Imperial College London

Dr Clements

Faculty of Natural SciencesDepartment of Physics

Reader in Astrophysics
 
 
 
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Contact

 

+44 (0)20 7594 7693d.clements

 
 
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Location

 

1011Blackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

457 results found

Greaves JS, Richards AMS, Bains W, Rimmer PB, Sagawa H, Clements DL, Seager S, Petkowski JJ, Sousa-Silva C, Ranjan S, Drabek-Maunder E, Fraser HJ, Cartwright A, Mueller-Wodarg I, Zhan Z, Friberg P, Coulson I, Lee E, Hoge Jet al., 2021, Phosphine gas in the cloud deck of Venus (vol 5, pg 655, 2021), Nature Astronomy, Vol: 5, Pages: 726-728, ISSN: 2397-3366

Journal article

Greaves JS, Richards AMS, Bains W, Rimmer PB, Clements DL, Seager S, Petkowski JJ, Sousa-Silva C, Ranjan S, Fraser HJet al., 2021, Reply to: No evidence of phosphine in the atmosphere of Venus from independent analyses, NATURE ASTRONOMY, Vol: 5, Pages: 636-+, ISSN: 2397-3366

Journal article

Zavala JA, Casey CM, Manning SM, Aravena M, Bethermin M, Caputi KI, Clements DL, da Cunha E, Drew P, Finkelstein SL, Fujimoto S, Hayward C, Hodge J, Kartaltepe JS, Knudsen K, Koekemoer AM, Long AS, Magdis GE, Man AWS, Popping G, Sanders D, Scoville N, Sheth K, Staguhn J, Toft S, Treister E, Vieira JD, Yun MSet al., 2021, The Evolution of the IR Luminosity Function and Dust-obscured Star Formation over the Past 13 Billion Years, ASTROPHYSICAL JOURNAL, Vol: 909, ISSN: 0004-637X

Journal article

Lacy M, Surace JA, Farrah D, Nyland K, Afonso J, Brandt WN, Clements DL, Lagos CDP, Maraston C, Pforr J, Sajina A, Sako M, Vaccari M, Wilson G, Ballantyne DR, Barkhouse WA, Brunner R, Cane R, Clarke TE, Cooper M, Cooray A, Covone G, D'Andrea C, Evrard AE, Ferguson HC, Frieman J, Gonzalez-Perez V, Gupta R, Hatziminaoglou E, Huang J, Jagannathan P, Jarvis MJ, Jones KM, Kimball A, Lidman C, Lubin L, Marchetti L, Martini P, McMahon RG, Mei S, Messias H, Murphy EJ, Newman JA, Nichol R, Norris RP, Oliver S, Perez-Fournon I, Peters WM, Pierre M, Polisensky E, Richards GT, Ridgway SE, Rottgering HJA, Seymour N, Shirley R, Somerville R, Strauss MA, Suntzeff N, Thorman PA, van Kampen E, Verma A, Wechsler R, Wood-Vasey WMet al., 2021, A Spitzer survey of Deep Drilling Fields to be targeted by the Vera C. Rubin Observatory Legacy Survey of Space and Time, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 501, Pages: 892-910, ISSN: 0035-8711

Journal article

Riechers DA, Nayyeri H, Burgarella D, Emonts BHC, Clements DL, Cooray A, Ivison RJ, Oliver S, Perez-Fournon I, Rigopoulou D, Scott Det al., 2021, Rise of the titans: gas excitation and feedback in a binary hyper-luminous dusty starburst galaxy at z~6, Astrophysical Journal Supplement Series, Vol: 907, Pages: 1-18, ISSN: 0067-0049

We report new observations toward the hyper-luminous dusty starbursting majormerger ADFS-27 (z=5.655), using ATCA and ALMA. We detect CO 2-1, 8-7, 9-8, 10-9and H2O(321-221) emission, and a P-Cygni-shaped OH+(11-01) absorption/emissionfeature. We also tentatively detect H2O(321-312) and OH+(12-01) emission andCH+(1-0) absorption. We find a total cold molecular mass of M_gas = (2.1+/-0.2)x 10^11 (alpha_CO/1.0) Msun. We also find that the excitation of thestar-forming gas is overall moderate for a z>5 dusty starburst, which isconsistent with its moderate dust temperature. A high density, high kinetictemperature gas component embedded in the gas reservoir is required to fullyexplain the CO line ladder. This component is likely associated with the"maximum starburst" nuclei in the two merging galaxies, which are separated byonly (140+/-13) km/s along the line of sight and 9.0 kpc in projection. Thekinematic structure of both components is consistent with galaxy disks, butthis interpretation remains limited by the spatial resolution of the currentdata. The OH+ features are only detected towards the northern component, whichis also the one that is more enshrouded in dust and thus remains undetected upto 1.6 um even in our sensitive new HST/WFC3 imaging. The absorption componentof the OH+ line is blueshifted and peaks near the CO and continuum emissionpeak while the emission is redshifted and peaks offset by 1.7 kpc from the COand continuum emission peak, suggesting that the gas is associated with amassive molecular outflow from the intensely star-forming nucleus that supplies125 Msun/yr of enriched gas to its halo.

