Schleicher, Dominik R. G.

[["dc.bibliographiccitation.firstpage","1676"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Monthly Notices of the Royal Astronomical Society"],["dc.bibliographiccitation.lastpage","1676"],["dc.bibliographiccitation.volume","504"],["dc.contributor.author","Navarrete, Felipe H"],["dc.contributor.author","Schleicher, Dominik R G"],["dc.contributor.author","Käpylä, Petri J"],["dc.contributor.author","Schober, Jennifer"],["dc.contributor.author","Völschow, Marcel"],["dc.contributor.author","Mennickent, Ronald E"],["dc.date.accessioned","2021-08-12T07:45:14Z"],["dc.date.available","2021-08-12T07:45:14Z"],["dc.date.issued","2021"],["dc.identifier.doi","10.1093/mnras/stab836"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/88402"],["dc.language.iso","en"],["dc.notes.intern","DOI Import GROB-448"],["dc.relation.eissn","1365-2966"],["dc.relation.iserratumof","/handle/2/75283"],["dc.relation.issn","0035-8711"],["dc.title","Erratum: Magnetohydrodynamical origin of eclipsing time variations in post-common-envelope binaries for solar mass secondaries"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","erratum_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2181"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Monthly Notices of the Royal Astronomical Society"],["dc.bibliographiccitation.lastpage","2187"],["dc.bibliographiccitation.volume","441"],["dc.contributor.author","Bovino, Stefano"],["dc.contributor.author","Latif, A. H. M. Mahbub"],["dc.contributor.author","Grassi, T."],["dc.contributor.author","Schleicher, Dominik R. G."],["dc.date.accessioned","2018-11-07T09:38:12Z"],["dc.date.available","2018-11-07T09:38:12Z"],["dc.date.issued","2014"],["dc.description.abstract","While Population III (Pop III) stars are typically thought to be massive, pathways towards lower mass Pop III stars may exist when the cooling of the gas is particularly enhanced. A possible route is enhanced HD cooling during the merging of dark-matter haloes. The mergers can lead to a high ionization degree catalysing the formation of HD molecules and may cool the gas down to the cosmic microwave background temperature. In this paper, we investigate the merging of mini-haloes with masses of a few 10(5) M-aS (TM) and explore the feasibility of this scenario. We have performed three-dimensional cosmological hydrodynamics calculations with the enzo code, solving the thermal and chemical evolution of the gas by employing the astrochemistry package krome. Our results show that the HD abundance is increased by two orders of magnitude compared to the no-merging case and the halo cools down to similar to 60 K triggering fragmentation. Based on Jeans estimates, the expected stellar masses are about 10 M-aS (TM). Our findings show that the merging scenario is a potential pathway for the formation of low-mass stars."],["dc.identifier.doi","10.1093/mnras/stu714"],["dc.identifier.isi","000338763600027"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/33019"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Oxford Univ Press"],["dc.relation.issn","1365-2966"],["dc.relation.issn","0035-8711"],["dc.title","Dark-matter halo mergers as a fertile environment for low-mass Population III star formation"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1"],["dc.bibliographiccitation.issue","1-4"],["dc.bibliographiccitation.journal","Space Science Reviews"],["dc.bibliographiccitation.lastpage","35"],["dc.bibliographiccitation.volume","166"],["dc.contributor.author","Ryu, D."],["dc.contributor.author","Schleicher, Dominik R. G."],["dc.contributor.author","Treumann, Rudolf A."],["dc.contributor.author","Tsagas, Christos G."],["dc.contributor.author","Widrow, Lawrence M."],["dc.date.accessioned","2018-11-07T09:10:44Z"],["dc.date.available","2018-11-07T09:10:44Z"],["dc.date.issued","2012"],["dc.description.abstract","Magnetic fields appear to be ubiquitous in astrophysical environments. Their existence in the intracluster medium is established through observations of synchrotron emission and Faraday rotation. On the other hand, the nature of magnetic fields outside of clusters, where observations are scarce and controversial, remains largely unknown. In this chapter, we review recent developments in our understanding of the nature and origin of intergalactic magnetic fields, and in particular, intercluster fields. A plausible scenario for the origin of galactic and intergalactic magnetic fields is for seed fields, created in the early universe, to be amplified by turbulent flows induced during the formation of the large scale structure. We present several mechanisms for the