GALAXY SED FITTING FROM AKARI TO HERSCHEL: 0.7 < z < 4 SUB-MILLIMETER LYMAN BREAK GALAXIES IN INFRARED

Burgarella, D.,The PEP-HerMES-COSMOS team, The PEP-HerMES-COSMOS team The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4

Lyman break Galaxies are galaxies selected in the rest-frame ultraviolet. But, one important and missing information for these Lyman break galaxies is the amount of dust attenuation. This is crucial to estimate the total star formation rate of this class of objects and, ultimately, the cosmic star formation density. AKARI, Spitzer and Herschel are therefore the major facilities that could provide us with this information. As part of the Herschel Multi-tiered Extragalactic Survey, we have began investigating the rest-frame far-infrared properties of a sample of more than 4,800 Lyman Break Galaxies in the GOODS-North fiels. Most LBGs are not detected individually, but we do detect a sub-sample of 12 objects at 0.7 < z <1.6 and one object at z = 2.0. The ones detected by Herschel SPIRE have redder observed NUV-U and U-R colors than the others, while the undetected ones have colors consistent with average LBGs at z > 2.5. We have analysed their UV-to-FIR spectral energy distributions using the code cigale to estimate their physical parameters. We find that LBGs detected by SPIRE are high mass, luminous infrared galaxies. They also appear to be located in a triangle-shaped region in the $A_{FUV}$ vs. $logL_{FUV}$ diagram limited by $A_{FUV}$ = 0 at the bottom and by a diagonal following the temporal evolution of the most massive galaxies from the bottom-right to the top-left of the diagram. In a second step, we move to the larger COSMOS field where we have been able to detect 80 Lyman break galaxies (out of ~ 15,600) in the far infrared. They form the largest sample of Lyman break galaxies at z > 2.5 detected in the far-infrared. We tentatively name them Submillimeter Lyman break galaxies (S-LBGs).

Ultraviolet-to-far infrared properties of Lyman break galaxies and luminous infrared galaxies at z∼1

Burgarella, D.,Perez-Gonzalez, P. G.,Tyler, K. D.,Rieke, G. H.,Buat, V.,Takeuchi, T. T.,Lauger, S.,Arnouts, S.,Ilbert, O.,Barlow, T. A. EDP Sciences 2006 Astronomy and astrophysics Vol.450 No.1

GALAXY SED FITTING

Burgarella Denis,Boquien Mederic,Buat Veronique,Ciesla Laure,Rhoelly Yannick 한국천문학회 2017 天文學論叢 Vol.32 No.1

Modelling and fitting the spectral energy distribution (SED) of galaxies or regions of galaxies is one of the most useful methods available to the astronomer nowadays. By modelling the SEDs and comparing the models to the observations, we can collect important information on the physical processes at play in the formation and evolution of galaxies. The models allow to follow the evolution of the galaxies from their formation on. The versatility of code is crucial because of the diversity of galaxies. The analysis is only relevant and useful if the models can correctly reproduce this diversity now and across (as best as possible) all redshifts. On the other hand, the code needs to run fast to compare several million or tens of millions of models and to select the best (on a probabilistic basis) one that best resembles the observations. With this important point in mind, it seems logical that we should efficiently make use of the computer power available to the average astronomer. For instance, it seems difficult, today, to model and fit SEDs without a parallelized code. We present the new Python version of CIGALE SED fitting code and its characteristics. CIGALE comes in two main flavours: {\it CIGALE Classic} to fit SEDs and {\it CIGALE Model} to create spectra and SEDs of galaxies at all redshifts. The latest can potentially be used in conjunction with galaxy evolution models of galaxy formation and evolution such as semi-analytic ones.

NEP-AKARI: EVOLUTION WITH REDSHIFT OF DUST ATTENUATION IN 8 μm SELECTED GALAXIES

V. Buat,N. Oi,D. Burgarella,K. Malek,H. Matsuhara,K. Murata,S. Serjeant,T.T. Takeuchi,M. Malkan,C. Pearson,T. Wada 한국천문학회 2017 天文學論叢 Vol.32 No.1

We built a 8 $\mu$m selected sample of galaxies in the NEP-AKARI field by defining 4redshift bins with the four AKARI bands at 11, 15, 18 and 24 microns (0.15 < z < 0.49,0.75 < z < 1.34, 1.34 < z < 1.7 and 1.7 < z < 2.05) . Our sample contains 4079 sources, 599 are securely detected with$Herschel$/PACS. Also adding ultraviolet (UV) data from $GALEX$, we fit the spectral energy distributions using the physically motivated codeCIGALE to extract the star formation rate, stellar mass, dustattenuation and the AGN contribution to the total infrared luminosity ($L_{\rm IR}$). We discuss the impact of the adoptedattenuation curve and that of the wavelength coverage to estimate these physical parameters. We focus on galaxies with a luminosity close the characteristic $L_{\rm IR}^*$ in the different redshift bins to studythe evolution with redshift of the dust attenuation in these galaxies.

