arXiv subjects

Toshio Matsumoto

Publications and source records attributed to Toshio Matsumoto.

At least 19 recordsLinked to original sources

arXiv2025

The Cosmic Infrared Background Experiment-2: An Intensity Mapping Optimized Sounding-rocket Payload to Understand the Near-IR Extragalactic Background Light

The background light produced by emission from all sources over cosmic history is a powerful diagnostic of structure formation and evolution. At near-infrared wavelengths, this extragalactic background light (EBL) is comprised of emission from galaxies stretching all the way back to the first-light objects present during the Epoch of Reionization. The Cosmic Infrared Background Experiment 2 (CIBER-2) is a sounding-rocket experiment designed to measure both the absolute photometric brightness of the EBL over 0.5 - 2.0 microns and perform an intensity mapping measurement of EBL spatial fluctuations in six broad bands over the same wavelength range. CIBER-2 comprises a 28.5 cm, 80K telescope that images several square degrees to three separate cameras. Each camera is equipped with an HAWAII-2RG detector covered by an assembly that combines two broadband filters and a linear-variable filter, which perform the intensity mapping and absolute photometric measurements, respectively. CIBER-2 has flown three times: an engineering flight in 2021; a terminated launch in 2023; and a successful science flight in 2024. In this paper, we review the science case for the experiment; describe the factors motivating the instrument design; review the optical, mechanical, and electronic implementation of the instrument; present preflight laboratory characterization measurements; and finally assess the instrument's performance in flight.

astro-ph.IM↗

arXiv2025

MIRIS Paα Galactic Plane Survey. II. The Catalog of Paα Emission-line Sources

Using data from the MIRIS Paα Galactic Plane Survey (MIPAPS), we present a Paα 1.87 um line image of the entire Galactic plane within the latitude range of -3° < b < +3°, revealing numerous Paα features. Based on the MIPAPS Paα image and the WISE H II region catalog, we compile a catalog of 1489 Paα emission-line sources in the Galactic plane within 90° < l < 330°. By comparing our Paα images with Hα images constructed from the IPHAS and VPHAS+ survey data, we demonstrate the advantages of Paα line observations. We identify 902 Paα sources associated with H II regions, and newly confirm 619 H II region candidates as definitive H II regions through Paα or Hα detections. We also identify 261 extended and 326 point-like Paα sources not included in the WISE catalog, most of which have Hα counterparts in the IPHAS or VPHAS+ images. A search of the SIMBAD database indicates that these sources originate from diverse object types. By measuring Paα and Hα fluxes, we estimate the E(B-V) color excesses derived from extended emissions for 138 Paα sources, showing good agreement with values obtained from spectrophotometry of ionizing stars in previous studies. Futhermore, we calculate total Lyman continuum luminosities for 42 Paα sources, providing constraints on the distances to H II regions and the spectral types of their ionizing stars. These results highlight the scientific potential of Paα line observations and the benefits of combining multiple hydrogen recombination lines in exploring ionized regions.

astro-ph.GA↗

arXiv2021

Polarization spectrum of near infrared zodiacal light observed with CIBER

We report the first measurement of the zodiacal light (ZL) polarization spectrum in the near-infrared between 0.8 and 1.8 $μ$m. Using the low-resolution spectrometer (LRS) on board the Cosmic Infrared Background Experiment (CIBER), calibrated for absolute spectrophotometry and spectropolarimetry, we acquire long-slit polarization spectral images of the total diffuse sky brightness towards five fields. To extract the ZL spectrum, we subtract contribution of other diffuse radiation, such as the diffuse galactic light (DGL), the integrated star light (ISL), and the extragalactic background light (EBL). The measured ZL polarization spectrum shows little wavelength dependence in the near-infrared and the degree of polarization clearly varies as a function of the ecliptic coordinates and solar elongation. Among the observed fields, the North Ecliptic Pole shows the maximum degree of polarization of $\sim$ 20$\%$, which is consistent with an earlier observation from the Diffuse Infrared Background Experiment (DIRBE) aboard on the Cosmic Background Explorer (COBE). The measured degree of polarization and its solar elongation dependence are reproduced by the empirical scattering model in the visible band and also by the Mie scattering model for large absorptive particles, while the Rayleigh scattering model is ruled out. All of our results suggest that the interplanetary dust is dominated by large particles.

