9 research outputs found
ALMA twenty-six arcmin survey of GOODS-S at one-millimeter (ASAGAO): Near-infrared-dark faint ALMA sources
We report detections of two 1.2 mm continuum sources ( ~
0.6 mJy) without any counterparts in the deep - and/or -band image (i.e.,
-band magnitude 26 mag). These near-infrared-dark faint millimeter
sources are uncovered by ASAGAO, a deep and wide-field ( 26 arcmin)
Atacama Large Millimeter/submillimeter Array (ALMA) 1.2 mm survey. One has a
red IRAC (3.6 and 4.5 m) counterpart, and the other has been independently
detected at 850 and 870 m using SCUBA2 and ALMA Band 7, respectively.
Their optical to radio spectral energy distributions indicate that they can lie
at 3-5 and can be in the early phase of massive galaxy formation.
Their contribution to the cosmic star formation rate density is estimated to be
~ 1 10 yr Mpc if they lie somewhere in
the redshift range of ~ 3-5. This value can be consistent with, or greater
than that of bright submillimeter galaxies ( 4.2 mJy) at
~ 3-5. We also uncover 3 more candidates near-infrared-dark faint ALMA
sources without any counterparts ( ~ 0.45-0.86 mJy). These
results show that an unbiased ALMA survey can reveal the dust-obscured star
formation activities, which were missed in previous deep optical/near-infrared
surveys.Comment: 10 pages, 6 figures, accepted for publication in Ap
Alma Twenty-six Arcmin^2 Survey Of Goods-s At One-millimeter (asagao): Source Catalog And Number Counts
We present the survey design, data reduction, construction of images, and
source catalog of the Atacama Large Millimeter/submillimeter Array (ALMA)
twenty-six arcmin^2 survey of GOODS-S at one-millimeter (ASAGAO). ASAGAO is a
deep (1sigma ~ 61 uJy/beam for a 250 klambda-tapered map with a synthesized
beam size of 0.51" x 0.45") and wide area (26 arcmin^2) survey on a contiguous
field at 1.2 mm. By combining with ALMA archival data in the GOODS-South field,
we obtained a deeper map in the same region (1sigma ~ 30 uJy/beam for a deep
region with a 250 klambda-taper, and a synthesized beam size of 0.59" x 0.53"),
providing the largest sample of sources (25 sources at >=5.0sigma, 45 sources
at >=4.5sigma) among ALMA blank-field surveys to date. The number counts shows
that 52(+11 -8)% of the extragalactic background light at 1.2 mm is resolved
into discrete sources at S1.2m > 135 uJy. We create infrared (IR) luminosity
functions (LFs) in the redshift range of z = 1-3 from the ASAGAO sources with
KS-band counterparts, and constrain the faintest luminosity of the LF at 2.0 <
z < 3.0. The LFs are consistent with previous results based on other ALMA and
SCUBA-2 observations, which suggest a positive luminosity evolution and
negative density evolution with increasing redshift. We find that obscured
star-formation of sources with IR luminosities of log(L(IR)/Lsun)} ~> 11.8
account for ~~60%-90% of the z ~ 2 cosmic star-formation rate density.Comment: 19 pages, 18 figures, accepted for publication in PAS
Large format imaging spectrograph for the Large Submillimeter Telescope (LST)
We present a conceptual study of a large format imaging spectrograph for next-generation large (50-m class) single-dish telescopes, i.e., the Large Submillimeter Telescope (LST) and Atacama Large Aperture Submillimeter Telescope (AtLAST). Recent discoveries of high-redshift star-forming galaxies at z=8-9 and candidate quiescent galaxies at z~6 indicate the onset of earliest star formation just a few 100 million years after the Big Bang (i.e., z = 12 - 15), and LST/AtLAST will provide a unique pathway to uncover spectroscopically-identified ``first forming galaxiesââ in the pre-reionization era, once it will be equipped with a large format imaging spectrograph. We describe the preliminary of 3-band, medium resolution (R=2000) imaging spectrograph with ~1.5 M detectors in total based on the KATANA concept (Karatsu et al.~2019), which exploits technologies of the integrated superconducting spectrometer (ISS) and a large-format imaging array like A-MKID.Green Open Access added to TU Delft Institutional Repository âYou share, we take care!â â Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Tera-Hertz Sensin
Large format imaging spectrograph for the Large Submillimeter Telescope (LST)
We present a conceptual study of a large format imaging spectrograph for next-generation large (50-m class) single-dish telescopes, i.e., the Large Submillimeter Telescope (LST) and Atacama Large Aperture Submillimeter Telescope (AtLAST). Recent discoveries of high-redshift star-forming galaxies at z=8-9 and candidate quiescent galaxies at z~6 indicate the onset of earliest star formation just a few 100 million years after the Big Bang (i.e., z = 12 - 15), and LST/AtLAST will provide a unique pathway to uncover spectroscopically-identified ``first forming galaxiesââ in the pre-reionization era, once it will be equipped with a large format imaging spectrograph. We describe the preliminary of 3-band, medium resolution (R=2000) imaging spectrograph with ~1.5 M detectors in total based on the KATANA concept (Karatsu et al.~2019), which exploits technologies of the integrated superconducting spectrometer (ISS) and a large-format imaging array like A-MKID
The onset of star formation 250 million years after the Big Bang
A fundamental quest of modern astronomy is to locate the earliest galaxies and study how they influenced the intergalactic medium a few hundred million years after the Big Bang1,2,3. The abundance of star-forming galaxies is known to decline4,5 from redshifts of about 6 to 10, but a key question is the extent of star formation at even earlier times, corresponding to the period when the first galaxies might have emerged. Here we report spectroscopic observations of MACS1149-JD16, a gravitationally lensed galaxy observed when the Universe was less than four per cent of its present age. We detect an emission line of doubly ionized oxygen at a redshift of 9.1096â±â0.0006, with an uncertainty of one standard deviation. This precisely determined redshift indicates that the red rest-frame optical colour arises from a dominant stellar component that formed about 250 million years after the Big Bang, corresponding to a redshift of about 15. Our results indicate that it may be possible to detect such early episodes of star formation in similar galaxies with future telescopes