The Milky Way stellar halo out to 40 kpc: squashed, broken but smooth

By A. Deason, V. Belokurov, N. Evans II. 2011

238 citations recorded by the source corpus.

We introduce a new maximum-likelihood method to model the density profile of blue horizontal branch and blue straggler stars and apply it to the Sloan Digital Sky Survey Data Release 8 photometric catalogue. There are a large number (∼20 000) of these tracers available over an impressive 14 000 deg2 in both Northern and Southern Galactic hemispheres, and they provide a robust measurement of the shape of the Milky Way stellar halo. After masking out stars in the vicinity of the Virgo overdensity and the Sagittarius stream, the data are consistent with a smooth, oblate stellar halo with a density that follows a broken power law. The best-fitting model has an inner slope αin∼ 2.3 and an outer slope αout∼ 4.6, together with a break radius occurring at ∼27 kpc and a constant halo flattening (i.e. ratio of minor axis to major axis) of q∼ 0.6. Although a broken power law describes the density fall-off most adequately, it is also well fitted by an Einasto profile. There is no strong evidence for variations in flattening with radius, or for triaxiality of the stellar halo.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/faf1b99bff6d597b37a6ad246dd91bcaf32913ba

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Citations in the corpus

A-type stars in the Canada–France Imaging Survey – II. Tracing the height of the disc at large distances with Blue Stragglers (2018, methodology): “This is done using the calibration of the absolute magnitude of the BSs in the g band provided by Deason et al. (2011), using the Sagittarius stream lying in the SDSS Stripe 82: Mg = 3.108 + 5.495 (g − r)0,SDSS .”
The Galaxy in Context: Structural, Kinematic, and Integrated Properties (2016, methodology): “…0.02 18 ± 1 3.8 ± 0.1 Pila-Dı́ez et al. (2015) nMSTO 10–60 2.5 ± 0.04 0.79 ± 0.02 19.5 ± 0.4 4.85 ± 0.04 Sesar et al. (2011) nMSTO 5–35 2.62 ± 0.04 0.70 ± 0.02 27.8 ± 0.8 3.8 ± 0.1 Deason et al. (2011) BHB, BS 10–45 2.3 ± 0.1 0.59 ± 0.03 27.1 ± 1 4.6 ± 0.15 Faccioli et al. (2014) RRL 9–49 2.8 ±…”
The influence of Sagittarius and the Large Magellanic Cloud on the stellar disc of the Milky Way Galaxy (2017, background): “More importantly, the Sgr dSph makes up the majority of the stellar halo within ∼40 kpc (Bell et al. 2008; Deason et al. 2011).”
ON THE SHOULDERS OF GIANTS: PROPERTIES OF THE STELLAR HALO AND THE MILKY WAY MASS DISTRIBUTION (2014, methodology): “Our estimates for the break radius is slightly smaller than∼ 27 kpc as claimed in Deason et al. (2011) or∼ 25 kpc as found in Watkins et al. (2009).”
SAGITTARIUS II, DRACO II AND LAEVENS 3: THREE NEW MILKY WAY SATELLITES DISCOVERED IN THE PAN-STARRS 1 3π SURVEY (2015, background): “Equation 7 in (Deason et al. 2011) describes the relation between the absolute magnitude of these HB stars and their SDSS g − r colors.”
Evidence from the H3 Survey That the Stellar Halo Is Entirely Comprised of Substructure (2020, background): “Another common choice is to rely on rare, standardizable candles like RR Lyrae and blue horizontal branch stars (BHBs) that are inherently metal poor and more abundant in older populations (e.g., Deason et al. 2011; Kafle et al. 2012; Janesh et al. 2016; Cohen et al. 2017; Iorio & Belokurov 2019).”
The hidden giant: discovery of an enormous Galactic dwarf satellite in Gaia DR2 (2018, background): “The red line indicates the BHB ridge-line from Deason et al. (2011) at the distance modulus of 20.6.”
Cosmological simulations of the formation of the stellar haloes around disc galaxies (2011, background): “…1985; Preston, Shectman Beers 1991; Wetterer & McGraw 1996; Ivezić et al. 2000; Morrison et al. 2000; Yanny et al. 2000; Chiba & Beers 2000; Chen et al. 2001; Siegel et al. 2002; Vivas & Zinn 2006; Bell et al. 2008; Juŕıc et al. 2008; Smith et al. 2009; Sesar et al. 2011; Deason et al. 2011b).”
The Milky Way's rotation curve out to 100 kpc and its constraint on the Galactic mass distribution (2016, background): “…can be easily estimated from the line-of-sight velocity dispersionσlos (Battaglia et al. 2005; Dehnen et al. 2006), while their number density is found to follow a double power law with a break radiusrb around 20 kpc (Bell et al. 2008; Watkins et al. 2009; Deason et al. 2011; Sesar et al. 2011).”
Co-formation of the disc and the stellar halo (2018, background): “At this characteristic radius (see e.g. Deason et al. 2011; Sesar et al. 2011), the properties of the stellar halo appear to change dramatically thus leading Deason et al. (2013a) to argue that this transition scale may correspond to the last apo-centre of the halo’s progenitor before disruption.”
THE LARGE-SCALE STRUCTURE OF THE HALO OF THE ANDROMEDA GALAXY. I. GLOBAL STELLAR DENSITY, MORPHOLOGY AND METALLICITY PROPERTIES (2013, background): “Note however, that recent analyses of distant blue horizontalbranch (BHB) stars (Xue et al. 2011; Deason et al. 2011), which represent very old stellar populations, and also of main sequence turn-off stars (Helmi et al. 2011), suggest that the incidence of substructure may be slightly lower than…”
Stellar Streams Discovered in the Dark Energy Survey (2018, background): “…of the Milky Way stellar halo, both through improved sensitivity to diffuse components (e.g., Carollo et al. 2007, 2010; de Jong et al. 2010; Deason et al. 2011; An et al. 2013; Kafle et al. 2013; Hattori et al. 2013; An et al. 2015; Das & Binney 2016) and by vastly increasing the number of…”
Precession of the Sagittarius stream (2013, methodology): “The behaviour of the centroid of the distribution of the Galactic globular cluster BHBs in the plane of absolute magnitude andg − r colour can be described accurately with a 4th degree polynomial, asproposed by Deason et al. (2011).”
Data Release 1 of the Dark Energy Spectroscopic Instrument (2025, unknown): “…they are intrinsically bright, so they can be observed to large distances, and there exists a simple polynomial relationship between their color and absolute magnitude ( A. J. Deason et al. 2011; V. Belokurov & S. E. Koposov 2016 ) , meaning that their distances can be computed with high precision.”
The Sausage Globular Clusters (2018, background): “For example, the radial density profile of the stellar halo shows a dramatic break at around 30 kpc in tracers such as RR Lyrae and blue horizontal branch stars (e.g., Watkins et al. 2009; Deason et al. 2011).”