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Journal Article•DOI•

Infrared luminosity functions based on 18 mid-infrared bands: revealing cosmic star formation history with AKARI and Hyper Suprime-Cam∗

Tomotsugu Goto1, Nagisa Oi2, Yousuke Utsumi3, Rieko Momose4, Rieko Momose1, Hideo Matsuhara5, Tetsuya Hashimoto1, Yoshiki Toba6, Youichi Ohyama6, Toshinobu Takagi, Chia-Ying Chiang1, Seong Jin Kim1, Ece Kilerci Eser1, Matthew A. Malkan7, Helen K. Kim7, Takamitsu Miyaji8, Myungshin Im9, Takao Nakagawa5, Woong-Seob Jeong10, Woong-Seob Jeong11, Chris Pearson12, Chris Pearson13, Laia Barrufet, Chris Sedgwick12, Denis Burgarella14, Veronique Buat14, Hiroyuki Ikeda •
National Tsing Hua University1, Tokyo University of Science2, SLAC National Accelerator Laboratory3, University of Tokyo4, Japan Aerospace Exploration Agency5, Academia Sinica Institute of Astronomy and Astrophysics6, University of California, Los Angeles7, National Autonomous University of Mexico8, Seoul National University9, Korea University of Science and Technology10, Korea Astronomy and Space Science Institute11, Open University12, Rutherford Appleton Laboratory13, Aix-Marseille University14
01 Apr 2019-Publications of the Astronomical Society of Japan (Oxford University Press (OUP))-Vol. 71, Iss: 2, pp 30
TL;DR: In this article, the authors used the Hyper Suprime-Cam on the Subaru telescope to obtain deep enough optical images of the entire AKARI NEP field in five broad bands (g ∼ 27.5 mag).
Abstract: 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 satellite’s lifetime, ∼10% of the entire pointed observations. By combining archival Spitzer (five bands) and WISE (four bands) mid-IR photometry, we have, in total, 18-band mid-IR photometry, which is the most comprehensive photometric coverage in the mid-IR for thousands of galaxies. However, we only had shallow optical imaging (∼25.9 AB magnitude) in a small area, 1.0 deg2. As a result, thousands of AKARI’s infrared sources remained undetected in the optical. Using the new Hyper Suprime-Cam on the Subaru telescope, we obtained deep enough optical images of the entire AKARI NEP field in five broad bands (g ∼ 27.5 mag). These provided photometric redshift, and thereby IR luminosity, for the previously undetected faint AKARI IR sources. Combined with the accurate mid-IR luminosity measurement, we constructed mid-IR luminosity functions (LFs), and thereby performed a census of dust-obscured CSFH in the entire AKARI NEP field. We have measured restframe 8 μm and 12 μm LFs, and estimated total infrared LFs at 0.35 < z < 2.2. Our results are consistent with our previous work, but with much reduced statistical errors thanks to the large-area coverage of the new data. We have possibly witnessed the turnover of CSFH at z ∼ 2.

Summary (3 min read)

Jump to: [1 Introduction] – [2 Data] – [3 Analysis] – [4 Results] – [4.4.1 Total IR Luminosity Density from L8µm LFs] – [4.4.2 Total IR Luminosity Density from L12µm LFs] – [4.4.3 Integration to TIR density] – [5 Discussion] – [6 Summary] and [Acknowledgments]

1 Introduction

  • Mid-infrared (mid-IR) is one of the less explored wavelengths due to the earth’s atmosphere, and difficulties in developing sensitive detectors.
  • Using AKARI’s 9 mid-IR band photometry, mid-IR SED diagnosis can be performed for thousands of galaxies, for the first time, over the large enough area to overcome cosmic variance.
  • Environmental effects on galaxy evolution can be also investigated with the large volume coverage (Koyama et al. 2008; Goto et al. 2010a).
  • Previously, the authors were limited by a poor optical coverage both in area and depths.
  • To overcome these problems, the authors have newly obtained deeper optical data over the entire AKARI NEP wide field, using the Hyper-Suprime Cam on the Subaru telescope.

2 Data

  • To rectify the situation and to fully exploit the AKARI’s spacebased data, the authors carried out an optical survey of the AKARI NEP wide field (PI:Goto) using Subaru’s new Hyper Suprime-Cam (HSC; Miyazaki et al. 2018) in five optical bands (g,r, i,z, and y, Oi et al. 2018 submitted).
  • The HSC has a field-of-view (FoV) of 1.5 deg in diameter, covered with 104 red-sensitive CCDs.
  • See Oi et al. (2018, submitted) for more details of the observation and data reduction.
  • Subaru telescope does not have u∗-band capability, while it is critically important to accurately estimate photometric redshifts (photo-z) of low-z galaxies.
  • Therefore, the authors obtained u∗band image of the AKARI NEP wide field using the Megaprime camera of Canada France Hawaii Telescope (PI:Goto, Goto et al. 2017).

3 Analysis

  • Uncertainties of the LF values include fluctuations in the number of sources in each luminosity bin, the photometric redshift uncertainties, the k-correction uncertainties, and the flux errors.
  • To estimate errors, the authors used Monte Carlo simulations from 1000 simulated catalogs.
  • These sources are assigned with a new redshift, to follow a Gaussian distribution centered at the photo-z with the width of ∆z/(1+ z) (∼ 0.060, Oi et al. in preparation).
  • A new flux is also assigned following a Gaussian distribution with the width of flux error.
  • For total infrared (TIR) LF errors, the authors re-performed the SED fit for the 1000 simulated catalogs.

4 Results

  • The authors first present monochromatic 8µm LFs, because the 8µm luminosity (L8µm) has been known as a good indicator of the TIR luminosity (Babbedge et al.
  • Various previous studies are shown in dash-dotted lines.
  • The authors 12µm LFs show steady evolution with increasing redshift.
  • The L18W flux (Matsuhara et al. 2006) are used to apply the 1/Vmax method, because it is a wide, sensitive filter (but using the L15 flux limit does not change their main results).
  • AKARI’s TIR LFs are at least consistent with one of the previous studies.

4.4.1 Total IR Luminosity Density from L8µm LFs

  • First, the authors estimate Total IR Luminosity Density from L8µm LFs.
  • To do so, the authors need to convert L8µm to the total infrared luminosity.
  • Possible SED evolution, and the presence of AGN will induce further uncertainty.
  • Murata et al. (2014) also reported that L8µm/LTIR is constant at below the main sequence, while it decreases with starburstiness at above the main sequence, concluding that starburst galaxies have deficient PAH emission compared with main-sequence galaxies.
  • The authors further test this issue using their data in Section 5.

