated by the straightforward and clear argumentation of this chronicle as by Ælnoth’s moralising. The fact is, however, that it employs exactly the same hermeneutics of salvation history with precisely the same reciprocal links between theology and politics, and informed by the same Augustinian ideas, although in a merely historiographical form and with different judgements. Chronicon Roskildense endeavours to convince the king, Erik III Lam, that the archbishopric ought to be transferred. Arguments from history prove the dignity of the Roskilde Cathedral and its bishops; and expose Erik Lam’s predecessor, Erik II Emune, the winner in the kings’ feud of 1131-35, as the servant of Antichrist. He is the negative example against which the successor, the present king, appears to be an alter David, of whom great deeds are to be expected. The typological statement is clearly if also subtly underlined by the construction of the kings’ history in 14 generations, analogous to the organisation of salvation history in St Matthew’s Gospel. However, in the end the King did not support Eskil. This produced a logical breach between Erik Lam’s place in salvation history and his extremely negative description in the last chapter. In two ways, Chronicon Roskildense clearly demonstrates the growing importance of German influence on Danish historiography: Firstly, Eskil was educated in Hildesheim, and he himself, just as the bishops depicted in the chronicle, shows conduct typical of very powerful bishops of high nobility, like those in the German parts of the Empire, especially before church reform. Secondly, the chronicle reflects the historiographical trauma provoked by the pervasive German influence under the kings’ feud. Denmark was from that time on, until the 1180s, at least formally an imperial fief. Although no chronicle mentions these facts – not in one single word – they eventually had a profound effect on the shaping of Danish historiography. The third step is taken by Chronicon Lethrense, written in the late 1160s under Bishop Absalon of Roskilde and dealing with the earliest history of Denmark. The whole chronicle is constructed as a historiographical reflection of Chronicon Roskildense, analogous to the relation between opus conditionis and opus restaurationis in medieval theology. It again employs the same 14-generationsscheme. Furthermore, it gives historical arguments for Danish success in holding its own against various emperors from Augustus and onwards, obviously a reaction to the problem of German influence in the present. With Chronicon Lethrense, the reception process of historiographical ideas came to a first conclusion: After opening Danish history from the vantage point of a holy centre and using historiography in internal struggles for power, one could now apply patterns of exegesis to pre-Christian history and win relevant typological and moral statements from it. A fourth step in this dynamic development was taken with Svend Aggesen’s Brevis historia regnum Daciæ, written between 1185 and 1188, which includes pre-Christian as well as Christian history. Again, the two stages in Danish history mirror each other – in both cases the narrative structure is based on royal dynasties of 14 generations. Recurrent motives are the Danish superiority over the Germans and their emperors, and the just rule of Danish kings. As a matter of fact, not only had the balance of power changed between the Empire and Denmark, even the educational network had experienced a significant shift towards Northern France after 1150. This is clearly recognised in Svend’s – negative – picture of the Germans, which he draws according to French stereotypes. From his use of unusual terms and his very early description of the later principle of rex imperator in regno suo, it furthermore appears extremely likely that he had studied under Alanus ab Insulis in Paris or Chartres. As to power structures in Denmark, Svend’s chronicle reveals that Archbishop Absalon did not want him to write a detailed contemporary history since he, the author, was the last survivor of an opposing and formerly most powerful family group. This is the reason for Svend’s primary focus on the kings; hence also his promulgation of transpersonal, abstract ideas of kingdom and of a »state«, reminiscent of Ælnoth, who did not have a powerbase in Danish society either. The authors of Chronicon Roskildense and Gesta Danorum, on the other hand, belonged to the same networks as the powerful magnates who had patronized the said works. They would therefore concentrate more on different nobles as agents of history and altogether follow a different ideology in this field, although they too build upon Augustinian ideas. All of them, including Saxo, nevertheless share the same essentially exegetical hermeneutics in the construction of history. For the same reason, they display a typical ambivalence: on the one hand, insights in salvation history, on the other hand, tough political argumentation. The great differences in the use of these hermeneutic tools produce very diverse works, with different judgements of historical figures and a steadily widening historical horizon. They are the result of threefold dynamics in the 12th century: The educational networks overlapped and changed, creating new baselines for the reception of ideas. Furthermore, the networks of power changed likewise, providing entirely new constitutive logics for historiography. Finally, the political influence of the emperors grew significantly in the middle of the century, giving rise to crisis both in politics and in the cultural self-consciousness of the élites. Interacting with each other, these three main factors caused an acceleration of acculturation processes and paved the way – a very special way – for Danish participation in the European culture of knowledge

