Multi-modal Embedding Fusion-based Recommender

Recommendation systems have lately been popularized globally, with primary use cases in online interaction systems, with significant focus on e-commerce platforms. We have developed a machine learning-based recommendation platform, which can be easily applied to almost any items and/or actions domain. Contrary to existing recommendation systems, our platform supports multiple types of interaction data with multiple modalities of metadata natively. This is achieved through multi-modal fusion of various data representations. We deployed the platform into multiple e-commerce stores of different kinds, e.g. food and beverages, shoes, fashion items, telecom operators. Here, we present our system, its flexibility and performance. We also show benchmark results on open datasets, that significantly outperform state-of-the-art prior work.Comment: 7 pages, 8 figure

A merger in the dusty, z=7.5z=7.5 galaxy A1689-zD1?

The gravitationally-lensed galaxy A1689-zD1 is one of the most distant spectroscopically confirmed sources ($z=7.5$). It is the earliest known galaxy where the interstellar medium (ISM) has been detected; dust emission was detected with the Atacama Large Millimetre Array (ALMA). A1689-zD1 is also unusual among high-redshift dust emitters as it is a sub-L* galaxy and is therefore a good prospect for the detection of gaseous ISM in a more typical galaxy at this redshift. We observed A1689-zD1 with ALMA in bands 6 and 7 and with the Green Bank Telescope (GBT) in band $Q$. To study the structure of A1689-zD1, we map the mm thermal dust emission and find two spatial components with sizes about $0.4-1.7$\,kpc (lensing-corrected). The rough spatial morphology is similar to what is observed in the near-infrared with {\it HST} and points to a perturbed dynamical state, perhaps indicative of a major merger or a disc in early formation. The ALMA photometry is used to constrain the far-infrared spectral energy distribution, yielding a dust temperature ($T_{\rm dust} \sim 35$--$45$\,K for $\beta = 1.5-2$). We do not detect the CO(3-2) line in the GBT data with a 95\% upper limit of 0.3\,mJy observed. We find a slight excess emission in ALMA band~6 at 220.9\,GHz. If this excess is real, it is likely due to emission from the [CII] 158.8\,$\mu$m line at $z_{\rm [CII]} = 7.603$. The stringent upper limits on the [CII]/$L_{\rm FIR}$ luminosity ratio suggest a [CII] deficit similar to several bright quasars and massive starbursts.Comment: 9 pages, accepted to MNRAS, in pres

DEMON: a Proposal for a Satellite-Borne Experiment to study Dark Matter and Dark Energy

We outline a novel satellite mission concept, DEMON, aimed at advancing our comprehension of both dark matter and dark energy, taking full advantage of two complementary methods: weak lensing and the statistics of galaxy clusters. We intend to carry out a 5000 sqdeg combined IR, optical and X-ray survey with galaxies up to a redshift of z~2 in order to determine the shear correlation function. We will also find ~100000 galaxy clusters, making it the largest survey of this type to date. The DEMON spacecraft will comprise one IR/optical and eight X-ray telescopes, coupled to multiple cameras operating at different frequency bands. To a great extent, the technology employed has already been partially tested on ongoing missions, therefore ensuring improved reliability.Comment: 12 pages, 3 figures, accepted for publication in the SPIE conference proceeding

The Burst Cluster: Dark Matter in a Cluster Merger Associated with the Short Gamma Ray Burst, GRB 050509B

