scholarly journals Are Ly α emitters segregated in protoclusters regions?

2020 ◽  
Vol 499 (2) ◽  
pp. 2104-2115
Author(s):  
Tomás Hough ◽  
Siddhartha Gurung-López ◽  
Álvaro Orsi ◽  
Sofía A Cora ◽  
Cedric G Lacey ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
High Redshift ◽  
Neutral Hydrogen ◽  
High Density ◽  
Lyman Alpha ◽  
Alpha Emitters ◽  
Galaxy Formation And Evolution ◽  
Galaxy Sample ◽  
Formation And Evolution ◽  
Lyman Alpha Emitters

ABSTRACT The presence of neutral hydrogen in the interstellar medium (ISM) and intergalactic medium (IGM) induces radiative transfer (RT) effects on $\rm {Ly}\,\alpha$ photons that affect the observability of Lyman alpha emitters (LAEs). We use the galform semi-analytic model of galaxy formation and evolution to analyse how these effects shape the spatial distribution of LAEs with respect to $\rm {H}\,\alpha$ emitters (HAEs) around high-density regions at high redshift. We find that when a large sample of protoclusters is considered, HAEs showing also $\rm {Ly}\,\alpha$ emission (HAEs + LAEs) populate the same regions as those that do not display the $\rm {Ly}\,\alpha$ line at $z$ = 2.2. We compare against the protocluster USS1558-003, one of the most massive protoclusters located at $z$ = 2.53. Our results indicate that the strong depletion of HAEs + LAEs present in the high-density regions of USS1558-003 may be due to cosmic variance. We find that at $z$ = 2.2 and $z$ = 3.0, RT of the ISM produces a strong decline (30–50 per cent) of the clustering amplitude of HAEs + LAEs with respect to HAEs towards the protoclusters centre. At $z$ = 5.7, given the early evolutionary state of protoclusters and galaxies, the clustering of HAEs + LAEs has a smaller variation (10–20 per cent) towards the protoclusters centre. Depending on the equivalent width and luminosity criteria of the emission-line galaxy sample, the IGM can have a mild or a null effect on galaxy properties and clustering in high-density regions.

scholarly journals New Results on DLA Systems: Statistics

2015 ◽  
Vol 11 (S319) ◽  
pp. 40-40
Author(s):  
Sandhya Rao ◽  
David Turnshek ◽  
Eric Monier ◽  
Gendith Sardane
Keyword(s):  
Galaxy Formation ◽  
Mass Density ◽  
Neutral Hydrogen ◽  
Gas Content ◽  
Neutral Gas ◽  
Quasar Spectra ◽  
Galaxy Formation And Evolution ◽  
Formation And Evolution ◽  
Space Data ◽  
The Universe

AbstractThe damped Lyman-α absorption-line systems (DLAs) that are observed in quasar spectra arise in neutral-gas-rich regions of intervening galaxies. With the highest neutral hydrogen column densities observed (N(HI) ⩾ 2 × 1020 atoms cm−2), they are known to trace the bulk of the neutral gas content of the Universe, and are thus powerful probes of galaxy formation and evolution. However, DLAs are extremely rare, and since the Lyman-α line falls in the UV for redshifts z < 1.65, not many are known at low redshift due to the limited availability of space data. Our HST surveys for DLAs in strong MgII absorbers have been successful at showing that MgII can be used as an unbiased tracer of DLAs. We present new results on their incidence, or redshift number density, dn/dz, and cosmological neutral gas mass density, ΩDLA, at redshifts 0.11 ⩽ z ⩽ 1.65, and incorporate results from higher and lower redshift studies in the literature to derive the evolution of neutral gas in the Universe.

scholarly journals Formation and Evolution of Nucleated Galaxies

2006 ◽  
Vol 2 (S235) ◽  
pp. 172-174
Author(s):  
Kenji Bekki
Keyword(s):  
Galaxy Formation ◽  
Globular Clusters ◽  
High Redshift ◽  
Galaxy Mergers ◽  
Galaxy Formation And Evolution ◽  
Central Regions ◽  
Low Mass ◽  
Formation And Evolution ◽  
Nuclear Structures ◽  
High Redshift Universe

