Browsing by Author "Kobayashi, Chiaki"

Now showing items 61-80 of 104

    • Metallicity effect on type Ia supernovae and galactic and cosmic chemical evolution 

      Kobayashi, Chiaki; Tsujimoto, T; Nomoto, K (Springer Nature, 2000)

    • A Minimum Dilution Scenario for Supernovae and Consequences for Extremely Metal-Poor Stars 

      Magg, Mattis; Nordlander, Thomas; Glover, Simon C. O.; Hansen, Camilla J.; Ishigaki, Miho; Heger, Alexander; Klessen, Ralf S.; Kobayashi, Chiaki; Nomoto, Ken'ichi (2020-11-01)
      To date no metal-free stars have been identified by direct observations. The most common method of constraining their properties is searching the spectra of the most metal-poor stars for the chemical elements created in ...

    • New Type Ia supernova Yields and the Manganese and Nickel Problems in the Milky Way and Dwarf Spheroidal Galaxies 

      Kobayashi, Chiaki; Leung, Shing-Chi; Nomoto, Ken'ichi (2020-06-04)
      In our quest to identify the progenitors of Type Ia supernovae (SNe Ia), we first update the nucleosynthesis yields both for Chandrasekhar (Ch) and sub-Ch mass white dwarfs (WDs), for a wide range of metallicity, with our ...

    • Numerical simulations of elliptical galaxies 

      Kobayashi, Chiaki (Cambridge University Press, 2010)

    • On the [α/Fe]-[Fe/H] relations in early-type galaxies 

      Vincenzo, Fiorenzo; Kobayashi, Chiaki; Taylor, Philip (2018-10-01)
      We study how the predicted [α/Fe]-[Fe/H] relations in early-type galaxies vary as functions of their stellar masses, ages, and stellar velocity dispersions, by making use of cosmological chemodynamical simulations with ...

    • On the α /Fe Bimodality of the M31 Disks 

      Kobayashi, Chiaki; Bhattacharya, Souradeep; Arnaboldi, Magda; Gerhard, Ortwin (2023-10-10)
      An outstanding question is whether the α/Fe bimodality exists in disk galaxies other than in the Milky Way. Here we present a bimodality using our state-of-the-art galactic chemical evolution models that can explain various ...

    • Origin of color gradients in elliptical galaxies 

      Tamura, N; Kobayashi, Chiaki; Arimoto, N; Ohta, K; Kodama, Tadayuki (2000-05)
      The origin of color gradients in elliptical galaxies is examined by comparing model gradients with those observed in the Hubble Deep Field. The models are constructed so as to reproduce color gradients in local elliptical ...

    • The Origin of Elements from Carbon to Uranium 

      Kobayashi, Chiaki; Karakas, Amanda I.; Lugaro, Maria (2020-09-15)
      To reach a deeper understanding of the origin of elements in the periodic table, we construct Galactic chemical evolution (GCE) models for all stable elements from C (A = 12) to U (A = 238) from first principles, i.e., ...

    • The origin of elements: the need for UV spectra 

      Kobayashi, Chiaki (2022-07-23)
      Thanks to the long-term collaborations between nuclear and astrophysics, we have good understanding on stellar nucleosynthesis, except for the elements around Ti and some neutron-capture elements. From the comparison between ...

    • The origin of kinematically distinct cores and misaligned gas discs in galaxies from cosmological simulations 

      Taylor, Philip; Federrath, Christoph; Kobayashi, Chiaki (2018-09-01)
      Integral field spectroscopy surveys provide spatially resolved gas and stellar kinematics of galaxies. They have unveiled a range of atypical kinematic phenomena, which require detailed modelling to understand. We present ...

    • The origin of low [alpha/Fe] ratios in extremely metal-poor stars 

      Kobayashi, Chiaki; Ishigaki, Miho N.; Tominaga, Nozomu; Nomoto, Ken'ichi (2014-03-25)
      We show that the low ratios of $\alpha$ elements (Mg, Si, and Ca) to Fe recently found for a small fraction of extremely metal-poor stars can be naturally explained with the nucleosynthesis yields of core-collapse supernovae, ...

    • Origin of metals in old Milky Way halo stars based on GALAH and Gaia 

      Ishigaki, Miho N.; Hartwig, Tilman; Tarumi, Yuta; Leung, Shing-Chi; Tominaga, Nozomu; Kobayashi, Chiaki; Magg, Mattis; Simionescu, Aurora; Nomoto, Ken'ichi (2021-10-01)
      Stellar and supernova nucleosynthesis in the first few billion years of the cosmic history have set the scene for early structure formation in the Universe, while little is known about their nature. Making use of stellar ...

    • The origin of the diversity of Type Ia supernovae and the environmental effects 

      Umeda, H; Nomoto, K; Kobayashi, Chiaki; Hachisu, I; Kato, M (1999-09-01)
      Observations suggest that the properties of Type Ia supernovae (SNe Ia) may depend on environmental characteristics, such as the morphology, metallicity, and age of the host galaxies. The influence of these environmental ...

    • Oxygen Loss from Simulated Galaxies and the Metal Flow Main Sequence : Predicting the Dependence on Mass and Environment 

      Taylor, Philip; Kobayashi, Chiaki; Kewley, Lisa J. (2020-08-01)
      We predict the mass fraction of oxygen lost from galaxies in a cosmological simulation as a function of stellar mass and environment at the present day. The distribution with stellar mass is bimodal, separating star-forming ...

