scholarly journals On the Recovery of Galaxy Properties from Spectral Fits

2012 ◽  
Vol 8 (S295) ◽  
pp. 317-317
Author(s):  
G. Magris ◽  
C. Mateu ◽  
G. Bruzual A. ◽  
I. Cabrera
Keyword(s):  
Statistical Treatment ◽  
Physical Parameters ◽  
Assembly Process ◽  
Spectral Fitting ◽  
Fitting Algorithm ◽  
The Galaxy ◽  
Bayesian Implementation ◽  
Galaxy Assembly ◽  
Fully Bayesian ◽  
Non Parametric

AbstractWe show the results of a non-parametric, fully bayesian implementation of a spectral fitting algorithm, designed to calculate the main physical parameters that govern the galaxy assembly process. In this work, we present results from a statistical treatment of SED fitting that allows for easy recovery and visualization of the galaxy physical parameters.

What do RR Lyrae tell us about the formation of the Milky Way and M31 haloes?

2017 ◽  
Vol 13 (S334) ◽  
pp. 290-291
Author(s):  
C. Gallart ◽  
G. Fiorentino ◽  
M. Monelli ◽  
C. Martínez-Vázquez ◽  
E. J. Bernard ◽  
...  
Keyword(s):  
Star Formation ◽  
Structure Formation ◽  
Milky Way ◽  
Building Blocks ◽  
Assembly Process ◽  
Stellar Content ◽  
Rr Lyrae ◽  
The Galaxy ◽  
Star Formation In Galaxies ◽  
Galaxy Assembly

RR Lyrae variables are old (>10 Gyr) stars and, as such, they are useful probes of the earliest events of star formation in galaxies (Bernard et al. 2008, Martínez-Vázquez et al. 2016) as well as of the galaxy assembly process predicted by ΛCDM simulations of structure formation. In fact, the nature of the building-blocks of galaxies such as the Milky Way, and in particular, those of their stellar haloes, has been a matter of a substantial debate (Venn et al. 2004). Unlike other stellar tracers, RR Lyrae offer a snapshot of the stellar content present at the epoch when most of the merging action is predicted to have taken place, and thus they are ideal witnesses of this process.

scholarly journals The Structure of Galaxies at Faint Light Levels: Probing Galaxy Assembly

2006 ◽  
Vol 2 (S235) ◽  
pp. 175-179
Author(s):  
Annette M. N. Ferguson
Keyword(s):  
Quantitative Study ◽  
Fossil Record ◽  
Recent Progress ◽  
Wide Area ◽  
Assembly Process ◽  
The Past ◽  
Light Levels ◽  
The Galaxy ◽  
Galaxy Assembly

AbstractMany clues about the galaxy assembly process lurk in the faint outer regions of galaxies. Although quantitative study of these parts has been severely limited in the past, breakthroughs are now being made thanks to the combination of wide-area star counts, deep HST imagery and 8-m class spectroscopy. I highlight here some recent progress made on deciphering the fossil record encoded in the outskirts of our nearest large neighbours, M31 and M33.

scholarly journals On particle acceleration and transport in plasmas in the Galaxy: theory and observations

2021 ◽  
Vol 87 (1) ◽  
Author(s):  
Elena Amato ◽  
Sabrina Casanova
Keyword(s):  
Particle Acceleration ◽  
Cosmic Rays ◽  
Galactic Cosmic Rays ◽  
Energetic Particles ◽  
Quality Data ◽  
Current Status ◽  
The Earth ◽  
The Galaxy ◽  
Formation And Evolution ◽  
Galaxy Assembly

Accelerated particles are ubiquitous in the Cosmos and play a fundamental role in many processes governing the evolution of the Universe at all scales, from the sub-AU scale relevant for the formation and evolution of stars and planets to the Mpc scale involved in Galaxy assembly. We reveal the presence of energetic particles in many classes of astrophysical sources thanks to their production of non-thermal radiation, and we detect them directly at the Earth as cosmic rays. In the last two decades both direct and indirect observations have provided us a wealth of new, high-quality data about cosmic rays and their interactions both in sources and during propagation, in the Galaxy and in the Solar System. Some of the new data have confirmed existing theories about particle acceleration and propagation and their interplay with the environment in which they occur. Some others have brought about interesting surprises, whose interpretation is not straightforward within the standard framework and may require a change of paradigm in terms of our ideas about the origin of cosmic rays of different species or in different energy ranges. In this article, we focus on cosmic rays of galactic origin, namely with energies below a few petaelectronvolts, where a steepening is observed in the spectrum of energetic particles detected at the Earth. We review the recent observational findings and the current status of the theory about the origin and propagation of galactic cosmic rays.

