記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Astronomical Society  

Abstract

We present Atacama Large Millimeter/submillimeter Array [C ii] 158 μm line and far-infrared (FIR) continuum emission observations toward HSC J120505.09−000027.9 (J1205−0000) at z = 6.72 with a beam size of ∼0.″8 × 0.″5 (or 4.1 kpc × 2.6 kpc), the most distant red quasar known to date. Red quasars are modestly reddened by dust and are thought to be in rapid transition from an obscured starburst to an unobscured normal quasar, driven by powerful active galactic nucleus (AGN) feedback that blows out a cocoon of interstellar medium. The FIR continuum of J1205−0000 is bright, with an estimated luminosity of L_FIR ∼ 3 × 10¹²L_⊙. The [C ii] line emission is extended on scales of r ∼ 5 kpc, greater than that of the FIR continuum. The line profiles at the extended regions are complex and broad (FWHM ∼ 630–780 km s⁻¹). Although it is not practical to identify the nature of this extended structure, possible explanations include (i) companion/merging galaxies and (ii) massive AGN-driven outflows. For the case of (i), the companions are modestly star-forming (∼10 M_⊙ yr⁻¹) but are not detected by our Subaru optical observations (y_AB,5σ = 24.4 mag). For the case of (ii), our lower limit to the cold neutral outflow rate is ∼100 M_⊙ yr⁻¹. The outflow kinetic energy and momentum are both much lower than predicted in energy-conserving wind models, suggesting that the AGN feedback in this quasar is not capable of completely suppressing its star formation.

DOI： 10.3847/1538-4357/abd7ef

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その他リンク： https://iopscience.iop.org/article/10.3847/1538-4357/abd7ef/pdf

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Astronomical Society  

Abstract

We report the discovery of a 10 comoving megaparsec (cMpc)-scale structure traced by massive submillimeter galaxies (SMGs) at z ∼ 4.6. These galaxies are selected from an emission line search of ALMA Band 7 observations targeting 184 luminous submillimeter sources (S_850μm ≥ 6.2 mJy) across 1.6 degrees² in the COSMOS field. We identify four [C ii] emitting SMGs and two probable [C ii] emitting SMG candidates at z = 4.60–4.64 with velocity-integrated signal-to-noise ratio of S/N > 8. Four of the six emitters are near-infrared blank SMGs. After excluding one SMG whose emission line is falling at the edge of the spectral window, all galaxies show clear velocity gradients along the major axes that are consistent with rotating gas disks. The estimated rotation velocities of the disks are 330–550 km s⁻¹ and the inferred host dark-matter halo masses are ∼2–8 × 10¹²M_⊙. From their estimated halo masses and [C ii] luminosity function, we suggest that these galaxies have a high (50%–100%) duty cycle and high (∼0.1) baryon conversion efficiency (SFR relative to baryon accretion rate), and that they contribute ≃2% to the total star formation rate density at z = 4.6. These SMGs are concentrated within just 0.3% of the full survey volume, suggesting they are strongly clustered. The extent of this structure and the individual halo masses suggest that these SMGs will likely evolve into members of a ∼10¹⁵M_⊙ cluster at z = 0. This survey reveals a synchronized dusty starburst in massive halos at z > 4, which could be driven by mergers or fed by smooth gas accretion.

DOI： 10.3847/1538-4357/abcc72

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その他リンク： https://iopscience.iop.org/article/10.3847/1538-4357/abcc72

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

ABSTRACT

We have used ALMA and NOEMA to study the molecular gas reservoirs in 61 ALMA-identified submillimetre galaxies (SMGs) in the COSMOS, UDS, and ECDFS fields. We detect 12CO ($J_{\rm up} =$ 2–5) emission lines in 50 sources, and [C i](3P1 − 3P0) emission in eight, at $z =$ 1.2–4.8 and with a median redshift of 2.9 ± 0.2. By supplementing our data with literature sources, we construct a statistical CO spectral line energy distribution and find that the 12CO line luminosities in SMGs peak at Jup ∼ 6, consistent with similar studies. We also test the correlations of the CO, [C i], and dust as tracers of the gas mass, finding the three to correlate well, although the CO and dust mass as estimated from the 3-mm continuum are preferable. We estimate that SMGs lie mostly on or just above the star-forming main sequence, with a median gas depletion timescale, tdep = Mgas/SFR, of 210 ± 40 Myr for our sample. Additionally, tdep declines with redshift across z ∼ 1–5, while the molecular gas fraction, μgas = Mgas/M*, increases across the same redshift range. Finally, we demonstrate that the distribution of total baryonic mass and dynamical line width, Mbaryon–σ, for our SMGs is consistent with that followed by early-type galaxies in the Coma cluster, providing strong support to the suggestion that SMGs are progenitors of massive local spheroidal galaxies. On the basis of this, we suggest that the SMG populations above and below an 870-μm flux limit of S870 ∼ 5 mJy may correspond to the division between slow and fast rotators seen in local early-type galaxies.