AbstractWe discuss how stellar galactic nuclei (SGN) form and evolve during galaxy formation and evolution based on chemodynamical simulations on the central regions (1-1000 pc) of galaxies. Our simulations demonstrate that dissipative formation of SGN through rapid transfer of gas into the central 10 pc of galaxies is more consistent with recent observations of SGN than dissipationless formation of SGN through merging of globular clusters (GCs). Nuclear structures in the remnants of major galaxy mergers between low-mass, nucleated spirals are found to depend strongly on the mass-ratio of massive black holes (MBHs) to SGN in spirals in the sense that the remnants have more distinct SGN in the mergers with the smaller MBH-to-SGN-mass-ratios. During the destruction of low-mass, nucleated galaxies by strong tidal fields of giant galaxies, SGN can remain intact. The stripped SGN can be observed as bright GCs around the giant galaxies. The color-magnitude relation of metal-poor GCs (referred to as “the blue tilt”) recently discovered for bright galaxies is similar to that of SGN, which suggests that the origin of the blue tilt is closely associated with the formation processes of SGN of gas-rich, low-mass dwarfs in the high redshift universe.

scholarly journals Panchromatic radiation from galaxies as a probe of galaxy formation and evolution

2011 ◽  
Vol 7 (S284) ◽  
pp. 446-455 ◽  
Author(s):  
Michael Rowan-Robinson
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
High Redshift ◽  
Star Formation History ◽  
Spherically Symmetric ◽  
3 Dimensional ◽  
Dust Extinction ◽  
Galaxy Formation And Evolution ◽  
Formation History ◽  
Formation And Evolution

AbstractI review work on modelling the infrared and submillimetre SEDs of galaxies. The underlying physical assumptions are discussed and spherically symmetric, axisymmetric, and 3-dimensional radiative transfer codes are reviewed. Models for galaxies with Spitzer IRS data and for galaxies in the Herschel-Hermes survey are discussed. Searches for high redshift infrared and submillimetre galaxies, the star formation history, the evolution of dust extinction, and constraints from source-counts, are briefly discussed.

scholarly journals Physical Properties of Dlas: Metallicity and Neutral Hydrogen Column Density

2004 ◽  
Vol 217 ◽  
pp. 246-251
Author(s):  
J. L. Hou ◽  
C. G. Shu ◽  
W. P. Chen ◽  
R. X. Chang ◽  
C. Q. Fu
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Column Density ◽  
High Redshift ◽  
Formation Rate ◽  
Neutral Hydrogen ◽  
Gas Content ◽  
Lyman Alpha ◽  
Formation Mode ◽  
Damped Lyman Alpha Systems

We investigate some basic properties of Damped Lyman alpha systems based on the Semi-Analytical model of disk galaxy formation theory. We derive the DLA metallicity, column density, number density, gas content and cosmic star formation rate by assuming that disks form at the center of dark halos, and the modelled DLAs are selected by Monte Carlo simulation according to the distributions of halo properties. We find that DLA hosts are dominated by small galaxies and biased to extended galaxies. In terms of model results, DLAs could naturally arise in a ACDM universe from radiatively cooled gas in dark matter halos. However, model predicts a reverse correlation between metallicity and the column density when compared with observations, regardless of the proposed observational bias. We argue that this could be resulted from the model limitations, or the inadequacy of Schmidt-type star formation mode at high redshift, or/and the diversities of DLA populations.

scholarly journals Superwind Galaxies at High Redshift: the Case of LAE J1044-0130

2004 ◽  
Vol 217 ◽  
pp. 300-301
Author(s):  
Masaru Ajiki ◽  
Shinobu S. Fujita ◽  
Yasuhiro Shioya ◽  
Tohru Nagao ◽  
Takashi Murayama ◽  
...  
Keyword(s):  
Emission Line ◽  
Line Width ◽  
Line Profile ◽  
High Redshift ◽  
Broad Line ◽  
Large Sample ◽  
Lyman Alpha ◽  
Alpha Emitters ◽  
Lyman Alpha Emitters ◽  
Emission Line Profile

Superwind galaxies at high-redshift are now considered to be the important clue for understanding the interaction and evolution of both galaxies and intergalactic matter. In order to improve our knowledge of superwind galaxies at high redshift, a large sample of superwind candidates is needed. During the course of our new search for Lyman alpha emitters at z = 5.7, we have found a candidate superwind galaxy, LAE J1044-0130, at z = 5.69. The emission-line profile of this object is asymmetric, showing excess red-wing emission and the observed broad line width (= 340 km/s). In this poster, we report detailed observed properties of LAE J1044-0130 as an example of a superwind galaxy.