astro-ph.EP↗

arXiv2021

Probing Intra-Halo Light with Galaxy Stacking in CIBER Images

We study the stellar halos of $0.2\lesssim z \lesssim 0.5$ galaxies with stellar masses spanning $M_*\sim 10^{10.5}$ to $10^{12}M_\odot$ (approximately $L_*$ galaxies at this redshift) using imaging data from the Cosmic Infrared Background Experiment (CIBER). A previous CIBER fluctuation analysis suggested that intra-halo light (IHL) contributes a significant portion of the near-infrared extragalactic background light (EBL), the integrated emission from all sources throughout cosmic history. In this work, we carry out a stacking analysis with a sample of $\sim$30,000 Sloan Digital Sky Survey (SDSS) photometric galaxies from CIBER images in two near-infrared bands (1.1 and 1.8 $μ$m) to directly probe the IHL associated with these galaxies. We stack galaxies in five sub-samples split by brightness, and detect an extended galaxy profile, beyond the instrument point spread function (PSF), derived by stacking stars. We jointly fit a model for the inherent galaxy light profile, plus large-scale one- and two-halo clustering to measure the extended galaxy IHL. We detect non-linear one-halo clustering in the 1.8 $μ$m band, at a level consistent with numerical simulations. Our results on the galaxy profile suggest that $\sim 50\%$ of the total galaxy light budget in our galaxy sample resides in the outskirts of the galaxies at $r > 10$ kpc. We describe this extended emission as IHL and and are able to study how this fraction evolves with cosmic time. These results are new in the near-infrared wavelength at the $L_*$ mass scale, and suggest that IHL has a significant contribution to the integrated galactic light, and to the amplitude of large-scale background fluctuations.

astro-ph.GA↗

arXiv2021

Measurements of the Zodiacal Light Absolute Intensity through Fraunhofer Absorption Line Spectroscopy with CIBER

Scattered sunlight from the interplanetary dust (IPD) cloud in our Solar system presents a serious foreground challenge for spectro-photometric measurements of the Extragalactic Background Light (EBL). In this work, we report on measurements of the absolute intensity of the Zodiacal Light (ZL) using the novel technique of Fraunhofer line spectroscopy on the deepest 8542 Angstrom line of the near-infrared CaII absorption triplet. The measurements are performed with the Narrow Band Spectrometer (NBS) aboard the Cosmic Infrared Background Experiment (CIBER) sounding rocket instrument. We use the NBS data to test the accuracy of two ZL models widely cited in the literature; the Kelsall and Wright models, which have been used in foreground removal analyses that produce high and low EBL results respectively. We find a mean reduced chi squared of 3.5 for the Kelsall model and a chi squared of 2.0 for the Wright model. The best description of our data is provided by a simple modification to the Kelsall model which includes a free ZL offset parameter. This adjusted model describes the data with a reduced chi squared of 1.5 and yields an inferred offset amplitude of 46 +- 19 nW m^-2 sr^-1 extrapolated to 12500 Angstroms. These measurements elude to the potential existence of a dust cloud component in the inner Solar system whose intensity does not strongly modulate with the Earth's motion around the Sun.

astro-ph.EP↗

arXiv2020

On the origin of the optical and near-infrared extragalactic background light

In optical and near-infrared background light, excess brightness and fluctuation over the known backgrounds have been reported. To delineate their origin, a fluctuation analysis of the deepest optical images was performed, leading to the detection of a flat fluctuation down to 0.2 arcsec, which is much larger than that expected for galaxies. The sky brightness obtained from the detected fluctuation is a few times brighter than the integrated light of the galaxies. These findings require some new objects. As a candidate, faint compact objects (FCOs) whose surface number density rapidly increases to the faint end were proposed. FCOs are very compact and show peculiar spectra with infrared excess. If FCOs cause the excess brightness and fluctuation, the surface number density reaches 2.6e3 in 1 square arcsec. Gamma ray observations require the redshift of FCOs to be less than 0.1 with FCOs consisting of missing baryons. A very low M/L indicates that FCOs are powered by gravitational energy associated with black holes.

astro-ph.GA↗

arXiv2019

Fluctuation of the background sky in the Hubble Extremely Deep Field (XDF) and its origin

