Updated on 2022/08/11

写真a

 
NAKAMURA, Osamu
 
Affiliation
Faculty of Political Science and Economics, School of Political Science and Economics
Job title
Associate Professor

Concurrent Post

  • Affiliated organization   Global Education Center

  • Faculty of Political Science and Economics   Graduate School of Political Science

  • Faculty of Science and Engineering   Graduate School of Advanced Science and Engineering

Education

  •  
    -
    2001

    University of Tokyo   Graduate School, Division of Science   Astronomy  

  •  
    -
    2001

    University of Tokyo   Graduate School, Division of Science   Astronomy  

  •  
    -
    1993

    Kyoto University   Faculty of Science   Division of Physics  

Degree

  • University of Tokyo   Doctor

  • University of Tokyo   Master

Research Experience

  • 2011.04
    -
    2014.03

    Parttime lecturer, Tokyo Kasei Gakuin University

  • 2002.04
    -
    2012.03

    Parttime lecturer, Tokyo City University (Musashi Institute of Technology)

  •  
     
     

    ResearchAssociate,WasedaUniversity

  •  
     
     

    ResearchAssociate,WasedaUniversity

  •  
     
     

    AssistantProfessor,WasedaUniversity

  •  
     
     

    Lecturer,WasedaUniversity

  •  
     
     

    ResearchAssociate,WasedaUniversity

  •  
     
     

    PPARCResearcher,NottinghamUniversity

  •  
     
     

    CoEResearcher,InstituteforCosmic-RayResearch,UniversityofTokyo

▼display all

Professional Memberships

  •  
     
     

    Astronomical Society of Japan

  •  
     
     

    Japan Society for Science Education

  •  
     
     

    Japanese Society for Science and Technology Studies

  •  
     
     

    日本マス・コミュニケーション学会

 

Research Areas

  • Astronomy

  • Sociology of science, history of science and technology

  • Science education

Research Interests

  • Astronomy

  • Science Communication

  • Science, Technology and Society

  • journalism

Papers

  • The Tully-Fisher relation of intermediate redshift field and cluster galaxies from Subaru spectroscopy

    O Nakamura, A Aragon-Salamanca, B Milvang-Jensen, N Arimoto, C Ikuta, SP Bamford

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY   366 ( 1 ) 144 - 162  2006.02  [Refereed]

     View Summary

    We have carried out spectroscopic observations in four cluster fields using Subaru's FOCAS multislit spectrograph and obtained spectra for 103 bright disc field and cluster galaxies at 0.06 <= z <= 1.20. 77 of these show emission lines, and 33 provide reasonably secure determinations of the galaxies' rotation velocity. The rotation velocities, luminosities, colours and emission-line properties of these galaxies are used to study the possible effects of the cluster environment on the star formation history of the galaxies. Comparing the Tully-Fisher relations of cluster and field galaxies at similar redshifts we find no measurable difference in rest-frame B-band luminosity at a given rotation velocity (the formal difference is 0.18 +/- 0.33). The colours of the cluster emission line galaxies are only marginally redder in rest-frame B-V(by 0.06 +/- 0.04 mag) than the field galaxies in our sample. Taken at face value, these results seem to indicate that bright star-forming cluster spirals are similar to their field counterparts in their star formation properties. However, we find that the fraction of disc galaxies with absorption-line spectra (i.e. with no current star formation) is larger in clusters than in the field by a factor of similar to 3-5. This suggests that the cluster environment has the overall effect of switching off star formation in (at least) some spiral galaxies. To interpret these observational results, we carry out simulations of the possible effects of the cluster environment on the star formation history of disc galaxies and thus their photometric and spectroscopic properties. This allows us to create mock samples of unperturbed 'field' galaxies [with approximately constant star formation rates (SFRs)] and perturbed 'cluster' galaxies with different star formation histories, including star formation truncation, with or without an associated starburst. We show that, if we select only bright galaxies with current star formation (i.e. with emission lines strong enough for rotation-curve measurements), the average colours and luminosities of the 'cluster' galaxies may not be very different from those of galaxies in the 'field' sample, even though their star formation histories may be significantly different. However, the fraction of emission and absorption-line galaxies would change significantly. We also use these simulations to estimate the size of field and cluster galaxy samples that would allow us to differentiate the different star formation scenarios considered. Finally, we find that the rest-frame absolute B-band magnitude of the field galaxies in our sample shows an evolution of -1.30 +/- 1.04 mag per unit redshift at fixed rotation velocity. This indicates that the average SFR of bright disc galaxies evolves more slowly than the universal SFR as determined from ultraviolet, H alpha, far-infrared and radio studies. This suggests the evolution of the universal SFR density is not dominated by bright star-forming disc galaxies, in agreement with previous studies.