Journal article

Dudzeviciute U, Smail I, Swinbank AM, Lim C-F, Wang W-H, Simpson JM, Ao Y, Chapman SC, Chen C-C, Clements D, Dannerbauer H, Ho LC, Hwang HS, Koprowski M, Lee C-H, Scott D, Shim H, Shirley R, Toba Yet al., 2021, Tracing the evolution of dust-obscured activity using sub-millimetre galaxy populations from STUDIES and AS2UDS, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 500, Pages: 942-961, ISSN: 0035-8711

Journal article

Clements DL, Serjeant S, Jin S, 2020, Explain ESA's late ditching of new space telescope, NATURE, Vol: 587, Pages: 548-548, ISSN: 0028-0836

Journal article

Shim H, Kim Y, Lee D, Lee HM, Goto T, Matsuhara H, Scott D, Serjeant S, Ao Y, Barrufet L, Chapman S, Clements DL, Conselice CJ, Greve TR, Hashimoto T, Hwang HS, Im M, Jeong W-S, Jiang L, Kim M, Kim SJ, Kong AKH, Koprowski M, Marchetti L, Michalowski MJ, Parsons H, Pearson C, Seo H, Toba Y, White Get al., 2020, NEPSC2, the North Ecliptic Pole SCUBA-2 survey: 850-mu m map and catalogue of 850-mu m-selected sources over 2 deg(2), MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 498, Pages: 5065-5079, ISSN: 0035-8711

Journal article

Greaves J, Richards A, Bains W, Rimmer P, Sagawa H, Clements D, Seager S, Petkowski J, Sousa-Silva C, Ranjan S, Drabek-Maunder E, Fraser H, Cartwright A, Muller-Wodarg I, Zhan Z, Friberg P, Coulson I, Lee E, Hoge Jet al., 2020, Phosphine gas in the cloud decks of Venus, Nature Astronomy, Vol: 5, Pages: 655-664, ISSN: 2397-3366

Measurements of trace gases in planetary atmospheres help us explore chemical conditions different to those on Earth. Our nearest neighbour, Venus, has cloud decks that are temperate but hyperacidic. Here we report the apparent presence of phosphine (PH3) gas in Venus’s atmosphere, where any phosphorus should be in oxidized forms. Single-line millimetre-waveband spectral detections (quality up to ~15σ) from the JCMT and ALMA telescopes have no other plausible identification. Atmospheric PH3 at ~20 ppb abundance is inferred. The presence of PH3 is unexplained after exhaustive study of steady-state chemistry and photochemical pathways, with no currently known abiotic production routes in Venus’s atmosphere, clouds, surface and subsurface, or from lightning, volcanic or meteoritic delivery. PH3 could originate from unknown photochemistry or geochemistry, or, by analogy with biological production of PH3 on Earth, from the presence of life. Other PH3 spectral features should be sought, while in situ cloud and surface sampling could examine sources of this gas.

Journal article

Bakx TJLC, Dannerbauer H, Frayer D, Eales SA, Perez-Fournon I, Cai Z-Y, Clements DL, De Zotti G, Gonzalez-Nuevo J, Ivison RJ, Lapi A, Michalowski MJ, Negrello M, Serjeant S, Smith MWL, Temi P, Urquhart S, van der Werf Pet al., 2020, IRAM 30-m-EMIR redshift search of z=3-4 lensed dusty starbursts selected from the HerBS sample, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 496, Pages: 2372-2390, ISSN: 0035-8711

Journal article

De Looze I, Lamperti I, Saintonge A, Relano M, Smith MWL, Clark CJR, Wilson CD, Decleir M, Jones AP, Kennicutt RC, Accurso G, Brinks E, Bureau M, Cigan P, Clements DL, De Vis P, Fanciullo L, Gao Y, Gear WK, Ho LC, Hwang HS, Michalowski MJ, Lee JC, Li C, Lin L, Liu T, Lomaeva M, Pan H-A, Sargent M, Williams T, Xiao T, Zhu Met al., 2020, JINGLE - IV. Dust, HI gas, and metal scaling laws in the local Universe, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 496, Pages: 3668-3687, ISSN: 0035-8711

Journal article

Greenslade J, Clements DL, Petitpas G, Asboth V, Conley A, Pérez-Fournon I, Riechers Det al., 2020, The nature of 500 micron risers I: SMA observations, Monthly Notices of the Royal Astronomical Society, Vol: 496, Pages: 2315-2333, ISSN: 0035-8711

We present SMA observations at resolutions from 0.35 to 3 arcsec of a sample of 34 candidate high redshift dusty star forming galaxies (DSFGs). These sources were selected from the HerMES Herschel survey catalogues to have SEDs rising from 250 to 350 to 500 μm, a population termed 500-risers. We detect counterparts to 24 of these sources, with four having two counterparts. We conclude that the remaining ten sources that lack detected counterparts are likely to have three or more associated sources which blend together to produce the observed Herschel source. We examine the role of lensing, which is predicted to dominate the brightest (F500 > 60 mJy) half of our sample. We find that while lensing plays a role, at least 35 per cent of the bright sources are likely to be multiple sources rather than the result of lensing. At fainter fluxes we find a blending rate comparable to, or greater than, the predicted 40 per cent. We determine far-IR luminosities and star formation rates for the non-multiple sources in our sample and conclude that, in the absence of strong lensing, our 500-risers are very luminous systems with LFIR > 1013 L⊙ and star formation rates >1000 M⊙ yr−1.

Journal article

Lim C-F, Chen C-C, Smail I, Wang W-H, Tee W-L, Lin Y-T, Scott D, Toba Y, Chang Y-Y, Ao Y, Babul A, Bunker A, Chapman SC, Clements DL, Conselice CJ, Gao Y, Greve TR, Ho LC, Hong SE, Hwang HS, Koprowski M, Michalowski MJ, Shim H, Shu X, Simpson JMet al., 2020, SCUBA-2 ultra deep imaging EAO survey (STUDIES). IV. spatial clustering and halo masses of submillimeter galaxies, The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 895, Pages: 1-18, ISSN: 0004-637X