Unequal mass binary neutron star simulations with neutrino transport: Ejecta and neutrino emission

We present 12 new simulations of unequal mass neutron star mergers. The simulations are performed with the SpEC code, and utilize nuclear-theory-based equations of state and a two-moment gray neutrino transport scheme with an improved energy estimate based on evolving the number density. We model the neutron stars with the SFHo, LS220, and DD2 equations of state (EOS) and we study the neutrino and matter emission of all 12 models to search for robust trends between binary parameters and emission characteristics. We find that the total mass of the dynamical ejecta exceeds 0.01  M⊙ only for SFHo with weak dependence on the mass ratio across all models. We find that the ejecta have a broad electron fraction (Y_e) distribution (≈0.06–0.48), with mean 0.2. Y_e increases with neutrino irradiation over time, but decreases with increasing binary asymmetry. We also find that the models have ejecta with a broad asymptotic velocity distribution (≈0.05–0.7c). The average velocity lies in the range 0.2c−0.3c and decreases with binary asymmetry. Furthermore, we find that disk mass increases with binary asymmetry and stiffness of the EOS. The Y_e of the disk increases with softness of the EOS. The strongest neutrino emission occurs for the models with soft EOS. For (anti) electron neutrinos we find no significant dependence of the magnitude or angular distribution or neutrino luminosity with mass ratio. The heavier neutrino species have a luminosity dependence on mass ratio but an angular distribution which does not change with mass ratio

Low mass binary neutron star mergers : gravitational waves and neutrino emission

Neutron star mergers are among the most promising sources of gravitational waves for advanced ground-based detectors. These mergers are also expected to power bright electromagnetic signals, in the form of short gamma-ray bursts, infrared/optical transients, and radio emission. Simulations of these mergers with fully general relativistic codes are critical to understand the merger and post-merger gravitational wave signals and their neutrinos and electromagnetic counterparts. In this paper, we employ the SpEC code to simulate the merger of low-mass neutron star binaries (two $1.2M_\odot$ neutron stars) for a set of three nuclear-theory based, finite temperature equations of state. We show that the frequency peaks of the post-merger gravitational wave signal are in good agreement with predictions obtained from simulations using a simpler treatment of gravity. We find, however, that only the fundamental mode of the remnant is excited for long periods of time: emission at the secondary peaks is damped on a millisecond timescale in the simulated binaries. For such low-mass systems, the remnant is a massive neutron star which, depending on the equation of state, is either permanently stable or long-lived. We observe strong excitations of l=2, m=2 modes, both in the massive neutron star and in the form of hot, shocked tidal arms in the surrounding accretion torus. We estimate the neutrino emission of the remnant using a neutrino leakage scheme and, in one case, compare these results with a gray two-moment neutrino transport scheme. We confirm the complex geometry of the neutrino emission, also observed in previous simulations with neutrino leakage, and show explicitly the presence of important differences in the neutrino luminosity, disk composition, and outflow properties between the neutrino leakage and transport schemes.Comment: Accepted by PRD; 23 pages; 24 figures; 4 table

Neutron star-black hole mergers with a nuclear equation of state and neutrino cooling: Dependence in the binary parameters

