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An ESO internal ALMA development study, BRAIN, is addressing the ill-posed inverse problem of synthesis image analysis employing astrostatistics and astroinformatics. These emerging fields of research offer interdisciplinary approaches at the intersection of observational astronomy, statistics, algorithm development, and data science. In this study, we provide evidence of the benefits of employing these approaches to ALMA imaging for operational and scientific purposes. We show the potential of two techniques, RESOLVE and DeepFocus, applied to ALMA calibrated science data. Significant advantages are provided with the prospect to improve the quality and completeness of the data products stored in the science archive and overall processing time for operations. Both approaches evidence the logical pathway to address the incoming revolution in data rates dictated by the planned electronic upgrades. Moreover, we bring to the community additional products through a new package, ALMASim, to promote advancements in these fields, providing a refined ALMA simulator usable by a large community for training and/or testing new algorithms., Comment: 9 pages, 5 figures, MaxEnt2023 conference

The astronomical community is grappling with the increasing volume and complexity of data produced by modern telescopes, due to difficulties in reducing, accessing, analyzing, and combining archives of data. To address this challenge, we propose the establishment of a coordinating body, an "entity," with the specific mission of enhancing the interoperability, archiving, distribution, and production of both astronomical data and software. This report is the culmination of a workshop held in February 2023 on the Future of Astronomical Data Infrastructure. Attended by 70 scientists and software professionals from ground-based and space-based missions and archives spanning the entire spectrum of astronomical research, the group deliberated on the prevailing state of software and data infrastructure in astronomy, identified pressing issues, and explored potential solutions. In this report, we describe the ecosystem of astronomical data, its existing flaws, and the many gaps, duplication, inconsistencies, barriers to access, drags on productivity, missed opportunities, and risks to the long-term integrity of essential data sets. We also highlight the successes and failures in a set of deep dives into several different illustrative components of the ecosystem, included as an appendix., Comment: 59 pages; please send comments and/or questions to foadi@googlegroups.com

We present a long-term overview of the atmospheric phase stability at the Atacama Large Millimeter/submillimeter Array (ALMA) site, using >5 years of data, that acts as the successor to the studies summarized two decades ago by Evans et al 2003. Importantly, we explore the atmospheric variations, the `phase RMS', and associated metadata of over 17000 accrued ALMA observations taken since Cycle 3 (2015) by using the Bandpass calibrator source scans. We indicate the temporal phase RMS trends for average baseline lengths of 500, 1000, 5000, and 10000m, in contrast to the old stability studies that used a single 300m baseline phase monitor system. At the ALMA site, on the Chajnantor plateau, we report the diurnal variations and monthly changes in the phase RMS on ALMA relevant baselines lengths, measured directly from data, and we reaffirm such trends in atmospheric transmission (via Precipitable Water Vapour - PWV). We confirm that day observations have respectively higher phase RMS and PWV in contrast to night, while the monthly variations show Chilean winter (June - August) providing the best, high-frequency and long-baseline observing conditions - low (stable) phase RMS and low PWV. Yet, not all good phase stability condition occur when the PWV is low. Measurements of the phase RMS as a function of short timescales, 30 to 240s, that tie with typical target source scan times, and as a function of baseline length indicate that phase variations are smaller for short timescales and baselines and larger for longer timescales and baselines. We illustrate that fast-switching phase-referencing techniques, that allow short target scan times, could work well in reducing the phase RMS to suitable levels specifically for high-frequencies (Band 8, 9 and 10), long-baselines, and the two combined., Comment: 34 pages, 19 Figures, 10 Tables ALMA Memo 624: https://library.nrao.edu/public/memos/alma/main/memo624.pdf