We have identified a merging galaxy cluster with evidence of two distinct sub-clusters. The X-ray and optical data suggest that the subclusters are moving away from each other after closest approach. This cluster merger was discovered from observations of the well localized short-duration gamma-ray burst (GRB), GRB 050509B. The Swift/Burst Alert Telescope (BAT) source position is coincident with a cluster of galaxies ZwCl 1234.0+02916. The subsequent Swift/X-Ray Telescope (XRT) localization of the X-ray afterglow found the GRB coincident with 2MASX J12361286+2858580, a giant red elliptical galaxy in the cluster. Deep multi-epoch optical images were obtained to constrain the evolution of the GRB afterglow, including a 27480s exposure in the F814W band with Hubble Space Telescope Advanced Camera for Surveys (ACS), among the deepest imaging ever obtained towards a known galaxy cluster in a single passband. We perform a weak gravitational lensing analysis, including mapping the total mass distribution of the merger system. Combined with Chandra X-ray Observatory and Swift/XRT observations, we investigate the dynamical state of the merger to probe the nature of the dark matter component. Our weak gravitational lensing measurements reveal a separation of the X-ray centroid of the western subcluster from the center of the mass and galaxy light distributions, similar to that of the famous "Bullet cluster". We conclude that the "Burst cluster" is another candidate merger system for determining the nature of dark matter and for studying the environment of short GRBs. We discuss connections between the cluster dynamical state and/or matter composition and compact object mergers, the leading model for the origin of short GRBs. Finally, we present results from a weak lensing survey based on archival Very Large Telescope (VLT) images in the areas of 5 other short GRBs.Comment: 17 pages, 7 figures, accepted by Ap

The host galaxy of the short GRB 050709

The host of the short gamma-ray burst (GRB) 050709 is a morphologically disturbed low-luminous galaxy. At a redshift of z = 0.16, it belongs to one of the cosmologically nearest short-GRB hosts identified to date. Consequently, it represents a promising target for sensitive, spatially resolved observational studies. We have used the Multi Unit Spectroscopic Explorer (MUSE) mounted at the Very Large Telescope to characterize the GRB host galaxy. In addition, we performed deep radio-continuum observations of the host with the Australia Telescope Compact Array (ATCA) and with ALMA at 1.3 mm. Moreover, we made use of archival Spitzer Space Telescope 24 μm and Hubble Space Telescope/F814W imaging data of this galaxy. The spatially resolved MUSE data reveal that the entire host is a source of strong line emission, in particular from Hα and [O II

The MALATANG Survey : The L GAS-L IR Correlation on Sub-kiloparsec Scale in Six Nearby Star-forming Galaxies as Traced by HCN J = 4 → 3 and HCO + J = 4 → 3

This is an author-created, un-copyedited version of an article published in The Astrophysical Journal. The Version of Record is available online at https://doi.org/10.3847/1538-4357/aac512.We present HCN J = 4→3 and HCO+ J = 4→3 maps of six nearby star-forming galaxies, NGC 253, NGC 1068, IC 342, M82, M83, and NGC 6946, obtained with the James Clerk Maxwell Telescope as part of the MALATANG survey. All galaxies were mapped in the central 2×2 region at 14 (FWHM) resolution (corresponding to linear scales of ∼0.2-1.0 kpc). The LIR-Ldense relation, where the dense gas is traced by the HCN J = 4→3 and the HCO+ J = 4→3 emission, measured in our sample of spatially resolved galaxies is found to follow the linear correlation established globally in galaxies within the scatter. We find that the luminosity ratio, LIR/Ldense, shows systematic variations with LIR within individual spatially resolved galaxies, whereas the galaxy-integrated ratios vary little. A rising trend is also found between LIR/Ldense ratio and the warm-dust temperature gauged by the 70 μm/100 μm flux ratio. We find that the luminosity ratios of IR/HCN (4-3) and IR/HCO+ (4-3), which can be taken as a proxy for the star formation efficiency (SFE) in the dense molecular gas (SFE dense), appear to be nearly independent of the dense gas fraction ( f dense) for our sample of galaxies. The SFE of the total molecular gas (SFEmol) is found to increase substantially with f dense when combining our data with those on local (ultra)luminous infrared galaxies and high-z quasars. The mean LHCN(4-3) LHCO+(4-3) line ratio measured for the six targeted galaxies is 0.9±0.6. No significant correlation is found for the L'HCN(4-3) L'HCO+(4-3) ratio with the star formation rate as traced by L IR, nor with the warm-dust temperature, for the different populations of galaxies.Peer reviewe

JINGLE V: Dust properties of nearby galaxies derived from hierarchical Bayesian SED fitting

We study the dust properties of 192 nearby galaxies from the JINGLE survey using photometric data in the 22-850μm 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 black-body 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 anti-correlation 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 modified black-body (BMBB) and the two modified black-bodies (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 anti-correlates with the HI mass fraction (MHI/M*, R = -0.65), whereas the dust temperature correlates strongly with the SFR 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