To W. E. Heather 1 April 1818

Hogg, James; Hughes, Gillian

doi:10.1093/oseo/instance.00174096

Cited by 5 publications

(6 citation statements)

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“…Mitschang et al (2013) combine weighted absolute distances in a large number of chemical elements between two stars into a single metric and use this as the basis for deriving a function that describes the probability that two stars of common evolutionary origin. Hogg et al (2016) identify overdensities in a 15-dimensional chemical-abundance space provided by APOGEE data using the k-means algorithm, which is a method for clustering points in a high-dimensional space. This algorithm has also been applied as a basis in the chemical tagging work of (Bland-Hawthorn, Krumholz & Freeman 2010) but with less chemical elements and later on confirmed with simulations in Feng & Krumholz (2014).…”

Section: How Does a Phylogenetic Approach Compare To Other Methods?mentioning

confidence: 99%

“…As with chemical tagging studies, the method presented here relies on the uniqueness of stellar DNA. We ascertain that as long as enough elements are used in the analysis, this should be the case (Hogg et al 2016). We need to be aware however that our sample needs to be chosen such that the chemical distances are reflecting differences in chemical evolution and not systematic differences due to internal processes happening in stars, such as atomic diffusion (e.g.…”

Section: Uncertainties In the Analysismentioning

confidence: 99%

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Cosmic phylogeny: reconstructing the chemical history of the solar neighbourhood with an evolutionary tree

Jofré

Das

Bertranpetit

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Using 17 chemical elements as a proxy for stellar DNA, we present a full phylogenetic study of stars in the solar neighbourhood. This entails applying a clustering technique that is widely used in molecular biology to construct an evolutionary tree from which three branches emerge. These are interpreted as stellar populations which separate in age and kinematics and can be thus attributed to the thin disk, the thick disk, and an intermediate population of probable distinct origin. We further find six lone stars of intermediate age that could not be assigned to any population with enough statistical significance. Combining the ages of the stars with their position on the tree, we are able to quantify the mean rate of chemical enrichment of each of the populations, and thus show in a purely empirical way that the star formation rate in the thick disk is much higher than in the thin disk. We are also able to estimate the relative contribution of dynamical processes such as radial migration and disk heating to the distribution of chemical elements in the solar neighbourhood. Our method offers an alternative approach to chemical tagging methods with the advantage of visualising the behaviour of chemical elements in evolutionary trees. This offers a new way to search for 'common ancestors' that can reveal the origin of solar neighbourhood stars.Phylogenetic techniques have existed as long as evolutionary biology, but the strength of phylogenies based on DNA rather than phenotypes (aspects of morphology or biological structures, such as skulls), is that the mechanisms of change can be quantic 0000 RAS

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Section: How Does a Phylogenetic Approach Compare To Other Methods?mentioning

confidence: 99%

Section: Uncertainties In the Analysismentioning

confidence: 99%

Cosmic phylogeny: reconstructing the chemical history of the solar neighbourhood with an evolutionary tree

Jofré

Das

Bertranpetit

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…As a shorthand, we denote this 6D phase space X, and data points in it X n . Within the framework developed by Hogg et al (2010) and Hogg (2012), the probability of a model point x k generating a data point X n is then:…”

Section: The Fast-forward Methodsmentioning

confidence: 99%

Milky Way Mass and Potential Recovery Using Tidal Streams in a Realistic Halo

Bonaca

Geha

Küpper

et al. 2014

ApJ

132

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We present a new method for determining the Galactic gravitational potential based on forward modeling of tidal stellar streams. We use this method to test the performance of smooth and static analytic potentials in representing realistic dark matter halos, which have substructure and are continually evolving by accretion. Our FAST-FORWARD method uses a Markov Chain Monte Carlo algorithm to compare, in 6D phase space, an "observed" stream to models created in trial analytic potentials. We analyze a large sample of streams evolved in the Via Lactea II (VL2) simulation, which represents a realistic Galactic halo potential. The recovered potential parameters are in agreement with the best fit to the global, present-day VL2 potential. However, merely assuming an analytic potential limits the dark matter halo mass measurement to an accuracy of 5 to 20%, depending on the choice of analytic parametrization. Collectively, mass estimates using streams from our sample reach this fundamental limit, but individually they can be highly biased. Individual streams can both under-and overestimate the mass, and the bias is progressively worse for those with smaller perigalacticons, motivating the search for tidal streams at galactocentric distances larger than 70 kpc. We estimate that the assumption of a static and smooth dark matter potential in modeling of the GD-1 and Pal5-like streams introduces an error of up to 50% in the Milky Way mass estimates.

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“…Our comparison of the models to the observed overdensities is based on the framework developed in Hogg et al (2010) and Hogg (2012), and applied to Pal 5 in Küpper et al (2015). We use a likelihood of the form:…”

Section: Comparison To Observational Datamentioning

confidence: 99%

Tidal Stream Morphology as an Indicator of Dark Matter Halo Geometry: The Case of Palomar 5

Pearson

Küpper

Johnston

et al. 2015

ApJ

127

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This paper presents an example where the morphology of a single stellar stream can be used to rule out a specific galactic potential form without the need for velocity information. We investigate the globular cluster Palomar 5 (Pal 5), which is tidally disrupting into a cold, thin stream mapped over 22 degrees on the sky with a typical width of 0.7 degrees. We generate models of this stream by fixing Pal 5's present-day position, distance and radial velocity via observations, while allowing its proper motion to vary. In a spherical dark matter halo we easily find models that fit the observed morphology. However, no plausible Pal 5 model could be found in the triaxial potential of Law & Majewski (2010), which has been proposed to explain the properties of the Sagittarius stream. In this case, the long, thin and curved morphology of the Pal 5 stream alone can be used to rule out such a potential configuration. Pal 5 like streams in this potential are either too straight, missing the curvature of the observations, or show an unusual morphology which we dub stream-fanning: a signature sensitive to the triaxiality of a potential. We conclude that the mere existence of other thin tidal streams must provide broad constraints on the orientation and shape of the dark matter halo they inhabit.

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To W. E. Heather 1 April 1818

Cited by 5 publications

References 0 publications

Cosmic phylogeny: reconstructing the chemical history of the solar neighbourhood with an evolutionary tree

Cosmic phylogeny: reconstructing the chemical history of the solar neighbourhood with an evolutionary tree

Milky Way Mass and Potential Recovery Using Tidal Streams in a Realistic Halo

Tidal Stream Morphology as an Indicator of Dark Matter Halo Geometry: The Case of Palomar 5

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