We present a first exploration of the results of neutron star-black hole mergers using black hole masses in the most likely range of $7M_\odot-10M_\odot$, a neutrino leakage scheme, and a modeling of the neutron star material through a finite-temperature nuclear-theory based equation of state. In the range of black hole spins in which the neutron star is tidally disrupted ($\chi_{\rm BH}\gtrsim 0.7$), we show that the merger consistently produces large amounts of cool ($T\lesssim 1\,{\rm MeV}$), unbound, neutron-rich material ($M_{\rm ej}\sim 0.05M_\odot-0.20M_\odot$). A comparable amount of bound matter is initially divided between a hot disk ($T_{\rm max}\sim 15\,{\rm MeV}$) with typical neutrino luminosity $L_\nu\sim 10^{53}\,{\rm erg/s}$, and a cooler tidal tail. After a short period of rapid protonization of the disk lasting $\sim 10\,{\rm ms}$, the accretion disk cools down under the combined effects of the fall-back of cool material from the tail, continued accretion of the hottest material onto the black hole, and neutrino emission. As the temperature decreases, the disk progressively becomes more neutron-rich, with dimmer neutrino emission. This cooling process should stop once the viscous heating in the disk (not included in our simulations) balances the cooling. These mergers of neutron star-black hole binaries with black hole masses $M_{\rm BH}\sim 7M_\odot-10M_\odot$ and black hole spins high enough for the neutron star to disrupt provide promising candidates for the production of short gamma-ray bursts, of bright infrared post-merger signals due to the radioactive decay of unbound material, and of large amounts of r-process nuclei.Comment: 20 pages, 19 figure

Binary Neutron Stars with Arbitrary Spins in Numerical Relativity

We present a code to construct initial data for binary neutron star systems in which the stars are rotating. Our code, based on a formalism developed by Tichy, allows for arbitrary rotation axes of the neutron stars and is able to achieve rotation rates near rotational breakup. We compute the neutron star angular momentum through quasi-local angular momentum integrals. When constructing irrotational binary neutron stars, we find a very small residual dimensionless spin of $\sim 2\times 10^{-4}$. Evolutions of rotating neutron star binaries show that the magnitude of the stars' angular momentum is conserved, and that the spin- and orbit-precession of the stars is well described by post-Newtonian approximation. We demonstrate that orbital eccentricity of the binary neutron stars can be controlled to $\sim 0.1\%$. The neutron stars show quasi-normal mode oscillations at an amplitude which increases with the rotation rate of the stars.Comment: 20 pages, 22 figure

Post-merger evolution of a neutron star-black hole binary with neutrino transport

We present a first simulation of the post-merger evolution of a black hole-neutron star binary in full general relativity using an energy-integrated general relativistic truncated moment formalism for neutrino transport. We describe our implementation of the moment formalism and important tests of our code, before studying the formation phase of a disk after a black hole-neutron star merger. We use as initial data an existing general relativistic simulation of the merger of a neutron star of 1.4 solar mass with a black hole of 7 solar mass and dimensionless spin a/M=0.8. Comparing with a simpler leakage scheme for the treatment of the neutrinos, we find noticeable differences in the neutron to proton ratio in and around the disk, and in the neutrino luminosity. We find that the electron neutrino luminosity is much lower in the transport simulations, and that the remnant is less neutron-rich. The spatial distribution of the neutrinos is significantly affected by relativistic effects. Over the short timescale evolved, we do not observe purely neutrino-driven outflows. However, a small amount of material (3e-4Msun) is ejected in the polar region during the circularization of the disk. Most of that material is ejected early in the formation of the disk, and is fairly neutron rich. Through r-process nucleosynthesis, that material should produce high-opacity lanthanides in the polar region, and could thus affect the lightcurve of radioactively powered electromagnetic transients. We also show that by the end of the simulation, while the bulk of the disk is neutron-rich, its outer layers have a higher electron fraction. As that material would be the first to be unbound by disk outflows on longer timescales, the changes in Ye experienced during the formation of the disk could have an impact on the nucleosynthesis outputs from neutrino-driven and viscously-driven outflows. [Abridged]Comment: 29 pages, 25 figure