Science archives are cornerstones of modern astronomical facilities. In this paper we describe the version 1.0 milestone of the Atacama Large Millimeter/submillimeter Array Science Archive. This version features a comprehensive query interface with rich metadata and visualisation of the spatial and spectral locations of the observations, a complete set of virtual observatory services for programmatic access, text-based similarity search, display and query for types of astronomical objects in SIMBAD and NED, browser-based remote visualisation, interactive previews with tentative line identification and extensive documentation including video and Jupyter Notebook tutorials. The development is regularly evaluated by means of user surveys and is entirely focused on providing the best possible user experience with the goal of helping to maximise the scientific productivity of the observatory., Comment: 6 pages, 7 figues

ALMA products are stored in the Science Archive in the form of FITS images. It is a common idea that the FITS image headers should collect in their keywords all the information that an archive User might want to search for in order to quickly select, compare, or discard datasets. With this perspective in mind, we first present a short description of the current status of the ALMA FITS archive and images. We realized that at the moment most of the parameters that could be useful for a general User are still missing in the archived data. We then provide a CASA task generating the image header keywords that we suggest to be relevant for the scientific exploitation of the ALMA archival data. The proposed tool could be also applied to several types of interferometer data and part of it is implemented in a web interface. An example of the scientific application of the keywords is also discussed., Comment: 20 pages, 6 figures, ALMA Memo 613 https://library.nrao.edu/public/memos/alma/main/memo613.pdf

Since its inception in the early 2000, the Virtual Observatory (VO), developed as a collaboration of many national and international projects, has become a major factor in the discovery and dissemination of astronomical information worldwide. The IVOA has been coordinating all these efforts worldwide to ensure a common VO framework that enables transparent access to and interoperability of astronomy resources (data and software) around the world. The VO is not a magic solution to all astronomy data management challenges but it does bring useful solutions in many areas borne out by the fact that VO interfaces are broadly found in astronomy major data centres and projects worldwide. Astronomy data centres have been building VO services on top of their existing data services to increase interoperability with other VO-compliant data resources to take advantage of the continuous and increasing development of VO applications. VO applications have made multi-instrument and multi-wavelength science, a difficult and fruitful part of astronomy, somewhat easier. More recently, several major new astronomy projects have been directly adopting VO standards to build their data management infrastructure, giving birth to VO built-in archives. Embracing the VO framework from the beginning brings the double gain of not needing to reinvent the wheel and ensuring from the start interoperability with other astronomy VO resources. Some of the IVOA standards are also starting to be used by neighbour disciplines like planetary sciences. There is still quite a lot to be done on the VO, in particular tackling the upcoming big data challenge and how to find interoperable solutions to the new data analysis paradigm of bringing and running the software close to the data., Comment: 4 pages, no figures, ADASS 2015 conference proceedings

This document presents HiPS, a hierarchical scheme for the description, storage and access of sky survey data. The system is based on hierarchical tiling of sky regions at finer and finer spatial resolution which facilitates a progressive view of a survey, and supports multi-resolution zooming and panning. HiPS uses the HEALPix tessellation of the sky as the basis for the scheme and is implemented as a simple file structure with a direct indexing scheme that leads to practical implementations.

With high over-subscription rates and significant operational costs, observatories must ensure that their operations are efficient and effective. A number of key performance indicators are generally used to evaluate the observatory's performance among which are the numbers of publications and citations of refereed journal articles to measure the overall scientific impact. Those measures, however, are broad and can not assess whether the observatory was successful on a project-by-project basis to deliver data to the PIs enabling them to carry out their science and to publish their results. In particular the reasons that prevented PIs from publishing remain hidden. Understanding and acting upon those reasons, however, have the potential to substantially improve the observatory's operational model. Of course not every approved project even should lead to a publication. Indeed, the risk of not finding the expected (or any unexpected) science in the data the PI receives is an inherent and indispensable part of the scientific process. But even here, measuring the fraction of such projects can lead to valuable insights which might then be used to instruct future proposal review committees. To fully close the loop on the end-to-end data-flow, ALMA has started in March 2015 to send survey questions to PIs where two years after the end of the proprietary period no publication making use of the delivered data could be identified. We describe our method as well as the type of conclusions we hope to be able to draw once a statistically relevant sample of answers has been received., Comment: 6 pages, 2 figures