4.4.2 Total IR Luminosity Density from L12µm LFs

  • Due to the same reasons as L8µm (improved statistics, and availability of 140 and 160µm), the authors use the following conversion (Goto et al. 2011b).
  • The authors caution readers again here for the use of a single conversion for varieties of galaxies with different SFR at different redshifts.
  • Results should be interpreted with this uncertainty in mind.

4.4.3 Integration to TIR density

  • The derived total LFs are multiplied by LTIR and integrated to measure the TIR density ( ΩTIR).
  • With the lowest redshift LF, the authors first fit the normalization (Φ∗) and slopes (α,β).
  • At the first glance, ΩIR from 8µm and TIR LFs are consistent with each other.
  • Even with AKARI’s sensitivity, the observation might not be deep enough to reliably measure the faint-end slope of 12µm LFs, possibly because 12µm does not contain as luminous emission lines as in the case of 8µm.
  • This is an interesting implication, but it is unfortunate that their error bars are too large to draw significant conclusions.

5 Discussion

  • In the previous section, in addition to LTIR measurement, the authors converted L8µm and L12µm into LTIR.
  • The conversions are based on local star-forming galaxies.
  • Following the results in the literature discussed in Section 4.3, in this section, the authors compare LTIR estimated from L8µm and L12µm from equations 1 and 2 in three overlapping redshift ranges in Fig.6 using their data.
  • One can immediately notice that the relation deviates at logLTIR >12 (or equivalently at z > 1).
  • 4 and 5 between midand far-IR measurements could be the result of the change in the SED, rather than incorrect measurements on either.

6 Summary

  • Previously AKARI NEP wide field lacked deep optical photometry, and thereby, accurate photo-z, despite the presence of space-based 9-band mid-IR photometry from AKARI.
  • Combined with the CFHT u-band imaging the authors have also taken, for the first time, they used all of the AKARI’s data over the 5.4 deg2.
  • The authors also estimated total infrared LFs through SED fitting to the 18- band mid-IR data.
  • Thanks to the large area coverage, the brightends are better-determined.
  • It is interesting to note that ΩIR becomes smaller at z > 1.2, possibly suggesting the turnover of the CSFH.

Acknowledgments

  • The authors thank the anonymous referee for many insightful comments, which significantly improved the paper.
  • The authors are grateful for Tina Wang, and Simon Ho for careful proof-reading of the paper.
  • TG acknowledges the support by the Ministry of Science and Technology of Taiwan through grant 105-2112-M-007-003-MY3.
  • MI acknowledges the support from the grant No. 2017R1A3A3001362 of the National Research Foundation of Korea (NRF).
  • YO acknowledges the support by the Ministry of Science and Technology of Taiwan through grant MOST 107-2119-M-001-026.