    • A Precise Benchmark for Cluster Scaling Relations: Fundamental Plane, Mass Plane and IMF in the Coma Cluster from Dynamical Models 

      Shetty, Shravan; Cappellari, Michele; McDermid, Richard M.; Krajnovic, Davor; Zeeuw, P. T. de; Davies, Roger L.; Kobayashi, Chiaki (2020-04-26)
      We study a sample of 148 early-type galaxies in the Coma cluster using SDSS photometry and spectra, and calibrate our results using detailed dynamical models for a subset of these galaxies, to create a precise benchmark ...

    • Proceedings of Abstracts, School of Physics, Engineering and Computer Science Research Conference 2022 

      Amafabia, Daerefa-a; Asimea, Laurel; Bally, John; Baran, Anthony; Boies, Adam; Borjali, Amirhossein; Bosomworth, Chloe; Burningham, Ben; Chaliasou, Napoleana-Anna; CHEN, Yong Kang; Cheong, Yuen Ki; Chizari, Mahmoud; Chung, Etelka; Coppin, Kristen; David-West, Opukuro; Dennler, Nik; Dhakal, Hom; Dimov, Nikolay; Dmitruk, Emil; Donald, Allen; Drix, Damien; Dzib, Sergio A.; Eltaweel, Mahmoud; Fadlelseed, Sajid; Farahani, Atena; Felix, Adrian; Foat, Tim; Forbrich, Jan; Franco, Maximilien; Gaarn, Joesphine; Garratt, Tracy; Geach, Jim; Ghias, Narges; Ghita, Adrian; Giannetti, Niccolo; Vargas-Gonzalez, Jaime; Greenaway, Richard; Haritos, George; Hatami, Sara; Haydock, David; Helian, Na; Herfatmanesh, Mohammad Reza; Herve, Jean-Baptiste; Hesse, Evelyn; Korani, Hossein; Hosseini, Vahid; Hu, Wei; Hubbard, Thomas; Inal, Jameel; Irigo, Patrick; Ismail, Sikiru O.; Jepleting, Fiona; Ji, Wei; Johnston, Ian; Jombo, Gbanaibolou; Kadir, Shabnam; Kalyvas, Christos; Kamran, Syed Muhammad; Kanellopoulos, Antonios; Kiflay, Aklil Zenebe; Kirner, Raimund; Knox, Kerry; Kobayashi, Chiaki; Kumar, Dhirendra; Kumar, Ritesh; Lane, Peter; Lekkala, Himayasri; Lewis, Andrew; Li, Liang; Luo, Qi; Madani, Hossein; Mallet, Colin; Maruthupandian, Surya; Mathen, Elizabeth Reeja; Matousek, Pavel; McCool, Simon; McGarry, James C.; Menon, Catherine; Metzner, Christoph; Miles, Rachael E. H.; Moeinnia, Hadi; Moggridge, Paul; Mohseni, Mahdi; Montalvão, Diogo; Moraby, Mohammad Najeeb; Murnane, Darragh; Norgate, Marc; Nourani, Amir; Prasad, Kumar Shantanu; Ramalingam, Soodamani; Rastogi, Shavika; Reid, Jonathan P.; Ren, Guogang; Rivilla, Victor M.; Saidpour, Hossein; Saito, Kiyoshi; Sajedi, Seyed Amir Hossein; Salge, Christoph; Samararatne, Samadhi; Schmuker, Michael; Sensoy, Elif; Shriram, Ajay; Singh, Harpreet; Sorouraddin, Yasser; Steuber, Volker; Stone, Nicholas; Sun, Yi; Sureddi, Roopesh; Sutton, Samuel; Thomas, Peter; Timms, Andrew R; Tiwari, P. R.; Tsokanos, Athanasios; Vadalia, Mansukhlal; Yaqoob, Muhammad; Yulianto, Muhamad; Zheng, Minghua (University of Hertfordshire, 2022-11-04)
      The present proceedings record the abstracts submitted and accepted for presentation at SPECS 2022, the second edition of the School of Physics, Engineering and Computer Science Research Conference that took place online, ...

    • Quantifying AGN-Driven Metal-Enhanced Outflows in Chemodynamical Simulations 

      Taylor, Philip; Kobayashi, Chiaki (2015-09-30)
      We show the effects of AGN-driven outflows on the ejection of heavy elements using our cosmological simulations, where super-massive black holes originate from the first stars. In the most massive galaxy, we have identified ...

    • The RADIOSTAR Project 

      Lugaro, Maria; Côté, Benoit; Pignatari, Marco; Yagüe López, Andrés Yagüe; Brinkman, Hannah; Cseh, Borbála; Den Hartogh, Jacqueline; Doherty, Carolyn Louise; Karakas, Amanda Irene; Kobayashi, Chiaki; Lawson, Thomas; Peto, Mária; Soós, Benjámin; Trueman, Thomas; Világos, Blanka (2022-02-17)
      Radioactive nuclei are the key to understanding the circumstances of the birth of our Sun because meteoritic analysis has proven that many of them were present at that time. Their origin, however, has been so far elusive. ...

    • Rapid Chemical Enrichment by Intermittent Star Formation in GN-z11 

      Kobayashi, Chiaki; Ferrara, Andrea (2024-02-06)
      We interpret the peculiar supersolar nitrogen abundance recently reported by the James Webb Space Telescope observations for GN-z11 (z = 10.6) using our state-of-the-art chemical evolution models. The observed CNO ratios ...

    • Re-ionizing the universe without stars 

      Dopita, Michael A.; Krauss, Lawrence M.; Sutherland, Ralph S.; Kobayashi, Chiaki; Lineweaver, Charles H. (2011-10)
      Recent observations show that the measured rates of star formation in the early universe are insufficient to produce re-ionization, and therefore, another source of ionizing photons is required. In this Letter, we examine ...