Niemeyer, J

[["dc.bibliographiccitation.artnumber","058"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Journal of High Energy Physics"],["dc.bibliographiccitation.volume","2010"],["dc.contributor.author","Staub, F."],["dc.contributor.author","Niemeyer, J."],["dc.contributor.author","Porod, W."],["dc.date.accessioned","2018-11-07T08:47:59Z"],["dc.date.accessioned","2020-07-07T08:16:05Z"],["dc.date.available","2018-11-07T08:47:59Z"],["dc.date.available","2020-07-07T08:16:05Z"],["dc.date.issued","2010"],["dc.description.abstract","We reconsider the dark matter problem in supersymmetric models with gauge mediated supersymmetry breaking, with and without R-parity breaking. In these classes of models, a light gravitino forms the dark matter.Consistency with the experimental data, in particular the dark matter abundance and the small-scale power spectrum, requires additional entropy production after the decoupling of the gravitino from the thermal bath. We demonstrate that the usual mechanism via messenger number violating interactions does not work in models where the messenger belongs to SU (5) representations. This is mainly a consequence of two facts: (i) there are at least two different types of lightest messenger particles and (ii) the lightest messenger particle with SU (2) quantum numbers decays dominantly into vector bosons once messenger number is broken, a feature which has been overlooked so far. In case of SO(10) messenger multiplets we find scenarios which work if the SM gauge singlet component is rather light."],["dc.description.sponsorship","DFG [GRK-1147]; DAAD [D/07/13468]"],["dc.identifier.doi","10.1007/JHEP01(2010)058"],["dc.identifier.isi","000273717700029"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/7632"],["dc.identifier.scopus","2-s2.0-77954993426"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/21090"],["dc.identifier.url","http://www.scopus.com/inward/record.url?eid=2-s2.0-77954993426&partnerID=MN8TOARS"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","1029-8479"],["dc.rights","Goescholar"],["dc.rights.uri","https://goedoc.uni-goettingen.de/licenses"],["dc.title","Strong dark matter constraints on GMSB models"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","A14"],["dc.bibliographiccitation.firstpage","A14"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.volume","526"],["dc.contributor.author","Seifried, D."],["dc.contributor.author","Schmidt, W."],["dc.contributor.author","Niemeyer, J. C."],["dc.date.accessioned","2018-11-07T08:59:43Z"],["dc.date.accessioned","2020-07-22T09:32:26Z"],["dc.date.available","2018-11-07T08:59:43Z"],["dc.date.available","2020-07-22T09:32:26Z"],["dc.date.issued","2010"],["dc.description.abstract","Context: The thermal instability is one of the dynamical agents for turbulence in the diffuse interstellar medium, where both, turbulence and thermal instability interact in a highly non-linear manner. Aims: We study basic properties of turbulence in thermally bistable gas for variable simulation parameters. The resulting cold gas fractions can be applied as parameterisation in simulations on galactic scales. Methods: Turbulent flow is induced on large scales by means of compressive stochastic forcing in a periodic box. The compressible Euler equations with constant UV heating and a parameterised cooling function are solved on uniform grids. We investigate several values of the mean density of the gas and different magnitudes of the forcing. For comparison with other numerical studies, solenoidal forcing is applied as well. Results: After a transient phase, we observe that a state of statistically stationary turbulence is approached. Compressive forcing generally produces a two-phase medium, with a decreasing fraction of cold gas for increasing forcing strength. This behaviour can be explained on the basis of turbulent mixing. We also find indications for power-law tails of probability density functions of the gas density. Solenoidal forcing, on the other hand, appears to prevent the evolution into a two-phase-medium for certain parameter regions. Conclusions: The dynamics of thermally bistable turbulence shows a substantial sensitivity on the initial state and the forcing properties."],["dc.description.sponsorship","DFG [BA3706]"],["dc.identifier.doi","10.1051/0004-6361/201014373"],["dc.identifier.isi","000286458400026"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/8618"],["dc.identifier.scopus","2-s2.0-78650105619"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/67384"],["dc.identifier.url","http://www.scopus.com/inward/record.url?eid=2-s2.0-78650105619&partnerID=MN8TOARS"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.eissn","1432-0746"],["dc.relation.issn","0004-6361"],["dc.rights","Goescholar"],["dc.rights.uri","https://goedoc.uni-goettingen.de/licenses"],["dc.title","Forced turbulence in thermally bistable gas: A parameter