generation of seed fields both before and after recombination. We then discuss the evolution and role of magnetic fields during the formation of the first starts. We describe the turbulent amplification of seed fields during the formation of large scale structure and the nature of the magnetic fields that arise. Finally, we discuss implications of intergalactic magnetic fields."],["dc.identifier.doi","10.1007/s11214-011-9839-z"],["dc.identifier.isi","000303862200001"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/26560"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.relation.issn","1572-9672"],["dc.relation.issn","0038-6308"],["dc.title","Magnetic Fields in the Large-Scale Structure of the Universe"],["dc.type","review"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","L3"],["dc.bibliographiccitation.firstpage","L3"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","The Astrophysical Journal"],["dc.bibliographiccitation.volume","772"],["dc.contributor.author","Latif, A. H. M. Mahbub"],["dc.contributor.author","Schleicher, Dominik R. G."],["dc.contributor.author","Schmidt, W."],["dc.contributor.author","Niemeyer, J."],["dc.date.accessioned","2018-11-07T09:22:19Z"],["dc.date.accessioned","2020-07-21T06:05:19Z"],["dc.date.available","2018-11-07T09:22:19Z"],["dc.date.available","2020-07-21T06:05:19Z"],["dc.date.issued","2013"],["dc.description.abstract","Population III stars forming in the infant universe at z = 30 heralded the end of the cosmic dark ages. They are presumed to be assembled in the so-called minihalos with virial temperatures of a few thousand K where collapse is triggered by molecular hydrogen cooling. A central question concerns their final masses, and whether fragmentation occurs during their formation. While studies employing Lagrangian codes suggest fragmentation via a self-gravitating disk, recent high-resolution simulations indicated that disk formation is suppressed. Here we report the first high-resolution large-eddy simulations performed with the Eulerian grid-based code Enzo following the evolution beyond the formation of the first peak to investigate the accretion of the central massive clump and potential fragmentation. For a total of three halos, we see that a disk forms around the first clump. The central clump reaches similar to 10 solar masses after 40 yr, while subsequent accretion is expected at a rate of 10(-2) solar masses per year. In one of these halos, additional clumps form as a result of fragmentation which proceeds at larger scales. We note that subgrid-scale (SGS) turbulence yields relevant contributions to the stability of the protostellar disks. Both with and without the SGS model, the disk evolution appears rather stable during the timescale considered here. We conclude that the first protostar may reach masses up to 40-100 M-circle dot, which are only limited by the effect of radiative feedback."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft (DFG) [SFB 963/1, A12]; HLRN [nip00029]"],["dc.identifier.doi","10.1088/2041-8205/772/1/L3"],["dc.identifier.isi","000321696500003"],["dc.identifier.scopus","2-s2.0-84880624699"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/29315"],["dc.identifier.url","http://www.scopus.com/inward/record.url?eid=2-s2.0-84880624699&partnerID=MN8TOARS"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.eissn","2041-8213"],["dc.relation.issn","2041-8205"],["dc.title","The formation of massive population III stars in the presence of turbulence"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","37"],["dc.bibliographiccitation.issue","1-4"],["dc.bibliographiccitation.journal","Space Science Reviews"],["dc.bibliographiccitation.lastpage","70"],["dc.bibliographiccitation.volume","166"],["dc.contributor.author","Widrow, Lawrence M."],["dc.contributor.author","Ryu, Dongsu"],["dc.contributor.author","Schleicher, Dominik R. G."],["dc.contributor.author","Subramanian, Kandaswamy"],["dc.contributor.author","Tsagas, Christos G."],["dc.contributor.author","Treumann, Rudolf A."],["dc.date.accessioned","2018-11-07T09:10:45Z"],["dc.date.available","2018-11-07T09:10:45Z"],["dc.date.issued","2012"],["dc.description.abstract","We review current ideas on the origin of galactic and extragalactic magnetic fields. We begin by summarizing observations of magnetic fields at cosmological redshifts and on cosmological scales. These observations translate into constraints on the strength and scale magnetic fields must have during the early stages of galaxy formation in order to seed the galactic dynamo. We examine mechanisms for the generation of magnetic fields that operate prior during inflation