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 arcsec, indicating the existence of a spatial structure even at the 0.2 arcsec scale. The detected auto and cross-correlations provide a lower limit of 24 nW m$^{-2}$ sr$^{-1}$ for the absolute sky brightness at 700-900 nm, which is consistent with previous observations. We searched for candidate objects to explain the detected large fluctuation using the catalog of the Hubble Ultra Deep Field (UDF), and found that the surface number density of faint compact objects (FCOs) rapidly increases toward the faint end. Radial profiles of FCOs are indistinguishable from the PSF, and the effective radius based on de Vaucouleur's law is estimated to be smaller than 0.02 arcsec. The SEDs of FCOs follow a power law at optical wavelengths, but show greater emission and structure at $λ$ > 1 $μ$m. Assuming that the FCOs are the cause of the excess brightness and fluctuations, the faint magnitude limit is 34.9 mag for the F775W band, and the surface number density reaches $2.6 \times 10^3$ (arcsec)$^{-2}$. Recent gamma-ray observations require that the redshift of FCOs must be less than 0.1, if FCOs are the origin of the excess optical and infrared background. Assuming that FCOs consist of missing baryons, the mass and luminosity of a single FCO range from $10^{2}$ to 1$0^{3}$ solar units, and mass-to-luminosity ratio is significantly lower than 1.0 solar unit. The maximum effective radius of an FCO is 4.7 pc. These results and the good correlation between near-infrared and X-ray background indicate that FCOs could be powered by the gravitational energy associated with black holes.

astro-ph.GA↗

arXiv2018

MIRIS Paα Galactic Plane Survey. I. Comparison with IPHAS Hα in l = 96°-116°

The Multipurpose InfraRed Imaging System (MIRIS) performed the MIRIS Paα Galactic Plane Survey (MIPAPS), which covers the entire Galactic plane within the latitude range of -3° < b < +3° at Paα (1.87 um). We present the first result of the MIPAPS data extracted from the longitude range of l = 96.5°-116.3°, and demonstrate the data quality and scientific potential of the data by comparing them with Hα maps obtained from the INT Photometric Hα Survey (IPHAS) data. We newly identify 90 H II region candidates in the WISE H II region catalog as definite H II regions by detecting the Paα and/or Hα recombination lines, out of which 53 H II regions are detected at Paα. We also report the detection of additional 29 extended and 18 point-like sources at Paα. We estimate the E(B-V) color excesses and the total Lyman continuum luminosities for H II regions by combining the MIPAPS Paα and IPHAS Hα fluxes. The E(B-V) values are found to be systematically lower than those estimated from point stars associated with H II regions. Utilizing the MIPAPS Paα and IPHAS Hα images, we obtain an E(B-V) map for the entire region of the H II region Sh2-131 with an angular size of ~2.5°. The E(B-V) map shows not only numerous high-extinction filamentary features but also negative E(B-V) regions, indicating Hα excess. The Hα excess and the systematic underestimation of E(B-V) are attributed to light scattered by dust.

astro-ph.GA↗

arXiv2017

New Spectral Evidence of an Unaccounted Component of the Near-infrared Extragalactic Background Light from the CIBER

The Extragalactic Background Light (EBL) captures the total integrated emission from stars and galaxies throughout the cosmic history. The amplitude of the near-infrared EBL from space absolute photometry observations has been controversial and depends strongly on the modeling and subtraction of the Zodiacal light foreground. We report the first measurement of the diffuse background spectrum at 0.8-1.7 um from the CIBER experiment. The observations were obtained with an absolute spectrometer over two flights in multiple sky fields to enable the subtraction of Zodiacal light, stars, terrestrial emission, and diffuse Galactic light. After subtracting foregrounds and accounting for systematic errors, we find the nominal EBL brightness, assuming the Kelsall Zodiacal light model, is 42.7+11.9/-10.6 nW/m2/sr at 1.4 um. We also analyzed the data using the Wright Zodiacal light model, which results in a worse statistical fit to the data and an unphysical EBL, falling below the known background light from galaxies at <1.3 um. Using a model-independent analysis based on the minimum EBL brightness, we find an EBL brightness of 28.7+5.1/-3.3 nW/m2/sr at 1.4 um. While the derived EBL amplitude strongly depends on the Zodiacal light model, we find that we cannot fit the spectral data to Zodiacal light, Galactic emission, and EBL from solely integrated galactic light from galaxy counts. The results require a new diffuse component, such as an additional foreground or an excess EBL with a redder spectrum than that of Zodiacal light.

astro-ph.GA↗

arXiv2017

Low-Resolution Near-infrared Stellar Spectra Observed by the Cosmic Infrared Background Experiment (CIBER)

