Stellar Substructures Around the Hercules Dwarf Spheroidal Galaxy

Roderick, T. A.; Jerjen, Helmut; Mackey, A. D.; Costa, G. S. Da

doi:10.1088/0004-637x/804/2/134

Cited by 55 publications

(103 citation statements)

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“…Deason et al (2012) found likely blue horizontal branch members up to 500 pc from the center of Hercules and further evidence for a velocity gradient consistent with Adén et al (2009a). Several photometric studies (e.g., Coleman et al 2007;Sand et al 2009;Roderick et al 2015) have found Hercules to have an extended morphology, with features up to 2 kpc from the dwarf's center. These are all excellent hints that Hercules could be in the throes of tidal disruption.…”

Section: Introductionmentioning

confidence: 66%

“…Our DECam data included newly acquired observations, as well as archival data from Roderick et al (2015).…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…Few wide-field imaging searches sufficiently deep to detect the low surface-brightness extensions typical of tidal stripping have been performed on post-SDSS UFDs. However, most of the photometric UFD tidal debris searches (e.g., Coleman et al 2007;Sand et al 2009Sand et al , 2012Roderick et al 2015Roderick et al , 2016 have found some degree of extended structure, hinting that tidal disruption may be quite common for UFDs.…”

Section: Introductionmentioning

confidence: 99%

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Mapping the Tidal Destruction of the Hercules Dwarf: A Wide-field DECam Imaging Search for RR Lyrae Stars

Garling

Willman

Sand

et al. 2018

ApJ

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We investigate the hypothesized tidal disruption of the Hercules ultra-faint dwarf galaxy (UFD). Previous tidal disruption studies of the Hercules UFD have been hindered by the high degree of foreground contamination in the direction of the dwarf. We bypass this issue by using RR Lyrae stars, which are standard candles with a very low field-volume density at the distance of Hercules. We use wide-field imaging from the Dark Energy Camera on CTIO to identify candidate RR Lyrae stars, supplemented with observations taken in coordination with the Beijing-Arizona Sky Survey on the Bok Telescope. Combining color, magnitude, and light-curve information, we identify three new RR Lyrae stars associated with Hercules. All three of these new RR Lyrae stars lie outside its published tidal radius. When considered with the nine RR Lyrae stars already known within the tidal radius, these results suggest that a substantial fraction of Hercules' stellar content has been stripped. With this degree of tidal disruption, Hercules is an interesting case between a visibly disrupted dwarf (such as the Sagittarius dwarf spheroidal galaxy) and one in dynamic equilibrium. The degree of disruption also shows that we must be more careful with the ways we determine object membership when estimating dwarf masses in the future. One of the three discovered RR Lyrae stars sits along the minor axis of Hercules, but over two tidal radii away. This type of debris is consistent with recent models that suggest Hercules' orbit is aligned with its minor axis.

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Section: Introductionmentioning

confidence: 66%

“…Our DECam data included newly acquired observations, as well as archival data from Roderick et al (2015).…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mapping the Tidal Destruction of the Hercules Dwarf: A Wide-field DECam Imaging Search for RR Lyrae Stars

Garling

Willman

Sand

et al. 2018

ApJ

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“…Nevertheless, these two objects are not strong outliers from the relation. Conversely, the ellipticy criterion correctly excludes some dSphs that show signs of disruption like Ursa Minor (Palma et al 2003), Hercules (Roderick et al 2015), and Leo V (Collins et al 2016). …”

Section: Ultrafaint Dsphs: a Low-acceleration Flattening?mentioning

confidence: 99%

One Law to Rule Them All: The Radial Acceleration Relation of Galaxies

Lelli

McGaugh

Schombert

et al. 2017

ApJ

410

604

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We study the link between baryons and dark matter in 240 galaxies with spatially resolved kinematic data. Our sample spans 9 dex in stellar mass and includes all morphological types. We consider (i) 153 late-type galaxies (LTGs; spirals and irregulars) with gas rotation curves from the SPARC database; (ii) 25 early-type galaxies (ETGs; ellipticals and lenticulars) with stellar and H I data from ATLAS 3D or X−ray data from Chandra; and (iii) 62 dwarf spheroidals (dSphs) with individual-star spectroscopy. We find that LTGs, ETGs, and "classical" dSphs follow the same radial acceleration relation: the observed acceleration (g obs ) correlates with that expected from the distribution of baryons (g bar ) over 4 dex. The relation coincides with the 1:1 line (no dark matter) at high accelerations but systematically deviates from unity below a critical scale of ∼10 −10 m s −2 . The observed scatter is remarkably small ( 0.13 dex) and largely driven by observational uncertainties. The residuals do not correlate with any global or local galaxy property (baryonic mass, gas fraction, radius, etc.). The radial acceleration relation is tantamount to a Natural Law: when the baryonic contribution is measured, the rotation curve follows, and vice versa. Including ultrafaint dSphs, the relation may extend by another 2 dex and possibly flatten at g bar 10 −12 m s −2 , but these data are significantly more uncertain. The radial acceleration relation subsumes and generalizes several well-known dynamical properties of galaxies, like the Tully-Fisher and Faber-Jackson relations, the "baryon-halo" conspiracies, and Renzo's rule.

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“…the Hercules dSph; Roderick et al 2015) show signs of having been affected by tides. Around M31 there is evidence of ongoing tidal disturbance in sev-⋆ Email:meiyu@physics.tamu.edu eral satellite galaxies (Choi et al 2002;Crnojević et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Tidal features of classical Milky Way satellites in a Λ cold dark matter universe

Wang

Fattahi

Cooper

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We use the APOSTLE cosmological hydrodynamic simulations to examine the effects of tidal stripping on cold dark matter (CDM) subhaloes that host three of the most luminous Milky Way (MW) dwarf satellite galaxies: Fornax, Sculptor, and Leo I. We identify simulated satellites that match the observed spatial and kinematic distributions of stars in these galaxies, and track their evolution after infall. We find ∼ 30% of subhaloes hosting satellites with present-day stellar mass 10 6 -10 8 M ⊙ experience > 20% stellar mass loss after infall. Fornax analogues have earlier infall times compared to Sculptor and Leo I analogues. Star formation in Fornax analogues continues for ∼ 3-6 Gyr after infall, whereas Sculptor and Leo I analogues stop forming stars < 2-3 Gyr after infall. Fornax analogues typically show more significant stellar mass loss and exhibit stellar tidal tails, whereas Sculptor and Leo I analogues, which are more deeply embedded in their host DM haloes at infall, do not show substantial mass loss due to tides. When additionally comparing the orbital motion of the host subaloes to the measured proper motion of Fornax we find the matching more difficult; host subhaloes tend to have pericentres smaller than that measured ones for Fornax itself. From the kinematic and orbital data, we estimate that Fornax has lost 10 − 20% of its infall stellar mass. Our best estimate for the surface brightness of a stellar tidal stream associated with Fornax is Σ ∼ 32.6 mag arcsec −2 , which may be detectable with deep imaging surveys such as DES and LSST.

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Stellar Substructures Around the Hercules Dwarf Spheroidal Galaxy

Cited by 55 publications

References 64 publications

Mapping the Tidal Destruction of the Hercules Dwarf: A Wide-field DECam Imaging Search for RR Lyrae Stars

Mapping the Tidal Destruction of the Hercules Dwarf: A Wide-field DECam Imaging Search for RR Lyrae Stars

One Law to Rule Them All: The Radial Acceleration Relation of Galaxies

Tidal features of classical Milky Way satellites in a Λ cold dark matter universe

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