The scientific impact of a facility is the most important measure of its success. Monitoring and analysing the scientific return can help to modify and optimise operations and adapt to the changing needs of scientific research. The methodology that we have developed to monitor the scientific productivity of the ALMA Observatory, as well as the first results, are described. We focus on the outcome of the first cycle (Cycle 0) of ALMA Early Science operations. Despite the fact that only two years have passed since the completion of Cycle 0 and operations have already changed substantially, this analysisconfirms the effectiveness of the underlying concepts. We find that ALMA is fulfilling its promise as a transformational facility for the observation of the Universe in the submillimetre., Comment: 5 pages, 9 figures

The Atacama Large Millimeter/submillimeter Array (ALMA), an international partnership of Europe, North America and East Asia in cooperation with the Republic of Chile, is the largest astronomical project in existence. While ALMA's capabilities are ramping up, Early Science observations have started. The ALMA Archive is at the center of the operations of the telescope array and is designed to manage the 200 TB of data that will be taken each year, once the observatory is in full operations. We briefly describe design principles. The second part of this paper focuses on how astronomy is likely to evolve as the amount and complexity of data taken grows. We argue that in the future observatories will compete for astronomers to work with their data, that observatories will have to reorient themselves to from providing good data only to providing an excellent end-to-end user-experience with all its implications, that science-grade data-reduction pipelines will become an integral part of the design of a new observatory or instrument and that all this evolution will have a deep impact on how astronomers will do science. We show how ALMA's design principles are in line with this paradigm., Comment: 9 pages, 5 figures, published in the Proceedings of SPIE, vol. 9149, 914902 (2014)

Telescope bibliographies are integral parts of observing facilities. They are used to associate the published literature with archived observational data, to measure an observatory's scientific output through publication and citation statistics, and to define guidelines for future observing strategies. The ESO and NRAO librarians as well as NAOJ jointly maintain the ALMA (Atacama Large Millimeter/submillimeter Array) bibliography, a database of refereed papers that use ALMA data. In this paper, we illustrate how relevant articles are identified, which procedures are used to tag entries in the database and link them to the correct observations, and how results are communicated to ALMA stakeholders and the wider community. Efforts made to streamline the process will be explained and evaluated, and a first analysis of ALMA papers published after two years of observations will be given., Comment: 7 pages; to be published in the Proceedings of SPIE, vol. 9149, 9149-81 (2014)

We use a hybrid approach that combines high-resolution simulations of the formation of a Milky Way-like halo with a semi-analytic model of galaxy formation to study the mass content of dwarf galaxies in the concordance $\Lambda$CDM cosmology. We find that the mass within 600 pc of dark matter haloes hosting luminous satellites has a median value of $\sim 3.2\times 10^7$ Msun with very little object-to-object scatter. In contrast, the present day total luminosities of the model satellites span nearly five orders of magnitude. These findings are in very good agreement with the results recently reported in the literature for the dwarf spheroidal galaxies of the Milky Way. In our model, dwarf irregular galaxies like the Small Magellanic Cloud, are predicted to have similar or slightly larger dark matter mass within 600 pc., Comment: 5 pages, 3 figures, to match the version accepted in MNRAS Letters. One paragraph added to explain the spread in luminosities more explicitly. References updated and Conclusions remain unchanged

The Hubble Legacy Archive (HLA) aims to create calibrated science data from the Hubble Space Telescope archive and make them accessible via user-friendly and Virtual Observatory (VO) compatible interfaces. It is a collaboration between the Space Telescope Science Institute (STScI), the Canadian Astronomy Data Centre (CADC) and the Space Telescope - European Coordinating Facility (ST-ECF). Data produced by the Hubble Space Telescope (HST) instruments with slitless spectroscopy modes are among the most difficult to extract and exploit. As part of the HLA project, the ST-ECF aims to provide calibrated spectra for objects observed with these HST slitless modes. In this paper, we present the HLA NICMOS G141 grism spectra. We describe in detail the calibration, data reduction and spectrum extraction methods used to produce the extracted spectra. The quality of the extracted spectra and associated direct images is demonstrated through comparison with near-IR imaging catalogues and existing near-IR spectroscopy. The output data products and their associated metadata are publicly available through a web form at http://hla.stecf.org and via VO interfaces. In total, 2470 spectra of 1923 unique targets are included in the current release., Comment: 18 pages, 21 figures, accepted for publication in Astronomy & Astrophysics