and during subsequent phase transitions such as electroweak symmetry breaking and the quark-hadron phase transition. The implications of strong primordial magnetic fields for the reionization epoch as well as the first generation of stars are discussed in detail. The exotic, early-Universe mechanisms are contrasted with astrophysical processes that generate fields after recombination. For example, a Biermann-type battery can operate in a proto-galaxy during the early stages of structure formation. Moreover, magnetic fields in either an early generation of stars or active galactic nuclei can be dispersed into the intergalactic medium."],["dc.identifier.doi","10.1007/s11214-011-9833-5"],["dc.identifier.isi","000303862200002"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/26562"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.relation.issn","1572-9672"],["dc.relation.issn","0038-6308"],["dc.title","The First Magnetic Fields"],["dc.type","review"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","77"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Monthly Notices of the Royal Astronomical Society"],["dc.bibliographiccitation.lastpage","87"],["dc.bibliographiccitation.volume","449"],["dc.contributor.author","Latif, A. H. M. Mahbub"],["dc.contributor.author","Schleicher, Dominik R. G."],["dc.date.accessioned","2018-11-07T09:57:35Z"],["dc.date.available","2018-11-07T09:57:35Z"],["dc.date.issued","2015"],["dc.description.abstract","Our understanding of Population III star formation is still in its infancy. They are formed in dark matter minihaloes of 10(5)-10(6) M-circle dot at z = 20-30. Recent high-resolution cosmological simulations show that a protostellar disc forms as a consequence of gravitational collapse and fragments into multiple clumps. However, it is not entirely clear if these clumps will be able to survive to form multiple stars as simulations are unable to follow the disc evolution for longer times. In this study, we employ a simple analytical model to derive the properties of marginally stable steady-state discs. Our results show that the stability of the disc depends on the critical value of the viscous parameter alpha. For alpha(crit) = 1, the disc is stable for an accretion rate of <= 10(-3) M-circle dot yr(-1) and becomes unstable at radii about >= 100 au in the presence of an accretion rate of 10(-2) M-circle dot yr(-1). For 0.06 < alpha(crit) < 1, the disc can be unstable for both accretion rates. The comparison of the migration and the Kelvin-Helmholtz time-scales shows that clumps are expected to migrate inwards before reaching the main sequence. Furthermore, in the presence of a massive central star, the clumps within the central 1 au will be tidally disrupted. We also find that UV feedback from the central star is unable to disrupt the disc, and that photoevaporation becomes important only once the accretion rate has dropped to 2 x 10(-4) M-circle dot yr(-1). As a result, the central star may reach a mass of 100 M-circle dot or even higher."],["dc.description.sponsorship","European Research Council under the European Community [614199]"],["dc.identifier.doi","10.1093/mnras/stu2573"],["dc.identifier.isi","000355345600007"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/37194"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Oxford Univ Press"],["dc.relation.issn","1365-2966"],["dc.relation.issn","0035-8711"],["dc.title","Disc fragmentation and the formation of Population III stars"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2989"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Monthly Notices of the Royal Astronomical Society"],["dc.bibliographiccitation.lastpage","2996"],["dc.bibliographiccitation.volume","436"],["dc.contributor.author","Latif, A. H. M. Mahbub"],["dc.contributor.author","Schleicher, Dominik R. G."],["dc.contributor.author","Schmidt, Wolfram"],["dc.contributor.author","Niemeyer, J. C."],["dc.date.accessioned","2018-11-07T09:17:04Z"],["dc.date.accessioned","2020-07-09T08:43:58Z"],["dc.date.available","2018-11-07T09:17:04Z"],["dc.date.available","2020-07-09T08:43:58Z"],["dc.date.issued","2013"],["dc.description.abstract","Black holes of a billion solar masses are observed in the infant universe a few hundred million years after the Big Bang. The direct collapse of protogalactic gas clouds in primordial halos with $\\rm T_{vir} \\geq 10^{4} K$ provides the most promising way to assemble massive black holes. In this study, we aim to determine the characteristic mass scale of seed black holes and the time evolution of the accretion rates resulting from the direct collapse model. We explore the