We analyze an extremely deep 450 μm image (1σ = 0.56 mJy beam−1) of a sime300 arcmin2 area in the CANDELS/COSMOS field as part of the Sub-millimeter Common User Bolometric Array-2 Ultra Deep Imaging EAO Survey. We select a robust (signal-to-noise ratio ≥4) and flux-limited (≥4 mJy) sample of 164 submillimeter galaxies (SMGs) at 450 μm that have K-band counterparts in the COSMOS2015 catalog identified from radio or mid-infrared imaging. Utilizing this SMG sample and the 4705 K-band-selected non-SMGs that reside within the noise level ≤1 mJy beam−1 region of the 450 μm image as a training set, we develop a machine-learning classifier using K-band magnitude and color–color pairs based on the 13-band photometry available in this field. We apply the trained machine-learning classifier to the wider COSMOS field (1.6 deg2) using the same COSMOS2015 catalog and identify a sample of 6182 SMG candidates with similar colors. The number density, radio and/or mid-infrared detection rates, redshift and stellar-mass distributions, and the stacked 450 μm fluxes of these SMG candidates, from the S2COSMOS observations of the wide field, agree with the measurements made in the much smaller CANDELS field, supporting the effectiveness of the classifier. Using this SMG candidate sample, we measure the two-point autocorrelation functions from z = 3 down to z = 0.5. We find that the SMG candidates reside in halos with masses of sime(2.0 ± 0.5) × 1013 h −1 M ☉ across this redshift range. We do not find evidence of downsizing that has been suggested by other recent observational studies.

Journal article

Cheng T, Clements DL, Greenslade J, Cairns J, Andreani P, Bremer M, Conversi L, Cooray A, Dannerbauer H, De Zotti G, Eales S, Gonzalez-Nuevo J, Ibar E, Leeuw L, Ma J, Michalowski MJ, Nayyeri H, Riechers DA, Scott D, Temi P, Vaccari M, Valtchanov I, van Kampen E, Wang Let al., 2020, SCUBA-2 overdensities associated with candidate protoclusters selected from Planck data, Monthly Notices of the Royal Astronomical Society, Vol: 494, Pages: 5985-5991, ISSN: 0035-8711

We measure the 850-μm source densities of 46 candidate protoclusters selected from the Planck high-z catalogue (PHz) and the Planck Catalogue of Compact Sources (PCCS) that were followed up with Herschel-SPIRE and SCUBA-2. This paper aims to search for overdensities of 850-μm sources in order to select the fields that are most likely to be genuine protoclusters. Of the 46 candidate protoclusters, 25 have significant overdensities (>5 times the field counts), 11 have intermediate overdensities (3–5 times the field counts), and 10 have no overdensity (<3 times the field counts) of 850-μm sources. We find that the enhanced number densities are unlikely to be the result of sample variance. Compared with the number counts of another sample selected from Planck’s compact source catalogues, this [PHz + PCCS]-selected sample has a higher fraction of candidate protoclusters with significant overdensities, though both samples show overdensities of 850-μm sources above intermediate level. Based on the estimated star formation rate densities (SFRDs), we suggest that both samples can efficiently select protoclusters with starbursting galaxies near the redshift at which the global field SFRD peaks (2 < z < 3). Based on the confirmation of overdensities found here, future follow-up observations on other PHz targets may greatly increase the number of genuine dusty star-forming galaxy-rich clusters/protoclusters.

Journal article

Bakx TJLC, Eales SA, Negrello M, Smith MWL, Valiante E, Holland WS, Baes M, Bourne N, Clements DL, Dannerbauer H, De Zotti G, Dunne L, Dye S, Furlanetto C, Ivison RJ, Maddox S, Marchetti L, Michalowski MJ, Omont A, Oteo I, Wardlow JL, van der Werf P, Yang Cet al., 2020, The Herschel Bright Sources (HerBS): sample definition and SCUBA-2 observations (vol 473, pg 1751, 2018), MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 494, Pages: 10-16, ISSN: 0035-8711

Journal article

Lim C-F, Wang W-H, Smail I, Scott D, Chen C-C, Chang Y-Y, Simpson JM, Toba Y, Shu X, Clements D, Greenslade J, Ao Y, Babul A, Birkin J, Chapman SC, Cheng T-A, Cho BS, Dannerbauer H, Dudzeviciute U, Dunlop J, Gao Y, Goto T, Ho LC, Hsu L-T, Hwang HS, Jeong W-S, Koprowski M, Lee C-H, Lin M-Y, Lin W-C, Michalowski MJ, Parsons H, Sawicki M, Shirley R, Shim H, Urquhart S, Wang J, Wang Tet al., 2020, SCUBA-2 ultra deep imaging EAO survey (studies). III. multiwavelength properties, luminosity functions, and preliminary source catalog of 450 mu m selected galaxies, The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 889, Pages: 1-33, ISSN: 0004-637X

We construct a SCUBA-2 450 μm map in the COSMOS field that covers an area of 300 arcmin2 and reaches a 1σ noise level of 0.65 mJy in the deepest region. We extract 256 sources detected at 450 μm with signal-to-noise ratios >4.0 and analyze the physical properties of their multiwavelength counterparts. We find that most of the sources are at z lesssim 3, with a median of $z={1.79}_{-0.15}^{+0.03} \% $. About ${35}_{-25}^{+32} \% $ of our sources are classified as starburst galaxies based on their total star formation rates (SFRs) and stellar masses (M *). By fitting the far-infrared spectral energy distributions, we find that our 450 μm selected sample has a wide range of dust temperatures (20 K lesssim T d lesssim 60 K), with a median of ${T}_{{\rm{d}}}={38.3}_{-0.9}^{+0.4}$ K. We do not find a redshift evolution in dust temperature for sources with ${L}_{\mathrm{IR}}\gt {10}^{12}\,{L}_{\odot }$ at z < 3. However, we find a moderate correlation where the dust temperature increases with the deviation from the SFR–M * relation. The increase in dust temperature also correlates with optical morphology, which is consistent with merger-triggered starbursts in submillimeter galaxies. Our galaxies do not show the tight IRX–β UV correlation that has been observed in the local universe. We construct the infrared luminosity functions of our 450 μm sources and measure their comoving SFR densities (SFRDs). The contribution of the ${L}_{\mathrm{IR}}\gt {10}^{12}\,{L}_{\odot }$ population to the SFRD rises dramatically from z = 0 to 2 (∝(1 + z)3.9±1.1) and dominates the total SFRD at z gsim 2.