DETECTION OF THE COSMIC FAR-INFRARED BACKGROUND IN AKARI DEEP FIELD SOUTH

Matsuura, S.,Shirahata, M.,Kawada, M.,Takeuchi, T. T.,Burgarella, D.,Clements, D. L.,Jeong, W.-S.,Hanami, H.,Khan, S. A.,Matsuhara, H.,Nakagawa, T.,Oyabu, S.,Pearson, C. P.,Pollo, A.,Serjeant, S.,Taka IOP Publishing 2011 The Astrophysical journal Vol.737 No.1

<P>We report new limits on the absolute brightness and spatial fluctuations of the cosmic infrared background (CIB) via the AKARI satellite. We carried out observations at 65, 90, 140, and 160 mu m as a cosmological survey in AKARI Deep Field South, which is one of the lowest cirrus regions with a contiguous area of the sky. After removing bright galaxies and subtracting zodiacal and Galactic foregrounds from the measured sky brightness, we successfully measured the CIB brightness and its fluctuations across a wide range of angular scales, from arcminutes to degrees. The measured CIB brightness is consistent with previous results reported from COBE data, but significantly higher than the lower limits at 70 and 160 mu m obtained via Spitzer from the stacking analysis of selected 24 mu m sources. The discrepancy with the Spitzer result is possibly due to a new galaxy population at high redshift obscured by hot dust or unknown diffuse emission. From a power spectrum analysis at 90 mu m, two components were identified: the CIB fluctuations with shot noise due to individual galaxies in a small angular scale from the beam size up to 10 arcminutes, and Galactic cirrus emission dominating at the largest angular scales of a few degrees. The overall shape of the power spectrum at 90 mu m is very similar to that at longer wavelengths, as observed by Spitzer and the Balloon-borne Large-Aperture Submillimeter Telescope (BLAST). Our power spectrum, with an intermediate angular scale of 10-30 arcminutes, gives a firm upper limit for galaxy clustering, which was found by Spitzer and BLAST. Moreover, the color of the CIB fluctuations, which is obtained by combining our data with the previous results, is as red as ultra-luminous infrared galaxies at high redshift. These galaxies are not likely to provide the majority of the CIB emission at 90 mu m, but are responsible for the fluctuations. Our results provide new constraints on the evolution and clustering properties of distant infrared galaxies and any diffuse emission from the early universe.</P>

HERSCHEL OBSERVATIONS IN THE AKARI NEP FIELD: INITIAL SOURCE COUNTS

Chris Pearson,Ryan Cheale,STEPHEN SERJEANT,Hideo Matsuhara,Glenn J. White,Denis Burgarella,Ivan Valtchanov,Bruno Altieri,David L. Clements,Ros Hopwood 한국천문학회 2017 天文學論叢 Vol.32 No.1

The preliminary data reduction, analysis and first results from the Herschel survey of the AKARI NEP field are presented. Herschel SPIRE observations of the NEP-Wide region and PACS observations of the NEP-Deep region have yielded galaxy catalogues of 4000 and 900 sources respectively down to flux density levels of approximately 15 mJy at 100-250 microns. Source counts produced from these catalogues reach cosmologically significant depths tracing the evolutionary upturn and turnover in the source counts. The source counts are in agreement with other large area surveys carried out with Herschel bridging the gap between the shallow and deep Herschel surveys.

STAR FORMATION RATE CALIBRATIONS FOR WISE LUMINOSITIES

Yuan, F.T.,Takeuchi, T.T,Buat, V.,Burgarella, D. The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4

Starting from an infrared selected GALEX-SDSS-2MASS-AKARI sample of local star forming galaxies, we built mock samples from redshift 0 to 2.5 to investigate star formation rate (SFR) calibrations using WISE luminosities. We find W3 and W4 band fluxes can indicate SFRs with small scatters when the rest-frame wavelengths are longer than ${\sim}6{\mu}m$. When the wavelength becomes shorter, the observed luminosities are more tightly connected to the emission of old stellar populations than dust, therefore lose the reliability to trace the SFR. The current SFR calibrations are consistent with previous studies.

