Eric N. Mack

Rowell, Charles H.

doi:10.1353/cal.2015.0125

Cited by 2 publications

(7 citation statements)

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“…This suggests that we are underestimating the star formation rate around 3 Gyr and overestimating at 6 Gyr by roughly 50% and 30%, respectively. This is consistent with the results of Rowell (2013) and Vergely et al (2002), as shown in the left-hand panel of Figure 10, who see an increase in star formation between 2 and 3 Gyr and a resulting decrease in the vicinity of 6 Gyr. This result is also in line with the recent work by Mor et al (2019), who compared simulations of the Besançon Galactic model with the colors, magnitudes, and parallaxes from Gaia DR2, which shows a burst of star formation between 2 and 3 Gyr in the past.…”

Section: Effect Of Star Formation Prescriptionsupporting

confidence: 92%

“…These solar position values were adopted from Robin et al (2017), who derived them by comparing the Besançon model to kinematic data from RAVE and Gaia DR1. These values are similar to those derived by Rowell & Hambly (2011) using white dwarfs in the SuperCOSMOS survey. We do not allow the velocities to vary in R or z, as shown in Robin et al (2017), since our sample is local (see Section 4) and therefore this gradient would have a minimal impact on our results.…”

Section: Model Functionssupporting

confidence: 88%

“…Owing to their intrinsic faintness, for a given temperature white dwarfs are well separated in the RPMD from main-sequence stars with similar colors (see, e.g, Harris et al 2006;Rowell & Hambly 2011;Fantin et al 2017;Munn et al 2017). Using model cooling tracks we select white dwarfs with tangential velocities greater than 20 kms −1 as shown in the left-hand panel of Figure 2.…”

Section: White Dwarf Selectionmentioning

confidence: 99%

“…Our resulting white dwarf contributions within the solar neighborhood break down to (83 ± 5) %, (17 ± 3) %, and (0.11 ± 0.05) % from the thin disk, thick disk, and stellar halo respectively. Rowell & Hambly (2011) constructed thin disk, thick disk, and halo luminosity functions using a statistical approach based on kinematics and photometry from the SuperCOSMOS survey in order to obtain local fractions of 79, 16, and 5 percent, respectively. This result was consistent with Reid (2005) who found that thick disk white dwarfs should comprise roughly 20% of the local population.…”

Section: Local Stellar Density and White Dwarf Number Densitymentioning

confidence: 99%

“…Noh & Scalo (1990) showed that varying the functional form for the star formation rate would leave imprints on the resulting WDLF, such as the slope and turn-off. This method was used by Rowell (2013) to invert the SDSS WDLF assembled by Harris et al (2006), and showed a resulting star formation history composed of two broad peaks (at 2 and 9 Gyr) separated by a significant dip. The advantage of using this method is that the volume that can be probed is considerably larger; the downside, however, is that volume and completeness corrections must be applied.…”

Section: Introductionmentioning

confidence: 99%

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The Canada–France Imaging Survey: Reconstructing the Milky Way Star Formation History from Its White Dwarf Population

Fantin

Côté

McConnachie

et al. 2019

ApJ

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As the remnants of stars with initial masses 8 M , white dwarfs contain valuable information on the formation histories of stellar populations. In this paper, we use deep, high-quality, u-band photometry from the Canada France Imaging Survey (CFIS), griz photometry from Pan-STARRS 1 (PS1), as well as proper motions from Gaia DR2, to select 25,156 white dwarf candidates over ∼4500 deg 2 using a reduced proper motion diagram. We develop a new white dwarf population synthesis code that returns mock observations of the Galactic field white dwarf population for a given star formation history, while simultaneously taking into account the geometry of the Milky Way, survey parameters, and selection effects. We use this model to derive the star formation histories of the thin disk, thick disk, and stellar halo. Our results show that the Milky Way disk began forming stars (11.3 ± 0.5) Gyr ago, with a peak rate of (8.8 ± 1.4) M yr −1 at (9.8 ± 0.4) Gyr, before a slow decline to a constant rate until the present day -consistent with recent results suggesting a merging event with a satellite galaxy. Studying the residuals between the data and best-fit model shows evidence for a slight increase in star formation over the past 3 Gyr. We fit the local fraction of helium-atmosphere white dwarfs to be (21 ± 3) %. Incorporating this methodology with data from future wide-field surveys such as LSST, Euclid, CASTOR, and WFIRST should provide an unprecedented view into the formation of the Milky Way at its earliest epoch through its white dwarfs.