Journal article

Duivenvoorden S, Oliver S, Bethermin M, Clements DL, De Zotti G, Efstathiou A, Farrah D, Hurley PD, Ivison RJ, Lagache G, Scott D, Shirley R, Wang L, Zemcov Met al., 2020, Have we seen all the galaxies that comprise the cosmic infrared background at 250 mu m <= lambda <= 500 mu m?, Monthly Notices of the Royal Astronomical Society, Vol: 491, Pages: 1355-1368, ISSN: 0035-8711

The cosmic infrared background (CIB) provides a fundamental observational constraint on the star formation history of galaxies over cosmic history. We estimate the contribution to the CIB from catalogued galaxies in the COSMOS field by using a novel map fitting technique on the Herschel SPIRE maps. Prior galaxy positions are obtained using detections over a large range in wavelengths in the Ks–3 GHz range. Our method simultaneously fits the galaxies, the system foreground, and the leakage of flux from galaxies located in masked areas and corrects for an ‘overfitting’ effect not previously accounted for in stacking methods. We explore the contribution to the CIB as a function of galaxy survey wavelength and depth. We find high contributions to the CIB with the deep r (mAB ≤ 26.5), Ks (mAB ≤ 24.0), and 3.6 μm (mAB ≤ 25.5) catalogues. We combine these three deep catalogues and find a total CIB contributions of 10.5 ± 1.6, 6.7 ± 1.5, and 3.1 ± 0.7 nWm−2 sr−1 at 250, 350, and 500 μm, respectively. Our CIB estimates are consistent with recent phenomenological models, prior based SPIRE number counts and with (though more precise than) the diffuse total measured by FIRAS. Our results raise the interesting prospect that the CIB contribution at λ≤500μm from known galaxies has converged. Future large-area surveys like those with the Large Synoptic Survey Telescope are therefore likely to resolve a substantial fraction of the population responsible for the CIB at 250 μm ≤ λ ≤ 500 μm.

Journal article

Kubo M, Toshikawa J, Kashikawa N, Chiang Y-K, Overzier R, Uchiyama H, Clements DL, Alexander DM, Matsuda Y, Kodama T, Ono Y, Goto T, Cheng T-A, Ito Ket al., 2019, Planck far-infrared detection of hyper suprime-cam protoclusters at z similar to 4: Hidden AGN and star formation activity, The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 887, Pages: 1-20, ISSN: 0004-637X

We perform a stacking analysis of Planck, AKARI, Infrared Astronomical Satellite, Wide-field Infrared Survey Explorer, and Herschel images of the largest number of (candidate) protoclusters at z ~ 3.8 selected from the Hyper Suprime-Cam Subaru Strategic Program. Stacking the images of the 179 candidate protoclusters, the combined infrared (IR) emission of the protocluster galaxies in the observed 12–850 μm wavelength range is successfully detected with >5σ significance (at Planck). This is the first time that the average IR spectral energy distribution (SED) of a protocluster has been constrained at z ~ 4. The observed IR SEDs of the protoclusters exhibit significant excess emission in the mid-IR compared to that expected from typical star-forming galaxies (SFGs). They are reproduced well using SED models of intense starburst galaxies with warm/hot dust heated by young stars, or by a population of active galactic nucleus (AGN)/SFG composites. For the pure star-forming model, a total IR (from 8–1000 μm) luminosity of ${19.3}_{-4.2}^{+0.6}\times {10}^{13}\,{L}_{\odot }$ and a star formation rate of ${16.3}_{-7.8}^{+1.0}\times {10}^{3}\,{M}_{\odot }$ yr−1 are found, whereas for the AGN/SFG composite model, ${5.1}_{-2.5}^{+2.5}\times {10}^{13}\,{L}_{\odot }$ and ${2.1}_{-1.7}^{+6.3}\times {10}^{3}\,{M}_{\odot }$ yr−1 are found. Uncertainty remains in the total SFRs; however, the IR luminosities of the most massive protoclusters are likely to continue increasing up to z ~ 4. Meanwhile, no significant IR flux excess is observed around optically selected QSOs at similar redshifts, which confirms previous results. Our results suggest that the z ~ 4 protoclusters trace dense, intensely star-forming environments that may also host obscured AGNs missed by the selection in the optical.

Journal article

Casey CM, Zavala JA, Aravena M, Bethermin M, Caputi K, Champagne JB, Clements DL, da Cunha E, Drew P, Finkelstein SL, Hayward CC, Kartaltepe JS, Knudsen K, Koekemoer AM, Magdis GE, Man A, Manning SM, Scoville NZ, Sheth K, Spilker J, Staguhn J, Talia M, Taniguchi Y, Toft S, Treister E, Yun Met al., 2019, Physical characterization of an unlensed, dusty star-forming galaxy at z=5.85, The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 887, Pages: 1-18, ISSN: 0004-637X

We present a physical characterization of MM J100026.36+021527.9 (a.k.a. "Mambo-9"), a dusty star-forming galaxy (DSFG) at z = 5.850 ± 0.001. This is the highest-redshift unlensed DSFG (and fourth most distant overall) found to date and is the first source identified in a new 2 mm blank-field map in the COSMOS field. Though identified in prior samples of DSFGs at 850 μm to 1.2 mm with unknown redshift, the detection at 2 mm prompted further follow-up as it indicated a much higher probability that the source was likely to sit at z > 4. Deep observations from the Atacama Large Millimeter and submillimeter Array (ALMA) presented here confirm the redshift through the secure detection of 12CO(J = 6→5) and p-H2O (21,1 → 20,2). Mambo-9 is composed of a pair of galaxies separated by 6 kpc with corresponding star formation rates of 590 M ⊙ yr−1 and 220 M ⊙ yr−1, total molecular hydrogen gas mass of (1.7 ± 0.4) × 1011 M ⊙, dust mass of (1.3 ± 0.3) × 109 M ⊙, and stellar mass of (${3.2}_{-1.5}^{+1.0}$) × 109 M ⊙. The total halo mass, (3.3 ± 0.8) × 1012 M ⊙, is predicted to exceed 1015 M ⊙ by z = 0. The system is undergoing a merger-driven starburst that will increase the stellar mass of the system tenfold in τ depl = 40−80 Myr, converting its large molecular gas reservoir (gas fraction of ${96}_{-2}^{+1} \% $) into stars. Mambo-9 evaded firm spectroscopic identification for a decade, following a pattern that has emerged for some of the highest-redshift DSFGs found. And yet, the systematic identification of unlensed DSFGs like Mambo-9 is key to measuring the global contribution of obscured star formation to the star formation rate density at z gsim 4, the formation of the first massive galaxies, and the formation of interstellar dust at early times (lesssim1 Gyr).

