Anke Arentsen; G. Monari; A. B. A. Queiroz; Else Starkenburg; Nicolas F. Martin; C. Chiappini
Proceedings of the International Astronomical Union · DOI
Abstract We present recent results from the Pristine Inner Galaxy Survey (PIGS), which used metallicity-sensitive narrow-band CaHK photometry to identify and follow up spectroscopically thousands of ancient metal-poor candidates in the bulge. For the spectroscopic PIGS sample, we derive distances with StarHorse and compute orbital properties in a realistic potential including a bar. We find that a significant fraction of metal-poor stars is confined to the inner Galaxy (apocentre < 4 kpc), with an estimated confined fraction of 80%/50% at [Fe/H] = − 1.0/ − 2.0. We also find that the very metal-poor population has a net prograde rotation, with a υ ϕ ∼ 40 kms −1 . It is still under discussion what the origin is of the population of very metal-poor inner Galaxy stars – it is likely a combination of in-situ and accreted stars. In future, spectroscopic observations from 4MOST will be crucial to complete our picture.
William Henry Jackson; J. M. Hays; Alex Owen; N. A. Walton; Alison Packer; Anish Mudaraddi
In this paper we outline the results of a project to evaluate the total climate/carbon impact of a digital research infrastructure for a defined snapshot period. We outline the carbon model used to calculate the impact and the data collected to quantify that impact for a defined set of resources. We discuss the variation in potential impact across both the active and embodied carbon for computing hardware and produce a range of estimates on the amount of carbon equivalent climate impact for the snapshot period.
Jackson, Adrian; Jon Hays; Alex Owen; N. A. Walton; Alison Packer; Anish Mudaraddi
arXiv (Cornell University) · DOI
In this paper we outline the results of a project to evaluate the total climate/carbon impact of a digital research infrastructure for a defined snapshot period. We outline the carbon model used to calculate the impact and the data collected to quantify that impact for a defined set of resources. We discuss the variation in potential impact across both the active and embodied carbon for computing hardware and produce a range of estimates on the amount of carbon equivalent climate impact for the snapshot period.
D. L. Harrison; F. van Leeuwen; P. Osborne; P. W. Burgess; F. De Angeli; D. W. Evans
arXiv (Cornell University) · DOI
Aims. To describe two potential options for the Source Environment Analysis pipeline, SEAPipe, for the Gaia mission. This pipeline will enable the discovery of sources which are new to Gaia, in the sense that they were not found by the on-board detection algorithm. These additional sources (secondaries) are discoverable in the vicinity of those Gaia sources (primaries) that were found by the on-board detection. Methods. The main algorithmic steps required are described; the 2-dimensional image reconstruction of 1-dimensional transit data, the analysis of these images to find the additional sources present, and the determination of the mean positions, proper motions, parallaxes and brightness of these sources. Additionally, the Monte Carlo simulations used to characterise the performance of the pipelines are described. Results. The performance of the two options for SEAPipe, the vanilla and image-subtraction versions, are compared. Their selection functions are computed in terms of the magnitude of the secondary sources and their angular separations from their corresponding primary source. The completeness and purity of the resultant catalogue of secondary sources as found by each of the pipelines, given the expected magnitude distribution of the primary sources and the magnitude and angular separation distributions of the secondary sources, is also presented. The image-subtraction pipeline is shown to out-perform the vanilla pipeline.