DOI： 10.1093/mnras/staa3862

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その他リンク： http://academic.oup.com/mnras/article-pdf/501/3/3926/35747942/staa3862.pdf

掲載種別：研究論文（学術雑誌）   出版者・発行元：arXiv e-prints  

We are developing an ultra-wideband spectroscopic instrument, DESHIMA (DEep Spectroscopic HIgh-redshift MApper), based on the technologies of an on-chip filter-bank and Microwave Kinetic Inductance Detector (MKID) to investigate dusty star-burst galaxies in the distant universe at millimeter and submillimeter wavelength. An on-site experiment of DESHIMA was performed using the ASTE 10-m telescope. We established a responsivity model that converts frequency responses of the MKIDs to line-of-sight brightness temperature. We estimated two parameters of the responsivity model using a set of skydip data taken under various precipitable water vapor (PWV, 0.4-3.0 mm) conditions for each MKID. The line-of-sight brightness temperature of sky is estimated using an atmospheric transmission model and the PWVs. As a result, we obtain an average temperature calibration uncertainty of $1\sigma=4$%, which is smaller than other photometric biases. In addition, the average forward efficiency of 0.88 in our responsivity model is consistent with the value expected from the geometrical support structure of the telescope. We also estimate line-of-sight PWVs of each skydip observation using the frequency response of MKIDs, and confirm the consistency with PWVs reported by the Atacama Large Millimeter/submillimeter Array....

DOI： 10.1007/s10909-020-02338-0

arXiv

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

ABSTRACT

We present an ALMA study of the ∼180 brightest sources in the SCUBA-2 850-μm map of the COSMOS field from the S2COSMOS survey, as a pilot study for AS2COSMOS – a full survey of the ∼1000 sources in this field. In this pilot study, we have obtained 870-μm continuum maps of an essentially complete sample of the brightest 182 sub-millimetre sources ($S_{850\, \mu \rm m}\gt $ 6.2 mJy) in COSMOS. Our ALMA maps detect 260 sub-millimetre galaxies (SMGs) spanning a range in flux density of $S_{870\, \mu \rm m}$ = 0.7–19.2 mJy. We detect more than one SMG counterpart in 34 ± 2 per cent of sub-millimetre sources, increasing to 53 ± 8 per cent for SCUBA-2 sources brighter than $S_{850\, \mu \rm m}\gt $ 12 mJy. We estimate that approximately one-third of these SMG–SMG pairs are physically associated (with a higher rate for the brighter secondary SMGs, $S_{870\, \mu \rm m}\gtrsim$ 3 mJy), and illustrate this with the serendipitous detection of bright [C ii] 157.74-μm line emission in two SMGs, AS2COS 0001.1 and 0001.2 at z = 4.63, associated with the highest significance single-dish source. Using our source catalogue, we construct the interferometric 870-μm number counts at $S_{870\, \mu \rm m}\gt $ 6.2 mJy. We use the extensive archival data of this field to construct the multiwavelength spectral energy distribution of each AS2COSMOS SMG, and subsequently model this emission with magphys to estimate their photometric redshifts. We find a median photometric redshift for the $S_{870\, \mu \rm m}\gt $ 6.2 mJy AS2COSMOS sample of z = 2.87 ± 0.08, and clear evidence for an increase in the median redshift with 870-μm flux density suggesting strong evolution in the bright end of the 870-μm luminosity function.

DOI： 10.1093/mnras/staa1345

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その他リンク： http://academic.oup.com/mnras/article-pdf/495/3/3409/33344748/staa1345.pdf

掲載種別：研究論文（学術雑誌）  

We present ALMA [C II] line and far-infrared (FIR) continuum observations of three z > 6 low-luminosity quasars (M_1450 > -25 mag) discovered by our Subaru Hyper Suprime-Cam (HSC) survey. The [C II] line was detected in all three targets with luminosities of (2.4-9.5) × 10^8 L_{☉}, about one order of magnitude smaller than optically luminous (M_1450 ≲ -25 mag) quasars. The FIR continuum luminosities range from < 9 × 10^{10} L_{☉} (3 σ limit) to {̃ } 2 × 10^{12} L_{☉}, indicating a wide range in star formation rates in these galaxies. Most of the HSC quasars studied thus far show [C II]/ FIR luminosity ratios similar to local star-forming galaxies. Using the [C II]-based dynamical mass (M_dyn) as a surrogate for bulge stellar mass (M_{ bulge}), we find that a significant fraction of low-luminosity quasars are located on or even below the local M_{ BH}-M_{ bulge} relation, particularly at the massive end of the galaxy mass distribution. In contrast, previous studies of optically luminous quasars have found that black holes are overmassive relative to the local relation. Given the low luminosities of our targets, we are exploring the nature of the early co-evolution of supermassive black holes and their hosts in a less biased way. Almost all of the quasars presented in this work are growing their black hole mass at a much higher pace at z ̃ 6 than the parallel growth model, in which supermassive black holes and their hosts grow simultaneously to match the local M_{ BH}-M_{ bulge} relation at all redshifts. As the low-luminosity quasars appear to realize the local co-evolutionary relation even at z ̃ 6, they should have experienced vigorous starbursts prior to the currently observed quasar phase to catch up with the relation....

DOI： 10.1093/pasj/psz096

arXiv

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

DOI： 10.1038/s41550-019-0850-8

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その他リンク： https://www.nature.com/articles/s41550-019-0850-8

掲載種別：研究論文（学術雑誌）   出版者・発行元：Cambridge University Press (CUP)  

<title>Abstract</title>We present ALMA [CII] line and far-infrared (FIR) continuum observations of seven <italic>z</italic> &gt; 6 low-luminosity quasars (<italic>M</italic>₁₄₅₀ &gt; −25 mag) discovered by our on-going Subaru Hyper Suprime-Cam survey. The [CII] line was detected in all targets with luminosities of ∼(2−10) × 10⁸ L_⊙, about one order of magnitude smaller than optically luminous quasars. Also found was a wide scatter of FIR continuum luminosity, ranging from <italic>L</italic>_FIR &lt; 10¹¹<italic>L</italic>_⊙ to ∼2 × 10¹²<italic>L</italic>_⊙. With the [CII]-based dynamical mass, we suggest that a significant fraction of low-luminosity quasars are located on or even below the local Magorrian relation, particularly at the massive end of the galaxy mass distribution. This is a clear contrast to the previous finding that luminous quasars tend to have overmassive black holes relative to the relation. Our result is expected to show a less-biased nature of the early co-evolution of black holes and their host galaxies.

