Search Publications
A systematic study of Galactic infrared bubbles along the Galactic plane with AKARI and Herschel
Oyabu, Shinki; Kaneda, Hidehiro; Ishihara, Daisuke +7 more
Galactic infrared (IR) bubbles, which have shell-like structures in the mid-IR wavelengths, are known to contain massive stars near their centers. Infrared bubbles in inner Galactic regions (|l| ≤ 65°, |b| ≤ 1°) have so far been studied well to understand the massive star formation mechanisms. In this study, we expand the research area to the whol…
A NuSTAR study of the 55 ks hard X-ray pulse-phase modulation in the magnetar 4U 0142+61
Enoto, Teruaki; Makishima, Kazuo; Nakazawa, Kazuhiro +1 more
Archival NuSTAR data of the magnetar 4U 0142+61, acquired in 2014 March for a total time span of 258 ks, were analyzed. This is to reconfirm the 55 ks modulation in the hard X-ray pulse phases of this source, found with a Suzaku observation in 2009 (Makishima et al., 2014, Phys. Rev. Lett., 112, 171102). Indeed, the 10-70 keV X-ray pulsation, dete…
Infrared luminosity functions based on 18 mid-infrared bands: revealing cosmic star formation history with AKARI and Hyper Suprime-Cam*
Momose, Rieko; Hashimoto, Tetsuya; Goto, Tomotsugu +21 more
Much of star formation is obscured by dust. For a complete understanding of the cosmic star formation history (CSFH), infrared (IR) census is indispensable. AKARI carried out deep mid-infrared observations using its continuous nine-band filters in the North Ecliptic Pole (NEP) field (5.4 deg2). This took a significant amount of the sate…
Fluctuation of the background sky in the Hubble Extremely Deep Field (XDF) and its origin
Matsumoto, Toshio; Tsumura, Kohji
We performed a fluctuation analysis of the Hubble Extremely Deep Field (XDF) at four optical wavelength bands and found large fluctuations that are significantly brighter than those expected for ordinary galaxies. Good cross-correlations with flat spectra are found down to {0{^''.}2}, indicating the existence of a spatial structure even…
Investigation of the origin of the anomalous microwave emission in Lambda Orionis
Doi, Yasuo; Onaka, Takashi; Kaneda, Hidehiro +5 more
The anomalous microwave emission (AME) still lacks a conclusive explanation. This excess of emission, roughly between 10 and 50 GHz, tends to defy attempts to explain it as synchrotron or free-free emission. The overlap with frequencies important for cosmic microwave background explorations, combined with a strong correlation with interstellar dus…
Universal detection of high-temperature emission in X-ray isolated neutron stars
Yoneyama, Tomokage; Hayashida, Kiyoshi; Nakajima, Hiroshi +1 more
Strongly magnetized isolated neutron stars (NSs) are categorized into two families, according mainly to their magnetic field strength. Those with a higher magnetic field of 1014-1015 G are called magnetars, characterized by repeated short bursts, and the others are X-ray isolated neutron stars (XINSs) with 1013 G. …
Near-infrared imaging polarimetry toward M 17 SWex
Kusune, Takayoshi; Nakamura, Fumitaka; Tamura, Motohide +7 more
We conducted near-infrared (JHK_s) imaging polarimetry toward the infrared dark cloud (IRDC) M 17 SWex, including almost all of the IRDC filaments as well as its outskirts, with the polarimeter SIRPOL on the IRSF 1.4 m telescope. We revealed the magnetic fields of M 17 SWex with our polarization-detected sources that were selected by some criteria…
Photospheric nitrogen abundances and carbon 12C/13C ratios of red giant stars
Sato, Bun'ei; Omiya, Masashi; Harakawa, Hiroki +1 more
Nitrogen abundances and carbon isotope ratios (12C/13C) in the atmospheres of red giants are known to be influenced by dredge-up of H-burning products, and serve as useful probes to study the nature of evolution-induced envelope mixing. We determined the [N/Fe] and 12C/13C ratios for 239 late-G/early-K g…
The UV spectral slope β and stellar population of most active star-forming galaxies at z ∼ 4
Yamada, Toru; Yamanaka, Satoshi
We investigate a stellar population of star-forming galaxies at z ∼ 4 by focusing on the slope of their rest-frame ultraviolet (UV) continuum, β, where fλ ∝ λβ. We investigate a sample of bright Lyman break galaxies (LBGs) with i' ≤ 26.0 in the Subaru/XMM-Newton Deep Survey field by using a spectral energy distribution fittin…
Characteristics of mid-infrared PAH emission from star-forming galaxies selected at 250 µm in the North Ecliptic Pole field
Hashimoto, Tetsuya; Goto, Tomotsugu; Kim, Seong Jin +11 more
Evolutionary properties of infrared (IR) luminous galaxies are important keys to understand dust-obscured star formation history and galaxy evolution. Based on near- to mid-IR imaging with nine continuous filters of the AKARI space telescope, we present the characteristics of dusty star-forming (SF) galaxies showing polycyclic aromatic hydrocarbon…