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Infrared luminosity functions based on 18 mid-infrared
bands: revealing cosmic star formation history with
AKARI and Hyper Suprime-Cam*
Journal Item
How to cite:
Goto, Tomotsugu; Oi, Nagisa; Utsumi, Yousuke; Momose, Rieko; Matsuhara, Hideo; Hashimoto, Tetsuya;
Toba, Yoshiki; Ohyama, Youichi; Takagi, Toshinobu; Chiang, Chia-Ying; Kim, Seong Jin; Kilerci Eser, Ece; Malkan,
Matthew; Kim, Helen; Miyaji, Takamitsu; Im, Myungshin; Nakagawa, Takao; Jeong, Woong-Seob; Pearson, Chris;
Barrufet, Laia; Sedgwick, Chris; Burgarella, Denis; Buat, Veronique and Ikeda, Hiroyuki (2019). Infrared luminosity
functions based on 18 mid-infrared bands: revealing cosmic star formation history with AKARI and Hyper Suprime-
Cam*. Publications of the Astronomical Society of Japan, 71(2), article no. 30.
For guidance on citations see FAQs.
c
2019 The Authors
https://creativecommons.org/licenses/by-nc-nd/4.0/
Version: Accepted Manuscript
Link(s) to article on publisher’s website:
http://dx.doi.org/doi:10.1093/pasj/psz009
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oro.open.ac.uk
arXiv:1902.02801v1 [astro-ph.GA] 7 Feb 2019
Publ. Astron. Soc. Japan (2014) 00(0), 1–10
doi: 10.1093/pasj/xxx000
1
Infrared luminosity functions based on 18
mid-infrared bands: revealing cosmic star
formation history with AKARI and Hyper
Suprime-Cam
∗
Tomotsugu GOTO
1
, Nagisa OI
2
, Yousuke UTSUMI
3
, Rieko MOMOSE
1,4
,
Hideo MATSUHARA
5
, Tetsuya HASHIMOTO
1
, Yoshiki TOBA
6
, Youichi
OHYAMA
6
, Toshinobu TAKAGI
7
, Chia Ying CHIANG
1
, Seong Jin KIM
1
, Ece
KILERCI ESER
1
, Matthew MALKAN
8
, Helen KIM
8
, Takamitsu MIYAJI
9
,
Myungshin IM
10
, Takao NAKAGAWA
5
, Woong-Seob JEONG
11,12
, Chris
PEARSON
13,14
, Laia BARRUFET
15
, Chris SEDGWICK
14
, Denis BURGARELLA
16
,
Veronique BUAT
16
and Hiroyuki IKEDA
17
1
National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, Taiwan 30013
2
Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
3
Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), SLAC National Accelerator
Laboratory, Stanford University, SLAC, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
4
Department of Astronomy, School of Science, The University of Tokyo 7-3-1 Hongo,
Bunkyo-ku, Tokyo 113-0033, JAPAN
5
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1
Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210, Japan
6
Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617,
Taiwan
7
Japan Space Forum, 3-2-1, Kandasurugadai, Chiyoda-k u, Tokyo 101-0062 Japan
8
Department of Physics and Astronomy, UCLA, Los Angeles, CA, 90095-1547, USA
9
Insitituto de Astronom´ıa, U niversidad Nacional Aut
´
onoma de M
´
exico
10
Astronomy Program, Department of Physics & Astr onomy, FPRD, Seoul National University,
Shillim-Dong, Kwanak-Gu, Seoul 151-742, Korea
11
Korea Astronomy and Space Science Institute (KASI), 776 Daedeok-daero, Yuseong-gu,
Daejeon 34055, Korea
12
Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113,
Korea
13
RAL Space, STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, UK
14
The Open University, Milton Keynes, MK7 6AA, UK
15
European Space Astronomy Centre, 28691 Villanueva de la Canada, Spain
16
Aix-Marseille Universit, CNRS LAM (Laboratoire dAstrophysique de Marseille) UMR 7326,
13388 Mars eille, France
c
2014. Astronomical Society of Japan.
2 Publications of the Astronomical Society of Japan, (2014), Vol. 00, No. 0
17
National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo, Japan
∗
E-mail: tomo@gapp.nthu.edu.tw
Received 2018 June 30; Accepted 2019 January 21
Abstract
Much of the star formation is obscured by dust. For the complete understanding of the cosmic
star formation history (CSFH), infrared (IR) census is indispensable. AKARI carried out deep
mid-infrared observations using its continuous 9-band filters in the North Ecliptic Pole (NEP)
field (5.4 deg
2
). This took significant amount of satellite’s lifetime, ∼10% of the entire pointed
observations. By combining archival Spitzer (5 bands) and WISE (4 bands) mid-IR photometry,
we have, in total, 18 band mid-IR photometry, which is the most comprehensive photometric
coverage in mid-IR for thousands of galaxies. However previously, we only had shallow optical
imaging (∼25.9ABmag) in a small area of 1.0 deg
2
. As a result, there remained thousands of
AKARI’s infrared sources undetected in optical. Using the new Hyper Suprime-Cam on Subaru
telescope, we obtained deep enough optical images of the entire AKARI NEP field in 5 broad
bands (g ∼27.5mag). These provided photometric redshift, and thereby IR luminosity for the
previously undetected faint AKARI IR sour ces. Combined with the accurate mid-IR luminosity
measurement, we constr ucted mid-IR LFs, and thereby performed a census of dust-obs cured
CSFH in the entire AKARI NEP field. We have measured restframe 8µm, 12µm luminosity
functions (LFs), and estimated total infrared LFs at 0.35<z<2.2. Our results are consistent with
our previous work, but with much reduced statistical err ors thanks to the large area coverage
of the new data. We have possibly witnessed the turnover of CSFH at z ∼2.
Key words: AKARI, infrared galaxies, cosmic star formation history
1 Introduction
Mid-infrared ( mid-IR) is one of the less explored wavelengths
due to the earth’s atmosphere, and difficulties in developing sen-
sitive detectors. NASA’s S pitzer and WISE space telescopes
only had four filters in the mid-IR wavelength range, hamper-
ing studies of distant galaxies.
AKARI space telescope has a potential to revolutionize the
field. Using its 9 continuous mid-IR filters (2-24µm), AKARI
performed a deep imaging survey in the North Ecliptic Pole
(NEP) field over 5.4 deg
2
. Using AKARI’s 9 mid-IR band pho-
tometry, mid-IR SED diagnosis can be performed for thousands
of galaxies, for the first time, over the large enough area to over-
come cosmic variance. Environmental effects on galaxy evolu-
tion can be also investigated with the large volume coverage
(Koyama et al. 2008; Goto et al. 2010a).
However, previously, we were limited by a poor optical cov-
erage both in area and depths. Over this wide area, only shal-
low optical/NIR imaging data have been available (Hwang et al.
2007; Jeon et al. 2010, 2014). Deep optical images are limited
to the central 0.25 deg
2
.
To overcome these problems, we have newly obtained
deeper optical data over the entire AKARI NEP wide field, us-
ing the Hyper-Suprime Cam on the Subaru telescope. Using
the deeper optical data, in this paper, we measure mid-infrared
galaxy LFs, and estimate total IR LFs (based on the mid-IR
SED fitting) from the entire AKARI NEP field. Unless oth-
erwise stated, we assume a cosmology with (h, Ω
m
, Ω
Λ
) =
(0.7,0.3,0.7).
2 Data
To rectify the situation and to fully exploit the AKARI’s space-
based data, we carr ied out an optical survey of the AKARI NEP
wide field (PI:Goto) using Subaru’s new Hyper Suprime-Cam
(HSC; Miyazaki et al. 2018) in five optical bands (g, r,i, z, and
