scholarly journals Galaxy Formation: ISOCAM Counts

1996 ◽  
Vol 168 ◽  
pp. 109-116 ◽  
Author(s):  
C.J. Cesarsky ◽  
D. Elbaz
Keyword(s):  
Galaxy Formation ◽  
Luminosity Function ◽  
High Redshift ◽  
Large Population ◽  
Large Redshift ◽  
Blue Galaxies ◽  
Very High

Detailed observations in the optical do not allow to discriminate between the following scenarii of galaxy formation:- synchronous formation at large redshift (z > 7).- hierarchical merging, down to z ≤ 1, of proto-galactic lumps formed at very high redshift (≈ 10).- galaxy formation at low z (≈ 2-5), but partially obscured by dust.More than 1500 galaxies in a field of 2.6′ × 4.6′ were detected by Tyson (1988) with CCD images in the B band. These deep counts of galaxies revealed the presence of an unexpectedly large population of blue galaxies, corresponding to a number excess of 3 to 5 times more galaxies at B > 23 than one can expect from the local luminosity function. These objects lie apparently at moderate redshift (z = 0.3 for B = 23–24) as shown by spectroscopy of B-selected galaxies (Collesset al.1990).

scholarly journals The Quest for Protogalaxies

1996 ◽  
Vol 171 ◽  
pp. 277-286
Author(s):  
S.G. Djorgovski
Keyword(s):  
Galaxy Formation ◽  
High Redshift ◽  
Large Population ◽  
Number Density ◽  
Field Surveys ◽  
Near Ir ◽  
Current State ◽  
Luminous Galaxies ◽  
Model Predictions ◽  
Density Regime

The current state and the future prospects of searches for protogalaxies (PGs) are reviewed. Many high-redshift objects are now known, mostly associated in some way with AGN, and at least some of them may be young galaxies. Quasars at z > 4 and high-z quasar pairs may mark galaxy formation sites. Deep field surveys for Lyα luminous galaxies powered by star formation alone have failed so far to reveal a large population of such objects, and the observed limits are in conflict with simple model predictions by three orders of magnitude. Some extinction by dust can account for this. However, strong limits from COBE place severe constraints on models of completely obscured PGs. New searches in the near IR are now beginning to probe the relevant line flux and number density regime, and first interesting PG candidates are being discovered. Searches from mid-IR to mm wavelengths would complement these efforts.

scholarly journals Prediction of H α and [O iii] emission line galaxy number counts for future galaxy redshift surveys

2019 ◽  
Vol 490 (3) ◽  
pp. 3667-3678 ◽  
Author(s):  
Zhongxu Zhai ◽  
Andrew Benson ◽  
Yun Wang ◽  
Gustavo Yepes ◽  
Chia-Hsun Chuang
Keyword(s):  
Emission Line ◽  
Galaxy Formation ◽  
Luminosity Function ◽  
Large Scale ◽  
High Redshift ◽  
Flux Ratio ◽  
Formation Model ◽  
Line Flux ◽  
Emission Line Galaxies ◽  
Number Counts

ABSTRACT We perform a simulation with Galacticus, a semi-analytical galaxy formation model, to predict the number counts of H α and [O iii] emitting galaxies. With a state-of-the-art N-body simulation, UNIT, we first calibrate Galacticus with the current observation of H α luminosity function. The resulting model coupled with a dust attenuation model, can reproduce the current observations, including the H α luminosity function from HiZELS and number density from WISP. We extrapolate the model prediction to higher redshift and the result is found to be consistent with previous investigations. We then use the same galaxy formation model to predict the number counts for [O iii] emitting galaxies. The result provides further validation of our galaxy formation model and dust model. We present number counts of H α and [O iii] emission line galaxies for three different line flux limits: 5 × 10−17erg s−1 cm−2, 1 × 10−16 erg s−1 cm−2 (6.5σ nominal depth for WFIRST GRS), and 2 × 10−16 erg s−1 cm−2 (3.5σ depth of Euclid GRS). At redshift 2 < z < 3, our model predicts that WFIRST can observe hundreds of [O iii] emission line galaxies per square degree with a line flux limit of 1 × 10−16 erg s−1 cm−2. This will provide accurate measurement of large-scale structure to probe dark energy over a huge cosmic volume to an unprecedented high redshift. Finally, we compare the flux ratio of H α/[O iii] within the redshift range of 0 < z < 3. Our results show the known trend of increasing H α/[O iii] flux ratio with H α flux at low redshift, which becomes a weaker trend at higher redshifts.

scholarly journals The MUSE Extremely Deep Field: The cosmic web in emission at high redshift

2021 ◽  
Vol 647 ◽  
pp. A107
Author(s):  
R. Bacon ◽  
D. Mary ◽  
T. Garel ◽  
J. Blaizot ◽  
M. Maseda ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Luminosity Function ◽  
Filling Factor ◽  
High Redshift ◽  
Large Population ◽  
Diffuse Emission ◽  
Average Surface ◽  
High Significance ◽  
Circumgalactic Medium