L. Eyer; M. Audard; B. Holl; L. Rimoldini; M. I. Carnerero; G. Clementini; J. De Ridder; E. Distefano; D. W. Evans; P. Gavras; R. Gomel; T. Lebzelter; G. Marton; N. Mowlavï; A. Panahi; V. Ripepi; Ł. Wyrzykowski; K. Nienartowicz; G. Jevardat de Fombelle; I. Lecœur-Taı̈bi; L. Rohrbasser; M. Riello; P. García-Lario; A. C. Lanzafame; T. Mazeh; C. M. Raiteri; S. Zucker; P. Ábrahám; C. Aerts; J. J. Aguado; Richard I. Anderson; Dolev Bashi; A. Binnenfeld; S. Faigler; A. Garofalo; L. Karbevska; Á. Kóspál; K. Kruszyńska; M. Kun; A. F. Lanza; S. Leccia; M. Marconi; S. Messina; R. Molinaro; L. Molnár; T. Muraveva; I. Musella; Z. Nagy; I. Pagano; L. Palaversa; E. Plachy; A. Prša; Krzysztof A. Rybicki; S. Shahaf; L. Szabados; E. Szegedi-Elek; Michele Trabucchi; F. Barblan; M. Grenon; M. Roelens; M. Süveges
Astronomy and Astrophysics · DOI
Context. Gaia has been in operations since 2014, and two full data releases (DR) have been delivered so far: DR1 in 2016 and DR2 in 2018. The third Gaia data release expands from the early data release (EDR3) in 2020, which contained the five-parameter astrometric solution and mean photometry for 1.8 billion sources by providing 34 months of multi-epoch observations that allowed us to systematically probe, characterise, and classify variable celestial phenomena. Aims. We present a summary of the variability processing and analysis of the photometric and spectroscopic time series of 1.8 billion sources carried out for Gaia DR3. Methods. We used statistical and machine learning methods to characterise and classify the variable sources. Training sets were built from a global revision of major published variable star catalogues. For a subset of classes, specific detailed studies were conducted to confirm their class membership and to derive parameters that are adapted to the peculiarity of the considered class. Results. In total, 10.5 million objects are identified as variable in Gaia DR3 and have associated time series in G , G BP , and G RP and, in some cases, radial velocity time series. The DR3 variable sources subdivide into 9.5 million variable stars and 1 million active galactic nuclei or ‘quasars’. In addition, supervised classification identified 2.5 million galaxies thanks to spurious variability induced by the extent of these objects. The variability analysis output in the DR3 archive amounts to 17 tables, containing a total of 365 parameters. We publish 35 types and subtypes of variable objects. For 11 variable types, additional specific object parameters are published. Here, we provide an overview of the estimated completeness and contamination of most variability classes. Conclusions. Thanks to Gaia , we present the largest whole-sky variability analysis based on coherent photometric, astrometric, and spectroscopic data. Future Gaia data releases will more than double the span of time series and the number of observations, allowing the publication of an even richer catalogue.
Akshara Viswanathan; Else Starkenburg; Tadafumi Matsuno; Kim A. Venn; Nicolas F. Martin; Nicolas Longeard; Anke Arentsen; R. G. Carlberg; S. Fabbro; G. Kordopatis; Martin Montelius; Federico Sestito; Zhen Yuan
arXiv (Cornell University) · DOI
Context. Gaia DR3 has offered the scientific community a remarkable dataset of approximately one million spectra acquired with the Radial Velocity Spectrometer (RVS) in the Calcium II triplet region, that is well-suited to identify very metal-poor (VMP) stars. However, over 40% of these spectra have no released parameters by Gaia's GSP Spec pipeline in the domain of VMP stars, whereas VMP stars are key tracers of early Galactic evolution. Aims. We aim to provide spectroscopic metallicities for VMP stars using Gaia RVS spectra, thereby producing a catalogue of bright VMP stars distributed over the full sky that can serve as the basis to study early chemical evolution throughout the Galaxy. Methods. We select VMP stars using photometric metallicities from the literature and analyse the Gaia RVS spectra to infer spectroscopic metallicities for these stars. Results. The inferred metallicities agree very well with literature high-resolution metallicities with a median systematic offset of 0.1 dex and standard deviation of $\sim$0.15 dex. The purity of this sample in the VMP regime is $\sim$80% with outliers representing a mere $\sim$3%. Conclusions. We make available an all-sky catalogue of $\sim$1500 stars with reliable spectroscopic metallicities down to [Fe/H]$\sim$-4.0, of which $\sim$1000 are VMP stars. More than 75% of these stars have either no metallicity value in the literature to date or are flagged to be unreliable in their literature metallicity estimates. This catalogue of bright (G<13) VMP stars is three times larger than the current sample of well-studied VMP stars in the literature in this magnitude range, making it ideal for high-resolution spectroscopic follow-up and to study the properties of VMP stars in different parts of our Galaxy.
