scholarly journals AKARI in Orbit—Scientific Potential for Understanding Galaxy Evolution

2006 ◽  
Vol 2 (S235) ◽  
pp. 322-322
Author(s):  
H. Matsuhara ◽  
H. Murakami ◽  
T. Nakagawa ◽  
T. Wada ◽  
S. Matsuura ◽  
...  

AbstractThe AKARI (formerly known as ASTRO-F) mission is the first Japanese satellite dedicated for large area surveys in the infrared (Murakami et al. 2004). AKARI was launched successfully on February 22nd 2006 (JST) from JAXA's Uchinoura Space Centre, Japan. AKARI is now orbiting around the Earth in a Sun-synchronous polar orbit at the altitude of 700 km. The 68.5 cm aperture telescope and scientific instruments are cooled to 6K by liquid Helium and mechanical coolers. The expected liquid Helium holding time is now found to be at least one year after the successful aperture lid-opening on 2006 April 13th (JST). AKARI will perform the most advanced all-sky survey in 6 mid- to far-infrared wavebands since the preceding IRAS mission over 2 decades ago. Deep imaging and spectroscopic surveys near the ecliptic poles with pointed observations are also on-going in 13 wavelength bands at 2-160 μm (see Table 1, details are given in Matsuhara et al. 2006). AKARI is a perfect complement to Spitzer in respect of its wide sky area and wavelength coverage. Two unique aspects of the pointing deep surveys with AKARI are: many imaging bands including the wavelength gap of Spitzer (8-24 μm), and the slitless spectroscopic capability (Ohyama et al. in this proceeding). Not only the All-Sky Survey but also the deep pointing surveys near the ecliptic poles over ~15 deg2 in total will be particularly well suited to construct the luminosity functions of the infrared galaxies, to evaluate their clustering nature, and also to discover rare, exotic objects at various redshifts out to z ~ 3. AKARI is also capable of detecting and measuring the spectrum and the fluctuations of the cosmic infrared background. The in-orbit sensitivity and spatial resolution of the surveys are found to be sufficient to achive the scientific goals listed above.

2020 ◽  
Vol 494 (2) ◽  
pp. 1894-1918
Author(s):  
Thibaud Moutard ◽  
Marcin Sawicki ◽  
Stéphane Arnouts ◽  
Anneya Golob ◽  
Jean Coupon ◽  
...  

ABSTRACT We constrain the rest-frame FUV (1546 Å), NUV (2345 Å), and U-band (3690 Å) luminosity functions (LFs) and luminosity densities (LDs) with unprecedented precision from z ∼ 0.2 to z ∼ 3 (FUV, NUV) and z ∼ 2 (U band). Our sample of over 4.3 million galaxies, selected from the CFHT Large Area U-band Deep Survey (CLAUDS) and HyperSuprime-Cam Subaru Strategic Program (HSC-SSP) data lets us probe the very faint regime (down to MFUV, MNUV, MU ≃ −15 at low redshift), while simultaneously detecting very rare galaxies at the bright end down to comoving densities <10−5 Mpc−3. Our FUV and NUV LFs are well fitted by single-Schechter functions, with faint-end slopes that are very stable up to z ∼ 2. We confirm, but self-consistently and with much better precision than previous studies, that the LDs at all three wavelengths increase rapidly with lookback time to z ∼ 1, and then much more slowly at 1 < z < 2–3. Evolution of the FUV and NUV LFs and LDs at z < 1 is driven almost entirely by the fading of the characteristic magnitude, $M^\star _{\rm UV}$, while at z > 1 it is due to the evolution of both $M^\star _{\rm UV}$ and the characteristic number density $\phi ^\star _{\rm UV}$. In contrast, the U-band LF has an excess of faint galaxies and is fitted with a double-Schechter form; $M^\star _{U}$, both $\phi ^\star _{U}$ components, and the bright-end slope evolve throughout 0.2 < z < 2, while the faint-end slope is constant over at least the measurable 0.05 < z < 0.6. We present tables of our Schechter parameters and LD measurements that can be used for testing theoretical galaxy evolution models and forecasting future observations.