DOI： 10.1017/s1743921319009487

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掲載種別：研究論文（学術雑誌）  

We present the survey design, data reduction, construction of images, and source catalog of the Atacama Large Millimeter/submillimeter Array (ALMA) twenty-six arcmin<SUP>2</SUP> survey of GOODS-S at one millimeter (ASAGAO). ASAGAO is a deep (1 σ depth ̃ 61 μJy beam<SUP>-1</SUP> for a 250 kλ-tapered map with a synthesized beam size of 0{^''<SUB>.</SUB>}51 × 0{^''<SUB>.</SUB>}45) and wide area (26 arcmin<SUP>2</SUP>) 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 (1 σ depth ̃ 30 μJy beam<SUP>-1</SUP> for a deep region with a 250 kλ-taper, and a synthesized beam size of 0{^''<SUB>.</SUB>}59 × 0{^''<SUB>.</SUB>}53), providing the largest sample of sources (25 sources at ≥5.0 σ, 45 sources at ≥4.5 σ) among ALMA blank-field surveys to date. The number counts show that 52^{+11}_{-8}% of the extragalactic background light at 1.2 mm is resolved into discrete sources at S<SUB>1.2 mm</SUB> &gt; 135 μJy. We create infrared (IR) luminosity functions (LFs) in the redshift range of z = 1-3 from the ASAGAO sources with K<SUB>s</SUB>-band counterparts, and constrain the faintest luminosity of the LF at 2.0 &lt; z &lt; 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<SUB>IR</SUB>/L<SUB>☉</SUB>) ≳ 11.8 account for ≈60%-90% of the z ̃ 2 cosmic star-formation rate density....

DOI： 10.1093/pasj/psy104

arXiv

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

DOI： 10.1038/s41586-018-0443-1

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その他リンク： http://www.nature.com/articles/s41586-018-0443-1.pdf

掲載種別：研究論文（学術雑誌）  

To search for dust-obscured star-formation activity in the early Universe, it is essential to obtain a deep and wide submillimeter/millimeter map. The advent of the Atacama Large Millimeter/submillimeter Array (ALMA) has enabled us to obtain such maps with sufficiently high spatial resolution to be free from source confusion. We present a new 1.1 mm-wave map obtained by ALMA in the SSA22 field. The field contains a remarkable proto-cluster at z = 3.09; therefore, it is an ideal region to investigate the role of a large-scale cosmic web on dust-obscured star formation. The typical 1σ depth of our map is 73 μJy beam<SUP>-1</SUP> with a {0^{^''<SUB>.</SUB>}5} resolution. Combining the present survey with earlier, archived observations, we map an area of 20 arcmin<SUP>2</SUP> (71 comoving Mpc<SUP>2</SUP> at z = 3.09). Within the combined survey area we have detected 35 sources at a signal-to-noise ratio (S/N) &gt;5, with flux densities of S<SUB>1.1mm</SUB> = 0.43-5.6 mJy, equivalent to star-formation rates of ≳100-1000 M<SUB>☉</SUB> yr<SUP>-1</SUP> at z = 3.09, for a Chabrier initial mass function: 17 sources out of 35 are new detections. The cumulative number counts show an excess by a factor of three to five compared to blank fields. The excess suggests enhanced, dust-enshrouded star-formation activity in the proto-cluster on a 10 comoving Mpc scale, indicating accelerated galaxy evolution in this overdense region....

DOI： 10.1093/pasj/psy065

arXiv

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掲載種別：研究論文（学術雑誌）  

We present our ALMA Cycle 4 measurements of the [C II] emission line and the underlying far-infrared (FIR) continuum emission from four optically low-luminosity (M<SUB>1450</SUB> &gt; -25) quasars at z ≳ 6 discovered by the Subaru Hyper Suprime Cam (HSC) survey. The [C II] line and FIR continuum luminosities lie in the ranges L_[C II] = (3.8-10.2)× 10<SUP>8</SUP> L_{☉} and L<SUB>FIR</SUB> = (1.2-2.0) × 10<SUP>11</SUP> L_{☉}, which are at least one order of magnitude smaller than those of optically-luminous quasars at z ≳ 6. We estimate the star formation rates (SFRs) of our targets as ≃ 23-40 M_{☉} yr<SUP>-1</SUP>. Their line and continuum-emitting regions are marginally resolved, and found to be comparable in size to those of optically-luminous quasars, indicating that their SFR or likely gas mass surface densities (key controlling parameter of mass accretion) are accordingly different. The L_[C II}]}/L_FIR ratios of the hosts, ≃ (2.2-8.7) × 10<SUP>-3</SUP>, are fully consistent with local star-forming galaxies. Using the [C II] dynamics, we derived their dynamical masses within a radius of 1.5-2.5 kpc as ≃ (1.4-8.2) × 10<SUP>10</SUP> M_{☉}. By interpreting these masses as stellar ones, we suggest that these faint quasar hosts are on or even below the star-forming main sequence at z ̃ 6, i.e., they appear to be transforming into quiescent galaxies. This is in contrast to the optically-luminous quasars at those redshifts, which show starburst-like properties. Finally, we find that the ratios of black hole mass to host galaxy dynamical mass of most of the low-luminosity quasars, including the HSC ones, are consistent with the local value. The mass ratios of the HSC quasars can be reproduced by a semi-analytical model that assumes merger-induced black hole host galaxy evolution....