y, Oi et al. 2018 submitted). The HSC has a field-of-view (FoV)
of 1.5 deg in diameter, covered with 104 red-sensitive CCDs. It
has the largest FoV among optical cameras on 8m-class tele-
scopes, and can cover the AKARI NEP wide field (5.4 deg
2
)
with only 4 FoV (Fig.1). The 5 sigma limiting magnitudes are
27.18, 26.71, 26.10, 25.26, and 24.78 mag [AB] in g,r,i,z, and
y-bands, respectively. See Oi et al. (2018, submitted) for more
details of the observation and data reduction.
Subaru telescope does not have u
∗
-band capability, while it
is critically important to accurately estimate photometric red-
shifts (photo-z) of low-z galaxies. Therefore, we obtained u
∗
-
band image of the AKARI NEP wide fi eld using the Megaprime
camera of Canada France Hawaii Telescope (PI :Goto, Goto
Publications of the Astronomical Society of Japan, (2014), Vol. 00, No. 0 3
45:00.0
17:50:00.0
55:00.0
18:00:00.0
05:00.0
10:00.0
15:00.0
65:00:00.0
30:00.0
66:00:00.0
30:00.0
67:00:00.0
30:00.0
Right ascension
Declination
Fig. 1. HSC three color (g, r, i) composite image of the NEP wide field (5.4 deg
2
). The AKARI NEP wide data exist within the white circle.
et al. 2017). Combining the optical six bands, we have obtained
accurate photo-z in the AKARI NEP field (Oi et al. 2018, sub-
mitted). To the detection limit in L18W filter (18.3 ABmag,
Kim et al. 2012), we have 5078 infrared sources.
In addition to the AKARI’s 9 mid-IR bands, in the AKARI
NEP field, there exit archival deep Spitzer (IRAC1,2,3,4 and
MIPS24, Nayyeri et al. 2018) and WISE (W 1, W 2, W 3, and
W 4) images as well. By combining all available mid-IR bands,
in total we used 18 mid-IR bands, which are one of the most
comprehensive mid-IR data sets for thousands of galaxies.
3 Analysis
To compute LFs, we use the 1/V
max
method, following Goto
et al. (2010b, 2015). Uncertainties of the LF values include
fluctuations in the number of sources in each luminosity bin,
the photometric redshift uncertainties, the k-correction uncer-
tainties, and the flux errors. To estimate errors, we used Monte
Carlo simulations from 1000 simulated catalogs. Each sim-
ulated catalog contains the same number of sources. These
sources are assigned with a new redshift, to follow a Gaussian
distribution centered at the photo-z with the width of ∆z/(1 +
z) (∼ 0.060, Oi et al. in preparation). A new flux is also as-
signed following a Gaussian distribution with the width of flux
error. For total infrared (TIR) LF errors, we re-performed the
SED fit for the 1000 simulated catalogs. Note that total in-
frared luminosity is estimated based on mid-IR SED fitting al-
though we have intensive 18-band filter coverage in mid-IR, as
explained in Section 4.3. We ignored the cosmic variance due
to our much improved volume coverage. All the other err ors
4 Publications of the Astronomical Society of Japan, (2014), Vol. 00, No. 0
Fig. 2. Restframe 8µm LFs based on the AKARI NEP wide field. The blue
diamonds, the purple triangles, the red squares, and the orange crosses
show the 8µm LFs at 0.28 < z < 0.47, 0.65 < z < 0.90, 1.09 < z < 1.41,
and 1.78 < z < 2.22, respectively. AKARI’s MIR filters can observe rest-
frame 8µm at these redshifts in a corresponding filter. Error bars are esti-
mated from the Monte Carlo simulations (§3). The dotted l ines show analytic
fits with a double-power law. The smaller data points at the faint ends are
adopted from the NEP deep field, where AKARI data are deeper (Goto et al.
2015), and are included in the fit. Vertical arrows show the 8µm luminos-
ity corresponding to the flux limit at the central redshift in each redshift bin.
Overplotted LFs are B abbedge et al. (2006) in the pink dash-dotted lines,
Caputi et al. (2007) in the cyan dash-dotted lines, Huang et al. (2007) in
the dark-yellow dash-dotted lines, F u et al. (2010), in the dark green dash-
dotted line, and Kim et al. (2015) in the bright green dash-dotted line. Best-fit
parameters are presented in Table 1.
described above are added to the Poisson errors for each LF bin
in quadrature.
4 Results
4.1 The 8µm LF
We firs t present monochromatic 8µm LFs, because the 8µm lu-
minosity (L
8µm
) has been known as a good indicator of the TIR
luminosity (Babbedge et al. 2006; Huang et al. 2007; Goto et al.
2011a).
An advantage of AKARI is that we do not need k-correction
because one of the continuous filters always convert the rest-
frame 8µm at our redshift range of 0.28 < z < 2.22. Often in
previous work, SED based extrapolation was needed to estimate
the 8µm luminosity. This was often the largest uncertainty. This
is not the case for the analysis present in this paper.
To estimate the restframe 8µm LFs, we followed our previ-
ous method in Goto et al. (2015) as we briefly summarize below.
We used sources down to 80% completeness limits ( Kim et al.
2012). Galaxies are excluded when SEDs were better fit to QSO
Fig. 3. Restframe 12µm LFs based on the AKARI NEP wide field.
Luminosity unit is logarithmic solar luminosity (L
⊙
). The blue diamonds,
the purple triangles, and the red squares show the 12µm LFs at 0.15 < z <
0.35, 0.38 < z < 0.62, and 0.84 < z < 1.16, respectively. The smaller data
points at the faint ends are adopted from the NEP deep field, where AKARI
data are deeper (Goto et al. 2015), and are included in the fit. Vertical arrows
show the 12µm luminosity corresponding to the flux limit at the central red-
shift in each redshift bin. Overplotted LFs are P
´
erez-Gonz
´
alez et al. (2005)
at z=0.3, 0.5 and 0.9 in the dark-cyan dash-dotted l ines, Toba et al. (2014)
at 0< z <0.05 based on WISE in the dark green dash-dotted lines, Rush
et al. (1993) at 0< z <0.3 in the light green dash-dotted lines, and Kim et al.
(2015) at 0< z <0.3 in the pink dash-dotted line. Note Rush et al. (1993) is
at higher redshifts than Toba et al. (2014). Best-fit parameters are presented
in Table 1.
templates (2% from the sample).
We corrected for the completeness using Kim et al. (2012)
(25% correction at maximum, with our selection to the 80%
completeness limits). Four redshift bins of 0.28< z <0.47,
0.65< z <0.90, 1.09< z <1.41, and 1.78< z <2.22, were used,
following our previous work. Then, the 1/V
max
method was
used to compensate for the flux limit.
The resulting restframe 8µm LFs are shown in Fig. 2. The
arrows show the flux limit at the m edian redshift in bin. We
performed the Monte Carlo simulation to obtain errors. They
are smaller than in our previous work (Goto et al. 2010b, 2015)
thanks to the improved area coverage. The faint end marked
with smaller data points are adopted from the NEP deep field,
where AKARI data are deeper (Goto et al. 2015).
Various previous studies are shown with dashed lines for
comparison. Compared to the local LF, our 8µm LFs show
strong evolution in luminosity up to z ∼ 0.9. Interestingly, the
8µm LFs peaks in the 3rd bin ( z∼1), then declines toward z∼2.
Citations
More filters
Journal Article•DOI•
The ALPINE-ALMA [CII] survey - The nature, luminosity function, and star formation history of dusty galaxies up to z ≃ 6

