Empirical completeness assessment of the <i>Gaia</i> DR2, Pan-STARRS 1, and ASAS-SN-II RR Lyrae catalogues

Mateu, C.; Holl, B.

doi:10.1093/mnras/staa1676

Cited by 14 publications

(9 citation statements)

References 39 publications

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“…However, our result is unaffected as long as the completeness is constant within the survey volume. Indeed, according to Figure 13 of Mateu et al (2020), the completeness of the RR Lyrae sample in Gaia DR2 at |𝑏| > 20 • is almost insensitive to the 𝐺-magnitude at 14 < 𝐺 < 18, where most of our sample reside. Thus, the simple selection function model in the above equations is reasonable for our analysis.…”

Section: Selection Function Modelmentioning

confidence: 84%

Action-based distribution function modelling for constraining the shape of the Galactic dark matter halo

Hattori,

Valluri,

Vasiliev

2020

Preprint

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We estimate the 3D density profile of the Galactic dark matter (DM) halo within 𝑟 30 kpc from the Galactic centre by using the astrometric data for halo RR Lyrae stars from Gaia DR2. We model both the stellar halo distribution function and the Galactic potential, fully taking into account the survey selection function, the observational errors, and the missing line-of-sight velocity data for RR Lyrae stars. With a Bayesian MCMC method, we infer the model parameters, including the density flattening of the DM halo 𝑞, which is assumed to be constant as a function of radius. We find that 99% of the posterior distribution of 𝑞 is located at 𝑞 > 0.963, which strongly disfavours a flattened DM halo. We cannot draw any conclusions as to whether the Galactic DM halo at 𝑟 30 kpc is prolate, because we restrict ourselves to axisymmetric oblate halo models with 𝑞 ≤ 1. Our result is inconsistent with predictions from cosmological hydrodynamical simulations that advocate more oblate ( 𝑞 ∼ 0.8 ± 0.15) DM halos within ∼ 15% of the virial radius for Milky-Way-sized galaxies. An alternative possibility, based on our validation tests with a cosmological simulation, is that the true value 𝑞 of the Galactic halo could be consistent with cosmological simulations but that disequilibrium in the Milky Way potential is inflating our measurement of 𝑞 by 0.1-0.2. As a by-product of our analysis, our model constrains the DM density in the Solar neighbourhood to be 𝜌 DM, = (9.01 +0.18 −0.20 ) × 10 −3 𝑀 pc −3 = 0.342 +0.007 −0.007 GeVcm −3 .

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Section: Selection Function Modelmentioning

confidence: 84%

Action-based distribution function modelling for constraining the shape of the Galactic dark matter halo

Hattori,

Valluri,

Vasiliev

2020

Preprint

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“…Of these, only 12 (six) are also consistent with the kinematic signature we detected in the space of l-b-pmra-pmdec 6 . Based on these results, and after correcting for the completeness of the RR Lyrae catalogue (estimated at 80% at these magnitudes in Mateu et al 2020), we conclude that MNC has, at most, 15 RR Lyrae and that the ACS has no more than eight. In parallel, we crossmatched the list of RR Lyrae with our sample to see the effect that the cut in parallax 12 has, and we observed that, from the 253 (253) stars that we had, only 123 (123) remain in MNC (ACS).…”

Section: Rr Lyrae To M Giant Ratiomentioning

confidence: 82%

“…Starting with the RR Lyrae, we used the catalogue described in Mateu et al (2020), which combines the VariClassifier and Specific Objects Studies (SOS) catalogues from Gaia DR2 (Holl et al 2018;Clementini et al 2019) with the ASAS-SN-II catalogue Jayasinghe et al (2019), providing optimal completeness at the bright end (G < 15). We selected only those sources that fall within the sky patches defined in Fig.…”

Section: Rr Lyrae To M Giant Ratiomentioning

confidence: 99%

The outer disc in shambles: Blind detection of Monoceros and the ACS with Gaia’s astrometric sample