The kinematical properties of elliptical galaxies formed during the mergers of equal mass, stars+gas+dark matter spiral galaxies are compared to the observed low velocity dispersions found for planetary nebulae on the outskirts of ellipticals, which have been interpreted as pointing to a lack of dark matter in ellipticals (which poses a problem for the standard model of galaxy formation). We find that the velocity dispersion profiles of the stars in the simulated ellipticals match well the observed ones. The low outer stellar velocity dispersions are mainly caused by the radial orbits of the outermost stars, which, for a given binding energy must have low angular momentum to reach their large radial distances, usually driven out along tidal tails., Comment: Talk presented at 21st IAP meeting, Mass Profiles andShapes of Cosmological Structures. Ed. G. A. Mamon, F. Combes, C. Deffayet & B. Fort (Paris: EDP), 4 pages, 3 figures (4 plots)

While kinematical modelling of the low PN velocity dispersions observed in the outer regions of elliptical galaxies suggest a lack of dark matter around these galaxies, we report on an analysis of a suite of $N$-body simulations (with gas) of major mergers of spiral galaxies embedded in dark matter halos, and find that the outer velocity dispersions are as low as observed for the PNe. The inconsistency between our dynamical modelling and previous kinematical modelling is caused by very radial stellar orbits and projection effects when viewing face-on oblate ellipticals. Our simulations (weakly) suggest the youth of PNe around ellipticals, and we propose that the universality of the PN luminosity function may be explained if the bright PNe in ellipticals are formed after the regular accretion of very low mass gas-rich galaxies., Comment: Contributed talk at meeting, "Planetary Nebulae as astronomical tools", Gdansk, Poland, June-July 2005, ed. R. Szczerba, G. Stasi\'nska, and S. K. G\'orny, AIP Conference Proceedings, Melville, New York, 2005. 4 or 5 pages, 6 figures

The cosmic star formation histories are evaluated for different minimum masses of the initial halo structures, with allowance for realistic gas outflows. With a minimum halo mass of 10^{7} - 10^{8} M_odot and a moderate outflow efficiency, we reproduce both the current baryon fraction and the early chemical enrichment of the IGM. The intensity of the formation rate of ``normal'' stars is also well constrained by the observations: it has to be dominated by star formation in elliptical galaxies, except perhaps at very low redshift. The fraction of baryons in stars is predicted as are also the type Ia and II supernova event rates. Comparison with SN observations in the redshift range z=0-2 allows us to set strong constraints on the time delay of type Ia supernovae (a total delay of \sim 4 Gyr is required to fit the data), the lower end of the mass range of the progenitors (2 - 8 M_odot) and the fraction of white dwarfs that reproduce the type Ia supernova (about 1 per cent). The intensity in the initial starburst of zero metallicity stars below 270 M_\odot must be limited in order to avoid premature overenrichment of the IGM. Only about 10 - 20 % of the metals present in the IGM at z = 0 have been produced by population III stars at very high z. The remaining 80 - 90 % are ejected later by galaxies forming normal stars, with a maximum outflow efficiency occurring at a redshift of about 5. We conclude that 10^{-3} of the mass in baryons must lie in first massive stars in order to produce enough ionizing photons to allow early reionization of the IGM by z \sim 15., Comment: 51 pages, 23 eps figures