study"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1065"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.lastpage","1070"],["dc.bibliographiccitation.volume","506"],["dc.contributor.author","Niklaus, M."],["dc.contributor.author","Schmidt, W."],["dc.contributor.author","Niemeyer, J. C."],["dc.date.accessioned","2018-11-07T11:22:23Z"],["dc.date.accessioned","2020-07-09T09:00:09Z"],["dc.date.available","2018-11-07T11:22:23Z"],["dc.date.available","2020-07-09T09:00:09Z"],["dc.date.issued","2009"],["dc.description.abstract","Colliding flows are a commonly used scenario for the formation of molecular clouds in numerical simulations. Due to the thermal instability of the warm neutral medium, turbulence is produced by cooling. We carry out a two-dimensional numerical study of such colliding flows in order to test whether statistical properties inferred from adaptive mesh refinement (AMR) simulations are robust with respect to the applied refinement criteria. We compare probability density functions of various quantities as well as the clump statistics and fractal dimension of the density fields in AMR simulations to a static-grid simulation. The static grid with 2048^2 cells matches the resolution of the most refined subgrids in the AMR simulations. The density statistics is reproduced fairly well by AMR. Refinement criteria based on the cooling time or the turbulence intensity appear to be superior to the standard technique of refinement by overdensity. Nevertheless, substantial differences in the flow structure become apparent. In general, it is difficult to separate numerical effects from genuine physical processes in AMR simulations."],["dc.identifier.doi","10.1051/0004-6361/200912483"],["dc.identifier.isi","000271374800051"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/5921"],["dc.identifier.scopus","2-s2.0-70350459161"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/55986"],["dc.identifier.url","http://www.scopus.com/inward/record.url?eid=2-s2.0-70350459161&partnerID=MN8TOARS"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.eissn","1432-0746"],["dc.relation.issn","0004-6361"],["dc.rights","Goescholar"],["dc.rights.uri","http://goedoc.uni-goettingen.de/licenses"],["dc.title","Two-dimensional adaptive mesh refinement simulations of colliding flows"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","A5"],["dc.bibliographiccitation.firstpage","A5"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.volume","556"],["dc.contributor.author","Behrens, C."],["dc.contributor.author","Niemeyer, J."],["dc.date.accessioned","2018-11-07T09:21:41Z"],["dc.date.accessioned","2020-07-16T12:45:12Z"],["dc.date.available","2018-11-07T09:21:41Z"],["dc.date.available","2020-07-16T12:45:12Z"],["dc.date.issued","2013"],["dc.description.abstract","We investigate the correlations between the observed fraction of Lyman alpha emission from star-forming galaxies and the large scale structure by post-processing snapshots of a large, high resolution hydrodynamical simulation with a Lyman alpha radiative transfer code at redshifts z=4, 3, 2. We find correlations of the observed fraction with density, density gradient along the line of sight, velocity and velocity gradient along the line of sight, all within the same order of magnitude (tens of percent). Additionally, a correlation with the angular momentum of the dark matter halo is detected. In contrast to a previous study, we find no significant deformation of the 2-point correlation function due to selection effects from radiative transfer in the IGM within the limited statistics of the simulation volume."],["dc.description.sponsorship","DFG [SFB 963/1]"],["dc.identifier.doi","10.1051/0004-6361/201321172"],["dc.identifier.isi","000323893500005"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/10865"],["dc.identifier.scopus","2-s2.0-84880680801"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/67191"],["dc.identifier.url","http://www.scopus.com/inward/record.url?eid=2-s2.0-84880680801&partnerID=MN8TOARS"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.eissn","1432-0746"],["dc.relation.issn","0004-6361"],["dc.rights","Goescholar"],["dc.rights.uri","https://goedoc.uni-goettingen.de/licenses"],["dc.title","Effects of Lyman-alpha scattering in the IGM on clustering statistics of Lyman-alpha emitters"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","A77"],["dc.bibliographiccitation.firstpage","A77"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.volume","563"],["dc.contributor.author","Behrens, C."],["dc.contributor.author","Dijkstra, M."],["dc.contributor.author","Niemeyer, J. C."],["dc.date.accessioned","2018-11-07T09:42:57Z"],["dc.date.accessioned","2020-07-22T09:28:22Z"],["dc.date.available","2018-11-07T09:42:57Z"],["dc.date.available","2020-07-22T09:28:22Z"],["dc.date.issued","2014"],["dc.description.abstract","We investigate the radiative transfer of Lyman alpha photons through simplified anisotropic gas distributions, which represent physically motivated extensions of the popular 