scholarly journals Distinguishing AGN from starbursts as the origin of double-peaked Lyman-alpha emitters in the reionization era

2021 ◽  
Vol 646 ◽  
pp. L10
Author(s):  
Hamsa Padmanabhan ◽  
Abraham Loeb
Keyword(s):  
Active Galactic Nuclei ◽  
Peak Velocity ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Radio Observations ◽  
Space Telescope ◽  
X Ray ◽  
Lyman Alpha ◽  
Alpha Emitters ◽  
Lyman Alpha Emitters

We discuss the possible origin of the double-peaked profiles recently observed in Lyman-alpha emitters (LAEs) at the epoch of reionization (z  ≳  6.5) from obscured active galactic nuclei (AGN). In combining the extent of the Lyman-α near-zones estimated from the blue peak velocity offset in these galaxies, with the ionizing emissivity of quasars at z ≳ 6, we forecast the intrinsic UV and X-ray luminosities of the AGN needed to give rise to their double-peaked profiles. We also estimate the extent of the obscuration of the AGN by comparing their luminosities to those of similar quasar samples at these epochs. Future X-ray and radio observations, as well as those with the James Webb Space Telescope, will be valuable tools to test the AGN contribution to the intergalactic-scale ionization zones of high-redshift LAEs.

scholarly journals The Structure of Halo Gas around M33

2016 ◽  
Vol 11 (S321) ◽  
pp. 244-247
Author(s):  
Olivia C. Keenan ◽  
Jonathan I. Davies ◽  
Rhys Taylor ◽  
Robert F. Minchin
Keyword(s):  
Galaxy Formation ◽  
Local Group ◽  
Neutral Hydrogen ◽  
Galaxy Formation And Evolution ◽  
Formation And Evolution ◽  
Galaxy Environment ◽  
Optically Detected ◽  
Halo Gas ◽  
Group Galaxy ◽  
Local Group Galaxy

AbstractUnderstanding the distribution of gas in and around galaxies is vital for our interpretation of galaxy formation and evolution. As part of the Arecibo Galaxy Environment Survey (AGES) we have observed the neutral hydrogen (HI) gas in and around the nearby Local Group galaxy M33 to a greater depth than previous observations. As part of this project we investigated the absence of optically detected dwarf galaxies in its neighbourhood, which is contrary to predictions of galaxy formation models. We observed 22 discrete clouds, 11 of which were previously undetected and none of which have optically detected counterparts. We find one particularly interesting hydrogen cloud, which has many similar characteristics to hydrogen distributed in the disk of a galaxy. This cloud, if it is at the distance of M33, has a HI mass of around 107 M⊙ and a diameter of 18 kpc, making it larger in size than M33 itself.

scholarly journals Galaxies at high z: The MUSE revolution

2019 ◽  
Vol 15 (S352) ◽  
pp. 325-325
Author(s):  
Roland Bacon
Keyword(s):  
High Redshift ◽  
Lyman Alpha ◽  
Alpha Emitters ◽  
Spectroscopic Observations ◽  
Alpha Emission ◽  
Order Of Magnitude ◽  
Low Mass ◽  
Deep Fields ◽  
Lyman Alpha Emitters ◽  
High Redshift Universe

AbstractSpectroscopic observations of galaxies at high redshift has recently been revolutionised by the Multi Unit Spectroscopic Explorer (MUSE) instrument in operation at the VLT since 2014. Thanks to its unrivalled capabilities, MUSE has been able to increase by an order of magnitude the number of spectroscopic redshifts in these fields. The most spectacular increase is at high redshift (z > 3), where MUSE was able to detect thousands of Lyman-alpha emitters. In the deepest exposures, MUSE is even able to goes beyond the limiting magnitude of the deepest HST exposures. These observations have led to a breakthrough in our understanding of the high redshift universe: e.g. the discovery of Lyman-alpha emission from the circumgalactic medium around individual galaxies, the role and property of low mass galaxies. In this talk I will present the latest results obtained with the MUSE observations of the Hubble deep and ultra-deep fields.

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