Journal article

Lamperti I, Saintonge A, De Looze I, Accurso G, Clark CJR, Smith MWL, Wilson CD, Brinks E, Brown T, Bureau M, Clements DL, Eales S, Glass DHW, Hwang HS, Lee JC, Lin L, Michalowski MJ, Sargent M, Williams TG, Xiao T, Yang Cet al., 2019, JINGLE - V. Dust properties of nearby galaxies derived from hierarchical Bayesian SED fitting, Monthly Notices of the Royal Astronomical Society, Vol: 489, Pages: 4389-4417, ISSN: 0035-8711

We study the dust properties of 192 nearby galaxies from the JINGLE survey using photometric data in the 22–850 μm range. We derive the total dust mass, temperature T, and emissivity index β of the galaxies through the fitting of their spectral energy distribution (SED) using a single modified blackbody model (SMBB). We apply a hierarchical Bayesian approach that reduces the known degeneracy between T and β. Applying the hierarchical approach, the strength of the T–β anticorrelation is reduced from a Pearson correlation coefficient R = −0.79 to R = −0.52. For the JINGLE galaxies we measure dust temperatures in the range 17−30 K and dust emissivity indices β in the range 0.6−2.2. We compare the SMBB model with the broken emissivity law modified blackbody (BMBB) and the two modified blackbody (TMBB) models. The results derived with the SMBB and TMBB are in good agreement, thus applying the SMBB, which comes with fewer free parameters, does not penalize the measurement of the cold dust properties in the JINGLE sample. We investigate the relation between T and β and other global galaxy properties in the JINGLE and Herschel Reference Survey (HRS) sample. We find that β correlates with the stellar mass surface density (R = 0.62) and anticorrelates with the H I mass fraction (MH I/M*, R = −0.65), whereas the dust temperature correlates strongly with the star formation rate normalized by the dust mass (R = 0.73). These relations can be used to estimate T and β in galaxies with insufficient photometric data available to measure them directly through SED fitting.

Journal article

Greenslade J, Aguilar E, Clements DL, Dannerbauer H, Cheng T, Petitpas G, Yang C, Messias H, Oteo I, Farrah D, Michalowski MJ, Fournon IP, Aretxaga I, Yun MS, Eales S, Dunne L, Cooray A, Andreani P, Hughes DH, Velazquez M, Sanchez-Arguelles D, Ponthieu Net al., 2019, A SCUBA-2 selected herschel-SPIRE dropout and the nature of this population, Publisher: arXiv

Dusty star-forming galaxies (DSFGs) detected at $z > 4$ provide importantexamples of the first generations of massive galaxies. However, few exampleswith spectroscopic confirmation are currently known, with Hershel struggling todetect significant numbers of $z > 6$ DSFGs. NGP6_D1 is a bright 850 $\mu m$source (12.3 $\pm$ 2.5 mJy) with no counterparts at shorter wavelengths (aSPIRE dropout). Interferometric observations confirm it is a single source,with no evidence for any optical or NIR emission, or nearby likely foregroundlensing sources. No $>3\sigma$ detected lines are seen in both LMT RSR and IRAM30m EMIR spectra of NGP6_D1 across 32 $GHz$ of bandwidth despite reachingdetection limits of $\sim 1 mJy/500 km~s^{-1}$, so the redshift remainsunknown. Template fitting suggests that NGP6_D1 is most likely between $z =5.8$ and 8.3. SED analysis finds that NGP6_D1 is a ULIRG, with a dust mass$\sim 10^8$ - $10^9$ $M_{\odot}$ and a SFR of $\sim$ 500 $M_{\odot}~yr^{-1}$.We place upper limits on the gas mass of NGP6_D1 of $M_{H2}$ $ < (1.1~\pm~3.5)\times 10^{11}$ $M_{\odot}$, consistent with a gas-to-dust ratio of $\sim$ 100- 1000. We discuss the nature of NGP6_D1 in the context of the broader submmpopulation, and find that comparable SPIRE dropouts account for $\sim$ 20% ofall SCUBA-2 detected sources, but with a similar flux density distribution tothe general population.

Working paper

Ma J, Cooray A, Nayyeri H, Brown A, Ghotbi N, Ivison R, Oteo I, Duivenvoorden S, Greenslade J, Clements D, Wardlow J, Battisti A, da Cunha E, Ashby MLN, Perez-Fournon I, Riechers D, Oliver S, Eales S, Negrello M, Dye S, Dunne L, Omont A, Scott D, Cox P, Serjeant S, Maddox S, Valiante Eet al., 2019, Spitzer catalog of herschel-selected ultrared dusty star-forming galaxies, Astrophysical Journal Supplement Series, Vol: 244, Pages: 1-19, ISSN: 0067-0049