[...]

Carlotta Gruppioni, Matthieu Béthermin1, F. Loiacono2, O. Le Fèvre1, Peter Capak3, Paolo Cassata4, Andreas L. Faisst3, Daniel Schaerer5, John D. Silverman6, Lin Yan3, S. Bardelli, Médéric Boquien7, R. Carraro8, Andrea Cimatti2, Andrea Cimatti9, Miroslava Dessauges-Zavadsky5, Michele Ginolfi5, Seiji Fujimoto10, Nimish P. Hathi11, G. C. Jones12, Y. Khusanova1, Anton M. Koekemoer11, Guilaine Lagache1, Brian C. Lemaux13, Pascal Oesch5, Francesca Pozzi2, Dominik A. Riechers14, Dominik A. Riechers15, Giulia Rodighiero4, M. Romano4, Margherita Talia2, Livia Vallini, Daniela Vergani, G. Zamorani, E. Zucca •
Aix-Marseille University1, University of Bologna2, California Institute of Technology3, University of Padua4, University of Geneva5, Institute for the Physics and Mathematics of the Universe6, University of Antofagasta7, Valparaiso University8, INAF9, University of Copenhagen10, Space Telescope Science Institute11, University of Cambridge12, University of California, Davis13, Cornell University14, Max Planck Society15
27 Oct 2020-Astronomy and Astrophysics
TL;DR: In this article, a sample of 56 sources serendipitously detected in ALMA band 7 as part of the ALMA Large Program to Investigate CII at Early Times (ALPINE) has been used to derive the total infrared luminosity function (LF) and to estimate the cosmic star formation rate density (SFRD) up to z ǫ ≥ 6.
Abstract: Aims. We present the detailed characterisation of a sample of 56 sources serendipitously detected in ALMA band 7 as part of the ALMA Large Program to INvestigate CII at Early Times (ALPINE). These sources, detected in COSMOS and ECDFS, have been used to derive the total infrared luminosity function (LF) and to estimate the cosmic star formation rate density (SFRD) up to z ≃ 6.Methods. We looked for counterparts of the ALMA sources in all the available multi-wavelength (from HST to VLA) and photometric redshift catalogues. We also made use of deeper UltraVISTA and Spitzer source lists and maps to identify optically dark sources with no matches in the public catalogues. We used the sources with estimated redshifts to derive the 250 μ m rest-frame and total infrared (8–1000 μ m) LFs from z ≃ 0.5 to 6.Results. Our ALMA blind survey (860 μ m flux density range: ∼0.3–12.5 mJy) allows us to further push the study of the nature and evolution of dusty galaxies at high-z , identifying luminous and massive sources to redshifts and faint luminosities never probed before by any far-infrared surveys. The ALPINE data are the first ones to sample the faint end of the infrared LF, showing little evolution from z ≃ 2.5 to z ≃ 6, and a “flat” slope up to the highest redshifts (i.e. 4.5 ≃ 2 and z ≃ 6, and significantly higher than the optical or ultra-violet derivations, showing a significant contribution of dusty galaxies and obscured star formation at high-z . About 14% of all the ALPINE serendipitous continuum sources are found to be optically and near-infrared (near-IR) dark (to a depth K s ∼ 24.9 mag). Six show a counterpart only in the mid-IR and no HST or near-IR identification, while two are detected as [C II] emitters at z ≃ 5. The six HST+near-IR dark galaxies with mid-IR counterparts are found to contribute about 17% of the total SFRD at z ≃ 5 and to dominate the high-mass end of the stellar mass function at z > 3.

50 citations

Journal Article•DOI•
UV and U-band luminosity functions from CLAUDS and HSC-SSP - I. Using four million galaxies to simultaneously constrain the very faint and bright regimes to z ∼ 3

[...]

Thibaud Moutard1, Marcin Sawicki1, Stéphane Arnouts2, Anneya Golob1, Jean Coupon3, Olivier Ilbert2, Xiaohu Yang4, Stephen Gwyn •
University of Saint Mary1, Aix-Marseille University2, University of Geneva3, Shanghai Jiao Tong University4
11 May 2020-Monthly Notices of the Royal Astronomical Society
TL;DR: In this article, the authors constrain the rest-frame FUV, NUV and U-band luminosity functions with unprecedented precision from z ∼ 0.2 to z ∼ 3.
Abstract: We constrain the rest-frame FUV (1546 A), NUV (2345 A), and U-band (3690 A) 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 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.

34 citations

Journal Article•DOI•
Fast radio bursts to be detected with the Square Kilometre Array

[...]

Tetsuya Hashimoto1, Tomotsugu Goto1, Alvina Y. L. On1, Alvina Y. L. On2, Ting-Yi Lu1, Daryl Joe D. Santos1, Simon C. C. Ho1, Ting-Wen Wang1, Seong Jin Kim1, Tiger Y. Y. Hsiao1 •
National Tsing Hua University1, University College London2
01 Oct 2020-Monthly Notices of the Royal Astronomical Society
TL;DR: In this article, the authors estimate the detections of non-repeating and repeating fast radio bursts separately, based on latest observational constraints on their physical properties including the spectral indices, FRB luminosity functions, and their redshift evolutions.
Abstract: Fast radio bursts (FRBs) are mysterious extragalactic radio signals. Revealing their origin is one of the central foci in modern astronomy. Previous studies suggest that occurrence rates of non-repeating and repeating FRBs could be controlled by the cosmic stellar-mass density (CSMD) and star formation-rate density (CSFRD), respectively. The Square Kilometre Array (SKA) is one of the best future instruments to address this subject due to its high sensitivity and high-angular resolution. Here, we predict the number of FRBs to be detected with the SKA. In contrast to previous predictions, we estimate the detections of non-repeating and repeating FRBs separately, based on latest observational constraints on their physical properties including the spectral indices, FRB luminosity functions, and their redshift evolutions. We consider two cases of redshift evolution of FRB luminosity functions following either the CSMD or CSFRD. At $z\gtrsim2$, $z\gtrsim6$ and $z\gtrsim10$, non-repeating FRBs will be detected with the SKA at a rate of $\sim10^{4}$, $\sim10^{2}$, and $\sim10$ (sky$^{-1}$ day$^{-1}$), respectively, if their luminosity function follows the CSMD evolution. At $z\gtrsim1$, $z\gtrsim2$, and $z\gtrsim4$, sources of repeating FRBs will be detected at a rate of $\sim10^{3}$, $\sim10^{2}$, and $\lesssim10$ (sky$^{-1}$ day$^{-1}$), respectively, assuming that the redshift evolution of their luminosity function is scaled with the CSFRD. These numbers could change by about one order of magnitude depending on the assumptions on the CSMD and CSFRD. In all cases, abundant FRBs will be detected by the SKA, which will further constrain the luminosity functions and number density evolutions.

30 citations

Journal Article•DOI•
Search for Optically Dark Infrared Galaxies without Counterparts of Subaru Hyper Suprime-Cam in the AKARI North Ecliptic Pole Wide Survey Field

[...]