DOI： 10.1093/pasj/psy026

arXiv

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掲載種別：研究論文（学術雑誌）  

DOI： 10.3847/2041-8213/aa9572

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

We report the identification of four millimeter line-emitting galaxies with the Atacama Large Milli/submillimeter Array (ALMA) in SSA22 Field (ADF22). We analyze the ALMA 1.1-mm survey data, with an effective survey area of 5 arcmin<SUP>2</SUP>, frequency ranges of 253.1-256.8 and 269.1-272.8 GHz, angular resolution of 0{^''<SUB>.</SUB>}7 and rms noise of 0.8 mJy beam<SUP>-1</SUP> at 36 km s<SUP>-1</SUP> velocity resolution. We detect four line-emitter candidates with significance levels above 6σ. We identify one of the four sources as a CO(9-8) emitter at z = 3.1 in a member of the proto-cluster known in this field. Another line emitter with an optical counterpart is likely a CO(4-3) emitter at z = 0.7. The other two sources without any millimeter continuum or optical/near-infrared counterpart are likely to be [C II] emitter candidates at z = 6.0 and 6.5. The equivalent widths of the [C II] candidates are consistent with those of confirmed high-redshift [C II] emitters and candidates, and are a factor of 10 times larger than that of the CO(9-8) emitter detected in this search. The [C II] luminosity of the candidates are 4-7 × 10<SUP>8</SUP> L<SUB>☉</SUB>. The star formation rates (SFRs) of these sources are estimated to be 10-20 M<SUB>☉</SUB> yr<SUP>-1</SUP> if we adopt an empirical [C II] luminosity-SFR relation. One of them has a relatively low S/N ratio, but shows features characteristic of emission lines. Assuming that at least one of the two candidates is a [C II] emitter, we derive a lower limit of [C II]-based star formation rate density (SFRD) at z ̃ 6. The resulting value of &gt;10<SUP>-2</SUP> M<SUB>☉</SUB> yr<SUP>-1</SUP> Mpc<SUP>-3</SUP> is consistent with the dust-uncorrected UV-based SFRD. Future millimeter/submillimeter surveys can be used to detect a number of high-redshift line emitters, with which to study the star formation history in the early universe....

DOI： 10.1093/pasj/psx018

arXiv

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We investigate gas contents of star-forming galaxies associated with
protocluster 4C23.56 at z = 2.49 by using the redshifted CO(3-2) and 1.1 mm
dust continuum with the Atacama Large Millimeter/submillimeter Array. The
observations unveil seven CO detections out of 22 targeted H$\alpha$ emitters
(HAEs) and four out of 19 in 1.1 mm dust continuum. They have high stellar mass
($M_{\star}>4\times 10^{10}$ $M_{\odot}$) and exhibit a specific star-formation
rate typical of main-sequence star forming galaxies at $z\sim2.5$. Different
gas mass estimators from CO(3-2) and 1.1 mm yield consistent values for
simultaneous detections. The gas mass ($M_{\rm gas}$) and gas fraction ($f_{\rm
gas}$) are comparable to those of field galaxies, with $M_{\rm gas}=[0.3,
1.8]\times10^{11} \times (\alpha_{\rm CO}/(4.36\times A(Z)$)) M$_{\odot}$,
where $\alpha_{\rm CO}$ is the CO-to-H$_2$ conversion factor and $A(Z)$ the
additional correction factor for the metallicity dependence of $\alpha_{\rm
CO}$, and $\langle f_{\rm gas}\rangle = 0.53 \pm 0.07$ from CO(3-2). Our
measurements place a constraint on the cosmic gas density of high-$z$
protoclusters, indicating the protocluster is characterized by a gas density
higher than that of the general fields by an order of magnitude. We found $\rho
(H_2)\sim 5 \times 10^9 \,M_{\odot}\,{\rm Mpc^{-3 } }$ with the CO(3-2)
detections. The five ALMA CO detections occur in the region of highest galaxy
surface density, where the density positively correlates with global
star-forming efficiency (SFE) and stellar mass. Such correlations imply a
potentially critical role of environment on early galaxy evolution at high-z
protoclusters, although future observations are necessary for confirmation.

DOI： 10.3847/1538-4357/aa74c2

arXiv

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We present spatially resolved ALMA observations of the CO J=3-2 emission line
in two massive galaxies at z=2.5 on the star-forming main sequence. Both
galaxies have compact dusty star-forming cores with effective radii of Re=1.3
kpc and Re=1.2 kpc in the 870 um continuum emission. The spatial extent of
star-forming molecular gas is also compact with Re=1.9 kpc and Re=2.3 kpc, but
more extended than the dust emission. Interpreting the observed
position-velocity diagrams with dynamical models, we find the starburst cores
to be rotation-dominated with the ratio of the maximum rotation velocity to the
local velocity dispersion of v/sigma=7.0 (v=386 km/s) and v/sigma_0=4.1 (v=391
km/s). Given that the descendants of these massive galaxies in the local
universe are likely ellipticals with v/sigma nearly an order of magnitude
lower, the rapidly rotating galaxies would lose significant net angular
momentum in the intervening time. The comparisons among dynamical, stellar,
gas, and dust mass suggest that the starburst CO-to-H2 conversion factor of
alpha_CO=0.8 Msun/(K km/s/pc2) is appropriate in the spatially resolved cores.
The dense cores are likely to be formed in extreme environments similar to the
central regions of local ultraluminous infrared galaxies. Our work also
demonstrates that a combination of medium-resolution CO and high-resolution
dust continuum observations is a powerful tool for characterizing the dynamical
state of molecular gas in distant galaxies.