The largest Herschel extragalactic surveys, H-ATLAS and HerMES, have selected a sample of "ultrared" dusty star-forming galaxies (DSFGs) with rising SPIRE flux densities (S 500 > S 350 > S 250; the so-called "500 μm risers") as an efficient way for identifying DSFGs at higher redshift (z > 4). In this paper, we present a large Spitzer follow-up program of 300 Herschel ultrared DSFGs. We have obtained high-resolution Atacama Large Millimeter/submillimeter Array, Northern Extended Millimeter Array, and SMA data for 63 of them, which allow us to securely identify the Spitzer/IRAC counterparts and classify them as gravitationally lensed or unlensed. Within the 63 ultrared sources with high-resolution data, ~65% appear to be unlensed and ~27% are resolved into multiple components. We focus on analyzing the unlensed sample by directly performing multiwavelength spectral energy distribution modeling to derive their physical properties and compare with the more numerous z ~ 2 DSFG population. The ultrared sample has a median redshift of 3.3, stellar mass of 3.7 × 1011 M ⊙, star formation rate (SFR) of 730 M ⊙ yr−1, total dust luminosity of 9.0 × 1012 L ⊙, dust mass of 2.8 × 109 M ⊙, and V-band extinction of 4.0, which are all higher than those of the ALESS DSFGs. Based on the space density, SFR density, and stellar mass density estimates, we conclude that our ultrared sample cannot account for the majority of the star-forming progenitors of the massive, quiescent galaxies found in infrared surveys. Our sample contains the rarer, intrinsically most dusty, luminous, and massive galaxies in the early universe that will help us understand the physical drivers of extreme star formation.

Journal article

Harikane Y, Ouchi M, Ono Y, Fujimoto S, Donevski D, Shibuya T, Faisst AL, Goto T, Hatsukade B, Kashikawa N, Kohno K, Hashimoto T, Higuchi R, Inoue AK, Lin Y-T, Martin CL, Overzier R, Smail I, Toshikawa J, Umehata H, Ao Y, Chapman S, Clements DL, Im M, Jing Y, Kawaguchi T, Lee C-H, Lee MM, Lin L, Matsuoka Y, Marinello M, Nagao T, Onodera M, Toft S, Wang W-Het al., 2019, SILVERRUSH. VIII. spectroscopic identifications of early large-scale structures with protoclusters over 200 Mpc at z similar to 6-7: strong associations of dusty star-forminggalaxies, The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 883, Pages: 1-16, ISSN: 0004-637X

We have obtained three-dimensional maps of the universe in ~200 × 200 × 80 comoving Mpc3 (cMpc3) volumes each at z = 5.7 and 6.6 based on a spectroscopic sample of 179 galaxies that achieves gsim80% completeness down to the Lyα luminosity of $\mathrm{log}({L}_{\mathrm{Ly}\alpha }/[\mathrm{erg}\,{{\rm{s}}}^{-1}])=43.0$, based on our Keck and Gemini observations and the literature. The maps reveal filamentary large-scale structures and two remarkable overdensities made out of at least 44 and 12 galaxies at z = 5.692 (z57OD) and z = 6.585 (z66OD), respectively, making z66OD the most distant overdensity spectroscopically confirmed to date, with >10 spectroscopically confirmed galaxies. We compare spatial distributions of submillimeter galaxies at z sime 4–6 with our z = 5.7 galaxies forming the large-scale structures, and detect a 99.97% signal of cross-correlation, indicative of a clear coincidence of dusty star-forming galaxy and dust-unobscured galaxy formation at this early epoch. The galaxies in z57OD and z66OD are actively forming stars with star-formation rates (SFRs) gsim5 times higher than the main sequence, and particularly the SFR density in z57OD is 10 times higher than the cosmic average at the redshift (a.k.a. the Madau-Lilly plot). Comparisons with numerical simulations suggest that z57OD and z66OD are protoclusters that are progenitors of the present-day clusters with halo masses of ~1014 M ⊙.

Journal article

Cheng T, Clements DL, Greenslade J, Cairns J, Andreani P, Bremer M, Conversi L, Cooray A, Dannerbauer H, De Zotti G, Eales S, González-Nuevo J, Ibar E, Leeuw L, Ma J, Michałowski MJ, Nayyeri H, Riechers DA, Scott D, Temi P, Vaccari M, Valtchanov I, van Kampen E, Wang Let al., 2019, SCUBA-2 observations of candidate starbursting protoclusters selected by Planck and Herschel-SPIRE, Monthly Notices of the Royal Astronomical Society, Vol: 490, Pages: 3840-3859, ISSN: 0035-8711

We present SCUBA-2 850-μm observations of 13 candidate starbursting protoclusters selected using Planck and Herschel data. The cumulative number counts of the 850-μm sources in 9/13 of these candidate protoclusters show significant overdensities compared to the field, with the probability <10−2 assuming the sources are randomly distributed in the sky. Using the 250-, 350-, 500- and 850-μm flux densities, we estimate the photometric redshifts of individual SCUBA-2 sources by fitting spectral energy distribution (SED) templates with an MCMC method. The photometric redshift distribution, peaking at 2<z<3, is consistent with that of known z>2 protoclusters and the peak of the cosmic star-formation rate density (SFRD). We find that the 850-μm sources in our candidate protoclusters have infrared luminosities of LIR ≳ 1012L⊙ and star-formation rates of SFR=(500-1,500)M⊙yr−1. By comparing with results in the literature considering only Herschel photometry, we conclude that our 13 candidate protoclusters can be categorised into four groups: six of them being high-redshift starbursting protoclusters, one being a lower-redshift cluster/protocluster, three being protoclusters that contain lensed DSFG(s) or are rich in 850-μm sources, and three regions without significant Herschel or SCUBA-2 source overdensities. The total SFRs of the candidate protoclusters are found to be comparable or higher than those of known protoclusters, suggesting our sample contains some of the most extreme protocluster population. We infer that cross-matching Planck and Herschel data is a robust method for selecting candidate protoclusters with overdensities of 850-μm sources.