Yoshiki Toba1, Yoshiki Toba2, Yoshiki Toba3, Tomotsugu Goto4, Nagisa Oi, Ting Wen Wang4, Seong Jin Kim4, Simon C. C. Ho4, Denis Burgarella5, Tetsuya Hashimoto4, Bau-Ching Hsieh3, Ting Chi Huang6, Ho Seong Hwang7, Hiroyuki Ikeda8, Helen K. Kim9, Seongjae Kim7, Dongseob Lee10, Matthew A. Malkan9, Hideo Matsuhara6, Takamitsu Miyaji11, Takamitsu Miyaji12, Rieko Momose13, Youichi Ohyama3, Shinki Oyabu14, Chris Pearson15, Chris Pearson16, Daryl Joe D. Santos4, Hyunjin Shim10, Toshinobu Takagi, Yoshihiro Ueda1, Yousuke Utsumi17, Takehiko Wada •
Kyoto University1, Ehime University2, Academia Sinica Institute of Astronomy and Astrophysics3, National Tsing Hua University4, Lam Research5, Graduate University for Advanced Studies6, Korea Astronomy and Space Science Institute7, National Institutes of Natural Sciences, Japan8, University of California, Los Angeles9, Kyungpook National University10, National Autonomous University of Mexico11, Leibniz Institute for Astrophysics Potsdam12, University of Tokyo13, University of Tokushima14, University of Oxford15, Rutherford Appleton Laboratory16, Stanford University17
13 Jun 2020-The Astrophysical Journal
TL;DR: In this article, the physical properties of AKARI sources without optical counterparts in optical images from the Hyper Suprime-Cam (HSC) on the Subaru telescope were investigated.
Abstract: We present the physical properties of AKARI sources without optical counterparts in optical images from the Hyper Suprime-Cam (HSC) on the Subaru telescope. Using the AKARI infrared (IR) source catalog and HSC optical catalog, we select 583 objects that do not have HSC counterparts in the AKARI North Ecliptic Pole wide survey field (~5 deg2). Because the HSC limiting magnitude is deep (gAB ~ 28.6), these are good candidates for extremely red star-forming galaxies (SFGs) and/or active galactic nuclei (AGNs), possibly at high redshifts. We compile multiwavelength data out to 500 μm and use them for fitting the spectral energy distribution with CIGALE to investigate the physical properties of AKARI galaxies without optical counterparts. We also compare their physical quantities with AKARI mid-IR selected galaxies with HSC counterparts. The estimated redshifts of AKARI objects without HSC counterparts range up to z ~ 4, significantly higher than for AKARI objects with HSC counterparts. We find that (i) 3.6 – 4.5 μm color, (ii) AGN luminosity, (iii) stellar mass, (iv) star formation rate, and (v) V-band dust attenuation in the interstellar medium of AKARI objects without HSC counterparts are systematically larger than those of AKARI objects with counterparts. These results suggest that our sample includes luminous, heavily dust-obscured SFGs/AGNs at z ~ 1–4 that are missed by previous optical surveys, providing very interesting targets for the coming era of the James Webb Space Telescope.

28 citations

Journal Article•DOI•
The Variability of the Star Formation Rate in Galaxies. I. Star Formation Histories Traced by EW(Hα) and EW(Hδ A)

[...]

Enci Wang, Simon J. Lilly
01 Apr 2020-The Astrophysical Journal

21 citations

References
More filters
Journal Article•DOI•
Star formation in galaxies along the hubble sequence

[...]

Robert C. Kennicutt1•
University of Arizona1
17 Jul 1998-Annual Review of Astronomy and Astrophysics
TL;DR: In this article, the authors focus on the broad patterns in the star formation properties of galaxies along the Hubble sequence and their implications for understanding galaxy evolution and the physical processes that drive the evolution.
Abstract: Observations of star formation rates (SFRs) in galaxies provide vital clues to the physical nature of the Hubble sequence and are key probes of the evolutionary histories of galaxies. The focus of this review is on the broad patterns in the star formation properties of galaxies along the Hubble sequence and their implications for understanding galaxy evolution and the physical processes that drive the evolution. Star formation in the disks and nuclear regions of galaxies are reviewed separately, then discussed within a common interpretive framework. The diagnostic methods used to measure SFRs are also reviewed, and a self-consistent set of SFR calibrations is presented as an aid to workers in the field. One of the most recognizable features of galaxies along the Hubble sequence is the wide range in young stellar content and star formation activity. This variation in stellar content is part of the basis of the Hubble classification itself (Hubble 1926), and understanding its physical nature and origins is fundamental to understanding galaxy evolution in its broader context. This review deals with the global star formation properties of galaxies, the systematics of those properties along the Hubble sequence, and their implications for galactic evolution. I interpret “Hubble sequence” in this context very loosely, to encompass not only morphological type but other properties such as gas content, mass, bar structure, and dynamical environment, which can strongly influence the largescale star formation rate (SFR).

6,640 citations

Journal Article•DOI•
The James Webb Space Telescope

[...]

Jonathan P. Gardner1, John C. Mather1, Mark Clampin1, René Doyon2, Matthew A. Greenhouse1, Heidi B. Hammel3, J. B. Hutchings4, Peter Viggo Jakobsen5, Simon J. Lilly6, Knox S. Long7, Jonathan I. Lunine8, Mark J. McCaughrean9, Matt Mountain7, John Nella, George H. Rieke8, Marcia J. Rieke8, Hans-Walter Rix10, Eric P. Smith11, George Sonneborn1, Massimo Stiavelli7, H. S. Stockman7, Rogier A. Windhorst12, Gillian S. Wright13 •
Goddard Space Flight Center1, Université de Montréal2, Space Science Institute3, Herzberg Institute of Astrophysics4, European Space Agency5, École Polytechnique Fédérale de Lausanne6, Space Telescope Science Institute7, University of Arizona8, University of Exeter9, Max Planck Society10, NASA Headquarters11, Arizona State University12, UK Astronomy Technology Centre13
01 Nov 2006-Space Science Reviews
TL;DR: The James Webb Space Telescope (JWST) as discussed by the authors is a large (6.6 m), cold (<50 K), infrared-optimized space observatory that will be launched early in the next decade into orbit around the second Earth-Sun Lagrange point.
Abstract: The James Webb Space Telescope (JWST) is a large (6.6 m), cold (<50 K), infrared (IR)-optimized space observatory that will be launched early in the next decade into orbit around the second Earth–Sun Lagrange point. The observatory will have four instruments: a near-IR camera, a near-IR multiobject spectrograph, and a tunable filter imager will cover the wavelength range, 0.6 < ; < 5.0 μ m, while the mid-IR instrument will do both imaging and spectroscopy from 5.0 < ; < 29 μ m. The JWST science goals are divided into four themes. The key objective of The End of the Dark Ages: First Light and Reionization theme is to identify the first luminous sources to form and to determine the ionization history of the early universe. The key objective of The Assembly of Galaxies theme is to determine how galaxies and the dark matter, gas, stars, metals, morphological structures, and active nuclei within them evolved from the epoch of reionization to the present day. The key objective of The Birth of Stars and Protoplanetary Systems theme is to unravel the birth and early evolution of stars, from infall on to dust-enshrouded protostars to the genesis of planetary systems. The key objective of the Planetary Systems and the Origins of Life theme is to determine the physical and chemical properties of planetary systems including our own, and investigate the potential for the origins of life in those systems. Within these themes and objectives, we have derived representative astronomical observations. To enable these observations, JWST consists of a telescope, an instrument package, a spacecraft, and a sunshield. The telescope consists of 18 beryllium segments, some of which are deployed. The segments will be brought into optical alignment on-orbit through a process of periodic wavefront sensing and control. The instrument package contains the four science instruments and a fine guidance sensor. The spacecraft provides pointing, orbit maintenance, and communications. The sunshield provides passive thermal control. The JWST operations plan is based on that used for previous space observatories, and the majority of JWST observing time will be allocated to the international astronomical community through annual peer-reviewed proposal opportunities.