Evolution of the Magnetized, Neutrino-Cooled Accretion Disk in the Aftermath of a Black Hole Neutron Star Binary Merger

Black hole-torus systems from compact binary mergers are possible engines for gamma-ray bursts (GRBs). During the early evolution of the post-merger remnant, the state of the torus is determined by a combination of neutrino cooling and magnetically-driven heating processes, so realistic models must include both effects. In this paper, we study the post-merger evolution of a magnetized black hole-neutron star binary system using the Spectral Einstein Code (SpEC) from an initial post-merger state provided by previous numerical relativity simulations. We use a finite-temperature nuclear equation of state and incorporate neutrino effects in a leakage approximation. To achieve the needed accuracy, we introduce improvements to SpEC's implementation of general-relativistic magnetohydrodynamics (MHD), including the use of cubed-sphere multipatch grids and an improved method for dealing with supersonic accretion flows where primitive variable recovery is difficult. We find that a seed magnetic field triggers a sustained source of heating, but its thermal effects are largely cancelled by the accretion and spreading of the torus from MHD-related angular momentum transport. The neutrino luminosity peaks at the start of the simulation, and then drops significantly over the first 20\,ms but in roughly the same way for magnetized and nonmagnetized disks. The heating rate and disk's luminosity decrease much more slowly thereafter. These features of the evolution are insensitive to grid structure and resolution, formulation of the MHD equations, and seed field strength, although turbulent effects are not fully convergedComment: 17 pages, 18 figure

Unequal mass binary neutron star simulations with neutrino transport: Ejecta and neutrino emission

We present 12 new simulations of unequal mass neutron star mergers. The simulations are performed with the SpEC code, and utilize nuclear-theory-based equations of state and a two-moment gray neutrino transport scheme with an improved energy estimate based on evolving the number density. We model the neutron stars with the SFHo, LS220, and DD2 equations of state (EOS) and we study the neutrino and matter emission of all 12 models to search for robust trends between binary parameters and emission characteristics. We find that the total mass of the dynamical ejecta exceeds 0.01  M⊙ only for SFHo with weak dependence on the mass ratio across all models. We find that the ejecta have a broad electron fraction (Y_e) distribution (≈0.06–0.48), with mean 0.2. Y_e increases with neutrino irradiation over time, but decreases with increasing binary asymmetry. We also find that the models have ejecta with a broad asymptotic velocity distribution (≈0.05–0.7c). The average velocity lies in the range 0.2c−0.3c and decreases with binary asymmetry. Furthermore, we find that disk mass increases with binary asymmetry and stiffness of the EOS. The Y_e of the disk increases with softness of the EOS. The strongest neutrino emission occurs for the models with soft EOS. For (anti) electron neutrinos we find no significant dependence of the magnitude or angular distribution or neutrino luminosity with mass ratio. The heavier neutrino species have a luminosity dependence on mass ratio but an angular distribution which does not change with mass ratio

Gravitational waveforms for neutron star binaries from binary black hole simulations

Gravitational waves from binary neutron star (BNS) and black-hole/neutron star (BHNS) inspirals are primary sources for detection by the Advanced Laser Interferometer Gravitational-Wave Observatory. The tidal forces acting on the neutron stars induce changes in the phase evolution of the gravitational waveform, and these changes can be used to constrain the nuclear equation of state. Current methods of generating BNS and BHNS waveforms rely on either computationally challenging full 3D hydrodynamical simulations or approximate analytic solutions. We introduce a new method for computing inspiral waveforms for BNS/BHNS systems by adding the post-Newtonian (PN) tidal effects to full numerical simulations of binary black holes (BBHs), effectively replacing the non-tidal terms in the PN expansion with BBH results. Comparing a waveform generated with this method against a full hydrodynamical simulation of a BNS inspiral yields a phase difference of < 1 radian over ~ 15 orbits. The numerical phase accuracy required of BNS simulations to measure the accuracy of the method we present here is estimated as a function of the tidal deformability parameter ⋋