Journal article

Cairns J, Stroe A, De Breuck C, Mroczkowski T, Clements Det al., 2019, Large molecular gas reservoirs in star-forming cluster galaxies, The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 882, Pages: 1-26, ISSN: 0004-637X

We present CO (2−1) observations of 72 galaxies in the nearby, disturbed Antlia Cluster with the Atacama Pathfinder Experiment telescope. The galaxies in our sample are selected to span a wide range of stellar masses (108 M ⊙ lesssim M sstarf lesssim 1010 M ⊙) and star formation rates (0.0005 M ⊙ yr−1 < SFR < 0.3 M ⊙ yr−1). Reaching a depth of 23 mJy in 50 km s−1 channels, we report a total CO detection rate of 37.5% and a CO detection rate of 86% for sources within 1 dex of the main sequence. We compare our sample with a similar sample of galaxies in the field, finding that, for a fixed stellar mass and SFR, galaxies in the Antlia Cluster have comparable molecular gas reservoirs to field galaxies. We find that ~41% (11/27) of our CO detections display non-Gaussian CO (2−1) emission-line profiles, and a number of these sources display evidence of quenching in their optical images. We also find that the majority of our sample lies either just below or far below the main sequence of field galaxies, further hinting at potential ongoing quenching. We conclude that the Antlia Cluster represents an intermediate environment between fields and dense clusters, where the gentler intracluster medium (ICM) allows the cluster members to retain their reservoirs of molecular gas, but in which the disturbed ICM is just beginning to influence the member galaxies, resulting in high SFRs and possible ongoing quenching.

Journal article

Marques-Chaves R, Perez-Fournon I, Villar-Martin M, Gavazzi R, Riechers D, Rigopoulou D, Wardlow J, Cabrera-Lavers A, Clements DL, Colina L, Cooray A, Farrah D, Ivison RJ, Jimenez-Angel C, Martinez-Navajas P, Nayyeri H, Oliver S, Omont A, Scott D, Shu Yet al., 2019, Discovery of a giant and luminous Ly alpha plus C IV plus He II nebula at z=3.326 with extreme emission line ratios, Astronomy and Astrophysics: a European journal, Vol: 629, Pages: 1-12, ISSN: 0004-6361

We present the discovery of HLock01-LAB, a luminous and large Lyα nebula at z = 3.326. Medium-band imaging and long-slit spectroscopic observations with the Gran Telescopio Canarias reveal extended emission in the Lyα 1215 Å, C IV 1550 Å, and He II 1640 Å lines over ∼100 kpc, and a total luminosity LLyα = (6.4 ± 0.1)×1044 erg s−1. HLock01-LAB presents an elongated morphology aligned with two faint radio sources contained within the central ∼8 kpc of the nebula. The radio structures are consistent with faint radio jets or lobes of a central galaxy, whose spectrum shows nebular emission characteristic of a type-II active galactic nucleus (AGN). The continuum emission of the AGN at short wavelengths is however likely dominated by stellar emission of the host galaxy, for which we derive a stellar mass M* ≃ 2.3 × 1011 M⊙. Our kinematic analysis shows that the ionized gas is perturbed almost exclusively in the inner region between the radio structures, probably as a consequence of jet–gas interactions, whereas in the outer regions the ionized gas appears more quiescent. The detection of extended emission in C IV and C III] indicates that the gas within the nebula is not primordial. Feedback may have enriched the halo at at least 50 kpc from the nuclear region. Using rest-frame UV emission-line diagnostics, we find that the gas in the nebula is likely heated by the AGN. Nevertheless, at the center of the nebula we find extreme emission line ratios of Lyα/C IV ∼60 and Lyα/He II ∼80, one of the highest values measured to date, and well above the standard values of photoionization models (Lyα/He II ∼30 for case B photoionization). Our data suggest that jet-induced shocks are likely responsible for the increase of the electron temperature and, thus, the observed Lyα enhancement in the center of the nebula. This scenario is further supported by the presence of radio st

Journal article

Smith MWL, Clark CJR, De Looze I, Lamperti I, Saintonge A, Wilson CD, Accurso G, Brinks E, Bureau M, Chung EJ, Cigan PJ, Clements DL, Dharmawardena T, Fanciullo L, Gao Y, Gao Y, Gear WK, Gomez HL, Greenslade J, Hwang HS, Kemper F, Lee JC, Li C, Lin L, Liu L, Molnar DC, Mok A, Pan H-A, Sargent M, Scicluna P, Smith CMA, Urquhart S, Williams TG, Xiao T, Yang C, Zhu Met al., 2019, JINGLE, a JCMT legacy survey of dust and gas for galaxy evolution studies: II. SCUBA-2 850 mu m data reduction and dust flux density catalogues, Monthly Notices of the Royal Astronomical Society, Vol: 486, Pages: 4166-4185, ISSN: 0035-8711

We present the SCUBA-2 850μm component of JINGLE, the new JCMT large survey for dust and gas in nearby galaxies, which with 193 galaxies is the largest targeted survey of nearby galaxies at 850 μm. We provide details of our SCUBA-2 data reduction pipeline, optimized for slightly extended sources, and including a calibration model adjusted to match conventions used in other far-infrared (FIR) data. We measure total integrated fluxes for the entire JINGLE sample in 10 infrared/submillimetre bands, including all WISE, Herschel-PACS, Herschel-SPIRE, and SCUBA-2 850 μm maps, statistically accounting for the contamination by CO(J = 3–2) in the 850 μm band. Of our initial sample of 193 galaxies, 191 are detected at 250 μm with a ≥5σ significance. In the SCUBA-2 850 μm band we detect 126 galaxies with ≥3σ significance. The distribution of the JINGLE galaxies in FIR/sub-millimetre colour–colour plots reveals that the sample is not well fit by single modified-blackbody models that assume a single dust-emissivity index (β). Instead, our new 850 μm data suggest either that a large fraction of our objects require β < 1.5, or that a model allowing for an excess of sub-mm emission (e.g. a broken dust emissivity law, or a very cold dust component ≲10 K) is required. We provide relations to convert FIR colours to dust temperature and β for JINGLE-like galaxies. For JINGLE the FIR colours correlate more strongly with star-formation rate surface-density rather than the stellar surface-density, suggesting heating of dust is greater due to younger rather than older stellar-populations, consistent with the low proportion of early-type galaxies in the sample.