1,372 citations

Journal Article•DOI•
Interpreting the Cosmic Infrared Background: Constraints on the Evolution of the Dust-enshrouded Star Formation Rate

[...]

Ranga-Ram Chary1, David Elbaz1•
University of California, Santa Cruz1
01 Aug 2001-The Astrophysical Journal
TL;DR: In this article, the evolution of the mid-infrared local luminosity function with redshift to the spectrum of the cosmic infrared background (CIRB) at j[ 5 km and the galaxy counts from various surveys at midinfrared, far infrared, and submillimeter wavelengths was investigated.
Abstract: The mid-infrared local luminosity function is evolved with redshift to —t the spectrum of the cosmic infrared background (CIRB) at j[ 5 km and the galaxy counts from various surveys at mid-infrared, far-infrared, and submillimeter wavelengths. A variety of evolutionary models provide satisfactory —ts to the CIRB and the number counts. The degeneracy in the range of models cannot be broken by current observations. However, the diUerent evolutionary models yield approximately the same comoving number density of infrared luminous galaxies as a function of redshift. Since the spectrum of the cosmic background at j[ 200 km is quite sensitive to the evolution at high redshift, i.e., z [ 1, all models that —t the counts require a —attening at z D 0.8 to avoid overproducing the CIRB. About 80% of the 140 km CIRB is produced at 0 \ z \ 1.5, while only about 30% of the 850 km background is produced within the same redshift range. The nature of the evolution is then translated into a measure of the dustenshrouded star formation rate (SFR) density as a function of redshift and compared with estimates from rest-frame optical/ultraviolet surveys. The dust-enshrouded SFR density appears to peak at z \ 0.8 ^ 0.1, much sooner than previously thought, with a value of yr~1 Mpc~3, and remains almost 0.25 ~0.10.12 M _ constant up to z D 2. At least 70% of this star formation takes place in infrared luminous galaxies with The long-wavelength observations that constrain our evolutionary models do not strongL IR [ 1011 L _ . ly trace the evolution at z [ 2 and a drop-oU in the dust-enshrouded SFR density is consistent with both the CIRB spectrum and the number counts. However, a comparison with the infrared luminosity function derived from extinction-corrected rest-frame optical/ultraviolet observations of the Lyman break galaxy population at z D 3 suggests that the almost —at comoving SFR density seen between redshifts of 0.8 and 2 extends up to a redshift of z D 4. (%)

1,292 citations

Journal Article•DOI•
GOODS–Herschel: an infrared main sequence for star-forming galaxies

[...]

David Elbaz1, Mark Dickinson, Ho Seong Hwang1, Tanio Díaz-Santos2, Georgios E. Magdis1, Benjamin Magnelli3, D. Le Borgne4, Frédéric Galliano1, Maurilio Pannella1, P. Chanial1, Lee Armus5, Vassilis Charmandaris2, Vassilis Charmandaris6, Emanuele Daddi1, Herve Aussel1, P. Popesso3, Jeyhan S. Kartaltepe, Bruno Altieri7, Ivan Valtchanov7, D. Coia7, Helmut Dannerbauer1, Kalliopi Dasyra1, Roger Leiton1, Roger Leiton8, Joseph M. Mazzarella5, David M. Alexander9, V. Buat10, Denis Burgarella10, R.-R. Chary5, Roberto Gilli11, Rob Ivison12, Rob Ivison13, Stéphanie Juneau14, E. Le Floc'h1, Dieter Lutz3, G. E. Morrison15, James Mullaney1, Eric J. Murphy5, Alexandra Pope16, Douglas Scott17, Mark Brodwin, Daniela Calzetti16, C. Cesarsky1, Stéphane Charlot4, Herve Dole18, Peter Eisenhardt5, Henry C. Ferguson19, N. M. Förster Schreiber3, Dave Frayer20, Mauro Giavalisco16, Minh Huynh5, Anton M. Koekemoer19, Casey Papovich21, Naveen A. Reddy, Christian Surace10, Harry I. Teplitz5, Min S. Yun16, G. W. Wilson16 •
Paris Diderot University1, University of Crete2, Max Planck Society3, Institut d'Astrophysique de Paris4, California Institute of Technology5, Foundation for Research & Technology – Hellas6, European Space Agency7, University of Concepción8, Durham University9, Aix-Marseille University10, INAF11, University of Edinburgh12, UK Astronomy Technology Centre13, University of Arizona14, University of Hawaii15, University of Massachusetts Amherst16, University of British Columbia17, University of Paris-Sud18, Space Telescope Science Institute19, National Radio Astronomy Observatory20, Texas A&M University21
01 Sep 2011-Astronomy and Astrophysics
TL;DR: In this paper, the authors examined the infrared (IR) 3-500μm spectral energy distributions (SEDs) of galaxies at 0 < z < 2.5, supplemented by a local reference sample from IRAS, ISO, Spitzer, and AKARI data.
Abstract: We present the deepest 100 to 500 μm far-infrared observations obtained with the Herschel Space Observatory as part of the GOODS-Herschel key program, and examine the infrared (IR) 3–500 μm spectral energy distributions (SEDs) of galaxies at 0 < z < 2.5, supplemented by a local reference sample from IRAS, ISO, Spitzer, and AKARI data. We determine the projected star formation densities of local galaxies from their radio and mid-IR continuum sizes. We find that the ratio of total IR luminosity to rest-frame 8 μm luminosity, IR8 (≡ L_(IR)^(tot)/L_8), follows a Gaussian distribution centered on IR8 = 4 (σ = 1.6) and defines an IR main sequence for star-forming galaxies independent of redshift and luminosity. Outliers from this main sequence produce a tail skewed toward higher values of IR8. This minority population ( 3 × 10^(10) L_⊙ kpc^(-2)) and a high specific star formation rate (i.e., starbursts). The rest-frame, UV-2700 A size of these distant starbursts is typically half that of main sequence galaxies, supporting the correlation between star formation density and starburst activity that is measured for the local sample. Locally, luminous and ultraluminous IR galaxies, (U)LIRGs (L_(IR)^(tot)≥ 10^(11) L_☉), are systematically in the starburst mode, whereas most distant (U)LIRGs form stars in the “normal” main sequence mode. This confusion between two modes of star formation is the cause of the so-called “mid-IR excess” population of galaxies found at z > 1.5 by previous studies. Main sequence galaxies have strong polycyclic aromatic hydrocarbon (PAH) emission line features, a broad far-IR bump resulting from a combination of dust temperatures (T_(dust) ~ 15–50 K), and an effective T_(dust) ~ 31 K, as derived from the peak wavelength of their infrared SED. Galaxies in the starburst regime instead exhibit weak PAH equivalent widths and a sharper far-IR bump with an effective T_(dust)~ 40 K. Finally, we present evidence that the mid-to-far IR emission of X-ray active galactic nuclei (AGN) is predominantly produced by star formation and that candidate dusty AGNs with a power-law emission in the mid-IR systematically occur in compact, dusty starbursts. After correcting for the effect of starbursts on IR8, we identify new candidates for extremely obscured AGNs.