E. A. González-Solares; A. Dariush; Carlos González‐Fernández; A. Yoldaş; Alireza Molaeinezhad; Mohammad Al Sa’d; Leigh M. Smith; Tristan Whitmarsh; Neil S. Millar; N. Chornay; Ilaria Falciatori; Atefeh Fatemi; Daniel Goodwin; Laura Kuett; Claire M. Mulvey; Marta Páez Ribes; Fatime Qosaj; Andrew Roth; Ignacio Vázquez-Garćıa; Spencer S. Watson; Jonas Windhager; Samuel Aparício; Bernd Bodenmiller; Ed Boyden; Carlos Caldas; Owen Harris; Sohrab P. Shah; Simon Tavaré; CRUK IMAXT Grand Challenge Team; Dario Bressan; Gregory J. Hannon; N. A. Walton
Biological Imaging · DOI
With the aim of producing a 3D representation of tumors, imaging and molecular annotation of xenografts and tumors (IMAXT) uses a large variety of modalities in order to acquire tumor samples and produce a map of every cell in the tumor and its host environment. With the large volume and variety of data produced in the project, we developed automatic data workflows and analysis pipelines. We introduce a research methodology where scientists connect to a cloud environment to perform analysis close to where data are located, instead of bringing data to their local computers. Here, we present the data and analysis infrastructure, discuss the unique computational challenges and describe the analysis chains developed and deployed to generate molecularly annotated tumor models. Registration is achieved by use of a novel technique involving spherical fiducial marks that are visible in all imaging modalities used within IMAXT. The automatic pipelines are highly optimized and allow to obtain processed datasets several times quicker than current solutions narrowing the gap between data acquisition and scientific exploitation.
C. Spiniello; G. D’Ago; L. Coccato; Johanna Hartke; C. Tortora; Anna Ferré-Mateu; C. Pulsoni; Michele Cappellari; Michalina Maksymowicz-Maciata; M. Arnaboldi; Davide Bevacqua; Anna Gallazzi; L. K. Hunt; F. La Barbera; Ignacio Martín-Navarro; Nicola R. Napolitano; M. Radovich; Saracco, P.; Diana Scognamiglio; Marilena Spavone; S. Zibetti
arXiv (Cornell University) · DOI
This paper presents the third data release of the INvestigating Stellar Population In RElics (INSPIRE) project, comprising 52 ultra-compact massive galaxies (UCMGs) observed with the X-Shooter spectrograph. We measure integrated stellar velocity dispersion, [Mg/Fe] abundances, ages, and metallicities for all the INSPIRE objects. We thus infer star formation histories and confirm the existence of a degree of relicness (DoR), defined in terms of the fraction of stellar mass formed by $z=2$, the time at which a galaxy has assembled 75\% of its mass, and the final assembly time. Objects with a high DoR assembled their stellar mass at early epochs, while low-DoR objects show a non-negligible fraction of later-formed populations and hence a spread in ages and metallicities. A higher DoR correlates with larger [Mg/Fe], super-solar metallicity, and larger velocity dispersion values. The 52 UMCGs span a large range of DoR from 0.83 to 0.06, with 38 of them having formed more than 75\% of their mass by $z=2$. Of these, nine are extreme relics (DoR$>0.7$), since they formed the totality ($>99\%$) of their stellar mass by redshift $z=2$. The remaining 14 UCMGs cannot be considered relics, as they are characterised by more extended star formation histories. With INSPIRE, we built the first sizeable sample of relics outside the local Universe, up to $z\sim0.4$, increasing the number of confirmed relics by a factor of $>10$, and opening up an important window to explain the mass assembly of massive galaxies in the high-z Universe.