'shell-models'. Our study is motivated by the notion that (i) shell models do not always reproduce observed Lyman alpha spectral line profiles, (ii) (typical) shell models do not allow for the escape of ionizing photons, and (iii) the observation & expectation that winds are more complex, anisotropic phenomena. We examine the influence of inclination on the Lyman alpha spectra, relative fluxes and escape fractions. We find the flux to be enhanced/suppressed by factors up to a few depending on the parameter range of the models, corresponding to a boost in equivalent width of the same amplitude if we neglect dust. In general, lower mean optical depths tend to reduce the impact of anisotropies as is expected. We find a correlation between an observed peak in the -- occasionally triple-peaked -- spectrum at the systemic velocity and the existence of a low optical depth cavity along the line of sight. This can be of importance in the search for ionizing photons leaking from high- redshift galaxies since these photons will also be able to escape through the cavity."],["dc.description.sponsorship","Goettingen Academy of Sciences and Humanities"],["dc.identifier.doi","10.1051/0004-6361/201322949"],["dc.identifier.isi","000333798000077"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/10914"],["dc.identifier.scopus","2-s2.0-84896117350"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/67380"],["dc.identifier.url","http://www.scopus.com/inward/record.url?eid=2-s2.0-84896117350&partnerID=MN8TOARS"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.eissn","1432-0746"],["dc.relation.issn","0004-6361"],["dc.rights","Goescholar"],["dc.rights.uri","https://goedoc.uni-goettingen.de/licenses"],["dc.title","Beamed Ly α emission through outflow-driven cavities"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","A75"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.volume","509"],["dc.contributor.author","Pfannes, J. M. M."],["dc.contributor.author","Niemeyer, J. C."],["dc.contributor.author","Schmidt, W."],["dc.date.accessioned","2018-11-07T08:47:03Z"],["dc.date.accessioned","2020-07-09T08:21:58Z"],["dc.date.available","2018-11-07T08:47:03Z"],["dc.date.available","2020-07-09T08:21:58Z"],["dc.date.issued","2010"],["dc.description.abstract","Context: Superluminous type Ia supernovae (SNe Ia) may be explained by super-Chandrasekhar-mass explosions of rapidly rotating white dwarfs (WDs). In a preceding paper, we showed that the deflagration scenario applied to rapidly rotating WDs generates explosions that cannot explain the majority of SNe Ia. Aims: Rotation of the progenitor star allows super-Chandrasekhar-mass WDs to form that have a shallower density stratification. We use simple estimates of the production of intermediate and iron group elements in pure detonations of rapidly rotating WDs to assess their viability in explaining rare SNe Ia. Methods: We numerically construct WDs in hydrostatic equilibrium that rotate according to a variety of rotation laws. The explosion products are estimated by considering the density stratification and by evaluating the result of hydrodynamics simulations. Results: We show that a significant amount of intermediate mass elements is produced for theoretically motivated rotation laws, even for prompt detonations of WDs. Conclusions: Rapidly rotating WDs that detonate may provide an explanation of rare superluminous SNe Ia in terms of both burning species and explosion kinematics."],["dc.identifier.doi","10.1051/0004-6361/200912033"],["dc.identifier.isi","000274159400086"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9669"],["dc.identifier.scopus","2-s2.0-76349089555"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/20850"],["dc.identifier.url","http://www.scopus.com/inward/record.url?eid=2-s2.0-76349089555&partnerID=MN8TOARS"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.eissn","1432-0746"],["dc.relation.issn","0004-6361"],["dc.rights","Goescholar"],["dc.rights.uri","https://goedoc.uni-goettingen.de/licenses"],["dc.title","Thermonuclear explosions of rapidly rotating white dwarfs -II. Detonations"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","A74"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Astronomy and Astrophysics"],["dc.bibliographiccitation.volume","509"],["dc.contributor.author","Pfannes, J. M. M."],["dc.contributor.author","Niemeyer, J. C."],["dc.contributor.author","Schmidt, W."],["dc.contributor.author","Klingenberg, C."],["dc.date.accessioned","2018-11-07T08:47:04Z"],["dc.date.accessioned","2020-07-09T08:21:03Z"],["dc.date.available","2018-11-07T08:47:04Z"],["dc.date.available","2020-07-09T08:21:03Z"],["dc.date.issued","2010"],["dc.description.abstract","Context: Turbulent deflagrations of Chandrasekhar mass White Dwarfs are commonly used to model Type Ia Supernova explosions. In this context, rapid rotation of the progenitor star is plausible but has so far been neglected. Aims: The aim of this work is to explore the