Journal article

Gomez-Guijarro C, Riechers DA, Pavesi R, Magdis GE, Leung TKD, Valentino F, Toft S, Aravena M, Chapman SC, Clements DL, Dannerbauer H, Oliver SJ, Perez-Fournon I, Valtchanov Iet al., 2019, Confirming herschel candidate protoclusters from ALMA/VLA CO observations, The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 872, Pages: 1-21, ISSN: 0004-637X

ALMA 870 μm continuum imaging has uncovered a population of blends of multiple dusty star-forming galaxies (DSFGs) in sources originally detected with the Herschel Space Observatory. However, their pairwise separations are much smaller than what is found by ALMA follow-up of other single-dish surveys or expected from theoretical simulations. Using ALMA and the Very Large Array, we have targeted three of these systems to confirm whether the multiple 870 μm continuum sources lie at the same redshift, successfully detecting 12CO (J = 3–2) and 12CO (J = 1–0) lines and being able to confirm that in the three cases all the multiple DSFGs are likely physically associated within the same structure. Therefore, we report the discovery of two new gas-rich dusty protocluster cores (HELAISS02, z = 2.171 ± 0.004; HXMM20, z = 2.602 ± 0.002). The third target is located in the well-known COSMOS overdensity at z = 2.51 (named CL J1001+0220 in the literature), for which we do not find any new secure CO (1–0) detection, although some of its members show only tentative detections and require further confirmation. From the gas, dust, and stellar properties of the two new protocluster cores, we find very large molecular gas fractions yet low stellar masses, pushing the sources above the main sequence (MS), while not enhancing their star formation efficiency. We suggest that the sources might be newly formed galaxies migrating to the MS. The properties of the three systems compared to each other and to field galaxies may suggest a different evolutionary stage between systems.

Journal article

Drabek-Maunder E, Greaves J, Fraser HJ, Clements DL, Alconcel LNet al., 2019, Ground-based detection of a cloud of methanol from Enceladus: when is a biomarker not a biomarker?, International Journal of Astrobiology, Vol: 18, Pages: 25-32, ISSN: 1473-5504

Saturn's moon Enceladus has vents emerging from a sub-surface ocean, offering unique probes into the liquid environment. These vents drain into the larger neutral torus in orbit around Saturn. We present a methanol (CH3OH) detection observed with IRAM 30-m from 2008 along the line-of-sight through Saturn's E-ring. Additionally, we also present supporting observations from the Herschel public archive of water (ortho-H2O; 1669.9 GHz) from 2012 at a similar elongation and line-of-sight. The CH3OH 5(1,1)-4(1,1) transition was detected at 5.9σ confidence. The line has 0.43 km s−1width and is offset by +8.1 km s−1in the moon's reference frame. Radiative transfer models allow for gas cloud dimensions from 1750 km up to the telescope beam diameter ~73 000 km. Taking into account the CH3OH lifetime against solar photodissociation and the redshifted line velocity, there are two possible explanations for the CH3OH emission: methanol is primarily a secondary product of chemical interactions within the neutral torus that: (1) spreads outward throughout the E-ring or (2) originates from a compact, confined gas cloud lagging Enceladus by several km s−1. We find either scenario to be consistent with significant redshifted H2O emission (4σ) measured from the Herschel public archive. The measured CH3OH:H2O abundance (>0.5%) significantly exceeds the observed abundance in the direct vicinity of the vents (~0.01%), suggesting CH3OH is likely chemically processed within the gas cloud with methane (CH4) as its parent species.

Journal article

Leung TKD, Riechers DA, Baker AJ, Clements DL, Cooray A, Hayward CC, Ivison RJ, Neri R, Omont A, Perez-Fournon I, Scott D, Wardlow JLet al., 2019, The ISM properties and gas kinematics of a redshift 3 massive dusty star-forming galaxy, Astrophysical Journal, Vol: 871, ISSN: 0004-637X

We present CO (J = 1 → 0; 3 → 2; 5 → 4; 10 → 9) and 1.2 kpc resolution [C II] line observations of the dustystar-forming galaxy (SFG) HXMM05—carried out with the Karl G. Jansky Very Large Array, the CombinedArray for Research in Millimeter-wave Astronomy, the Plateau de Bure Interferometer, and the Atacama LargeMillimeter/submillimeter Array, measuring an unambiguous redshift of z = 2.9850 ± 0.0009. We find thatHXMM05 is a hyperluminous infrared galaxy (LIR = (4 ± 1) × 1013 Le) with a total molecular gas mass of(2.1 ± 0.7) × 1011(aCO/0.8) Me. The CO (J = 1 → 0) and [C II] emission are extended over ∼9 kpc in diameter,and the CO line FWHM exceeds 1100 km s−1. The [C II] emission shows a monotonic velocity gradient consistentwith a disk, with a maximum rotation velocity of vc = 616 ± 100 km s−1 and a dynamical mass of(7.7 ± 3.1) × 1011 Me. We find a star formation rate of 2900-+595750 Me yr−1. HXMM05 is thus among the mostintensely SFGs known at high redshift. Photodissociation region modeling suggests physical conditions similar tonearby SFGs, showing extended star formation, which is consistent with our finding that the gas emission and dustemission are cospatial. Its molecular gas excitation resembles the local major merger Arp 220. The broad CO and[C II] lines and a pair of compact dust nuclei suggest the presence of a late-stage major merger at the center of theextended disk, again reminiscent of Arp 220. The observed gas kinematics and conditions, together with thepresence of a companion and the pair of nuclei, suggest that HXMM05 is experiencing multiple mergers as a partof the evolution.

Journal article

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