Chiara Spiniello; G. D’Ago; L. Coccato; Johanna Hartke; C. Tortora; Anna Ferré-Mateu; C. Pulsoni; Michele Cappellari; Michalina Maksymowicz-Maciata; M. Arnaboldi; Davide Bevacqua; Anna Gallazzi; L. K. Hunt; F. La Barbera; Ignacio Martín-Navarro; N. R. Napolitano; M. Radovich; P. Saracco; Diana Scognamiglio; Marilena Spavone; S. Zibetti
Monthly Notices of the Royal Astronomical Society · DOI
ABSTRACT This paper presents the third data release of the INvestigating Stellar Population In RElics (INSPIRE) project, comprising 52 ultra-compact massive galaxies (UCMGs) observed with the X-Shooter spectrograph. We measure integrated stellar velocity dispersion, [Mg/Fe] abundances, ages, and metallicities for all the INSPIRE objects. We thus infer star formation histories and confirm the existence of a degree of relicness (DoR), defined in terms of the fraction of stellar mass formed by z = 2, the time at which a galaxy has assembled 75 per cent of its mass, and the final assembly time. Objects with a high DoR assembled their stellar mass at early epochs, while low-DoR objects show a non-negligible fraction of later formed populations and hence a spread in ages and metallicities. A higher DoR correlates with larger [Mg/Fe], supersolar metallicity, and larger velocity dispersion values. The 52 UMCGs span a large range of DoR from 0.83 to 0.06, with 38 of them having formed more than 75 per cent of their mass by z = 2. Of these, nine are extreme relics (DoR>0.7), since they formed the totality ($\gt 99~{{\ \rm per\ cent}}$) of their stellar mass by redshift z = 2. The remaining 14 UCMGs cannot be considered relics, as they are characterized by more extended star formation histories. With INSPIRE we built the first sizeable sample of relics outside the local Universe, up to z ∼ 0.4, increasing the number of confirmed relics by a factor of >10, and opening up an important window to explain the mass assembly of massive galaxies in the high-z Universe.
M. Bellazzini; D. Massari; E. Ceccarelli; A. Mucciarelli; A. Bragaglia; M. Riello; F. De Angeli; P. Montegriffo
arXiv (Cornell University) · DOI
We use photometric metallicity estimates for about 700000 stars in the surroundings of the Sun, with very accurate distances and 3-D motions measures from Gaia DR3, to explore the properties of the metal-poor (-2.0<[Fe/H]<= -1.5; MP) and very metal-poor ([Fe/H]<= -2.0; VMP) stars with disc kinematics in the sample. We confirm the presence of a significant fraction of MP and VMP stars with disc-like orbits and that prograde orbits are prevalent among them, with prograde to retrograde ratio P/R ~3. We highlight for the first time a statistically significant difference in the distribution of the Z-component of the angular momentum (L_Z) and orbital eccentricity between prograde and retrograde disc-like MP stars. The same kind of difference is found also in the VMP subsample, albeit at a much lower level of statistical significance, likely due to the small sample size. We show that prograde disc-like MP and VMP stars display an additional component of the |L_Z| distribution with respect to their retrograde counterpart. This component is at higher |L_Z| with respect to the main peak of the distribution, possibly hinting at the presence of a pristine prograde disc in the Milky Way. This hypothesis is supported by the results of the analysis of a large sub-sample dominated by stars born in-situ. Also in this case the prevalence of prograde stars is clearly detected at [Fe/H]<= -1.5 and their |L_Z| distribution is more skewed toward high |L_Z| values than their retrograde counterpart. This suggests that the seed of what will eventually evolve into the main disc components of the Milky Way may have been already in place in the earliest phases of the Galaxy assembly.
