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					Galactic Astronomy 銀河物理学特論 I          overview
Seminar+lecture format
   • Lectures + reading “classic” papers in seminar format
   • Presentation in Japanese with English slides (not just words, but
                                                ゃ て
   make sentences for explanation, 単語の羅列じ なく 文章で書く う し う       よ に よ ).
Goals:
   1.Understand the “observed” properties of galaxies in the local
   universe, including AGNs
   2.Understand the “observed” evolution of the properties in the
   cosmic history
   3.Overview methods of the observations and instruments
Implicit goals:
   1.Used to reading English papers
   2.Used to English wording
   3.Used to summarizing papers,
   4.Used to explaining in English     including me…
Galactic Astronomy 銀河物理学特論 I                       overview
• Contents:
    1. Statistical properties of galaxies in the local universe
         •    Stellar properties of galaxies
         •    Emission line diagnostics of galaxies (藤井(慎))
               Tremonti et al. 2004, ApJ, 613, 898
         •    Morphological properties of galaxies
         •    Dynamical structure of galaxies (小室)
         •    Dependence of galaxy properties on “environment” (本間)
         •    Multi-wavelength view of galaxies (IR, 藤井(淳))
    2. Active galaxies and super massive black holes in the local universe
         •    Relation between bulges and super massive black holes of galaxies
         •    Unified model of Active Galactic Nuclei
    3. Observations of galaxies in the distant (high-redshift universe)
         •    Searching for distant galaxies, method
         •    Luminosity function of galaxies and its evolution
         •    Stellar mass function of galaxies (本田)
         •    Chemical evolution of galaxies
         •    Evolution of dynamical properties of galaxies (Akhlaghi)
         •    Co-evolution of galaxies and super massive black holes
    4. Observational astronomy in future
                Galactic Astronomy
                 銀河物理学特論 I


Lecture I: Statistical properties
of galaxies in the local universe

 Thanks to the imaging and spectroscopic survey
   database made by Sloan Digital Sky Survey,
 statistical properties of galaxies can be discussed
                with high “precision”.


                 2011/10/03
Sloan Digital Sky Survey :
Imaging and spectroscopic surveys in the optical wavelength conducted with a
dedicated (専用) 2.5m telescope @ NewMexico.The imaging survey covers 8,423
sq. degree (in red) in 5 bands, and the spectroscopic survey covers 8.032
sq.degree (in green). The spectroscopic survey obtains optical spectra of galaxies
and quasars in the 3800-9200A wavelength range with spectral resolution
R=1800-2200.




               http://www.sdss.org/
Sloan Digital Sky Survey : Imaging survey
Imaging data are obtained in u(3551A; 22.0mag), g(4686A; 22.2mag), r(6165A;
22.2mag), i(7481A; 21.3mag), z(8931A: 20.5mag) bands (the numbers in the
parenthesis shows the “effective wavelength” and detection limit in magnitude for
point sources) with drift-scan mode of the mosaic CCD camera. Typical image size
is 1.4” in r-band.




                                    “Efficiency” curves of filters used in the
                                    imaging survey. They includes atmosphere
                                    transparency, CCD quantum efficiency (QE),
                                    and telescope throughput.
                         http://www.astro.princeton.edu/PBOOK/camera/camera.htm
                         http://home.fnal.gov/~annis/astrophys/filters/filters.html
Sloan Digital Sky Survey : Imaging survey
Sample of galaxy images with r<16mag




                                       Fukugita et al. 2007, ApJ, 134, 579
Sloan Digital Sky Survey : Imaging survey
Sample of galaxy images with r<16mag




                                        Fukugita et al. 2007, ApJ, 134, 579
Sloan Digital Sky Survey : Imaging survey
Sample of galaxy images with r<16mag




                                       Fukugita et al. 2007, ApJ, 134, 579
Sloan Digital Sky Survey : Imaging survey
Sample of galaxy images with r<16mag




