scholarly journals Small-scale Intensity Mapping: Extended Halos as a Probe of the Ionizing Escape Fraction and Faint Galaxy Populations during Reionization

2017 ◽  
Vol 846 (1) ◽  
pp. 11 ◽  
Author(s):  
Lluís Mas-Ribas ◽  
Joseph F. Hennawi ◽  
Mark Dijkstra ◽  
Frederick B. Davies ◽  
Jonathan Stern ◽  
...  
Keyword(s):  
Small Scale ◽  
Intensity Mapping ◽  
Faint Galaxy ◽  
Galaxy Populations

scholarly journals Isophotal Effects in Faint Galaxy Samples

1996 ◽  
Vol 171 ◽  
pp. 347-347
Author(s):  
P. Bristow ◽  
S. Philllipps
Keyword(s):  
Monte Carlo ◽  
Number Magnitude ◽  
Faint Galaxy ◽  
Total Luminosity ◽  
Galaxy Populations ◽  
Galaxy Population ◽  
Observational Techniques

Using Monte Carlo style simulations of galaxy populations we create artificial faint galaxy samples which mimic those obtained by actual observational techniques. By comparison of samples selected according to total luminosity or luminosity within an isophote we are able to estimate the extent to which isophotal effects could cause number magnitude counts of faint galaxies to appear artificially steep (cf. McGaugh 1994, Phillipps 1993). We find that, if we assume a ‘standard’ non-evolving galaxy population (essentially that used by Broadhurst, Ellis & Shanks 1988 amongst others) then isophotal effects alone cannot account for the discrepancy between the observed steepness and no-evolution models, though they could significantly reduce the amount of evolution required and alter the median redshifts. Modifying the underlying galaxy population by the addition of a bivariate brightness dwarf component as observed in clusters (e.g. Irwin et al 1990) increases the significance of the isophotal effects, though only fractionally, despite the fact that such effects would be highly important for such a population considered on its own.

scholarly journals Small-scale Intensity Mapping: Extended Lyα, Hα, and Continuum Emission as a Probe of Halo Star Formation in High-redshift Galaxies

2017 ◽  
Vol 841 (1) ◽  
pp. 19 ◽  
Author(s):  
Lluís Mas-Ribas ◽  
Mark Dijkstra ◽  
Joseph F. Hennawi ◽  
Michele Trenti ◽  
Rieko Momose ◽  
...  
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Continuum Emission ◽  
Small Scale ◽  
Halo Star ◽  
High Redshift Galaxies ◽  
Intensity Mapping ◽  
Redshift Galaxies

scholarly journals Galaxy formation hydrodynamics: From cosmic flows to star-forming clouds

2010 ◽  
Vol 6 (S270) ◽  
pp. 491-498 ◽  
Author(s):  
Frédéric Bournaud
Keyword(s):  
Galaxy Formation ◽  
Three Dimensional ◽  
Small Scale ◽  
Star Forming ◽  
Global Evolution ◽  
Dominant Process ◽  
Galaxy Populations ◽  
Major Progress ◽  
Hubble Time ◽  
Internal Evolution

AbstractMajor progress has been made over the last few years in understanding hydrodynamical processes on cosmological scales, in particular how galaxies get their baryons. There is increasing recognition that a large part of the baryons accrete smoothly onto galaxies, and that internal evolution processes play a major role in shaping galaxies – mergers are not necessarily the dominant process. However, predictions from the various assembly mechanisms are still in large disagreement with the observed properties of galaxies in the nearby Universe. Small-scale processes have a major impact on the global evolution of galaxies over a Hubble time and the usual sub-grid models account for them in a far too uncertain way. Understanding when, where and at which rate galaxies formed their stars becomes crucial to understand the formation of galaxy populations. I discuss recent improvements and current limitations in “resolved” modeling of star formation, aiming at explicitly capturing star-forming instabilities, in cosmological and galaxy-sized simulations. Such models need to develop three-dimensional turbulence in the ISM, which requires parsec-scale resolution at redshift zero.