We use a large cosmological simulation and a variety of high resolution resimulations of individual cluster and galaxy haloes to study the systematics of subhalo populations over ranges of 1000 in halo mass and 1000 in the ratio of subhalo to parent halo mass. The subhalo populations of different haloes are not scaled copies of each other, but vary systematically with halo properties. On average, the amount of substructure increases with halo mass. At fixed mass, it decreases with halo concentration and with halo formation redshift. These trends are comparable in size to the scatter in subhalo abundance between similar haloes. Averaged over all haloes of given mass, the abundance of low mass subhaloes per unit parent halo mass is independendent of parent mass.It is very similar to the abundance per unit mass of low mass haloes in the universe as a whole, once differing boundary definitions for subhaloes and haloes are accounted for. The radial distribution of subhaloes within their parent haloes is substantially less centrally concentrated than that of the dark matter. It varies at most weakly with the mass(or concentration) of the parent halo and not at all with subhalo mass. It does depend on the criteria used to define the subhalo population considered. About 90% of present-day subhaloes were accreted after z=1 and about 70% after z=0.5. Only about 8% the total mass of all haloes accreted at z=1 survives as bound subhaloes at z=0. For haloes accreted at z=2, the survival mass fraction is just 2%. Subhaloes seen near the centre of their parent typically were accreted earlier and retain less of their original mass than those seen near the edge. These strong systematics mean that comparison with galaxies in real clusters is only possible if the formation of the luminous component is modelled appropriately., Comment: 18 pages, 15 figures. MNRAS in press. Accepted version. references added, a typo in equation (1) corrected

We use a high-resolution simulation of a galaxy-sized dark matter halo, published simulated data as well as four cluster-sized haloes from Fukushige, Kawai & Makino to study the inner halo structure in a Lambda cold dark matter cosmology. We find that the circular velocity curves are substantially better described by Stoehr et al. (SWTS) profiles than by Navarro, Frenk & White (NFW) or Moore et al. profiles. Our findings confirm that no asymptotic slope is reached and that the profiles are nearly universal, but not perfectly. The velocity profiles curve at a_constant_ rate in log(r) over the full converged range in radii and the corresponding extrapolated density profiles reach a finite maximum density. We find, that the claim of a strong discrepancy between the observed inner slopes of the density profiles of low surface brightness galaxies (LSB) and their simulated counterparts on the grounds of currently available observations and simulations is unfounded. In addition, if the SWTS profile turns out to be a good description of the halo profile for the regions that cannot be probed with simulations of today, then even in these regions the agreeement between simulations and observations is very reasonable., Comment: 7 pages, 3 figures, replaced with version accepted to MNRAS

We present a semi-analytic treatment of galactic winds within high resolution, large scale cosmological N-body simulations of a LCDM Universe. The evolution of winds is investigated by following the expansion of supernova driven superbubbles around the several hundred thousand galaxies that form in an approximately spherical region of space with diameter 52 Mpc/h and mean density close to the mean density of the Universe. We focus our attention on the impact of winds on the diffuse intergalactic medium. Initial conditions for mass loss at the base of winds are taken from Shu, Mo and Mao (2003). Results are presented for the volume filling factor and the mass fraction of the IGM affected by winds and their dependence on the model parameters is carefully investigated. The mass loading efficiency of bubbles is a key factor to determine the evolution of winds and their global impact on the IGM: the higher the mass loading, the later the IGM is enriched with metals. Galaxies with 10^9 < M_* < 10^10 M_sun are responsible for most of the metals ejected into the IGM at z=3, while galaxies with M_* < 10^9 M_sun give a non negligible contribution only at higher redshifts, when larger galaxies have not yet assembled. We find a higher mean IGM metallicity than Lyalpha forest observations suggest and we argue that the discrepancy may be explained by the high temperatures of a large fraction of the metals in winds, which may not leave detectable imprints in absorption in the Lyalpha forest., Comment: 18 pages, 15 figures. Major changes in the model. Manuscript with high resolution figures available upon request. MNRAS in press