DOI： 10.3847/2041-8213/aa7338

arXiv

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掲載種別：研究論文（学術雑誌）  

DOI： 10.3847/1538-4357/835/2/286

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IOP PUBLISHING LTD  

We present the detailed characterization of two extremely red submillimeter galaxies (SMGs), ASXDF1100.053.1 and 231.1, with the Atacama Large Millimeter/submillimeter Array (ALMA) and the Jansky Very Large Array. These SMGs were originally selected using AzTEC at 1100 mu m, and are observed by Herschel to be faint at 100-500 mu m. Their (sub)millimeter colors are as red as-or redder-than known z greater than or similar to 5 SMGs; indeed, ASXDF1100.053.1 is redder than HFLS 3, which lies at z = 6.3. They are also faint and red in the near- / midinfrared: similar to 1 mu Jy at IRAC 4.5 mu m and &lt;0.2 mu Jy in the K-s filter. These SMGs are also faint in the radio waveband, where F-6GHz = 4.5 mu Jy for ASXDF1100.053.1 and F-1.4GHz = 28 mu Jy for ASXDF1100.231.1, suggestive of = z 6.5(-1.1)(+1.4) and = z 4.1(-0.7)(+0.6) for ASXDF1100.053.1 and 231.1, respectively. ASXDF1100.231.1 has a flux excess in the 3.6 mu m filter, probably due to H alpha emission at z = 4-5. Derived properties of ASXDF1100.053.1 for z = 5.5-7.5 and 231.1 for z = 3.5-5.5 are as follows: their infrared luminosities are [6.5 - 7.4] x 10(12) and [4.2-4.5] x 10(12) L-circle dot; their stellar masses are [0.9-2] x 10(11) and [0.4-3] x 10(10) M-circle dot; their circularized half-light radii in the ALMA maps are similar to 1 and. less than or similar to 0.2 kpc (similar to 2-3 kpc for 90% of the total flux). Last, their surface infrared luminosity densities, SIR, are similar to 1 x 10(12) and. 1.5 x 10(13) L-circle dot kpc(-2), similar to values seen for local (U)LIRGs. These data suggest that ASXDF1100.053.1 and 231.1 are compact SMGs at z. 4 and can plausibly evolve into z greater than or similar to 3 compact quiescent galaxies.

DOI： 10.3847/1538-4357/835/2/286

Web of Science

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© 2017. The American Astronomical Society. All rights reserved. We report the result from observations conducted with the Atacama Large Millimeter/submillimeter Array (ALMA) to detect [C ii] 158 μm fine structure line emission from galaxies embedded in one of the most spectacular Lyα blobs (LABs) at z = 3.1, SSA22-LAB1. Of three dusty star-forming galaxies previously discovered by ALMA 860 μm dust continuum survey toward SSA22-LAB1, we detected the [C ii] line from one, LAB1-ALMA3 at z = 3.0993 0.0004. No line emission was detected, associated with the other ALMA continuum sources or from three rest-frame UV/optical selected zspec≃ 3.1 galaxies within the field of view. For LAB1-ALMA3, we find relatively bright [C ii] emission compared to the infrared luminosity (L[C ii]LIR≈ 0.01) and an extremely high [C ii] 158 μm and [N ii] 205 μm emission line ratio (L[C ii]L[N ii]&gt; 55). The relatively strong [C ii] emission may be caused by abundant photodissociation regions and sub-solar metallicity, or by shock heating. The origin of the unusually strong [C ii] emission could be causally related to the location within the giant LAB, although the relationship between extended Lyα emission and interstellar medium conditions of associated galaxies is yet to be understand.

DOI： 10.3847/2041-8213/834/2/L16

Scopus

arXiv

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掲載種別：研究論文（学術雑誌）  

DOI： 10.3847/1538-4357/833/2/195

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We present results from a deep 2'x3' (comoving scale of 3.7 Mpc x 5.5 Mpc at
z=3) survey at 1.1 mm taken with the Atacama Large Millimeter/submillimeter
Array (ALMA) in the SSA22 field. We observe the core region of a z = 3.09
protocluster, achieving a typical rms sensitivity of 60 micro-Jy/beam at a
spatial resolution of 0".7. We detect 18 robust ALMA sources at a
signal-to-noise ratio (SNR) > 5. Comparison between the ALMA map and a 1.1 mm
map taken with the AzTEC camera on the Atacama Submillimeter Telescope
Experiment (ASTE) indicates that three submillimeter sources discovered by the
AzTEC/ASTE survey are resolved into eight individual submillimeter galaxies
(SMGs) by ALMA. At least ten of our 18 ALMA SMGs have spectroscopic redshifts
of z = 3.09, placing them in the protocluster. This shows that a number of
dusty starburst galaxies are forming simultaneously in the core of the
protocluster. The nine brightest ALMA SMGs with SNR > 10 have a median
intrinsic angular size of 0".32+0".13-0".06 (2.4+1.0-0.4 physical kpc at z =
3.09), which is consistent with previous size measurements of SMGs in other
fields. As expected the source counts show a possible excess compared to the
counts in the general fields at S_1.1mm >= 1.0 mJy due to the protocluster. Our
contiguous mm mapping highlights the importance of large-scale structures on
the formation of dusty starburst galaxies.