scholarly journals Using GAMA to probe the impact of small-scale galaxy physics on nonlinear redshift-space distortions

2021 ◽  
Author(s):  
Shadab Alam ◽  
John A Peacock ◽  
Daniel J Farrow ◽  
J Loveday ◽  
A M Hopkins
Keyword(s):  
Degrees Of Freedom ◽  
Small Scale ◽  
Mcmc Algorithm ◽  
Peculiar Velocities ◽  
The Galaxy ◽  
Mass Assembly ◽  
Galaxy Populations ◽  
Using Data ◽  
The Impact ◽  
Perturbation Growth

Abstract We present improved modelling of the redshift-space distortions of galaxy clustering that arise from peculiar velocities. We create mock galaxy catalogues in the framework of the halo model, using data from the Bolshoi project. These mock galaxy populations are inserted into the haloes with additional degrees of freedom that govern spatial and kinematical biases of the galaxy populations relative to the dark matter. We explore this generalised halo model with an MCMC algorithm, comparing the predictions to data from the Galaxy And Mass Assembly (GAMA) survey, and thus derive one of the first constraints on the detailed kinematic degrees of freedom for satellite galaxies within haloes. With this approach, the distortions of the redshift-space galaxy autocorrelations can be accounted for down to spatial separations close to 10 kpc, opening the prospect of improved RSD measurements of the perturbation growth rate by the inclusion of data from nonlinear scales.

scholarly journals The Distribution of Faint Galaxies

1987 ◽  
Vol 124 ◽  
pp. 367-381 ◽  
Author(s):  
Richard Ellis
Keyword(s):  
Large Scale ◽  
Spectral Signatures ◽  
Number Magnitude ◽  
Redshift Surveys ◽  
Faint Galaxy ◽  
Faint Object ◽  
Luminous Galaxies ◽  
Blue Galaxies ◽  
Nearby Galaxies ◽  
Galaxy Populations

Faint galaxy data are reviewed in the context of standard evolutionary models and our understanding of the statistical properties of galaxy populations. The differences in number magnitude counts from group to group can largely be understood via fluctuations induced by large scale clustering. However count slopes still present convincing arguments for an extra component of faint blue galaxies beyond B ∼21. Colours provide an useful tool in estimating redshift distributions but the uncertainties are large for the bluest galaxies of interest. However, new faint object redshift surveys are now underway and promise to determine definitively the nature of this extra component. We discuss preliminary results from one of these surveys. Neither distant luminous galaxies nor intrinsically faint nearby galaxies appear to be very numerous to B = 21.5. Many of the galaxies with 0.2 < z < 0.4 show spectral signatures of prominent star-formation. If such objects are somehow related to the excess counts, the traditional redshift-dependent evolutionary theory may require revision.

scholarly journals Extracting H i astrophysics from interferometric Intensity Mapping

2021 ◽  
Author(s):  
Zhaoting Chen ◽  
Laura Wolz ◽  
Marta Spinelli ◽  
Steven G Murray
Keyword(s):  
Galaxy Formation ◽  
Shot Noise ◽  
Large Scale ◽  
Neutral Hydrogen ◽  
Mass Function ◽  
Small Scale ◽  
Number Density ◽  
Model Framework ◽  
Intensity Mapping ◽  
Cent Level