FAR INFRARED GALAXIES IN AKARI'S EYE

Malek, K.,Pollo, A.,Takeuchi, T.T.,Giovannoli, E.,Buat, V.,Burgarella, D.,Malkan, M. The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4

We present the results of Spectral Energy Distribution (SED) fitting of far-infrared galaxies detected in the AKARI Deep Field-South (ADF-S) Survey and discuss their physical properties. Additionally, we perform a comparison between photometric redshifts estimated using only optical and both optical and infrared data. We conclude that our sample consists mostly of nearby galaxies rich in dust and young stars. We observe an improvement in the estimation of photometric redshifts when the IR data are included, comparing to a standard approach based mainly on the optical to UV photometry.

Photometric redshift accuracy in <i>AKARI</i> deep surveys

Negrello, M.,Serjeant, S.,Pearson, C.,Takagi, T.,Efstathiou, A.,Goto, T.,Burgarella, D.,Jeong, W.-S.,Im, M.,Lee, H. M.,Matsuhara, H.,Oyabu, S.,Wada, T.,White, G. Blackwell Publishing Ltd 2009 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.394 No.1

<P>ABSTRACT</P><P>We investigate the photometric redshift accuracy achievable with the <I>AKARI</I> infrared data in deep multiband surveys, such as in the North Ecliptic Pole field. We demonstrate that the passage of redshifted polycyclic aromatic hydrocarbons (PAH) and silicate features into the mid-infrared wavelength window covered by <I>AKARI</I> is a valuable means to recover the redshifts of starburst galaxies. To this end, we have collected a sample of ∼60 galaxies drawn from the Great Observatories Origins Deep Survey-North Field with spectroscopic redshift 0.5 ≲<I>z</I><SUB>spec</SUB>≲ 1.5 and photometry from 3.6 to 24 μm, provided by the <I>Spitzer</I>, <I>Infrared Space Observatory</I> and <I>AKARI</I> satellites. The infrared spectra are fitted using synthetic galaxy spectral energy distributions which account for starburst and active nuclei emission. For ∼90 per cent of the sources in our sample, the redshift is recovered with an accuracy |<I>z</I><SUB>phot</SUB>−<I>z</I><SUB>spec</SUB>|/(1 +<I>z</I><SUB>spec</SUB>) ≲ 10 per cent. A similar analysis performed on a set of simulated spectra shows that the <I>AKARI</I> infrared data alone can provide photometric redshifts accurate to |<I>z</I><SUB>phot</SUB>−<I>z</I><SUB>spec</SUB>|/(1 +<I>z</I><SUB>spec</SUB>) ∼ 10 per cent (1σ) at <I>z</I>≲ 2. At higher redshifts, the PAH features are shifted outside the wavelength range covered by <I>AKARI</I> and the photo-<I>z</I> estimates rely on the less prominent 1.6 μm stellar bump; the accuracy achievable in this case on (1 +<I>z</I>) is ∼10–15 per cent, provided that the active galactic nuclei contribution to the infrared emission is subdominant. Our technique is no more prone to redshift aliasing than optical-ultraviolet photo-<I>z</I>, and it may be possible to reduce this aliasing further with the addition of submillimetre and/or radio data.</P>

PROPERTIES OF DUST OBSCURED GALAXIES IN THE NEP-DEEP FIELD

Nagisa Oi,Hideo Matsuhara,CHRIS PEARSON,Veronique Buat,Denis Burgarella,Matt Malkan,Takamitsu Miyaji 한국천문학회 2017 天文學論叢 Vol.32 No.1

We selected 47 DOGs at z ~ 1.5 using optical $R$ (or $r^{'}$), AKARI 18 $\mu$m, and 24 $\mu$m color in the AKARI North Ecliptic Pole (NEP) Deep survey field. Using the colors among 3, 4, 7, and $9\mu$m, we classified them into 3 groups; bump DOGs (23 sources), power-law DOGs (16 sources), and unknown DOGs (8 sources). We built spectral energy distributions (SEDs) with optical to far-infrared photometric data and investigated their properties using SED fitting method. We found that AGN activity such as a AGN contribution to the infrared luminosity and a Chandra detection rate for bump and power-law DOGs are significantly different, while stellar component properties like a stellar mass and a star-formation rate are similar to each other. A specific star-formation rate range of power-law DOGs is slightly higher than that of bump DOGs with wide overlap. Herschel/PACS detection rates are almost the same between bump and power-law DOGs. On the other hand SPIRE detection rates show large differences between bump and power-law DOGs. These results might be explained by differences in dust temperatures. Both groups of DOGs host hot and/or warm dust (~ 50 Kelvin), and many bump DOGs contain cooler dust ($\hspace{0.3em}\raisebox{0.4ex}{$<$}\hspace{-0.75em}\raisebox{-.7ex}{$\sim$}\hspace{0.3em}$ 30 Kelvin).