DOI： 10.3847/1538-4357/835/1/98

Scopus

arXiv

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We present stacking analyses on our ALMA deep 1.1 mm imaging in the SXDF
using 1.6 {\mu}m and 3.6 {\mu}m selected galaxies in the CANDELS WFC3 catalog.
We detect a stacked flux of ~0.03-0.05 mJy, corresponding to LIR < 10^11 Lsun
and a star formation rate (SFR) of ~ 15 Msun/yr at z = 2. We find that galaxies
brighter in the rest-frame near-infrared tend to be also brighter at 1.1 mm,
and galaxies fainter than m[3.6um] = 23 do not produce detectable 1.1 mm
emission. This suggests a correlation between stellar mass and SFR, but
outliers to this correlation are also observed, suggesting strongly boosted
star formation or extremely large extinction. We also find tendencies that
redder galaxies and galaxies at higher redshifts are brighter at 1.1 mm. Our
field contains z ~ 2.5 H-alpha emitters and a bright single-dish source.
However, we do not find evidence of bias in our results caused by the bright
source. By combining the fluxes of sources detected by ALMA and fluxes of faint
sources detected with stacking, we recover a 1.1 mm surface brightness of up to
20.3 +/- 1.2 Jy/deg, comparable to the extragalactic background light measured
by COBE. Based on the fractions of optically faint sources in our and previous
ALMA studies and the COBE measurements, we find that approximately half of the
cosmic star formation may be obscured by dust and missed by deep optical
surveys, Much deeper and wider ALMA imaging is therefore needed to better
constrain the obscured cosmic star formation history.

DOI： 10.3847/1538-4357/833/2/195

arXiv

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The central structure in three of the brightest unlensed z=3-4 submillimeter
galaxies are investigated through 0.015" - 0.05" (120 -- 360~pc) 860 micron
continuum images obtained using the Atacama Large Millimeter/submillimeter
Array (ALMA). The distribution in the central kpc in AzTEC1 and AzTEC8 are
extremely complex, and they are composed of multiple ~200 pc clumps. AzTEC4
consists of two sources that are separated by ~1.5 kpc, indicating a mid-stage
merger. The peak star formation rate densities in the central clumps are ~300 -
3000 Msun/yr/kpc^2, suggesting regions with extreme star formation near the
Eddington Limit. By comparing the flux obtained by ALMA and Submillimeter Array
(SMA), we find that 68-90% of the emission is extended (> 1 kpc) in AzTEC 4 and
8. For AzTEC1, we identify at least 11 additional compact (~200 pc) clumps in
the extended 3 - 4 kpc region. Overall, the data presented here suggest that
the luminosity surface densities observed at < 150 pc scales are roughly
similar to that observed in local ULIRGs, as in the eastern nucleus of Arp 220.
Between 10 to 30% of the 860 micron continuum is concentrated in clumpy
structures in the central kpc while the remaining flux is distributed over > 1
kpc regions, some of which could also be clumpy. These sources can be explained
by a rapid inflow of gas such as a merger of gas-rich galaxies, surrounded by
extended and clumpy starbursts. However, the cold mode accretion model is not
ruled out.

DOI： 10.3847/2041-8205/829/1/L10

Scopus

arXiv

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We present 0".2-resolution Atacama Large Millimeter/submillimeter Array
observations at 870 um for 25 Halpha-seleced star-forming galaxies (SFGs)
around the main-sequence at z=2.2-2.5. We detect significant 870 um continuum
emission in 16 (64%) of these SFGs. The high-resolution maps reveal that the
dust emission is mostly radiated from a single region close to the galaxy
center. Exploiting the visibility data taken over a wide $uv$ distance range,
we measure the half-light radii of the rest-frame far-infrared emission for the
best sample of 12 massive galaxies with logM*>11. We find nine galaxies to be
associated with extremely compact dust emission with R_{1/2,870um}<1.5 kpc,
which is more than a factor of 2 smaller than their rest-optical sizes,
R_{1/2,1.6um}=3.2 kpc, and is comparable with optical sizes of massive
quiescent galaxies at similar redshifts. As they have an exponential disk with
Sersic index of n=1.2 in the rest-optical, they are likely to be in the
transition phase from extended disks to compact spheroids. Given their high
star formation rate surface densities within the central 1 kpc of Sigma
SFR1kpc=40 Msol/yr/kpc^2, the intense circumnuclear starbursts can rapidly
build up a central bulge with Sigma M*1kpc>1e10 Msol/kpc^2 in several hundred
Myr, i.e. by z~2. Moreover, ionized gas kinematics reveal that they are
rotation-supported with an angular momentum as large as that of typical SFGs at
z=1-3. Our results suggest bulges are commonly formed in extended rotating
disks by internal processes, not involving major mergers.

DOI： 10.3847/1538-4357/834/2/135

arXiv

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We present a multi-wavelength analysis of five submillimeter sources (S_1.1mm
= 0.54-2.02 mJy) that were detected during our 1.1-mm-deep continuum survey in
the SXDF-UDS-CANDELS field (2 arcmin^2, 1sigma = 0.055 mJy beam^-1) using the
Atacama Large Millimeter/submillimeter Array (ALMA). The two brightest sources
correspond to a known single-dish (AzTEC) selected bright submillimeter galaxy
(SMG), whereas the remaining three are faint SMGs newly uncovered by ALMA. If
we exclude the two brightest sources, the contribution of the ALMA-detected
faint SMGs to the infrared extragalactic background light is estimated to be ~
4.1^{+5.4}_{-3.0} Jy deg^{-2}, which corresponds to ~ 16^{+22}_{-12}% of the
infrared extragalactic background light. This suggests that their contribution
to the infrared extragalactic background light is as large as that of bright
SMGs. We identified multi-wavelength counterparts of the five ALMA sources. One
of the sources (SXDF-ALMA3) is extremely faint in the optical to near-infrared
region despite its infrared luminosity (L_IR ~ 1e12 L_sun or SFR ~ 100 M_sun
yr^{-1}). By fitting the spectral energy distributions (SEDs) at the
optical-to-near-infrared wavelengths of the remaining four ALMA sources, we
obtained the photometric redshifts (z_photo) and stellar masses (M_*): z_photo
~ 1.3-2.5, M_* ~ (3.5-9.5)e10 M_sun. We also derived their star formation rates
(SFRs) and specific SFRs (sSFRs) as ~ 30-200 M_sun yr^{-1} and ~ 0.8-2
Gyr^{-1}, respectively. These values imply that they are main-sequence
star-forming galaxies.

