Sanae F. Yamada

Tohoku University, Sendai-shi, Miyagi-ken, Japan

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Publications (4)14.05 Total impact

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    ABSTRACT: We present an optical multicolor-imaging study of the galaxy cluster A521 at z = 0.25, using Suprime-Cam on the Subaru Telescope, covering an area of 32' × 20' (9.4 × 5.8 h Mpc2 at z = 0.25). Our imaging data taken with both a narrowband filter, NB816 (λ0 = 8150 Å and Δλ = 120 Å), and broadband filters, B,V,RC,i', and z', allow us to find 165 Hα emitters. We obtain the Hα luminosity function (LF) for the cluster galaxies within 2 Mpc; the Schechter parameters are α = -0.75 ± 0.23, * = 10-0.45 to 10-0.05 Mpc-3, and L* = 1041.86 to 1042.2 ergs s-1. Although the faint-end slope α is consistent with that of the local cluster Hα LFs, the characteristic luminosity L* is about 6 times (or ≈2 mag) brighter. This strong evolution implies that A521 contains more active star-forming galaxies than the local clusters, being consistent with the observed Butcher-Oemler effect. However, the bright L* of A521 may be, at least in part, due to the dynamical condition of this cluster.
    The Astrophysical Journal 12/2008; 601(2):805. · 6.73 Impact Factor
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    ABSTRACT: We present results of our intermediate-band optical imaging survey for high-$z$ Ly$\alpha$ emitters (LAEs) using the prime focus camera, Suprime-Cam, on the 8.2m Subaru Telescope. In our survey, we use eleven filters; four broad-band filters ($B$, $R_{\rm c}$, $i^\prime$, and $z^\prime$) and seven intermediate-band filters covering from 500 nm to 720 nm; we call this imaging program as the Mahoroba-11. The seven intermediate-band filters are selected from the IA filter series that is the Suprime-Cam intermediate-band filter system whose spectral resolution is $R = 23$. Our survey has been made in a $34^\prime \times 27^\prime$ sky area in the Subaru XMM Newton Deep Survey field. We have found 409 IA-excess objects that provide us a large photometric sample of strong emission-line objects. Applying the photometric redshift method to this sample, we obtained a new sample of 198 LAE candidates at $3 < z < 5$. We found that there is no evidence for evolution of the number density and the star formation rate density for LAEs with $\log L({\rm Ly}\alpha) ({\rm erg s^{-1}}) > 42.67$ between $z \sim 3$ and 5.
    Publications- Astronomical Society of Japan 12/2005; · 2.44 Impact Factor
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    ABSTRACT: We present the results of a survey for Lyalpha emitters at z ≈ 5.8 using a new intermediate-band filter centered at lambdac ≈ 8275 Å with DeltalambdaFWHM ≈ 340 Å (i.e., spectroscopic resolution is R ≈ 24) and a combination with a traditional narrow-band centered at lambdac ≈ 8150 Å with DeltalambdaFWHM ≈ 120 Å (R ≈ 68). Our observations were made using the Subaru Prime Focus Camera, Suprime-Cam, on the 8.2m Subaru telescope in a sky area surrounding the high-redshift quasar SDSSp J104433.04 - 012522.2 at z = 5.74, covering an effective sky area of ≈ 720 arcmin2. In this survey, we have found four Ly alpha-emitter candidates from the intermediate-band image (z ≈ 5.8 with Delta z ≈ 0.3). Combined with our previous results based on the NB816 imaging, we discuss the star-formation activity in galaxies between z ≈ 5.7 and z ≈ 5.9.
    Publications- Astronomical Society of Japan 01/2004; 56:597-603. · 2.44 Impact Factor
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    ABSTRACT: Several high-z (z > 5.7) quasars have been found during the course of Sloan Digital Sky Survey. The presence of such very high-z quasars is expected to put constraints on early structure formation. On one hand, it is suggested that these most luminous objects at high redshift are biased toward highly magnified objects by gravitational lensing. To clarify the effect of gravitational lensing on high-z quasars, we began an imaging survey of intervening lensing galaxies. Indeed, our previous optical image showed that SDSSp J104433.04 + 012502.2 at z = 5.74 is gravitationally magnified by a factor of 2. In this paper, we report our new optical imaging of two other high-zquasars, SDSSp J103027.10 + 052455.0 at z=6.28 and SDSSp J130608.26 + 035626.3 at z=5.99. Since we found neither an intervening galaxy nor a counter image with i' > 25.4 - 25.8 around each quasar, we conclude that they are not strongly ma gnified regardless that a lens galaxy is dusty.
    Publications- Astronomical Society of Japan 08/2003; 55:733-738. · 2.44 Impact Factor