Physical parameters of reflection nebulae in the galaxy

1989 ◽  
Vol 156 (1-2) ◽  
pp. 51-56
Author(s):  
M. Centuri�n ◽  
G. Vladilo
Keyword(s):  
Physical Parameters ◽  
The Galaxy ◽  
Reflection Nebulae

scholarly journals Inferring the three-dimensional distribution of dust in the Galaxy with a non-parametric method

2017 ◽  
Vol 598 ◽  
pp. A125 ◽  
Author(s):  
S. Rezaei Kh. ◽  
C. A. L. Bailer-Jones ◽  
R. J. Hanson ◽  
M. Fouesneau
Keyword(s):  
Parametric Method ◽  
Three Dimensional ◽  
The Galaxy ◽  
Dimensional Distribution ◽  
Non Parametric

scholarly journals Hidden infrared star clusters in our Galaxy: follow-up observations

2009 ◽  
Vol 5 (S266) ◽  
pp. 366-366
Author(s):  
Jura Borissova ◽  
Radostin Kurtev ◽  
Margaret M. Hanson ◽  
Leonid Georgiev ◽  
Valentin Ivanov ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Star Cluster ◽  
Open Clusters ◽  
Star Formation History ◽  
Stellar Disk ◽  
Physical Parameters ◽  
Formation History ◽  
The Galaxy ◽  
History Of ◽  
Infrared Star

AbstractWe are reporting some recent results from our long-term program aimed at characterizing the obscured present-day star cluster population in the Galaxy. Our goal is to expand the current census of the Milky Way's inner stellar disk to guide models seeking to understand the structure and recent star-formation history of our Galaxy. The immediate goal is to derive accurate cluster physical parameters using precise infrared photometry and spectroscopy. So far, we observed approximately 60 star cluster candidates selected from different infrared catalogs. Their nature, reddening, distance, age and mass are analyzed. Two of them, Mercer 3 and Mercer 5, are new obscured Milky Way globular clusters. Among the newly identified open clusters, the objects [DBS2003] 179, Mercer 23, Mercer 30, Mercer 70, and [DBS2003] 106 are particularly interesting because they contain massive young OB and Wolf–Rayet stars with strong emission lines.

scholarly journals Pulsations of Ob-Stars: New Observations

1998 ◽  
Vol 185 ◽  
pp. 347-354 ◽  
Author(s):  
Dietrich Baade
Keyword(s):  
Main Sequence ◽  
Physical Parameters ◽  
Be Stars ◽  
Instability Strip ◽  
Ob Stars ◽  
Analysis Strategies ◽  
The Galaxy ◽  
Order Line ◽  
Nonradial Pulsation ◽  
Radial Pulsations

Improved observing and data analysis strategies have initiated a considerable expansion of the empirical knowledge about the pulsations of OB stars. Possible correlations between physical parameters and associated pulsation characteristics are becoming more clearly perceivable. This starts to include the asteroseismologically fundamental areas of g-modes and rapid rotation. The β Cephei instability strip continues to be the only locus where radial pulsations occur (but apparently not in all stars located in that strip). Except for spectral types B8/B9 near the main sequence, where pulsations are hardly detected even at low amplitudes, any major group of stars in the Galaxy that are obviously not candidate pulsators still remains to be identified. However, the incidence and amplitudes of OB star pulsations decrease steeply with metallicity. The behaviour of high-luminosity stars is less often dominated by very few modes. In broad-lined stars the moving-bump phenomenon is more common than low-order line-profile variability. But its relation to nonradial pulsation is not clear. The beating of low-ℓ nonradial pulsation modes that have identical angular mode indices may be the clockwork of the outbursts of at least some Be stars. The physics of this episodic mass loss process remains to be identified.

scholarly journals Can assembly bias explain the lensing amplitude of the BOSS CMASS sample in a Planck cosmology?

