First Results From the Dragonfly Telephoto Array: The Apparent Lack of a Stellar Halo in the Massive Spiral Galaxy M101

Dokkum, Pieter van; Abraham, Roberto; Merritt, Allison

doi:10.1088/2041-8205/782/2/l24

Cited by 134 publications

(153 citation statements)

References 46 publications

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“…Assuming that the NGC 5485 group has a luminosity function between those of the MW/M31 (McConnachie 2012) and that of the Virgo cluster (Ferrarese et al 2016), we would expect between ∼10 and ∼30 dwarf group members in the examined magnitude range, -13 M g -10. However concluding that all or most of our candidates are members of the background NGC 5485 group would imply that M101 (a MW analog in certain respects, but deficient in stellar halo; van Dokkum et al 2014) has a dwarf population sparser than those of the MW or M31. Recent work has suggested that the scatter in satellite numbers around MW-analogs is significant (Geha et al 2017), and M101 may be a sparse member of the distribution.…”

Section: Distribution Of New Dwarfs Around M101mentioning

confidence: 87%

Discovery of Diffuse Dwarf Galaxy Candidates around M101

Bennet

Sand

Crnojević

et al. 2017

ApJ

106

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We have conducted a search of a 9 deg 2 region of the CFHTLS around the Milky Way analog M101 (D∼7 Mpc), in order to look for previously unknown low surface brightness galaxies. This search has uncovered 38 new low surface brightness dwarf candidates, and confirmed 11 previously reported galaxies, all with central surface brightness µ(g,0)>23mag/arcsec 2 , potentially extending the satellite luminosity function for the M101 group by ∼1.2 magnitudes. The search was conducted using an algorithm that nearly automates the detection of diffuse dwarf galaxies. The candidates small size and low surface brightness means that the faintest of these objects would likely be missed by traditional visual or computer detection techniques. The dwarf galaxy candidates span a range of −7.1 ≥ M g ≥ −10.2 and half light radii of 118-540 pc at the distance of M101, and they are well fit by simple Sérsic surface brightness profiles. These properties are consistent with dwarfs in the Local Group, and to match the Local Group luminosity function ∼10-20 of these candidates should be satellites of M101. Association with a massive host is supported by the lack of detected star formation and the over density of candidates around M101 compared to the field. The spatial distribution of the dwarf candidates is highly asymmetric, and concentrated to the northeast of M101 and therefore distance measurements will be required to determine if these are genuine members of the M101 group.

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Section: Distribution Of New Dwarfs Around M101mentioning

confidence: 87%

Discovery of Diffuse Dwarf Galaxy Candidates around M101

Bennet

Sand

Crnojević

et al. 2017

ApJ

106

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“…In the recent years, a big effort has been made to develop deep photometric surveys aimed at studying galaxy structures up to the faintest levels of surface brightness, which reveal lowluminosity structures and trace the stellar halos at very large distances from the galaxy center (Mihos et al 2005;Janowiecki et al 2010;Martínez-Delgado et al 2010;Roediger et al 2011;Ferrarese et al 2012;van Dokkum et al 2014;Duc et al 2015;Muñoz et al 2015;Trujillo & Fliri 2015). Recently, deep images of the Virgo cluster have revealed several faint (μ V =26-29 mag arcsec −2 ) streams of ICL among the galaxy members and made it possible to map the stellar halos of the bright cluster galaxies (BCGs) at very large distances from the center (Janowiecki et al 2010).…”