We present near-infrared (0.8-1.8 $μ$m) spectra of 105 bright (${m_{J}}$ $<$ 10) stars observed with the low resolution spectrometer on the rocket-borne Cosmic Infrared Background Experiment (CIBER). As our observations are performed above the earth's atmosphere, our spectra are free from telluric contamination, which makes them a unique resource for near-infrared spectral calibration. Two-Micron All Sky Survey (2MASS) photometry information is used to identify cross-matched stars after reduction and extraction of the spectra. We identify the spectral types of the observed stars by comparing them with spectral templates from the Infrared Telescope Facility (IRTF) library. All the observed spectra are consistent with late F to M stellar spectral types, and we identify various infrared absorption lines.

astro-ph.SR↗

arXiv2014

On the Origin of Near-Infrared Extragalactic Background Light Anisotropy

Extragalactic background light (EBL) anisotropy traces variations in the total production of photons over cosmic history, and may contain faint, extended components missed in galaxy point source surveys. Infrared EBL fluctuations have been attributed to primordial galaxies and black holes at the epoch of reionization (EOR), or alternately, intra-halo light (IHL) from stars tidally stripped from their parent galaxies at low redshift. We report new EBL anisotropy measurements from a specialized sounding rocket experiment at 1.1 and 1.6 micrometers. The observed fluctuations exceed the amplitude from known galaxy populations, are inconsistent with EOR galaxies and black holes, and are largely explained by IHL emission. The measured fluctuations are associated with an EBL intensity that is comparable to the background from known galaxies measured through number counts, and therefore a substantial contribution to the energy contained in photons in the cosmos.

astro-ph.CO↗

arXiv2014

High-z gamma-ray bursts for unraveling the dark ages mission HiZ-GUNDAM

We are now investigating and studying a small satellite mission HiZ-GUNDAM for future observation of gamma-ray bursts (GRBs). The mission concept is to probe "the end of dark ages and the dawn of formation of astronomical objects", i.e. the physical condition of early universe beyond the redshift z > 7. We will consider two kinds of mission payloads, (1) wide field X-ray imaging detectors for GRB discovery, and (2) a near infrared telescope with 30 cm in diameter to select the high-z GRB candidates effectively. In this paper, we explain some requirements to promote the GRB cosmology based on the past observations, and also introduce the mission concept of HiZ-GUNDAM and basic development of X-ray imaging detectors.

astro-ph.IM↗

arXiv2013

Low-Resolution Spectrum of the Diffuse Galactic Light and 3.3 um PAH emission with AKARI InfraRed Camera

We first obtained the spectrum of the diffuse Galactic light (DGL) at general interstellar space in 1.8-5.3 um wavelength region with the low-resolution prism spectroscopy mode of the AKARI Infra-Red Camera (IRC) NIR channel. The 3.3 um PAH band is detected in the DGL spectrum at Galactic latitude |b| < 15 deg, and its correlations with the Galactic dust and gas are confirmed. The correlation between the 3.3 um PAH band and the thermal emission from the Galactic dust is expressed not by a simple linear correlation but by a relation with extinction. Using this correlation, the spectral shape of DGL at optically thin region (5 deg < |b| < 15 deg) was derived as a template spectrum. Assuming that the spectral shape of this template spectrum is uniform at any position, DGL spectrum can be estimated by scaling this template spectrum using the correlation between the 3.3 um PAH band and the thermal emission from the Galactic dust.

astro-ph.GA↗

arXiv2013

Low-Resolution Spectrum of the Extragalactic Background Light with AKARI InfraRed Camera

The Extragalactic Background Light (EBL) as an integrated light from outside of our Galaxy includes information of the early universe and the Dark Ages. We analyzed the spectral data of the astrophysical diffuse emission obtained with the low-resolution spectroscopy mode on the AKARI Infra-Red Camera (IRC) in 1.8-5.3 um wavelength region. Although the previous EBL observation in this wavelength region is restricted to the observations by DIRBE and IRTS, this study adds a new independent result with negligible contamination of Galactic stars owing to higher sensitivity for point sources. Other two major foreground components, the zodiacal light (ZL) and the diffuse Galactic light (DGL), were subtracted by taking correlations with ZL brightness estimated by the DIRBE ZL model and with the 100 um dust thermal emission, respectively. The isotropic emission was obtained as EBL, which shows significant excess over integrated light of galaxies at <4 um. The obtained EBL is consistent with the previous measurements by IRTS and DIRBE.