Emily Pass; Jennifer G. Winters; David Charbonneau; Jonathan Irwin; David W. Latham; Perry Berlind; M. Calkins; Gilbert A. Esquerdo; Jessica Mink
The Astronomical Journal · DOI
Abstract Cold Jovian planets play an important role in sculpting the dynamical environment in which inner terrestrial planets form. The core accretion model predicts that giant planets cannot form around low-mass M dwarfs, although this idea has been challenged by recent planet discoveries. Here, we investigate the occurrence rate of giant planets around low-mass (0.1–0.3 M ⊙ ) M dwarfs. We monitor a volume-complete, inactive sample of 200 such stars located within 15 pc, collecting four high-resolution spectra of each M dwarf over six years and performing intensive follow-up monitoring of two candidate radial velocity variables. We use TRES on the 1.5 m telescope at the Fred Lawrence Whipple Observatory and CHIRON on the Cerro Tololo Inter-American Observatory 1.5 m telescope for our primary campaign, and MAROON-X on Gemini-North for high-precision follow up. We place a 95% confidence upper limit of 1.5% (68% confidence limit of 0.57%) on the occurrence of M P sin i > 1 M J giant planets out to the water snow line and provide additional constraints on the giant planet population as a function of M P sin i and period. Beyond the snow line (100 K < T eq < 150 K), we place 95% confidence upper limits of 1.5%, 1.7%, and 4.4% (68% confidence limits of 0.58%, 0.66%, and 1.7%) for 3 M J < M P sin i < 10 M J , 0.8 M J < M P sin i < 3 M J , and 0.3 M J < M P sin i < 0.8 M J giant planets, respectively; i.e., Jupiter analogs are rare around low-mass M dwarfs. In contrast, surveys of Sun-like stars have found that their giant planets are most common at these Jupiter-like instellations.
S. Lalitha; A. H. M. J. Triaud; Thomas A Baycroft; Jerome A. Orosz; I. Boisse; N. Heidari; Daniel Sebastian; Georgina Dransfield; David V. Martin; A. Santerne; Matthew R. Standing
Monthly Notices of the Royal Astronomical Society · DOI
ABSTRACT Ongoing ground-based radial-velocity observations seeking to detect circumbinary planets focus on single-lined binaries even though over 9 in every 10 binary systems in the solar neighbourhood are double lined. Double-lined binaries are on average brighter, and should in principle yield more precise radial velocities. However, as the two stars orbit one another, they produce a time-varying blending of their weak spectral lines. This makes an accurate measure of radial velocities difficult, producing a typical scatter of $10{\!-\!}15~\rm m\, s^{-1}$. This extra noise prevents the detection of most orbiting circumbinary planets. We develop two new data-driven approaches to disentangle the two stellar components of a double-lined binary, and extract accurate and precise radial velocities. Both approaches use a Gaussian process regression, with the first one working in the spectral domain, whereas the second works on cross-correlated spectra. We apply our new methods to TIC 172900988, a proposed circumbinary system with a double-lined binary, and detect a circumbinary planet with an orbital period of $150~\rm d$, different than previously proposed. We also measure a significant residual scatter, which we speculate is caused by stellar activity. We show that our two data-driven methods outperform the traditionally used TODCOR and TODMOR, for that particular binary system.