Section: Introductionmentioning

confidence: 99%

THE FORNAX DEEP SURVEY WITH VST. I. THE EXTENDED AND DIFFUSE STELLAR HALO OF NGC 1399 OUT TO 192 kpc

Iodice

Capaccioli

Grado

et al. 2016

ApJ

165

342

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We have started a new, deep multi-imaging survey of the Fornax cluster, dubbed the Fornax Deep Survey (FDS), at the VLT Survey Telescope (VST). In this paper we present the deep photometry inside two square degrees around the bright galaxy NGC1399 in the core of the cluster. We found that the core of the Fornax cluster is characterized by a very extended and diffuse envelope surrounding the luminous galaxy NGC1399: we map the surface brightness out to 33 arcmin (∼192 kpc) from the galaxy center and down to μ g ∼31 mag arcsec −2 in the g band. The deep photometry allows us to detect a faint stellar bridge in the intracluster region on the west side of NGC1399 and toward NGC1387. By analyzing the integrated colors of this feature, we argue that it could be due to the ongoing interaction between the two galaxies, where the outer envelope of NGC1387 on its east side is stripped away. By fitting the light profile, we found that there exists a physical break radius in the total light distribution at R=10 arcmin (∼58 kpc) that sets the transition region between the bright central galaxy and the outer exponential halo, and that the stellar halo contributes 60% of the total light of the galaxy (Section 3.5). We discuss the main implications of this work on the build-up of the stellar halo at the center of the Fornax cluster. By comparing with the numerical simulations of the stellar halo formation for the most massive bright cluster galaxies (i.e., M M 13 log 14, we find that the observed stellar halo mass fraction is consistent with a halo formed through the multiple accretion of progenitors with stellar mass in the range 10 8 -10 11 M e . This might suggest that the halo of NGC1399 has also gone through a major merging event. The absence of a significant number of luminous stellar streams and tidal tails out to 192 kpc suggests that the epoch of this strong interaction goes back to an early formation epoch. Therefore, different from the Virgo cluster, the extended stellar halo around NGC1399 is characterized by a more diffuse and well-mixed component, including the intracluster light.

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“…Integrated light observations are subject to degeneracies between age, metallicity, and extinction as well as being limited in sensitivity due to the sky brightness, flat-field and scattered light corrections (de Jong 2008). Even using optics with very low scatter light (van Dokkum, Abraham & Merritt 2014), it is not possible to obtain detailed population age and metallicity information.…”

Section: Introductionmentioning

confidence: 99%

The GHOSTS survey – II. The diversity of halo colour and metallicity profiles of massive disc galaxies

Monachesi

Bell

Radburn-Smith

et al. 2016

Mon. Not. R. Astron. Soc.

100

164

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We study the stellar halo colour properties of six nearby massive highly inclined disk galaxies using HST ACS and WFC3 observations in both F 606W and F 814W filters from the GHOSTS survey. The observed fields probe the stellar outskirts out to projected distances of ∼ 50 -70 kpc from their galactic centre along the minor axis. The 50% completeness levels of the colour magnitude diagrams are typically at two mag below the tip of the red giant branch. We find that all galaxies have extended stellar haloes out to ∼ 50 kpc and two out to ∼ 70 kpc. We determined the halo colour distribution and colour profile for each galaxy using the median colours of stars in the RGB. Within each galaxy we find variations in the median colours as a function of radius which likely indicates population variations, reflecting that their outskirts were built from several small accreted objects. We find that half of the galaxies (NGC 0891, NGC 4565, and NGC 7814) present a clear negative colour gradient in their haloes, reflecting a declining metallicity; the other have no significant colour or population gradient. In addition, notwithstanding the modest sample size of galaxies, there is no strong correlation between their halo colour/metallicity or gradient with galaxy's properties such as rotational velocity or stellar mass. The diversity in halo colour profiles observed in the GHOSTS galaxies qualitatively supports the predicted galaxy-to-galaxy scatter in halo stellar properties; a consequence of the stochasticity inherent in the assembling history of galaxies.

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First Results From the Dragonfly Telephoto Array: The Apparent Lack of a Stellar Halo in the Massive Spiral Galaxy M101

Cited by 134 publications

References 46 publications

Discovery of Diffuse Dwarf Galaxy Candidates around M101

Discovery of Diffuse Dwarf Galaxy Candidates around M101

THE FORNAX DEEP SURVEY WITH VST. I. THE EXTENDED AND DIFFUSE STELLAR HALO OF NGC 1399 OUT TO 192 kpc

The GHOSTS survey – II. The diversity of halo colour and metallicity profiles of massive disc galaxies

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