DOI： 10.1093/pasj/psw073

arXiv

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掲載種別：研究論文（学術雑誌）  

We report 1.1-mm number counts revealed with the Atacama Large Millimeter/submillimeter Array (ALMA) in the Subaru/XMM-Newton Deep Survey Field (SXDF). The advent of ALMA enables us to reveal millimeter-wavelength number counts down to the faint end without source confusion. However, previous studies are based on the ensemble of serendipitously detected sources in fields originally targeting different sources and could be biased due to the clustering of sources around the targets. We derive number counts in the flux range of 0.2-2 mJy by using 23 (≥4σ) sources detected in a continuous 2.0-arcmin<SUP>2</SUP> area of the SXDF. The number counts are consistent with previous results within errors, suggesting that the counts derived from serendipitously detected sources are not significantly biased, although there could be field-to-field variation due to the small survey area. By using the best-fitting function of the number counts, we find that ̃40% of the extragalactic background light at 1.1 mm is resolved at S<SUB>1.1mm</SUB> &gt; 0.2 mJy....

DOI： 10.1093/pasj/psw026

arXiv

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Astronomical Society  

DOI： 10.1088/2041-8205/815/1/l8

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その他リンク： https://iopscience.iop.org/article/10.1088/2041-8205/815/1/L8

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1088/0004-637X/810/2/133

DOI： 10.48550/arXiv.1411.5038

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掲載種別：研究論文（学術雑誌）  

We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 1 observations of the central kiloparsec region of the luminous type 1 Seyfert galaxy NGC 7469 with unprecedented high resolution (0.″5 ×0.″4 = 165 × 132 pc) at submillimeter wavelengths. Utilizing the wide bandwidth of ALMA, we simultaneously obtained HCN(4-3), HCO<SUP>+</SUP>(4-3), CS(7-6), and partially CO(3-2) line maps, as well as the 860 μm continuum. The region consists of the central ̃1″ component and the surrounding starburst ring with a radius of ̃1.″5-2.″5. Several structures connect these components. Except for CO(3-2), these dense gas tracers are significantly concentrated toward the central ̃1″, suggesting their suitability to probe the nuclear regions of galaxies. Their spatial distribution resembles well those of centimeter and mid-infrared continuum emissions, but it is anticorrelated with the optical one, indicating the existence of dust-obscured star formation. The integrated intensity ratios of HCN(4-3)/HCO<SUP>+</SUP>(4-3) and HCN(4-3)/CS(7-6) are higher at the active galactic nucleus (AGN) position than at the starburst ring, which is consistent with our previous findings (submillimeter-HCN enhancement). However, the HCN(4-3)/HCO<SUP>+</SUP>(4-3) ratio at the AGN position of NGC 7469 (1.11 ± 0.06) is almost half of the corresponding value of the low-luminosity type 1 Seyfert galaxy NGC 1097 (2.0 ± 0.2), despite the more than two orders of magnitude higher X-ray luminosity of NGC 7469. But the ratio is comparable to that of the close vicinity of the AGN of NGC 1068 (̃1.5). Based on these results, we speculate that some heating mechanisms other than X-ray (e.g., mechanical heating due to an AGN jet) can contribute significantly for shaping the chemical composition in NGC 1097....

DOI： 10.1088/0004-637X/811/1/39

arXiv

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We present first results from the SXDF-ALMA 1.5 arcmin^2 deep survey at 1.1
mm using Atacama Large Millimeter Array (ALMA). The map reaches a 1sigma depth
of 55 uJy/beam and covers 12 Halpha-selected star-forming galaxies at z = 2.19
or z=2.53. We have detected continuum emission from three of our
Halpha-selected sample, including one compact star-forming galaxy with high
stellar surface density, NB2315-07. They are all red in the rest-frame optical
and have stellar masses of log (M*/Msun)>10.9 whereas the other blue,
main-sequence galaxies with log(M*/Msun)=10.0-10.8 are exceedingly faint, <290
uJy (2sigma upper limit). We also find the 1.1 mm-brightest galaxy, NB2315-02,
to be associated with a compact (R_e=0.7+-0.1 kpc), dusty star-forming
component. Given high gas fraction (44^{+20}_{-8}% or 37^{+25}_{-3}%) and high
star formation rate surface density (126^{+27}_{-30} Msun yr^{-1}kpc^{-2}), the
concentrated starburst can within less than 50^{+12}_{-11} Myr build up a
stellar surface density matching that of massive compact galaxies at z~2,
provided at least 19+-3% of the total gas is converted into stars in the galaxy
centre. On the other hand, NB2315-07, which already has such a high stellar
surface density core, shows a gas fraction (23+-8%) and is located in the lower
envelope of the star formation main-sequence. This compact less star-forming
galaxy is likely to be in an intermediate phase between compact dusty
star-forming and quiescent galaxies.