2020 ◽  
Vol 493 (4) ◽  
pp. 5551-5564
Author(s):  
Sihan Yuan ◽  
Daniel J Eisenstein ◽  
Alexie Leauthaud
Keyword(s):  
Cold Dark Matter ◽  
Cosmological Parameters ◽  
Bias Parameter ◽  
Projected Clustering ◽  
The Galaxy ◽  
Satellite Velocity ◽  
Galaxy Sample ◽  
Best Fitting ◽  
Galaxy Assembly ◽  
Halo Occupation Distribution

ABSTRACT In this paper, we investigate whether galaxy assembly bias can reconcile the 20–40 ${{\ \rm per\ cent}}$ disagreement between the observed galaxy projected clustering signal and the galaxy–galaxy lensing signal in the Baryon Oscillation Spectroscopic Survey CMASS galaxy sample. We use the suite of abacuscosmos lambda cold dark matter simulations at Planck best-fitting cosmology and two flexible implementations of extended halo occupation distribution (HOD) models that incorporate galaxy assembly bias to build forward models and produce joint fits of the observed galaxy clustering signal and the galaxy–galaxy lensing signal. We find that our models using the standard HODs without any assembly bias generalizations continue to show a 20–40 ${{\ \rm per\ cent}}$ overprediction of the observed galaxy–galaxy lensing signal. We find that our implementations of galaxy assembly bias do not reconcile the two measurements at Planck best-fitting cosmology. In fact, despite incorporating galaxy assembly bias, the satellite distribution parameter, and the satellite velocity bias parameter into our extended HOD model, our fits still strongly suggest a $\sim \! 34{{\ \rm per\ cent}}$ discrepancy between the observed projected clustering and galaxy–galaxy lensing measurements. It remains to be seen whether a combination of other galaxy assembly bias models, alternative cosmological parameters, or baryonic effects can explain the amplitude difference between the two signals.

scholarly journals The Twin-Nucleus Merging Galaxy MKN 266

1989 ◽  
Vol 134 ◽  
pp. 452-453
Author(s):  
J.B. Hutchings ◽  
S.G. Neff ◽  
J.H. van Gorkom
Keyword(s):  
Optical Emission ◽  
Physical Parameters ◽  
List Type ◽  
Imaging Data ◽  
Ccd Imaging ◽  
Spatially Resolved ◽  
The Galaxy ◽  
Extended Complex ◽  
Double Nucleus ◽  
Narrow Bands

We present results of observations of the double-nucleus galaxy Markarian 266 (NGC 5256) from 3 principal sources. These are 1:CCD imaging with the Canada-France-Hawaii telescope in broad and narrow bands. These indicate that the galaxy has extended, complex, faint outer plumes which indicate that a recent merger has occurred. The narrow-band images reveal remarkable knotty structure of the [O III] emitting gas, extending over the whole central part of the galaxy. This is not seen in Hα (see figure 1).2:21cm imaging with the VLA, covering velocity space near that of the optical nuclei. The continuum image reveals resolved triple structure, with the two outer peaks coincident with the optical nuclei. The 21cm velocity profiles indicate the presence of considerable H I absorption near the optical emission line velocities.3:Spatially resolved optical spectroscopy with the DAO 1.8m telescope. These data reveal the details of the [O III] velocity field and some of the physical parameters of the gas. The complexity and extended nature of the gas explains some conflicting redshift measurements in the literature. Together with the imaging data, we derive estimates of nuclear reddening and luminosity.

scholarly journals Hunting for Dwarf Galaxies Hosting the Formation and Coalescence of Compact Binaries

Physics ◽  
2019 ◽  
Vol 1 (3) ◽  
pp. 412-429 ◽  
Author(s):  
Luca Graziani
Keyword(s):  
Binary Systems ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Large Population ◽  
Compact Binaries ◽  
Compact Binary ◽  
The Galaxy ◽  
Low Metallicity ◽  
Formation And Evolution ◽  
Galaxy Assembly

Here we introduce the latest version of the GAMESH model, capable to consistently account for the formation and evolution of compact binary systems along the cosmic assembly of a Milky Way (MW)-like galaxy, centered on a local group volume resolving a large population of dwarf satellites. After describing the galaxy assembly process and how the formation of binary systems is accounted for, we summarize some recent findings on the properties and evolution of low-metallicity dwarf galaxies hosting the birth/coalescence of stellar/compact binaries generating GW150914-like signals. Finally, we focus on the mass and orbital properties of the above compact binary candidates assessing their impact on the resulting coalescence times and on selecting suitable galaxy hosts.

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