S. Lalitha; Amaury H. M. J. Triaud; Thomas A Baycroft; Jerome A. Orosz; I. Boisse; N. Heidari; Daniel Sebastian; Georgina Dransfield; David V. Martin; A. Santerne; Matthew R. Standing
arXiv (Cornell University) · DOI
Ongoing ground-based radial-velocity observations seeking to detect circumbinary planets focus on single-lined binaries even though over nine in every ten binary systems in the solar-neighbourhood are double-lined. Double-lined binaries are on average brighter, and should in principle yield more precise radial-velocities. However, as the two stars orbit one another, they produce a time-varying blending of their weak spectral lines. This makes an accurate measure of radial velocities difficult, producing a typical scatter of 10-15m/s. This extra noise prevents the detection of most orbiting circumbinary planets. We develop two new data-driven approaches to disentangle the two stellar components of a double-lined binary, and extract accurate and precise radial-velocities. Both approaches use a Gaussian Process regression, with the first one working in the spectral domain, whereas the second works on cross-correlated spectra. We apply our new methods to TIC 172900988, a proposed circumbinary system with a double-lined binary, and detect a circumbinary planet with an orbital period of 150 days, different than previously proposed. We also measure a significant residual scatter, which we speculate is caused by stellar activity. We show that our two data-driven methods outperform the traditionally used TODCOR and TODMOR, for that particular binary system.
Tyler Moulton; S. T. Hodgkin; Gareth Smith; Joshua T Briegal; Edward Gillen; Jack S Acton; Matthew P. Battley; M. R. Burleigh; S. L. Casewell; Samuel Gill; M. R. Goad; Beth A Henderson; Alicia Kendall; Gavin Ramsay; Rosanna H Tilbrook; P. J. Wheatley
Monthly Notices of the Royal Astronomical Society · DOI
ABSTRACT The dipper is a novel class of young stellar object associated with large drops in flux on the order of 10–50 per cent lasting for hours to days. Too significant to arise from intrinsic stellar variability, these flux drops are currently attributed to disc warps, accretion streams, and/or transiting circumstellar dust. Dippers have been previously studied in young star-forming regions, including the Orion Complex. Using Next Generation Transit Survey (NGTS) data, we identified variable stars from their light curves. We then applied a machine learning random forest classifier for the identification of new dipper stars in Orion using previous variable classifications as a training set. We discover 120 new dippers, of which 83 are known members of the Complex. We also investigated the occurrence rate of discs in our targets, again using a machine learning approach. We find that all dippers have discs, and most of these are full discs. We use dipper periodicity and model-derived stellar masses to identify the orbital distance to the inner disc edge for dipper objects, confirming that dipper stars exhibit strongly extended sublimation radii, adding weight to arguments that the inner disc edge is further out than predicted by simple models. Finally, we determine a dipper fraction (the fraction of stars with discs which are dippers) for known members of 27.8 ± 2.9 per cent. Our findings represent the largest population of dippers identified in a single cluster to date.
Gareth Smith; Edward Gillen; S. T. Hodgkin; D. R. Alves; D. R. Anderson; Matthew P. Battley; M. R. Burleigh; S. L. Casewell; Samuel Gill; M. R. Goad; Beth A Henderson; J. S. Jenkins; Alicia Kendall; Maximiliano Moyano; Gavin Ramsay; Rosanna H Tilbrook; José I Vines; R. G. West; P. J. Wheatley
Monthly Notices of the Royal Astronomical Society · DOI
ABSTRACT We present a study of rotation across 30 square degrees of the Orion Star-forming Complex, following a ∼200 d photometric monitoring campaign by the Next Generation Transit Survey (NGTS). From 5749 light curves of Orion members, we report periodic signatures for 2268 objects and analyse rotation period distributions as a function of colour for 1789 stars with spectral types F0–M5. We select candidate members of Orion using Gaia data and assign our targets to kinematic sub-groups. We correct for interstellar extinction on a star-by-star basis and determine stellar and cluster ages using magnetic and non-magnetic stellar evolutionary models. Rotation periods generally lie in the range 1–10 d, with only 1.5 per cent of classical T Tauri stars or Class I/II young stellar objects rotating with periods shorter than 1.8 d, compared with 14 per cent of weak-line T Tauri stars or Class III objects. In period–colour space, the rotation period distribution moves towards shorter periods among low-mass (>M2) stars of age 3–6 Myr, compared with those at 1–3 Myr, with no periods longer than 10 d for stars later than M3.5. This could reflect a mass-dependence for the dispersal of circumstellar discs. Finally, we suggest that the turnover (from increasing to decreasing periods) in the period–colour distributions may occur at lower mass for the older-aged population: ∼K5 spectral type at 1–3 Myr shifting to ∼M1 at 3–6 Myr.