We study the effect of galactic outflows on the Lya forest. The winds are modelled as fully ionised spherical bubbles centered around galactic haloes. The observed flux probability distribution and flux power spectrum limit the volume filling factor of bubbles to be less than 10%. We have compared the mean flux as a function of distance from haloes with the Adelberger etal (ASSP) measurement. A model with bubbles of constant radius of 1.5Mpc/h surrounding the most massive haloes matches the high transmissivity at separations <0.5Mpc/h, but the increase of the transmissivity at small scales is more gradual than observed. At separations <0.5Mpc/h, our estimate of the cosmic variance error is $\Delta F\sim 0.3$, 30% higher than that of ASSP. The difficulty in matching the rise in the transmissivity at small separations is caused by residual absorption of neutral hydrogen lying physically outside the bubbles but having a redshift position similar to the haloes. The flux level is thus sensitive to the amplitude of the coherent velocity shear near haloes which increases with halo mass in the simulation. A model where LBGs are starbursts in small mass haloes matches the observations with smaller bubble size than one where more massive haloes host the LBGs. A starburst model with a bubble radius of 1Mpc/h and a volume filling factor of 2% is consistent with the ASSP measurements at the 1-1.5$\sigma$ level. If this model is correct the sharp rise of the transmissivity at small separation in the ASSP sample is due to cosmic variance and is expected to become more moderate for a larger sample., Comment: Included discussion+figure on the clustering properties of LBGs. other minor changes. Accepted for publication in MNRAS

If the dark matter in the Universe is made of weakly self-interacting particles, they may self-annihilate and emit gamma-rays. We use high resolution numerical simulations to estimate directly the annihilation flux from the central regions of the Milky Way and from dark matter substructures in its halo. Although such estimates remain uncertain because of their strong dependence on the structure of the densest regions, our numerical experiments suggest that less direct calculations have overestimated the emission both from the centre and from halo substructure. We estimate a maximal enhancement of at most a factor of a few with respect to a smooth spherical halo of standard Navarro-Frenk-White (NFW) structure. We discuss detection strategies for the next generation of gamma-ray detectors and find that the annihilation flux may be detectable, regardless of uncertainties about the densest regions, for the annihilation cross-sections predicted by currently popular elementary particle models for the dark matter., Comment: 10 pages, 8 figures, replaced with version accepted by MNRAS (very minor changes)

We compare the structure and kinematics of the 11 known satellites of the Milky Way with high resolution simulations of the formation of its dark halo in a LambdaCDM universe. In contrast to earlier work, we find excellent agreement. The observed kinematics are exactly those predicted for stellar populations with the observed spatial structure orbiting within the most massive ``satellite'' substructures in our simulations. Less massive substructures have weaker potential wells than those hosting the observed satellites. If there is a halo substructure ``problem'', it consists in understanding why halo substructures have been so inefficient in making stars. Suggested modifications of dark matter properties (for example, self-interacting or warm dark matter) may well spoil the good agreement found for standard Cold Dark Matter., Comment: 5 pages, 2 figures, replaced with version accepted by MNRAS (minor changes)

We compare two techniques for following the cooling of gas and its condensation into galaxies within high resolution simulations of cosmologically representative regions. Both techniques treat the dark matter using N-body methods. One follows the gas using smoothed particle hydrodynamics (SPH) while the other uses simplified recipes from semi-analytic (SA) models. We compare the masses and locations predicted for dense knots of cold gas (the `galaxies') when the two techniques are applied to evolution from the same initial conditions and when the additional complications of star formation and feedback are ignored. We find that above the effective resolution limit of the two techniques, they give very similar results both for global quantities such as the total amount of cooled gas and for the properties of individual `galaxies'. The SA technique has systematic uncertainties arising from the simplified cooling model adopted, while details of the SPH implementation can produce substantial systematic variations in the galaxy masses it predicts. Nevertheless, for the best current SPH methods and the standard assumptions of the SA model, systematic differences between the two techniques are remarkably small. The SA technique gives adequate predictions for the condensation of gas into `galaxies' at less than one percent of the computational cost of obtaining similar results at comparable resolution using SPH., Comment: Revised, Figure 7 added. To appear in MNRAS