2017 ◽  
Vol 474 (4) ◽  
pp. 5008-5022 ◽  
Author(s):  
F de Gasperin ◽  
H T Intema ◽  
D A Frail

Abstract The radio spectral index is a powerful probe for classifying cosmic radio sources and understanding the origin of the radio emission. Combining data at 147 MHz and 1.4 GHz from the TIFR GMRT Sky Survey (TGSS) and the NRAO VLA Sky Survey (NVSS), we produced a large-area radio spectral index map of ∼80 per cent of the sky (Dec. > − 40 deg), as well as a radio spectral index catalogue containing 1396 515 sources, of which 503 647 are not upper or lower limits. Almost every TGSS source has a detected counterpart, while this is true only for 36 per cent of NVSS sources. We released both the map and the catalogue to the astronomical community. The catalogue is analysed to discover systematic behaviours in the cosmic radio population. We find a differential spectral behaviour between faint and bright sources as well as between compact and extended sources. These trends are explained in terms of radio galaxy evolution. We also confirm earlier reports of an excess of steep-spectrum sources along the galactic plane. This corresponds to 86 compact and steep-spectrum source in excess compared to expectations. The properties of this excess are consistent with normal non-recycled pulsars, which may have been missed by pulsation searches due to larger than average scattering along the line of sight.


2005 ◽  
Vol 619 (1) ◽  
pp. L63-L66 ◽  
Author(s):  
Denis Burgarella ◽  
Véronique Buat ◽  
Todd Small ◽  
Tom A. Barlow ◽  
Samuel Boissier ◽  
...  

2005 ◽  
Vol 216 ◽  
pp. 221-229 ◽  
Author(s):  
Christopher Martin ◽  

We report on early data from the Galaxy Evolution Explorer (GALEX), a NASA Explorer Mission launched on April 28, with a nominal mission start of June 19. GALEX is performing the first space UV sky-survey, including imaging and grism surveys in two bands (1350–1750 Å and 1750–2800 Å). The surveys include an all-sky imaging survey (limit AB∼20–21), a medium imaging survey of 1000 sq. deg (limit AB∼23.5), a deep imaging survey of 100 deg2 (limit AB∼25.5), and a nearby galaxy survey. Spectroscopic grism surveys (R=100–300) will be performed with various depths and sky coverage. Many targets overlap existing or planned surveys, including SDSS, DEEP, NOAODWS, VIRMOS, SWIRE, SINGS, SIRTF-GTO, Chandra, and HST/ACS. We will use the measured UV properties of local galaxies, along with corollary observations, to calibrate the UV-global star formation rate relationship in galaxies. We will apply this calibration to distant galaxies discovered in the deep imaging and spectroscopic surveys to map the history of star formation in the universe over the redshift range 0<z<2. The GALEX mission will include a Guest Investigator program for primary observations and supporting data analysis. This will support a wide variety of investigations made possible by the first UV sky survey.


2001 ◽  
Vol 204 ◽  
pp. 303-303
Author(s):  
T. T. Takeuchi ◽  
H. Hirashita ◽  
T. T. Ishii ◽  
K. Yoshikawa

Recently reported infrared galaxy number counts and cosmic infrared background (CIRB) measures all suggest that galaxies have experienced a strong evolutionary phase. We statistically estimated the galaxy evolution history from these data. We treated the evolution of galaxy luminosity as a stepwise nonparametric form, in order to explore the most suitable evolutionary history which satisfies the constraint from the CIRB. We found that an order of magnitude increase of the far infrared luminosity at redshift z = 0.75 - 1.0 was necessary to reproduce the very high CIRB intensity at ~ 150 μm reported by Hauser et al. (1998). We note that too large an evolutionary factor at high z overpredicts the CIRB intensity around 1 mm. The evolutionary history also satisfies the constraints from galaxy number counts obtained by IRAS, ISO and SCUBA. The rapid evolution of the IR luminosity density required from the CIRB well reproduces the very steep slope of galaxy number counts obtained by ISO. Based on this result and the evolution of optical luminosity density, we quantitatively discuss the contribution of starburst galaxies. In addition, we present the performance of the Japanese IRIS galaxy survey.


2010 ◽  
Vol 515 ◽  
pp. A8 ◽  
Author(s):  
G. Rodighiero ◽  
M. Vaccari ◽  
A. Franceschini ◽  
L. Tresse ◽  
O. Le Fevre ◽  
...  

2001 ◽  
Vol 204 ◽  
pp. 101-118 ◽  
Author(s):  
M. G. Hauser

The cosmic infrared background (CIB) radiation was a long-sought fossil of energetic processes associated with structure formation and chemical evolution since the Big Bang. The COBE Diffuse Infrared Background Experiment (DIRBE) and Far Infrared Absolute Spectrophotometer (FIRAS) were specifically designed to search for this background from 1.25 μm to millimeter wavelengths. These two instruments provided high quality, absolutely calibrated all-sky maps which have enabled the first detections of the CIB, initially at far infrared and submillimeter wavelengths, and more recently in the near infrared as well. The aim of this paper is to review the status of determinations of the CIB based upon COBE measurements. The results show that the energy in the CIB from far infrared to millimeter wavelengths is comparable to that in the integrated light of galaxies from UV to near infrared wavelengths: the universe had a luminous but dusty past. On the assumption that nucleosynthesis in stars is the energy source for most of this light, the results also imply that 1–8% of cosmic baryons has been converted to helium and heavier elements in stars. The integrated background light from UV to millimeter wavelengths, 60–120 nW m−2 sr−1, is about 10% of that in the cosmic microwave background. Current knowledge of the CIB provides significant new constraints on models of the history of star formation and galaxy evolution.