Hanyuan Zhang; Anke Arentsen; Vasily A Belokurov
arXiv (Cornell University) · DOI
There has been a discussion for many years on whether the disc in the Milky Way extends down to low metallicity. We aim to address the question by employing a large sample of giant stars with radial velocities and homogeneous metallicities based on the Gaia DR3 XP spectra. We study the 3D velocity distribution of stars in various metallicity ranges, including the very-metal poor regime (VMP, [M/H] $<-2.0$). We find that a clear disc population starts to emerge only around [M/H] $\sim -1.3$, and is not visible for [M/H] $<-1.6$. Using Gaussian Mixture Modeling (GMM), we show that there are two halo populations in the VMP regime: one stationary and one with a net prograde rotation of $\sim80\,\mathrm{km/s}$. In this low-metallicity range, we are able to place constraints on the contribution of a rotation-supported disc sub-population to a maximum of $\sim 3$\%. We compare our results to previous claims of discy VMP stars in both observations and simulations and find that having a prograde halo component could explain most of these.
M. Bellazzini; D. Massari; F. De Angeli; A. Mucciarelli; A. Bragaglia; M. Riello; P. Montegriffo
Astronomy and Astrophysics · DOI
We used two previous calibrations and the standardised synthetic photometry in the v , b , and y Strömgren passbands from Gaia DR3 BP / RP spectra to obtain photometric metallicities for a selected sample of 694 233 old Galactic giant stars having | b |&gt; 20.0° and parallax uncertainties lower than 10%. The zero point of both sets of photometric metallicities has been shifted to ensure an optimal match with the spectroscopic [Fe/H] values for 44 785 stars in common with APOGEE DR17, focusing on the metallicity range where they provide the highest accuracy. The metallicities derived in this way from one calibration display a typical accuracy of ≲0.1 dex and 1 σ precision ≲0.2 dex in the range −2.2 ≲ [Fe/H] ≲ −0.4, while they show a systematic trend with [Fe/H] at higher metallicity, beyond the applicability range of the relation. Those derived from the other calibration display, in general, reduced precision, and lower accuracy in the metal-poor regime, but have a median accuracy &lt; 0.05 dex for [Fe/H] ≥ − 0.8. These results are confirmed and, consequently, the metallicities are validated, by comparison with large sets of spectroscopic metallicities from various surveys. The newly obtained metallicities are used to derive metallicity distributions for several previously identified substructures in the Galactic halo with an unprecedented number of stars. The catalogue including the two sets of metallicities and the associated uncertainties is made publicly available.
M. Bellazzini; D. Massari; De Angeli F.; A. Mucciarelli; A Bragaglia.; M. Riello; P. Montegriffo
arXiv (Cornell University) · DOI
We use the calibrations by Calamida et al. and by Hilker et al., and the standardised synthetic photometry in the v, b, and y Stromgren passbands from Gaia DR3 BP/RP spectra, to obtain photometric metallicities for a selected sample of 694233 old Galactic giant stars having |b|&gt;20.0 and parallax uncertainties lower than 10%. The zero point of both sets of photometric metallicities has been shifted to to ensure optimal match with the spectroscopic [Fe/H] values for 44785 stars in common with APOGEE DR17, focusing on the metallicity range where they provide the highest accuracy. The metallicities derived in this way from the Calamida et al. calibration display a typical accuracy of ~0.1 dex and 1 sigma precision ~0.2 dex in the range -2.2 &lt;=[Fe/H]&lt;= -0.4, while they show a systematic trend with [Fe/H] at higher metallicity, beyond the applicability range of the relation. Those derived from the Hilker et al. calibration display, in general, worse precision, and lower accuracy in the metal-poor regime, but have a median accuracy &lt; 0.05 dex for [Fe/H]&gt;= -0.8. These results are confirmed and, consequently, the metallicities validated, by comparison with large sets of spectroscopic metallicities from various surveys. The newly obtained metallicities are used to derive metallicity distributions for several previously identified sub-structures in the Galactic halo with an unprecedented number of stars. The catalogue including both sets of metallicities and the associated uncertainties is made publicly available.