DOI： 10.1088/2041-8205/811/1/L3

arXiv

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Cambridge University Press  

We have conducted 1.1 mm ALMA observations of a contiguous 105 × 50 or 1.5 arcmin2 window in the SXDF-UDS-CANDELS. We achieved a 5σ sensitivity of 0.28 mJy, giving a flat sensus of dusty star-forming galaxies with L IR ∼6×1011 L O (if T dust=40K) up to z ∼ 10 thanks to the negative K-correction at this wavelength. We detected 5 brightest sources (S/N&gt
6) and 18 low-significant sources (5&gt
S/N&gt
4
they may contain spurious detections, though). One of the 5 brightest ALMA sources (S 1.1mm = 0.84 ± 0.09 mJy) is extremely faint in the WFC3 and VLT/HAWK-I images, demonstrating that a contiguous ALMA imaging survey uncovers a faint dust-obscured population invisible in the deep optical/near-infrared surveys. We find a possible [CII]-line emitter at z=5.955 or a low-z CO emitting galaxy within the field, allowing us to constrain the [CII] and/or CO luminosity functions across the history of the universe.

DOI： 10.1017/S1743921315010364

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ASTRONOMICAL SOC PACIFIC  

We present the results of an ALMA survey of submillimeter galaxies (SMGs) in the SSA22 field. Totally 45 sources discovered by the AzTEC/ASTE survey were observed at 1.1mm to find 64 ALMA-identified SMGs with S/N >= 4.5. This is the largest SMG survey in Band 6 in ALMA Cyclel. Previous panoramic Lyman-alpha emitter (LAE) surveys have unveiled that SSA22 is not a general field but a highly biased field at z = 3.1. We find large excess in the number counts and surface number density compared to the ALESS survey in ECDFS, which suggests SMGs are preferentially formed in the dense environment at z similar to 3.

Web of Science

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

DOI： 10.1093/mnras/stu447

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Cambridge University Press  

We present recent results on Karl Jansky Very Large Array (JVLA) deep S-band (2-4 GHz) observation towards a protocluster 4C23.56 at redshift z ∼ 2.5. The protocluster 4C23.56 is known to have a significant over density (∼ 5 times) of star-burst galaxies selected to be Hα line-bright by a Subaru narrow band imaging. Now we have found 25 HAEs associated with the protocluster. These starburst HAEs are likely to become massive ellipticals at z = 0 in a cluster. Various other galaxy populations also reside in this field and the fact makes the field very unique as a tool to understand galaxy formation in a over dense region. Subsequent deep 1100-μm continuum surveys by the ASTE 10-m dish have discovered that several submillimeter bright galaxies (SMGs) coincide with HAEs, suggesting HAEs undergoing dusty starbursts. As star formation rates (SFRs) of HAEs might have been underestimated, we use radio being resistant to dust extinction. We investigate the correlation between SFR1.4GHz and SFRHα for radio index α = 0.8 to see if the correlation holds for the sources and to check the number of dusty star forming galaxies. Our final results will allow us to evaluate quantitatively how the galaxy formation channel may be different under the condition of over-densities.

DOI： 10.1017/S1743921314009892

Web of Science

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Astronomical Society  

DOI： 10.1088/0004-637x/779/1/32

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その他リンク： http://stacks.iop.org/0004-637X/779/i=1/a=32?key=crossref.5c615417ca8e16c36b2c218f8573a212

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

DOI： 10.1093/mnras/stt1258

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

DOI： 10.1093/mnras/stt077

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ASTRONOMICAL SOC PACIFIC  

We performed deep and wide-field surveys at 1.1 mm using AzTEC camera mounted on ASTE. We calculate the two-point angular autocorrelation functions in seven deep survey fields: AKARI Deep Field South (ADF-S), COSMOS, GOODS-N, GOODS-S, Lockman Hole East, SSA 22, and SXDF. We detect evidence for clustering signals in all the fields. By averaging the results on the bright sources measured in the ADF-S, the SSA 22, and the SXDF fields, we derived a more significant correlation function of 1.1 mm sources. A comparison of the correlation length with a bias evolution model of dark halos suggests that dark halos hosting bright 1.1 mm sources evolve into galaxy clusters in the present-day universe.

Web of Science

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記述言語：英語   出版者・発行元：Astronomical Society of Japan  

DOI： 10.1093/pasj/64.4.L2

CiNii Books

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

DOI： 10.1111/j.1365-2966.2011.18918.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

DOI： 10.1111/j.1365-2966.2010.17658.x

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Astronomical Society  

DOI： 10.1088/0004-637x/724/2/1270

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：American Astronomical Society  

DOI： 10.1088/0004-637x/711/2/974

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：AMER INST PHYSICS  

We present number counts and clustering properties of millimeter-bright galaxies uncovered by the AzTEC camera mounted on the Atacama Submillimeter Telescope Experiment (ASTE). We surveyed the AKARI Deep Field South (ADF-S), the Subaru/XMM Newton Deep Field (SXDF), and the SSA22 fields with an area of similar to 0.25 deg(2) each with an rms noise level of similar to 0.4-1.0 mJy. We constructed differential and cumulative number counts, which provide currently the tightest constraints on the faint end. The integration of the best-fit number counts in the ADF-S find that the contribution of 1.1 mm sources with fluxes >= 1 mJy to the cosmic infrared background (CIB) at 1.1 mm is 12-16%, suggesting that the large fraction of the CIB originates from faint sources of which the number counts are not yet constrained. We estimate the cosmic star-formation rate density contributed by 1.1 mm sources with >= 1 mJy using the best-fit number counts in the ADF-S and find that it is lower by about a factor of 5-10 compared to those derived from UV/optically-selected galaxies at z similar to 2-3. The average mass of dark halos hosting bright 1.1 mm sources was calculated to be 10(13)-10(14) M-circle dot. Comparison of correlation lengths of 1.1 mm sources with other populations and with a bias evolution model suggests that dark halos hosting bright 1.1 mm sources evolve into systems of clusters at present universe and the 1.1 mm sources residing the dark halos evolve into massive elliptical galaxies located in the center of clusters.

DOI： 10.1063/1.3509298

Web of Science

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