2019 ◽  
Vol 15 (S356) ◽  
pp. 17-22
Author(s):  
Luigi Spinoglio ◽  
Juan A. Fernández-Ontiveros ◽  
Sabrina Mordini

AbstractTo study the dust obscured phase of the galaxy evolution during the peak of the Star Formation Rate (SFR) and the Black Hole Accretion Rate (BHAR) density functions (z = 1–4), rest frame mid-to-far infrared (IR) spectroscopy is needed. At these frequencies, dust extinction is at its minimum and a variety of atomic and molecular transitions, tracing most astrophysical domains, occur. The future IR space telescope mission, SPICA, fully redesigned with its 2.5m mirror cooled down to T < 8K, will be able to perform such observations. With SPICA, we will: 1) obtain a direct spectroscopic measurement of the SFR and of the BHAR histories, 2) measure the evolution of metals and dust to establish the matter cycle in galaxies, 3) uncover the feedback and feeding mechanisms in large samples of distant galaxies, either AGN- or starburst-dominated, reaching lookback times of nearly 12 Gyr. SPICA large-area deep surveys will provide low-resolution, mid-IR spectra and continuum fluxes for unbiased samples of tens of thousands of galaxies, and even the potential to uncover the youngest, most luminous galaxies in the first few hundred million years. In this paper a brief review of the scientific preparatory work that has been done in extragalactic astronomy by the SPICA Consortium will be given.


2020 ◽  
Vol 500 (2) ◽  
pp. 2127-2145
Author(s):  
Christopher C Lovell ◽  
Aswin P Vijayan ◽  
Peter A Thomas ◽  
Stephen M Wilkins ◽  
David J Barnes ◽  
...  

ABSTRACT We introduce the First Light And Reionisation Epoch Simulations (FLARES), a suite of zoom simulations using the EAGLE model. We resimulate a range of overdensities during the Epoch of Reionization (EoR) in order to build composite distribution functions, as well as explore the environmental dependence of galaxy formation and evolution during this critical period of galaxy assembly. The regions are selected from a large $(3.2 \, \mathrm{cGpc})^{3}$ parent volume, based on their overdensity within a sphere of radius 14 h−1 cMpc. We then resimulate with full hydrodynamics, and employ a novel weighting scheme that allows the construction of composite distribution functions that are representative of the full parent volume. This significantly extends the dynamic range compared to smaller volume periodic simulations. We present an analysis of the galaxy stellar mass function (GSMF), the star formation rate distribution function (SFRF), and the star-forming sequence (SFS) predicted by FLARES, and compare to a number of observational and model constraints. We also analyse the environmental dependence over an unprecedented range of overdensity. Both the GSMF and the SFRF exhibit a clear double-Schechter form, up to the highest redshifts (z = 10). We also find no environmental dependence of the SFS normalization. The increased dynamic range probed by FLARES will allow us to make predictions for a number of large area surveys that will probe the EoR in coming years, carried out on new observatories such as Roman and Euclid.


1996 ◽  
Vol 168 ◽  
pp. 17-29
Author(s):  
John C. Mather

The Cosmic Background Explorer (COBE) was developed by NASA Goddard Space Flight Center to measure the diffuse infrared and microwave radiation from the early universe. It also measured emission from nearby sources such as the stars, dust, molecules, atoms, ions, and electrons in the Milky Way, and dust and comets in the Solar System. It was launched 18 November 1989 on a Delta rocket, carrying one microwave instrument and two cryogenically cooled infrared instruments. The Far Infrared Absolute Spectrophotometer (FIRAS) mapped the sky at wavelengths from 0.01 to 1 cm, and compared the CMBR to a precise blackbody. The spectrum of the CMBR differs from a blackbody by less than 0.03%. The Differential Microwave Radiometers (DMR) measured the fluctuations in the CMBR originating in the Big Bang, with a total amplitude of 11 parts per million on a 10° scale. These fluctuations are consistent with scale-invariant primordial fluctuations. The Diffuse Infrared Background Experiment (DIRBE) spanned the wavelength range from 1.2 to 240 μm and mapped the sky at a wide range of solar elongation angles to distinguish foreground sources from a possible extragalactic Cosmic Infrared Background Radiation (CIBR). In this paper we summarize the COBE mission and describe the results from the FIRAS instrument. The results from the DMR and DIRBE were described by Smoot and Hauser at this Symposium.


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