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Section: Effect Of Star Formation Prescriptionsupporting

confidence: 92%

Section: Model Functionssupporting

confidence: 88%

Section: White Dwarf Selectionmentioning

confidence: 99%

Section: Local Stellar Density and White Dwarf Number Densitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Canada–France Imaging Survey: Reconstructing the Milky Way Star Formation History from Its White Dwarf Population

Fantin

Côté

McConnachie

et al. 2019

ApJ

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Set-theoretic solutions of the Yang–Baxter equation and new classes of R-matrices

Smoktunowicz

2018

Linear Algebra and its Applications

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We describe several methods of constructing R-matrices that are dependent upon many parameters, for example unitary R-matrices and R-matrices whose entries are functions. As an application, we construct examples of R-matrices with prescribed singular values. We characterise some classes of indecomposable set-theoretic solutions of the quantum Yang-Baxter equation (QYBE) and construct R-matrices related to such solutions. In particular, we establish a correspondence between one-generator braces and indecomposable, non-degenerate involutive set-theoretic solutions of the QYBE, showing that such solutions are abundant. We show that R-matrices related to involutive, non-degenerate solutions of the QYBE have special form. We also investigate some linear algebra questions related to R-matrices.constructed using set-theoretic solutions of the quantum Yang-Baxter equation, and have only one nonzero element in each column. This type of matrices appear frequently in the literature, for example in [17], where Baxterisation of some R-matrices of this type was obtained, and in [29], where they appear as universal gates for the quantum computation related to the circuit model (see Theorem 1,[29]). In [38,24,21] they appear in connection with Braid groups and topological quantum computation (see also [7,35,36,31]). They also appear as combinatorial R-matrices in the theory of crystal bases, geometric crystals and box-bell systems. The R-matrices related to involutive, non-degenerate settheoretic solutions of the QYBE give cocycles into abelian groups [20], therefore they can be given as an input in the construction of universal R-matrices and twists for Hopf algebras, for example as in Theorem 4.2, [18].Most of the R-matrices constructed in our paper are unitary. A unitary R-matrix leads to a unitary representation of the Braid group, and the resulting unitary matrices associated to braids can be used to process quantum information [38,15,21]. In connection with the topological quantum computation, it was conjectured in [24,42] that a single unitary R-matrix can generate only finite representations of Braid groups, and in [24] it was confirmed in several important classes of R-matrices. In [40], Rowell made the following comment: "From the quantum information point of view, a unitary R-matrix can be used to directly simulate topological quantum computers on the quantum circuit model. More recently people have begun to study what extra gates one needs to supplement braiding with in order to achieve universality (see e.g. [16]). If a single R-matrix can only generate a (nearly) finite group, can an additional small gate lead to a universal gate set?". This question provides the inspiration for our construction of R-matrices with many parameters. All of our examples are locally monomial BVS (we recall the definition in Section 2).Recall that locally monomial braided vector spaces (BVS) were introduced by Galindo and Rowell in [24], and localisation was introduced by Rowell and Wang in Definition 2.3 in [42]. A related notion of br...

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Eric N. Mack

Cited by 2 publications

References 0 publications

The Canada–France Imaging Survey: Reconstructing the Milky Way Star Formation History from Its White Dwarf Population

The Canada–France Imaging Survey: Reconstructing the Milky Way Star Formation History from Its White Dwarf Population

Set-theoretic solutions of the Yang–Baxter equation and new classes of R-matrices

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