3D outer bulge structure from near infrared star counts

Picaud, S.; Robin, A. C.

doi:10.1051/0004-6361:20041218

Cited by 66 publications

(96 citation statements)

References 55 publications

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“…The disk component can be reliably modeled as a Freeman stellar exponential thin disk of length scale (Picaud & Robin 2004;Robin et al 2008;Reylé 2009) R D = (2.5 ± 0.2) kpc. The stellar surface density is then: Σ(r) = (M D /2πR 2 D ) e −r/R D .…”

Section: A Model-independent Methodsmentioning

confidence: 99%

The dark matter density at the Sun’s location

Salucci

Nesti

Gentile

et al. 2010

A&A

363

300

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Aims. We derive the value of the dark matter density at the Sun's location (ρ ) without fully modeling the mass distribution in the Galaxy. Methods. The proposed method relies on the local equation of centrifugal equilibrium and is independent of i) the shape of the dark matter density profile, ii) knowledge of the rotation curve from the galaxy center out to the virial radius, and iii) the uncertainties and the non-uniqueness of the bulge/disk/dark halo mass decomposition. Results. The result can be obtained in analytic form, and it explicitly includes the dependence on the relevant observational quantities and takes their uncertainties into account. By adopting the reference, state-of-the-art values for these, we find ρ = 0.43(11)(10) GeV/cm 3 , where the quoted uncertainties are respectively due to the uncertainty in the slope of the circular-velocity at the Sun location and the ratio between this radius and the length scale of the stellar exponential thin disk. Conclusions. We obtained a reliable estimate of ρ , that, in addition has the merit of being ready to take any future change/improvement into account in the measures of the observational quantities it depends on.

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Section: A Model-independent Methodsmentioning

confidence: 99%

The dark matter density at the Sun’s location

Salucci

Nesti

Gentile

et al. 2010

A&A

363

300

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“…4.1.4), shows no significant difference between the two samples on the metal-poor side (that however only reaches [Fe/H] ∼ −1.2 to −1.5 dex). We estimated the expected contamination of our bulge red clump sample by foreground (and background) Galactic disc(s) stars and halo stars, using the latest population-synthesis Besançon model (Robin et al 2003;Picaud & Robin 2004). A 25 × 25 field, centred on Baade's window, was simulated without including the reddening.…”

Section: Line Of Sight Sample Contaminationmentioning

confidence: 99%

The metallicity distribution of bulge clump giants in Baade’s window

Hill

Lecureur

Gómez

et al. 2011

A&A

229

431

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Aims. We seek to constrain the formation of the Galactic bulge by analysing the detailed chemical composition of a large sample of red clump stars in Baade's window. These stars were selected to minimise the contamination by other Galactic components, so they are good tracers of the bulge metallicity distribution in Baade's window, at least for stars more metal-rich than ∼−1.5. Methods. We used an automatic procedure to measure [Fe/H] differentially with respect to the metal-rich star μLeo in a sample of 219 bulge red clump stars from R = 20 000 resolution spectra obtained with FLAMES/GIRAFFE at the VLT. 3), while stars in the metal-rich component are found to have nearly solar ratios. Kinematical differences between the two components have also been found: the metal-poor component shows kinematics compatible with an old spheroid, while the metal-rich component is consistent with a population supporting a bar. In view of their chemical and kinematical properties, we suggest different formation scenarii for the two populations: a rapid formation time scale as an old spheroid for the metal-poor component (old bulge) and for the metal-rich component, a formation on a longer time scale driven by the evolution of the bar (pseudo-bulge). The observations are described well by a simple model consisting of two components: a simple closed box model to predict the metal-poor population contribution and a local thin disc metallicity distribution, shifted in metallicity, to represent the metal-rich population. The pseudo-bulge is compatible with its being formed from the inner thin disc, assuming high (but plausible) values of the gradients in the early Galactic disc.

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“…Contopoulos et al 1989). For the scale-length of the hole of both the thin and thick disks we assume L h ∼ 1.3 kpc (Picaud & Robin 2004). The motion of bulge and disk stars has both bulk and random components.…”

Section: Distribution Of the Bulge And The Disk Starsmentioning

confidence: 99%

Probing isolated compact remnants with microlensing

Sartore

Treves

2010

A&A

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Aims. We consider isolated compact remnants (ICoRs), i.e. neutrons stars and black holes that do not reside in binary systems and therefore cannot be detected as X-ray binaries. ICoRs may represent ∼5 percent of the stellar mass budget of the Galaxy, but they are very hard to detect. Here we explore the possibility of using microlensing to identify ICoRs. Methods. In a previous paper we described a simulation of neutron star evolution in phase space in the Galaxy, taking into account the distribution of the progenitors and the kick at formation. Here we first reconsider the evolution and distribution of neutron stars and black holes with an added a bulge component. From the new distributions we calculate the microlensing optical depth, event rate and distribution of event time scales, comparing and contrasting the case of ICoRs and "normal stars". Results. We find that the contribution of remnants to optical depth is slightly lower than without kinematics, owing to the evaporation from the Galaxy. On the other hand, the relative contribution to the rate of events is a factor ∼5 higher. In all, ∼6−7 percent of the events are likely related to ICoRs. In particular, ∼30−40 percent of the events with duration >100 days are possibly related to black holes. Conclusions. It seems therefore that microlensing observations are a suitable tool to probe the population of Galactic ICoRs.

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3D outer bulge structure from near infrared star counts

Cited by 66 publications

References 55 publications

The dark matter density at the Sun’s location

The dark matter density at the Sun’s location

The metallicity distribution of bulge clump giants in Baade’s window

Probing isolated compact remnants with microlensing

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