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Ünlütürk, Kıvanç İbrahim

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Kıvanç İbrahim

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Ünlütürk

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Ünlütürk, Kıvanç İbrahim

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2019 - 201932020 - 20222

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Researcher Of Publications: search.filters.isAuthorOfPublication.4aa0654a-e350-4d39-83c1-73b32bce2bd8

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    A model of non-minimally coupled gravitation and electromagnetism in (1+2) dimensions
    (IOP Publishing Ltd, 2022) Ünlütürk, Kıvanç İbrahim; Yetişmişoğlu, Cem; PhD Student; Phd Student; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; N/A; N/A
    Following earlier works of Dereli and collaborators, we study a three dimensional toy model where we extend the topologically massive gravity with electrodynamics by the most general RF 2-type non-minimal coupling terms. Here R denotes the possible curvature terms and F denotes the electromagnetic 2-form. We derive the variational feld equations and look for exact solutions on constant negative curvature space-times with a constant, self-dual electromagnetic feld. The notion of self-dual electromagnetic felds in three dimensions is introduced by Dereli and collaborators in the study of exact solutions of models with gravity-electromagnetism couplings. We note the conditions that the parameters of the model have to satisfy for these self-dual solutions to exist.
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    Constraining scalar-tensor theories using neutron star mass and radius measurements
    (American Physical Society (APS), 2022) Tuna, Semih; N/A; Department of Physics; Ünlütürk, Kıvanç İbrahim; Ramazanoğlu, Fethi Mübin; PhD Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; N/A; 254225
    We use neutron star mass and radius measurements to constrain the spontaneous scalarization phenomenon in scalar-tensor theories using Bayesian analysis. Neutron star structures in this scenario can be significantly different from the case of general relativity, which can be used to constrain the theory parameters. We utilize this idea to obtain lower bounds on the coupling parameter ?? for the case of massless scalars. These constraints are currently weaker than the ones coming from binary observations, and they have relatively low precision due to the approximations in our method. Nevertheless, our results clearly demonstrate the power of the mass-radius data in testing gravity, and can be further improved with future observations. The picture is different for massive scalars, for which the same data is considerably less effective in constraining the theory parameters in an unexpected manner. We identify the main reason for this to be a large high-likelihood region in the parameter space where deviations from general relativity are relatively small. We hope this initial study to be an invitation to use neutron star structure measurements more commonly to test alternative theories in general.
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    PublicationOpen Access
    Hamilton-Jacobi formulation of the thermodynamics of Einstein-Born-Infeld-AdS black holes
    (Institute of Physics (IOP) Publishing, 2019) Department of Physics; Dereli, Tekin; Ünlütürk, Kıvanç İbrahim; PhD Student; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; 201358; N/A