                                       Fukugita et al. 2007, ApJ, 134, 579
     Sloan Digital Sky Survey : Spectroscopic survey
     Large spectroscopic survey with optical fiber spectrograph cunducted. alaxies, 929,555
     galaxies brighter than r(Petrosian)<17.77 and 111,693 z<2.3 quasars and 9,670
     (z>2.3) quasars are spectroscopically observed.




http://www.astro.princeton.edu/PBOOK/spectro/spectro.htm

   Optical design of the fiber spectrograph.
   Throughput of each element (bottom) and total
   spectrograph efficiency (top).
                Seminar 1:

Kauffmann et al. 2003, MNRAS, 341, 33 (Paper I)
Kauffmann et al. 2003, MNRAS, 341, 54 (Paper II)

                  Goal : 目的
        Sample, data : サンプル, データ
        Method : 方法、観測手法、装置
                 Results: 結果
        Discussion: 結果についての議論

                 2011/10/03
• Goal:

• Examine stellar mass of galaxies accurately considering their stellar
  population.

• So far, mass-to-light ratios of galaxies are estimated with their
  colors. In this paper, the ratios are estimated with absorption line
  indices.

• Then, examine statistical properties of galaxies as a function of their
  stellar mass.
• Sample



• Spectroscopic data of 122,808 galaxies from SDSS DR1
Method:
Absorption line indices, Dn(4000), HdA index, are used to quantitatively examine spectra
of galaxies
              Hd A index: after removing                                         Effect of different
              contamination of Hd emission line         Effect of different      metalicity (2.5solar,
              using Hb, Hg emission line strength.      stellar spectral model   solar, 0.2solar)

 Young




 Old




       Dn(4000) index                                O,Bstars have weak Hd abs.
                                                     Late-B early-F stars have strong Hd abs.
Method :
The actual measured data (left) and constructed models (model) are compared on the
Dn(4000), HdA index plane. The solid lines in the left panels are tracks of burst star
formation model and the points are “continuus” star formation model.




                                                  Models caluculated with BC2003 model.
                                                  Exponentially-decaying continnus star formation
                                                  model + random “bursty” star formation. Kroupa
                                                  IMF, 0.25-2 Zsolar。
       Method:
       For each galaxy, using its Dn(4000) Hd-a indices, likelihood of each model is caluculated with
       Bayesian statistics.




                            95% of the model
                            Fburst>0.05 >0.1Gyr
95% of the model
Fburst>0.05 <0.1Gyr




                                   95% of the model
                                   Fburst=0


                                                                               Examples of
               Dn(4000) HdA の上で特徴的な領域。                                         estimation
  Method:
  In order to determine the effect of dust reddening, the difference between observed colors and the
  best fit model are examined.




                                                        Estimated amount of dust reddening as a
                                                        function of z-band absolute magnitude and
                                                        Dn(4000).
The colors of model SEDs (blue dots) and
observed galaxies (black dots). Left panels shows
the colors without emission line correction and
right panels with emission line correction
Results:
Estimated stellar mass to light ratio of galaxies are summarized. In the right panel, the distributions
of 95% reliability range of each galaxy are shown for all, Dn(4000)>1.8 (dot), and Dn(4000)<1.4
(dash) galaxies.
Results 1
The relation between stellar mass of galaxies and their absorption line
strength are plotted. There is a strong variation at stellar mass of 3x10^11
Msolar.
Results 2
The stellar mass of galaxies and their absorption line strength are shown in
different way.
Results
Relation between stellar mass of galaxies and their surface stellar mass
density (left) and their concentration (right). More massive galaxies have
higher surface stellar mass density and higher concentration.
•   Discussions:
•   Galaxies properties changes at stellar mass of 3x10^11
     – More massive galaxies have older stellar population, higher stellar mass
        density, higher concentration.

				
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posted:3/4/2013
language:English
pages:22