1,235 citations

Journal Article•DOI•
GOODS-Herschel: an infrared main sequence for star-forming galaxies

[...]

David Elbaz, Mark Dickinson, Ho Seong Hwang, Tanio Díaz-Santos, Georgios E. Magdis, Benjamin Magnelli, D. Le Borgne, Frédéric Galliano, Maurilio Pannella, P. Chanial, Lee Armus, Vassilis Charmandaris, Emanuele Daddi, Herve Aussel, P. Popesso, Jeyhan S. Kartaltepe, Bruno Altieri, Ivan Valtchanov, D. Coia, Helmut Dannerbauer, Kalliopi Dasyra, Roger Leiton, Joseph M. Mazzarella, V. Buat, Denis Burgarella, Roberto Gilli, Rob Ivison, Stéphanie Juneau, E. LeFloch, Dieter Lutz, G. E. Morrison, James Mullaney, Eric J. Murphy, Alexandra Pope, Douglas Scott, David M. Alexander, Mark Brodwin, Daniela Calzetti, C. J. Cesarsky, Stéphane Charlot, H. Dole, Peter Eisenhardt, Henry C. Ferguson, N. Foerster-Schreiber, Dave Frayer, Mauro Giavalisco, Minh Huynh, Anton M. Koekemoer, Casey Papovich, Naveen A. Reddy, Christian Surace, Harry Teplitz, Min S. Yun, G. W. Wilson 
12 May 2011-arXiv: Cosmology and Nongalactic Astrophysics
TL;DR: In this article, deep far-IR observations obtained with Herschel and examined the 3-500um SEDs of galaxies at 0 3x10^10 Lsun kpc^-2 and a high specific SFR (i.e., SBs).
Abstract: We present the deepest far-IR observations obtained with Herschel and examine the 3-500um SEDs of galaxies at 0 3x10^10 Lsun kpc^-2) and a high specific SFR (i.e., SBs). The rest-frame, UV-2700A size of these distant SBs is typically half that of MS galaxies, supporting the correlation between star formation density and SB activity that is measured for the local sample. Locally, (U)LIRGs are systematically in the SB mode, whereas most distant (U)LIRGs form stars in the "normal" MS mode. This confusion between two modes of star formation is the cause of the so-called "mid-IR excess" population of galaxies found at z>1.5 by previous studies. MS galaxies have strong PAH emission line features, a broad far-IR bump resulting from a combination of dust temperatures (Tdust~15-50 K), and an effective Tdust~31 K, as derived from the peak wavelength of their IR SED. Galaxies in the SB regime instead exhibit weak PAH EW and a sharper far-IR bump with an effective Tdust~40 K. Finally, we present evidence that the mid-to-far IR emission of X-ray AGNs is predominantly produced by star formation and that candidate dusty AGNs with a power-law emission in the mid-IR systematically occur in compact, dusty SBs. After correcting for the effect of SBs on IR8, we identify new candidates for extremely obscured AGNs.

1,138 citations

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Spectral Energy Distributions of Hard X-Ray Selected Active Galactic Nuclei in the XMM-Newton Medium Deep Survey

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A simple model for the absorption of starlight by dust in galaxies

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Star formation in galaxies along the hubble sequence

[...]

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Frequently Asked Questions (6)
Q1. What are the contributions mentioned in the paper "Infrared luminosity functions based on 18 mid-infrared bands: revealing cosmic star formation history with akari and hyper suprime-cam*" ?

Combined with the accurate mid-IR luminosity measurement, the authors constructed mid-IR LFs, and thereby performed a census of dust-obscured CSFH in the entire AKARI NEP field. 

The L18W flux (Matsuhara et al. 2006) are used to apply the 1/Vmax method, because it is a wide, sensitive filter (but using the L15 flux limit does not change their main results). 

Mid-infrared (mid-IR) is one of the less explored wavelengths due to the earth’s atmosphere, and difficulties in developing sensitive detectors. 

Uncertainties of the LF values includefluctuations in the number of sources in each luminosity bin, the photometric redshift uncertainties, the k-correction uncertainties, and the flux errors. 

It has the largest FoV among optical cameras on 8m-class telescopes, and can cover the AKARI NEP wide field (5.4 deg2) with only 4 FoV (Fig.1). 

even with AKARI’s sensitivity, the observation might not be deep enough to reliably measure the faint-end slope of 12µm LFs, possibly because 12µm does not contain as luminous emission lines as in the case of 8µm.