Sumedha Biswas; Z. Kostrzewa-Rutkowska; P. G. Jonker; P. M. Vreeswijk; D. Eappachen; P. Groot; S. T. Hodgkin; Abdullah Yoldaş; G. Rixon; D. L. Harrison; M. van Leeuwen; D. W. Evans
Monthly Notices of the Royal Astronomical Society · DOI
ABSTRACT The discovery of gravitational wave (GW) events and the detection of electromagnetic counterparts from GW170817 has started the era of multimessenger GW astronomy. The field has been developing rapidly, and in this paper, we discuss the preparation for detecting these events with ESA’s Gaia satellite, during the 4th observing run of the LIGO–Virgo–KAGRA (LVK) collaboration that has started on 2023 May 24. Gaia is contributing to the search for GW counterparts by a new transient detection pipeline called GaiaX. In GaiaX, a new source appearing in the field of view of only one of the two telescopes on-board Gaia is sufficient to send out an alert on the possible detection of a new transient. Ahead of O4, an experiment was conducted over a period of about two months. During the two weeks around New Moon in this period of time, the MeerLICHT (ML) telescope located in South Africa tried (weather permitting) to observe the same region of the sky as Gaia within 10 min. Any GaiaX detected transient was published publicly. ML and Gaia have similar limiting magnitudes for typical seeing conditions at ML. At the end of the experiment, we had 11 861 GaiaX candidate transients and 15 806 ML candidate transients, which we further analysed and the results of which are presented in this paper. Finally, we discuss the possibility and capabilities of Gaia contributing to the search for electromagnetic counterparts of gravitational wave events during O4 through the GaiaX detection and alert procedure.
Sumedha Biswas; Z. Kostrzewa-Rutkowska; Peter Gustaaf Jonker; Paul M. Vreeswijk; D. Eappachen; P. Groot; S. T. Hodgkin; Abdullah Yoldaş; Guy T. Rixon; Diana L. Harrison; M. van Leeuwen; Dafydd Wyn Evans
arXiv (Cornell University) · DOI
The discovery of gravitational wave (GW) events and the detection of electromagnetic counterparts from GW170817 has started the era of multimessenger GW astronomy.The field has been developing rapidly and in this paper,we discuss the preparation for detecting these events with the ESA Gaia satellite,during the 4th observing run of the LIGO-Virgo-KAGRA (LVK) collaboration that has started on May 24,2023. Gaia is contributing to the search for GW counterparts by a new transient detection pipeline called GaiaX. In GaiaX, a new source appearing in the field of view of only one of the two telescopes on-board Gaia is sufficient to send out an alert on the possible detection of a new transient. Ahead of O4, an experiment was conducted over a period of about two months. During the two weeks around New Moon in this period of time, the MeerLICHT (ML) telescope located in South Africa tried (weather permitting) to observe the same region of the sky as Gaia within 10 minutes. Any GaiaX detected transient was published publicly. ML and Gaia have similar limiting magnitudes for typical seeing conditions at ML. At the end of the experiment, we had 11861 GaiaX candidate transients and 15806 ML candidate transients, which we further analysed and the results of which are presented in this paper. Finally, we discuss the possibility and capabilities of Gaia contributing to the search for electromagnetic counterparts of gravitational wave events during O4 through the GaiaX detection and alert procedure.