A Search for Ionized Gas in the Draco and Ursa Minor Dwarf Spheroidal Galaxies

Gallagher, J.; Madsen, G. J.; Reynolds, R. J.; Grebel, Eva K.; Smecker-Hane, T.

doi:10.1086/373951

Cited by 47 publications

(44 citation statements)

References 46 publications

(55 reference statements)

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“…We assume that, in each dSph galaxy, the neutral gas follows a homogeneous, spherical distribution within a radius r d = 0.5 kpc. This value is of the same order as the estimated tidal radii of some of these systems (Irwin & Hatzidimitriou 1995;Gallagher et al 2003). The constant C in Eq.…”

Section: The Spectro-photometric Codesupporting

confidence: 63%

The evolution of the photometric properties of Local Group dwarf spheroidal galaxies

Calura¹,

Lanfranchi

Matteuccí

2008

A&A

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Aims. We investigate the present-day photometric properties of the dwarf spheroidal galaxies in the Local Group. From the analysis of their integrated colours, we consider a possible link between dwarf spheroidals and giant ellipticals. From the analysis of the M V vs. (B− V) plot, we search for a possible evolutionary link between dwarf spheroidal galaxies (dSphs) and dwarf irregular galaxies (dIrrs). Methods. By means of chemical evolution models combined with a spectro-photometric model, we study the evolution of six Local Group dwarf spheroidal galaxies (Carina, Draco, Sagittarius, Sculptor, Sextans and Ursa Minor). The chemical evolution models, which adopt up-to-date nucleosynthesis from low and intermediate mass stars as well as nucleosynthesis and energetic feedback from supernovae type Ia and II, reproduce several observational constraints of these galaxies, such as abundance ratios versus metallicity and the metallicity distributions. The proposed scenario for the evolution of these galaxies is characterised by low star formation rates and high galactic wind efficiencies. Results. Such a scenario allows us to predict integrated colours and magnitudes which agree with observations. Our results strongly suggest that the first few Gyrs of evolution, when the star formation is most active, are crucial to define the luminosities, colours, and other photometric properties as observed today. After the star formation epoch, the galactic wind sweeps away a large fraction of the gas of each galaxy, which then evolves passively. Our results indicate that it is likely that at a certain stage of their evolution, dSphs and dIrrs presented similar photometric properties. However, after that phase, they evolved along different paths, leading them to their disparate present-day properties.

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Section: The Spectro-photometric Codesupporting

confidence: 63%

The evolution of the photometric properties of Local Group dwarf spheroidal galaxies

Calura¹,

Lanfranchi

Matteuccí

2008

A&A

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“…Past experience with this technique has shown that the degree to which the atmospheric emission in the off spectrum represents the emission in the on spectrum is usually the dominant source of uncertainty in the resulting Galactic spectrum (e.g., Madsen et al 2001;Gallagher et al 2003). The large number of short exposure time observations employed in this study, combined with the alternating on/off observing technique, yielded a very good subtraction of the atmospheric lines.…”

Section: Removal Of Atmospheric Emission Linesmentioning

confidence: 84%

A Multiwavelength Optical Emission Line Survey of Warm Ionized Gas in the Galaxy

Madsen

Reynolds²,

Haffner³

2006

ApJ

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167

270

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We report on observations of several optical emission lines toward a variety of newly revealed faint, large-scale H -emitting regions in the Galaxy. The lines include [, and He i k5876 obtained with the Wisconsin H Mapper (WHAM ) toward sight lines that probe superbubbles, high-latitude filamentary features, and the more diffuse warm ionized medium ( WIM). Our observations include maps covering thousands of square degrees toward the well-known Orion-Eridanus bubble, a recently discovered 60; 20 bipolar superbubble centered in Perseus, plus several classical H ii regions surrounding OB stars and hot evolved stellar cores. We use the emission-line data to explore the temperature and ionization conditions within the emitting gas and their variations between the different emission regions. We find that in the diffuse WIM and in the faint high-latitude filamentary structures the line ratios of [ N ii]/H and [S ii]/H are generally high, while [O iii]/ H and He i/H are generally low compared to the bright classical H ii regions. This suggests that the gas producing this faint widespread emission is warmer, in a lower ionization state, and ionized by a softer spectrum than gas in classical H ii regions surrounding O stars, the presumed ionization source for the WIM. In addition, we find differences in physical conditions between the large bubble structures and the more diffuse WIM, suggesting that the ionization of superbubble walls by radiation from interior O associations does not account entirely for the range of conditions found within the WIM, particularly the highest values of [ N ii]/H and [S ii]/ H .

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“…Dwarf spheroidal galaxies are exceptionally good objects for further study (Boyarsky et al 2006;Riemer-Sorensen & Hansen 2009;Malyshev et al 2014): they have very high mass-to-light ratios (e.g. Wolf et al 2010), they represent a different mass regime to clusters and L * galaxies, and also contain very little if any interstellar gas (see Gallagher et al 2003, and references therein). They therefore offer a set of circumstances in which the ratio of the predicted DM emission to the astrophysical background is very high.…”

Section: Dwarf Spheroidal Galaxiesmentioning

confidence: 99%

“…One particularly promising class of candidates is that of the Milky Way's dwarf spheroidal satellites (Boyarsky et al 2006). These galaxies have very high mass-to-light ratios (Walker et al 2009Wolf et al 2010), and very low gas fractions (Gallagher et al 2003, and references therein). Their X-ray emitting gas fractions will be lower still due to their small gas fractions.…”

mentioning

confidence: 99%

Decaying dark matter: the case for a deep X-ray observation of Draco

Lovell

Bertone

Boyarsky³

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Recent studies of M31, the Galactic centre, and galaxy clusters have made tentative detections of an X-ray line at ∼ 3.5 keV that could be produced by decaying dark matter. We use high resolution simulations of the Aquarius project to predict the likely amplitude of the X-ray decay flux observed in the GC relative to that observed in M31, and also of the GC relative to other parts of the Milky Way halo and to dwarf spheroidal galaxies. We show that the reported detections from M31 and the GC are compatible with each other, and with upper limits arising from high galactic latitude observations, and imply a decay time τ ∼ 10 28 seconds. We argue that this interpretation can be tested with deep observations of dwarf spheroidal galaxies: in 95 per cent of our mock observations, a 1.3 Msec pointed observation of Draco with XMM-Newton will enable us to discover or rule out at the 3σ level an X-ray feature from dark matter decay at 3.5 keV, for decay times τ < 0.8 × 10 28 sec.

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A Search for Ionized Gas in the Draco and Ursa Minor Dwarf Spheroidal Galaxies

Cited by 47 publications

References 46 publications

The evolution of the photometric properties of Local Group dwarf spheroidal galaxies

The evolution of the photometric properties of Local Group dwarf spheroidal galaxies

A Multiwavelength Optical Emission Line Survey of Warm Ionized Gas in the Galaxy

Decaying dark matter: the case for a deep X-ray observation of Draco

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