formation of supermassive black holes via cosmological large eddy simulations (LES) by employing sink particles and following their evolution for twenty thousand years after the formation of the first sink. As the resulting protostars were shown to have cool atmospheres in the presence of strong accretion, we assume here that UV feedback is negligible during this calculation. We confirm this result in a comparison run without sinks. Our findings show that black hole seeds with characteristic mass of $\\rm 10^{5} M_{\\odot}$ are formed in the presence of strong Lyman Werner flux which leads to an isothermal collapse. The characteristic mass is a about two times higher in LES compared to the implicit large eddy simulations (ILES). The accretion rates increase with time and reach a maximum value of 10 $\\rm M_{\\odot}/yr$ after $\\rm 10^{4}$ years. Our results show that the direct collapse model is clearly feasible as it provides the expected mass of the seed black holes."],["dc.identifier.doi","10.1093/mnras/stt1786"],["dc.identifier.isi","000327798100009"],["dc.identifier.scopus","2-s2.0-84889036204"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/66907"],["dc.identifier.url","http://www.scopus.com/inward/record.url?eid=2-s2.0-84889036204&partnerID=MN8TOARS"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.eissn","0035-8711"],["dc.relation.issn","1365-2966"],["dc.title","The characteristic black hole mass resulting from direct collapse in the early Universe"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2386"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Monthly Notices of the Royal Astronomical Society"],["dc.bibliographiccitation.lastpage","2419"],["dc.bibliographiccitation.volume","439"],["dc.contributor.author","Grassi, T."],["dc.contributor.author","Bovino, Stefano"],["dc.contributor.author","Schleicher, Dominik R. G."],["dc.contributor.author","Prieto, Jose Luis"],["dc.contributor.author","Seifried, D."],["dc.contributor.author","Simoncini, E."],["dc.contributor.author","Gianturco, F. A."],["dc.date.accessioned","2018-11-07T09:41:46Z"],["dc.date.available","2018-11-07T09:41:46Z"],["dc.date.issued","2014"],["dc.description.abstract","Chemistry plays a key role in many astrophysical situations regulating the cooling and the thermal properties of the gas, which are relevant during gravitational collapse, the evolution of discs and the fragmentation process. In order to simplify the usage of chemical networks in large numerical simulations, we present the chemistry package krome, consisting of a python pre-processor which generates a subroutine for the solution of chemical networks which can be embedded in any numerical code. For the solution of the rate equations, we make use of the high-order solver DLSODES, which was shown to be both accurate and efficient for sparse networks, which are typical in astrophysical applications. krome also provides a large set of physical processes connected to chemistry, including photochemistry, cooling, heating, dust treatment and reverse kinetics. The package presented here already contains a network for primordial chemistry, a small metal network appropriate for the modelling of low metallicities environments, a detailed network for the modelling of molecular clouds, a network for planetary atmospheres, as well as a framework for the modelling of the dust grain population. In this paper, we present an extended test suite ranging from one-zone and 1D models to first applications including cosmological simulations with enzo and ramses and 3D collapse simulations with the flash code. The package presented here is publicly available at https://bitbucket.org/krome/krome_stable."],["dc.identifier.doi","10.1093/mnras/stu114"],["dc.identifier.isi","000334114900014"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/33803"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Oxford Univ Press"],["dc.relation.issn","1365-2966"],["dc.relation.issn","0035-8711"],["dc.title","KROME - a package to embed chemistry in astrophysical simulations"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Monthly Notices of the Royal Astronomical Society"],["dc.bibliographiccitation.lastpage","17"],["dc.bibliographiccitation.volume","446"],["dc.contributor.author","Schober, Jennifer"],["dc.contributor.author","Schleicher, Dominik R. G."],["dc.contributor.author","Klessen, Ralf S."],["dc.date.accessioned","2018-11-07T10:03:45Z"],["dc.date.available","2018-11-07T10:03:45Z"],["dc.date.issued","2015"],["dc.description.abstract","The evolution of magnetic fields in galaxies is still an open problem in astrophysics. In nearby galaxies the