    A Hamilton-Jacobi formalism for thermodynamics was formulated by Rajeev (Ann. Phys., 323 (2008) 2265) based on the contact structure of the odd-dimensional thermodynamic phase space. This allows one to derive the equations of state of a family of substances by solving a Hamilton-Jacobi equation (HJE). In the same work it was applied to changeless non-rotating black holes, and the use of Born-Infeld electromagnetism was proposed to apply it to charged black holes as well. This paper fulfills this suggestion by deriving the HJE for charged non-rotating black holes using the Born-Infeld theory and a negative cosmological constant. The most general solution of this HJE is found. It is shown that there exist solutions which are distinct from the equations of state of the Einstein-Born-Infeld-AdS (EBIAdS) black hole. The meaning of these solutions is discussed.
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    PublicationOpen Access
    Black holes, gravitational waves and fundamental physics: a roadmap
    (Institute of Physics (IOP) Publishing, 2019) Barack, Leor; Cardoso, Vitor; Nissanke, Samaya; Sotiriou, Thomas P.; Askar, Abbas; Belczynski, Chris; Bertone, Gianfranco; Bon, Edi; Blas, Diego; Brito, Richard; Bulik, Tomasz; Burrage, Clare; Byrnes, Christian T.; Caprini, Chiara; Chernyakova, Masha; Chrusciel, Piotr; Colpi, Monica; Ferrari, Valeria; Gaggero, Daniele; Gair, Jonathan; Garcia-Bellido, Juan; Hassan, S. F.; Heisenberg, Lavinia; Hendry, Martin; Heng, Ik Siong; Herdeiro, Carlos; Hinderer, Tanja; Horesh, Assaf; Kavanagh, Bradley J.; Kocsis, Bence; Kramer, Michael; Le Tiec, Alexandre; Mingarelli, Chiara; Nardini, Germano; Nelemans, Gijs; Palenzuela, Carlos; Pani, Paolo; Perego, Albino; Porter, Edward K.; Rossi, Elena M.; Schmidt, Patricia; Sesana, Alberto; Sperhake, Ulrich; Stamerra, Antonio; Stein, Leo C.; Tamanini, Nicola; Tauris, Thomas M.; Arturo Urena-Lopez, L.; Vincent, Frederic; Volonteri, Marta; Wardell, Barry; Wex, Norbert; Yagi, Kent; Abdelsalhin, Tiziano; Angel Aloy, Miguel; Amaro-Seoane, Pau; Annulli, Lorenzo; Arca-Sedda, Manuel; Bah, Ibrahima; Barausse, Enrico; Barakovic, Elvis; Benkel, Robert; Bennett, Charles L.; Bernard, Laura; Bernuzzi, Sebastiano; Berry, Christopher P. L.; Berti, Emanuele; Bezares, Miguel; Juan Blanco-Pillado, Jose; Blazquez-Salcedo, Jose Luis; Bonetti, Matteo; Boskovic, Mateja; Bosnjak, Zeljka; Bricman, Katja; Bruegmann, Bernd; Capelo, Pedro R.; Carloni, Sante; Cerda-Duran, Pablo; Charmousis, Christos; Chaty, Sylvain; Clerici, Aurora; Coates, Andrew; Colleoni, Marta; Collodel, Lucas G.; Compere, Geoffrey; Cook, William; Cordero-Carrion, Isabel; Correia, Miguel; de la Cruz-Dombriz, Alvaro; Czinner, Viktor G.; Destounis, Kyriakos; Dialektopoulos, Kostas; Doneva, Daniela; Dotti, Massimo; Drew, Amelia; Eckner, Christopher; Edholm, James; Emparan, Roberto; Erdem, Recai; Ferreira, Miguel; Ferreira, Pedro G.; Finch, Andrew; Font, Jose A.; Franchini, Nicola; Fransen, Kwinten; Gal'tsov, Dmitry; Ganguly, Apratim; Gerosa, Davide; Glampedakis, Kostas; Gomboc, Andreja; Goobar, Ariel; Gualtieri, Leonardo; Guendelman, Eduardo; Haardt, Francesco; Harmark, Troels; Hejda, Filip; Hertog, Thomas; Hopper, Seth; Husa, Sascha; Ihanec, Nada; Ikeda, Taishi; Jaodand, Amruta; Jetzer, Philippe; Jimenez-Forteza, Xisco; Kamionkowski, Marc; Kaplan, David E.; Kazantzidis, Stelios; Kimura, Masashi; Kobayashi, Shiho; Kokkotas, Kostas; Krolik, Julian; Kunz, Jutta; Laemmerzahl, Claus; Lasky, Paul; Lemos, Jose P. S.; Said, Jackson Levi; Liberati, Stefano; Lopes, Jorge; Luna, Raimon; Ma, Yin-Zhe; Maggio, Elisa; Mangiagli, Alberto; Montero, Marina Martinez; Maselli, Andrea; Mayer, Lucio; Mazumdar, Anupam; Messenger, Christopher; Menard, Brice; Minamitsuji, Masato; Moore, Christopher J.; Mota, David; Nampalliwar, Sourabh; Nerozzi, Andrea; Nichols, David; Nissimov, Emil; Obergaulinger, Martin; Obers, Niels A.; Oliveri, Roberto; Pappas, George; Pasic, Vedad; Peiris, Hiranya; Petrushevska, Tanja; Pollney, Denis; Pratten, Geraint; Rakic, Nemanja; Racz, Istvan; Radia, Miren; Ramazanoglu, Fethi