arXiv subjects

Kiyoto Yabe

Publications and source records attributed to Kiyoto Yabe.

57 records · Page 4Linked to original sources

arXiv2009

Lyman Break Galaxies at z~5: Rest-Frame UV Spectra. III

We present results of optical spectroscopic observations of candidates of Lyman Break Galaxies (LBGs) at $z \sim 5$ in the region including the GOODS-N and the J0053+1234 region by using GMOS-N and GMOS-S, respectively. Among 25 candidates, five objects are identified to be at $z \sim 5$ (two of them were already identified by an earlier study) and one object very close to the color-selection window turned out to be a foreground galaxy. With this spectroscopically identified sample and those from previous studies, we derived the lower limits on the number density of bright ($M_{UV}<-22.0$ mag) LBGs at $z \sim 5$. These lower limits are comparable to or slightly smaller than the number densities of UV luminosity functions (UVLFs) that show the smaller number density among $z \sim 5$ UVLFs in literature. However, by considering that there remain many LBG candidates without spectroscopic observations, the number density of bright LBGs is expected to increase by a factor of two or more. The evidence for the deficiency of UV luminous LBGs with large Ly$α$ equivalent widths was reinforced. We discuss possible causes for the deficiency and prefer the interpretation of dust absorption.

astro-ph.CO↗

arXiv2008

The Stellar Populations of Lyman Break Galaxies at z~5

We present the results of Spectral Energy Distribution(SED) fitting analysis for Lyman Break Galaxies(LBGs) at z~5 in the GOODS-N and its flanking fields (the GOODS-FF). With the publicly available IRAC images in the GOODS-N and IRAC data in the GOODS-FF, we constructed the rest-frame UV to optical SEDs for a large sample (~100) of UV-selected galaxies at z~5. Comparing the observed SEDs with model SEDs generated with a population synthesis code, we derived a best-fit set of parameters (stellar mass, age, color excess, and star formation rate) for each of sample LBGs. The derived stellar masses range from 10^8 to 10^11M_sun with a median value of 4.1x10^9M_sun. The comparison with z=2-3 LBGs shows that the stellar masses of z~5 LBGs are systematically smaller by a factor of 3-4 than those of z=2-3 LBGs in a similar rest-frame UV luminosity range. The star formation ages are relatively younger than those of the z=2-3 LBGs. We also compared the results for our sample with other studies for the z=5-6 galaxies. Although there seem to be similarities and differences in the properties, we could not conclude its significance. We also derived a stellar mass function of our sample by correcting for incompletenesses. Although the number densities in the massive end are comparable to the theoretical predictions from semi-analytic models, the number densities in the low-mass part are smaller than the model predictions. By integrating the stellar mass function down to 10^8 M_sun, the stellar mass density at z~5 is calculated to be (0.7-2.4)x10^7M_sun Mpc^-3. The stellar mass density at z~5 is dominated by massive part of the stellar mass function. Compared with other observational studies and the model predictions, the mass density of our sample is consistent with general trend of the increase of the stellar mass density with time.

astro-ph↗

arXiv2008

The Stellar Populations of Lyman Break Galaxies at $z\sim5$

We present the results of Spectral Energy Distribution (SED) fitting analysis for Lyman Break Galaxies (LBGs) at $z\sim5$ in the GOODS-N and its flanking fields. From the SED fitting for $\sim100$ objects, we found that the stellar masses range from $10^{8}$ to $10^{11}M_{\odot}$ with a median value of $4\times10^{9}M_{\odot}$. By using the large sample of galaxies at $z\sim5$, we construct the stellar mass function (SMF) with incompleteness corrections. By integrating down to $10^{8}M_{\odot}$, the cosmic stellar mass density at $z\sim5$ is calculated to be $7\times10^{6}M_{\odot}\textrm{Mpc}^{-3}$.

astro-ph↗