far-infrared-radio correlation indicates the coupling between magnetic fields and star formation. The correlation arises from the synchrotron emission of cosmic ray electrons travelling through the interstellar magnetic fields. However, with an increase of the interstellar radiation field (ISRF), inverse Compton scattering becomes the dominant energy loss mechanism of cosmic ray electrons with a typical emission frequency in the X-ray regime. The ISRF depends on the one hand on the star formation rate and becomes stronger in starburst galaxies, and on the other hand increases with redshift due to the higher temperature of the cosmic microwave background. With a model for the star formation rate of galaxies, the ISRF, and the cosmic ray spectrum, we can calculate the expected X-ray luminosity resulting from the inverse Compton emission. Except for galaxies with an active galactic nucleus the main additional contribution to the X-ray luminosity comes from X-ray binaries. We estimate this contribution with an analytical model as well as with an observational relation, and compare it to the pure inverse Compton luminosity. Using data from the Chandra Deep Field Survey and far-infrared observations from Atacama Large Millimeter/Submillimeter Array, we then determine upper limits for the cosmic ray energy. Assuming that the magnetic energy in a galaxy is in equipartition with the energy density of the cosmic rays, we obtain upper limits for the magnetic field strength. Our results suggest that the mean magnetic energy of young galaxies is similar to the one in local galaxies. This points towards an early generation of galactic magnetic fields, which is in agreement with current dynamo evolution models."],["dc.identifier.doi","10.1093/mnras/stu1999"],["dc.identifier.isi","347518300001"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/38543"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Oxford Univ Press"],["dc.relation.issn","1365-2966"],["dc.relation.issn","0035-8711"],["dc.title","X-ray emission from star-forming galaxies - signatures of cosmic rays and magnetic fields"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","3112"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Monthly Notices of the Royal Astronomical Society"],["dc.bibliographiccitation.lastpage","3126"],["dc.bibliographiccitation.volume","442"],["dc.contributor.author","Naumann, Peter-Thomas"],["dc.contributor.author","Schleicher, Dominik R. G."],["dc.contributor.author","Smith, Rowan J."],["dc.contributor.author","Schmidt, Wolfram"],["dc.contributor.author","Klessen, Ralf S."],["dc.date.accessioned","2018-11-07T09:36:29Z"],["dc.date.available","2018-11-07T09:36:29Z"],["dc.date.issued","2014"],["dc.description.abstract","Low-metallicity star formation poses a central problem of cosmology, as it determines the characteristic mass scale and distribution for the first and second generations of stars forming in our Universe. Here, we present a comprehensive investigation assessing the relative impact of metals and magnetic fields, which may both be present during low-metallicity star formation. We show that the presence of magnetic fields generated via the small-scale dynamo stabilizes the protostellar disc and provides some degree of support against fragmentation. In the absence of magnetic fields, the fragmentation time-scale in our model decreases by a factor of similar to 10 at the transition from Z = 0 to Z > 0, with subsequently only a weak dependence on metallicity. Similarly, the accretion time-scale of the cluster is set by the large-scale dynamics rather than the local thermodynamics. In the presence of magnetic fields, the primordial disc can become completely stable, therefore forming only one central fragment. At Z > 0, the number of fragments is somewhat reduced in the presence of magnetic fields, though the shape of the mass spectrum is not strongly affected in the limits of the statistical uncertainties. The fragmentation time-scale, however, increases by roughly a factor of 3 in the presence of magnetic fields. Indeed, our results indicate comparable fragmentation time-scales in primordial runs without magnetic fields and Z > 0 runs with magnetic fields."],["dc.identifier.doi","10.1093/mnras/stu1097"],["dc.identifier.isi","000339924900023"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/32628"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Oxford Univ Press"],["dc.relation.issn","1365-2966"],["dc.relation.issn","0035-8711"],["dc.title","Low-metallicity star formation: relative impact of metals and magnetic fields"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]