influence of rapid rotation on the deflagration scenario. Methods: We use three dimensional hydrodynamical simulations to model turbulent deflagrations ignited within a variety of rapidly rotating CO WDs obeying rotation laws suggested by accretion studies. Results: We find that rotation has a significant impact on the explosion. The flame develops a strong anisotropy with a preferred direction towards the stellar poles, leaving great amounts of unburnt matter along the equatorial plane. Conclusions: The large amount of unburnt matter is contrary to observed spectral features of SNe Ia. Thus, rapid rotation of the progenitor star and the deflagration scenario are incompatible in order to explain SNe Ia."],["dc.identifier.doi","10.1051/0004-6361/200912032"],["dc.identifier.isi","000274159400085"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9407"],["dc.identifier.scopus","2-s2.0-76349101879"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/20853"],["dc.identifier.url","http://www.scopus.com/inward/record.url?eid=2-s2.0-76349101879&partnerID=MN8TOARS"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.eissn","1432-0746"],["dc.relation.issn","0004-6361"],["dc.rights","Goescholar"],["dc.rights.uri","https://goedoc.uni-goettingen.de/licenses"],["dc.title","Thermonuclear explosions of rapidly rotating white dwarfs I. Deflagrations"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","012032"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Journal of Physics. Conference Series"],["dc.bibliographiccitation.volume","186"],["dc.contributor.affiliation","C Peth, ; 1Laser-Laboratorium Goettingen, Hans-Adolf-Krebs-Weg 1, D-37077 Goettingen, Germany"],["dc.contributor.affiliation","F Barkusky, ; 1Laser-Laboratorium Goettingen, Hans-Adolf-Krebs-Weg 1, D-37077 Goettingen, Germany"],["dc.contributor.affiliation","J Sedlmair, ; 2Institute for X-Ray Physics, Georg-August-University, Friedrich-Hund-Platz 1, D-37077 Goettingen, Germany"],["dc.contributor.affiliation","S-C Gleber, ; 2Institute for X-Ray Physics, Georg-August-University, Friedrich-Hund-Platz 1, D-37077 Goettingen, Germany"],["dc.contributor.affiliation","E Novakova, ; 2Institute for X-Ray Physics, Georg-August-University, Friedrich-Hund-Platz 1, D-37077 Goettingen, Germany"],["dc.contributor.affiliation","J Niemeyer, ; 3Institut für Angewandte Biotechnolgie, Marie-Curie-Strasse 7, 37079 Goettingen, Germany"],["dc.contributor.affiliation","J Thieme, ; 2Institute for X-Ray Physics, Georg-August-University, Friedrich-Hund-Platz 1, D-37077 Goettingen, Germany"],["dc.contributor.affiliation","T Salditt, ; 2Institute for X-Ray Physics, Georg-August-University, Friedrich-Hund-Platz 1, D-37077 Goettingen, Germany"],["dc.contributor.affiliation","K Mann, ; 1Laser-Laboratorium Goettingen, Hans-Adolf-Krebs-Weg 1, D-37077 Goettingen, Germany"],["dc.contributor.author","Peth, Christian"],["dc.contributor.author","Barkusky, F."],["dc.contributor.author","Sedlmair, J."],["dc.contributor.author","Gleber, Sophie-Charlotte"],["dc.contributor.author","Nováková, Eva"],["dc.contributor.author","Niemeyer, J"],["dc.contributor.author","Thieme, J."],["dc.contributor.author","Salditt, Tim"],["dc.contributor.author","Mani, Nivedita"],["dc.contributor.author","Mann, K."],["dc.date.accessioned","2017-09-07T11:54:07Z"],["dc.date.available","2017-09-07T11:54:07Z"],["dc.date.issued","2009"],["dc.date.updated","2022-02-19T19:42:40Z"],["dc.description.abstract","We present a compact setup for near-edge x-ray absorption spectroscopy at the carbon K-edge based on a laser-driven plasma source. Thin polymer films were investigated, showing good agreement with corresponding synchrotron data. Furthermore we have examined the carbon near-edge structure of phospholipids and fulvic acids, providing detailed information on intermolecular binding states."],["dc.identifier.doi","10.1088/1742-6596/186/1/012032"],["dc.identifier.gro","3145123"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/2825"],["dc.language.iso","en"],["dc.notes.intern","Crossref Import"],["dc.notes.status","public"],["dc.relation.conference","9TH INTERNATIONAL CONFERENCE ON X-RAY MICROSCOPY"],["dc.relation.eventend","2008-07-23"],["dc.relation.eventlocation","Zürich, Switzerland"],["dc.relation.eventstart","2008-07-21"],["dc.relation.issn","1742-6596"],["dc.relation.orgunit","Institut für Röntgenphysik"],["dc.rights.uri","https://publishingsupport.iopscience.iop.org/open_access/"],["dc.subject.gro","x-ray imaging"],["dc.title","Near-edge X-ray absorption fine structure measurements using a laser plasma XUV source"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"],["local.message.claim","2021-06-17T08:58:35.832+0000|||rp114751|||submit_approve|||dc_contributor_author|||None"],["local.message.claim","2021-06-17T08:59:15.976+0000|||rp114751|||submit_approve|||dc_contributor_author|||None"],["local.message.claim","2021-06-17T08:59:15.976+0000|||rp114751|||submit_approve|||dc_contributor_author|||None"]]