astro-ph.CO↗

arXiv2013

Low-Resolution Spectrum of the Zodiacal Light with AKARI InfraRed Camera

We present the near- and mid-infrared zodiacal light spectrum obtained with the AKARI Infra-Red Camera (IRC). A catalog of 278 spectra of the diffuse sky covering a wide range of Galactic and ecliptic latitudes was constructed. The wavelength range of this catalog is 1.8-5.3 μm with wavelength resolution of λ/Δλ~20. Advanced reduction methods specialized for the slit spectroscopy of diffuse sky spectra are developed for constructing the spectral catalog. Based on the comparison analysis of the spectra collected in different seasons and ecliptic latitudes, we confirmed that the spectral shape of the scattered component and the thermal emission component of the zodiacal light in our wavelength range does not show any dependence on location and time, but relative brightness between them varies with location. We also confirmed that the color temperature of the zodiacal emission at 3-5 μm is 300+/-10 K at any ecliptic latitude. This emission is expected to be originated from sub-micron dust particles in the interplanetary space.

astro-ph.EP↗

arXiv2012

Brightness and Fluctuation of the Mid-Infrared Sky from AKARI Observations towards the North Ecliptic Pole

We present the smoothness of the mid-infrared sky from observations by the Japanese infrared astronomical satellite AKARI. AKARI monitored the north ecliptic pole (NEP) during its cold phase with nine wavebands covering from 2.4 to 24 micron, out of which six mid-infrared bands were used in this study. We applied power spectrum analysis to the images in order to search for the fluctuation of the sky brightness. Observed fluctuation is explained by fluctuation of photon noise, shot noise of faint sources, and Galactic cirrus. The fluctuations at a few arcminutes scales at short mid-infrared wavelengths (7, 9, and 11 micron) are largely caused by the diffuse Galactic light of the interstellar dust cirrus. At long mid-infrared wavelengths (15, 18, and 24 micron), photon noise is the dominant source of fluctuation over the scale from arcseconds to a few arcminutes. The residual fluctuation amplitude at 200 arcseconds after removing these contributions is at most 1.04 +/- 0.23 nW m^-2 sr^-1 or 0.05% of the brightness at 24 micron and at least 0.47 +/- 0.14 nW m^-2 sr^-1 or 0.02% at 18 micron. We conclude that the upper limit of the fluctuation in the zodiacal light towards the NEP is 0.03% of the sky brightness, taking 2σ error into account.

astro-ph.CO↗

arXiv2011

Measuring Light from the Epoch of Reionization with CIBER, the Cosmic Infrared Background Experiment

Ultraviolet emission from the first generation of stars in the Universe ionized the intergalactic medium in a process which was completed by z~6; the wavelength of these photons has been redshifted by (1+z) into the near infrared today and can be measured using instruments situated above the Earth's atmosphere. First flying in February 2009, the Cosmic Infrared Background Experiment (CIBER) comprises four instruments housed in a single reusable sounding rocket borne payload. CIBER will measure spatial anisotropies in the extragalactic IR background caused by cosmological structure from the epoch of reionization using two broadband imaging instruments, make a detailed characterization of the spectral shape of the IR background using a low resolution spectrometer, and measure the absolute brightness of the Zodical light foreground with a high resolution spectrometer in each of our six science fields. This paper presents the scientific motivation for CIBER and details of its first two flights, including a review of the published scientific results from the first flight and an outlook for future reionization science with CIBER data.

astro-ph.CO↗

arXiv2009

Cosmic Infrared Background ExpeRiment (CIBER): A Probe of Extragalactic Background Light from Reionization

The Cosmic Infrared Background ExpeRiment (CIBER) is a rocket-borne absolute photometry imaging and spectroscopy experiment optimized to detect signatures of first-light galaxies present during reionization in the unresolved IR background. CIBER-I consists of a wide-field two-color camera for fluctuation measurements, a low-resolution absolute spectrometer for absolute EBL measurements, and a narrow-band imaging spectrometer to measure and correct scattered emission from the foreground zodiacal cloud. CIBER-I was successfully flown on February 25th, 2009 and has one more planned flight in early 2010. We propose, after several additional flights of CIBER-I, an improved CIBER-II camera consisting of a wide-field 30 cm imager operating in 4 bands between 0.5 and 2.1 microns. It is designed for a high significance detection of unresolved IR background fluctuations at the minimum level necessary for reionization. With a FOV 50 to 2000 times largerthan existing IR instruments on satellites, CIBER-II will carry out the definitive study to establish the surface density of sources responsible for reionization.

astro-ph.CO↗