Ramos

Antoja

Mateu

et al. 2021

A&A

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Context. The Gaia astrometric sample allows us to study the outermost Galactic disc, the halo, and their interface. It is precisely at the very edge of the disc where the effects of external perturbations are expected to be the most noticeable. Aims. Our goal is to detect the kinematic substructure present in the halo and at the edge of the Milky Way (MW) disc and provide observational constraints on their phase-space distribution. Methods. We download, one HEALpix at a time, the proper motion histogram of distant stars, to which we apply a wavelet transformation to reveal the significant overdensities. We then analyse the large coherent structures that appear in the sky. Results. We reveal a sharp yet complex anticentre dominated by Monoceros (MNC) and the Anticentre Stream (ACS) in the north – which we find have intensities comparable to the Magellanic Clouds and the Sagittarius stream – and by MNC South and TriAnd at negative latitudes. Our method allows us to perform a morphological analysis of MNC and the ACS, both of which span more than 100° in longitude, and to provide a high purity sample of giants with which we track MNC down to latitudes as low as ∼5°. Their colour-magnitude diagram is consistent with extended structures at a distance of ∼10−11 kpc that originated in the disc, with a very low ratio of RR Lyrae over M giants, and with kinematics compatible with the rotation curve at those distances or slightly slower. Conclusions. We present a precise characterisation of MNC and the ACS, two previously known structures that our method reveals naturally, allowing us to detect them without limiting ourselves to a particular stellar type and, for the first time, using only kinematics. Our results will allow future studies to model their chemo-dynamics and evolution, thus constraining some of the most influential processes that shaped the MW.

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“…Gaia Data Release 2 provided such a sample 52,53 . However, these maps are incomplete at the depths necessary to detect RR Lyrae at > 60 kpc (G ≈ 20), driven largely by the Gaia scanning pattern 54 . For example, the local wake is not clearly visible in the Gaia RR Lyrae catalog despite the fact that it is so prominent in the Pan-STARRS data at > 60 kpc.…”

Section: The Stellar Halo Probed By Rr Lyraementioning

confidence: 99%

All-Sky Dynamical Response of the Galactic Halo to the Large Magellanic Cloud

Conroy,

Naidu,

Garavito-Camargo

et al. 2021

Preprint

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Gravitational interactions between the Large Magellanic Cloud (LMC) and the stellar and dark matter halo of the Milky Way are expected to give rise to disequilibrium phenomena in the outer Milky Way 1-7 . A local wake is predicted to trail the orbit of the LMC, while a large-scale over-density is predicted to exist across a large area of the northern Galactic hemisphere. Here we present the detection of both the local wake and Northern over-density (hereafter the "collective response") in an all-sky star map of the Galaxy based on 1301 stars at 60 < R gal < 100 kpc. The location of the wake is in good agreement with an N-body simulation that includes the dynamical effect of the LMC on the Milky Way halo. The density contrast of the wake and collective response are both stronger in the data than in the simulation. The detection of a strong local wake is independent evidence that the Magellanic Clouds are on their first orbit around the Milky Way. The wake traces the path of the LMC, which will provide insight into the orbit of the LMC, which in turn is a sensitive probe of the mass of the LMC and the Milky Way. These data demonstrate that the outer halo is not in dynamical equilibrium, as is often assumed. The morphology and strength of the wake could be used to test the nature of dark matter and gravity.We combined optical photometry from Gaia Early Data Release 3 8 and infrared photometry from WISE 9 to identify a pure sample of giant stars across the entire sky, excluding the Galactic plane (|b| < 10 • ). Photometric distances were estimated with a 10 Gyr [Fe/H]= −1.5 isochrone 10 . Distances were converted to Galactic physical coordinates, and the final sample was selected to lie at Galactocentric distances of 60 < R gal < 100 kpc, where simulations predict a strong signal due to the dynamical response of the LMC and where contamination from previously known structures is minimized. Selections in sky coordinates and Gaia proper motions were used to remove stars associated with known objects including the LMC and SMC, Milky Way disk stars, and the Sagittarius stream (see Methods

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Empirical completeness assessment of the Gaia DR2, Pan-STARRS 1, and ASAS-SN-II RR Lyrae catalogues

Cited by 14 publications

References 39 publications

Action-based distribution function modelling for constraining the shape of the Galactic dark matter halo

Action-based distribution function modelling for constraining the shape of the Galactic dark matter halo

The outer disc in shambles: Blind detection of Monoceros and the ACS with Gaia’s astrometric sample

All-Sky Dynamical Response of the Galactic Halo to the Large Magellanic Cloud

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