M.; Ramos-Buades, Antoni; Raposo, Guilherme; Rogatko, Marek; Rosca-Mead, Roxana; Rosinska, Dorota; Rosswog, Stephan; Ruiz-Morales, Ester; Sakellariadou, Mairi; Sanchis-Gual, Nicolas; Salafia, Om Sharan; Samajdar, Anuradha; Sintes, Alicia; Smole, Majda; Sopuerta, Carlos; Souza-Lima, Rafael; Stalevski, Marko; Stergioulas, Nikolaos; Stevens, Chris; Tamfal, Tomas; Torres-Forne, Alejandro; Tsygankov, Sergey; Valiante, Rosa; van de Meent, Maarten; Velhinho, Jose; Verbin, Yosef; Vercnocke, Bert; Vernieri, Daniele; Vicente, Rodrigo; Vitagliano, Vincenzo; Weltman, Amanda; Whiting, Bernard; Williamson, Andrew; Witek, Helvi; Wojnar, Aneta; Yakut, Kadri; Yan, Haopeng; Yazadjiev, Stoycho; Zaharijas, Gabrijela; Zilhao, Miguel; Department of Physics; Ramazanoğlu, Fethi Mübin; Ünlütürk, Kıvanç İbrahim; Faculty Member; PhD Student; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; 254225; N/A
    The grand challenges of contemporary fundamental physics dark matter, dark energy, vacuum energy, inflation and early universe cosmology, singularities and the hierarchy problem all involve gravity as a key component. And of all gravitational phenomena, black holes stand out in their elegant simplicity, while harbouring some of the most remarkable predictions of General Relativity: event horizons, singularities and ergoregions.The hitherto invisible landscape of the gravitational Universe is being unveiled before our eyes: the historical direct detection of gravitational waves by the LIGO-Virgo collaboration marks the dawn of a new era of scientific exploration. Gravitational-wave astronomy will allow us to test models of black hole formation, growth and evolution, as well as models of gravitational-wave generation and propagation. It will provide evidence for event horizons and ergoregions, test the theory of General Relativity itself, and may reveal the existence of new fundamental fields. The synthesis of these results has the potential to radically reshape our understanding of the cosmos and of the laws of Nature.The purpose of this work is to present a concise, yet comprehensive overview of the state of the art in the relevant fields of research, summarize important open problems, and lay out a roadmap for future progress.
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    PublicationOpen Access
    Generalized disformal coupling leads to spontaneous tensorization
    (American Physical Society (APS), 2019) Department of Physics; Ramazanoğlu, Fethi Mübin; Ünlütürk, Kıvanç İbrahim; Faculty Member; PhD Student; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; 254225; N/A
    We show that gravity theories involving disformally transformed metrics in their matter coupling lead to spontaneous growth of various fields in a similar fashion to the spontaneous scalarization scenario in scalar-tensor theories. Scalar-dependent disformal transformations have been investigated in this context, and our focus is understanding the transformations that depend on more general fields. We show that vector-dependent disformal couplings can be obtained in various different ways, each leading to spontaneous vectorization as indicated by the instabilities in linearized equations of motion. However, we also show that spontaneous growth is not evident beyond vectors. For example, we could not identify a spontaneous growth mechanism for a spinor field through disformal transformations, even though there is a known example for conformal transformations. This invites further work on the fundamental differences between the two types of metric transformations. We argue that our results are relevant for observations in strong gravity such as gravitational wave detections due to their promise of large deviations from general relativity in this regime.