    DOI

  • The H alpha luminosity function of morphologically classified galaxies in the Sloan Digital Sky Survey

    O Nakamura, M Fukugita, J Brinkmann, DP Schneider

    ASTRONOMICAL JOURNAL   127 ( 5 ) 2511 - 2521  2004.05  [Refereed]

     View Summary

    We present a study of the Halpha line emission from a sample of 1482 optically selected, morphologically classified bright galaxies (median redshift of 0.05) derived from the Sloan Digital Sky Survey. The luminosity function is calculated for each morphological class and for the total sample. The luminosity function fitted with the Schechter form gives a slope alpha = -1.43 +/- 0.10 for the total sample, and the Halpha luminosity density is 10(-0.07)(39.31 +/- 0.04)(+0.10) h ergs s(-1) Mpc(-3), where the first error is statistical and the second is systematic. This value is consistent with that derived by Gallego et al. in 1995, but this agreement is caused by a fortuitous cancellation of their neglect of stellar absorption that affects the estimate of extinction corrections and a significant sample incompleteness of emission-line galaxies. The fraction of Halpha emitters monotonically increases from early ( a few percent for elliptical galaxies) to late types (100% for irregular galaxies), whereas strong emitters exist in all classes of morphological types. We find that 83% of the luminosity density comes from spiral galaxies, 5% from irregular galaxies, and 9% from early-type galaxies; a small number of morphologically disturbed galaxies contribute by 3%.

  • The luminosity function of morphologically classified galaxies in the Sloan Digital Sky Survey

    O Nakamura, M Fukugita, N Yasuda, J Loveday, J Brinkmann, DP Schneider, K Shimasaku, M SubbaRao

    ASTRONOMICAL JOURNAL   125 ( 4 ) 1682 - 1688  2003.04  [Refereed]

     View Summary

    The morphological dependence of the luminosity function is studied, using a sample containing approximately 1500 bright galaxies classified into Hubble types by visual inspection, for a homogeneous sample obtained from the Sloan Digital Sky Survey northern equatorial stripes. Early-type galaxies are shown to have a characteristic magnitude 0.45 mag brighter than that of spiral galaxies in the r* band, consistent with the "universal characteristic luminosity'' in the B band. The shape of the luminosity function differs rather little among different morphological types: we do not see any symptoms of the sharp decline in the faint end of the luminosity function for early-type galaxies at least 2 mag fainter than the characteristic magnitude, although the faint-end behavior shows a slight decline (alpha less than or similar to -1) compared with the total sample. We also show that the rather. at faint-end slope for early-type galaxies is not due to an increasing mixture of dwarf galaxies, which have softer cores. This means that there are numerous faint early-type galaxies with highly concentrated cores.

Research Projects

  • A Comparative Study of Press Conference of Japanese Government and News coverage on the Fukushima Nuclear Disaster in Its Early Stage

    Project Year :

    2014.04
    -
    2017.03
     

     View Summary

    We tried to analyze the relationship between the three elements, “actual situation of accident,” “press conferences of Japanese government (including TEPCO),” and “coverage of major newspapers” on the Fukushima Daiichi nuclear plant accident (March 2011) in its early stage. When analyzed in quantitative and qualitative way narrowing to “meltdown”, there was a tendency that press conference officers underestimated the actual situation of meltdown and news reporting quoted comments of press conference officers as their major news source. Analyzing news coverage of major newspapers in China as a foreign coverage, it was found that news articles of China quoted Japanese news media as their major news source.As important data for our research, we created transcript of Japanese press conferences and constructed a site “FUKUSHIMA STUDY”. Utilizing this transcript, we conducted further research on press conference and news coverage in more detail

 

Syllabus

▼display all