Abstract We present a new halo model of neutral hydrogen (H i) calibrated to galaxy formation simulations at redshifts z ∼ 0.1 and z ∼ 1.0 which we employ to investigate the constraining power of interferometric H i Intensity Mapping on H i astrophysics. We demonstrate that constraints on the small-scale H i power spectrum can break the degeneracy between the H i density $\Omega _{\rm H\, \rm \small {I}}$ and the H i bias $b_{\rm H\, \rm \small {I}}$. For z ∼ 0.1, we forecast that an accurate measurement of $\Omega _{\rm H\, \rm \small {I}}$ up to 6 per cent level precision and the large scale H i bias $b_{\rm H\, \rm \small {I}}^0$ up to 1 per cent level precision can be achieved using Square Kilometre Array (SKA) pathfinder data from MeerKAT and ASKAP. We also propose a new description of the H i shot noise in the halo model framework in which a scatter of the relation between the H i mass of galaxies and their host halo mass is taken into account. Furthermore, given the number density of H i galaxies above a certain H i mass threshold, future surveys will also be able to constrain the H i Mass Function using only the H i shot noise. This will lead to constraints at the 10 per cent level using the standard Schechter function. This technique will potentially provide a new way of measuring the H i Mass Function, independent from existing methods. We predict that the SKA will be able to further improve the low redshift constraints by a factor of three, as well as pioneering measurements of H i astrophysics at higher redshifts.

Reasons to strike first

2019 ◽  
Vol 42 ◽  
Author(s):  
William Buckner ◽  
Luke Glowacki
Keyword(s):  
Intergroup Conflict ◽  
Small Scale

Abstract De Dreu and Gross predict that attackers will have more difficulty winning conflicts than defenders. As their analysis is presumed to capture the dynamics of decentralized conflict, we consider how their framework compares with ethnographic evidence from small-scale societies, as well as chimpanzee patterns of intergroup conflict. In these contexts, attackers have significantly more success in conflict than predicted by De Dreu and Gross's model. We discuss the possible reasons for this disparity.

Exploring Coronal Structures with SOHO

2000 ◽  
Vol 179 ◽  
pp. 403-406
Author(s):  
M. Karovska ◽  
B. Wood ◽  
J. Chen ◽  
J. Cook ◽  
R. Howard
Keyword(s):  
Solar Corona ◽  
Image Enhancement ◽  
Coronal Mass Ejections ◽  
Dynamical Evolution ◽  
Small Scale ◽  
Low Contrast ◽  
Contrast Structures ◽  
Scale Structures ◽  
Small Scale Structures ◽  
Coronal Structures

AbstractWe applied advanced image enhancement techniques to explore in detail the characteristics of the small-scale structures and/or the low contrast structures in several Coronal Mass Ejections (CMEs) observed by SOHO. We highlight here the results from our studies of the morphology and dynamical evolution of CME structures in the solar corona using two instruments on board SOHO: LASCO and EIT.

Scanning tunneling microscopy and atomic force microscopy: New tools for biology

1989 ◽  
Vol 47 ◽  
pp. 778-779
Author(s):  
CE Bracker ◽  
P. K. Hansma
Keyword(s):  
Physical Property ◽  
Scanning Probe ◽  
Scanning Tunneling ◽  
Small Scale ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
New Family ◽  
Small Probe ◽  
Atomic Force ◽  
Transmission Electron

A new family of scanning probe microscopes has emerged that is opening new horizons for investigating the fine structure of matter. The earliest and best known of these instruments is the scanning tunneling microscope (STM). First published in 1982, the STM earned the 1986 Nobel Prize in Physics for two of its inventors, G. Binnig and H. Rohrer. They shared the prize with E. Ruska for his work that had led to the development of the transmission electron microscope half a century earlier. It seems appropriate that the award embodied this particular blend of the old and the new because it demonstrated to the world a long overdue respect for the enormous contributions electron microscopy has made to the understanding of matter, and at the same time it signalled the dawn of a new age in microscopy. What we are seeing is a revolution in microscopy and a redefinition of the concept of a microscope.Several kinds of scanning probe microscopes now exist, and the number is increasing. What they share in common is a small probe that is scanned over the surface of a specimen and measures a physical property on a very small scale, at or near the surface. Scanning probes can measure temperature, magnetic fields, tunneling currents, voltage, force, and ion currents, among others.

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