We report the discovery of diffuse extended Lyα emission from redshift 3.1 to 4.5, tracing cosmic web filaments on scales of 2.5−4 cMpc. These structures have been observed in overdensities of Lyα emitters in the MUSE Extremely Deep Field, a 140 h deep MUSE observation located in the Hubble Ultra-Deep Field. Among the 22 overdense regions identified, five are likely to harbor very extended Lyα emission at high significance with an average surface brightness of 5 × 10−20 erg s−1 cm−2 arcsec−2. Remarkably, 70% of the total Lyα luminosity from these filaments comes from beyond the circumgalactic medium of any identified Lyα emitter. Fluorescent Lyα emission powered by the cosmic UV background can only account for less than 34% of this emission at z ≈ 3 and for not more than 10% at higher redshift. We find that the bulk of this diffuse emission can be reproduced by the unresolved Lyα emission of a large population of ultra low-luminosity Lyα emitters (< 1040 erg s−1), provided that the faint end of the Lyα luminosity function is steep (α ⪅ −1.8), it extends down to luminosities lower than 1038 − 1037 erg s−1, and the clustering of these Lyα emitters is significant (filling factor < 1/6). If these Lyα emitters are powered by star formation, then this implies their luminosity function needs to extend down to star formation rates < 10−4 M⊙ yr−1. These observations provide the first detection of the cosmic web in Lyα emission in typical filamentary environments and the first observational clue indicating the existence of a large population of ultra low-luminosity Lyα emitters at high redshift.

scholarly journals Distant Compact Narrow Emission Line Galaxies as Progenitors of Today’s Spheroidal Galaxies

1998 ◽  
Vol 11 (1) ◽  
pp. 145-146
Author(s):  
David C. Koo ◽  
Rafael Guzmán
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Luminosity Function ◽  
Cold Dark Matter ◽  
Dwarf Galaxies ◽  
Faint Galaxy ◽  
Blue Galaxies ◽  
Low Mass ◽  
Emission Line Galaxies ◽  
Narrow Emission

Dwarf galaxies at high redshifts are important to study for a variety of reasons. By dwarf, we mean galaxies with low-mass, though galaxies with low-luminosities or small sizes are also commonly referred to as dwarfs. Several groups have suggested that such galaxies may be major contributors to faint blue galaxies, whose nature remains unclear. Dwarfs are viable candidates for faint blue galaxies if many undergo strong bursts of star-formation at redshifts z ~ 1 (Babul and Ferguson 1996) or even lower redshifts z ~ 0.3 (Cowie, Songaila, and Hu 1991; Broadhurst et al. 1988) and fade or disappear by today; if they have a much steeper luminosity function (Driver et al. 1994) than generally adopted in faint galaxy models; or if they represent small pre-merger fragments of larger galaxies today (Guiderdoni and Rocca-Volmerange 1990; Broadhurst, Ellis, and Glazebrook 1992), as might be expected in standard cold dark matter models with hierarchical galaxy formation.

Models for galaxy and massive black hole formation and early evolution

2020 ◽  
Vol 15 (S359) ◽  
pp. 11-16
Author(s):  
Rainer Weinberger
Keyword(s):  
Black Holes ◽  
Galaxy Formation ◽  
Luminosity Function ◽  
Accretion Rate ◽  
High Redshift ◽  
Massive Black Hole ◽  
Massive Black Holes ◽  
Complex Processes ◽  
Accretion Rates ◽  
Eddington Limit

AbstractModels for massive black holes are a key ingredient for modern cosmological simulations of galaxy formation. The necessity of efficient AGN feedback in these simulations makes it essential to model the formation, growth and evolution of massive black holes, and parameterize these complex processes in a simplified fashion. While the exact formation mechanism is secondary for most galaxy formation purposes, accretion modeling turns out to be crucial. It can be informed by the properties of the high redshift quasars, accreting close to their Eddington limit, by the quasar luminosity function at peak activity and by low-redshift scaling relations. The need for halo-wide feedback implies a feedback-induced reduction of the accretion rate towards low redshift, amplifying the cosmological trend towards lower accretion rates at low redshift.

scholarly journals Connecting observations of the first galaxies and the Epoch of Reionisation

2019 ◽  
Vol 15 (S352) ◽  
pp. 348-348
Author(s):  
Simon Mutch
Keyword(s):  
Power Spectrum ◽  
Galaxy Formation ◽  
Luminosity Function ◽  
Dwarf Galaxies ◽  
High Redshift ◽  
High Redshift Galaxies ◽  
Relative Contribution ◽  
Redshift Galaxy ◽  
Upper Limits ◽  
First Galaxies

AbstractDwarf galaxies are thought to be dominant contributors of ionizing photons during the Epoch of Reionisation (EoR). Our knowledge of the statistics of these high redshift galaxies is constantly improving and will take yet another important step forward with the launch of JWST. At the same time, the upper limits on the EoR 21cm power spectrum are continually falling, with a firm measurement from SKA-low being a certainty in coming years. In order to maximise what we can learn from these two complimentary observational datasets, we need to be able to model them together, self-consistently. In this talk, I will present insights into the connection between galaxy formation and the EoR gained from the DRAGONS suite of semi-analytic and hydrodynamic galaxy formation simulations. Using these we find that the steep faint end slope of the high- redshift galaxy UV luminosity function extends well beyond current observational limits, indicating that only ∼ 50% of the ionising photons available for reionisation have been observed at z < 7. I will also discuss the relative contribution of quasars to reionisation and present constraints on ionising escape fraction models.

scholarly journals The MUSE view of the Frontier Field clusters

2015 ◽  
Vol 11 (A29B) ◽  
pp. 764-767
Author(s):  
Johan Richard ◽  
Guillaume Mahler ◽  
Benjamin Clément ◽  
David Lagattuta ◽  
Vera Patriício ◽  
...  
Keyword(s):  
Luminosity Function ◽  
High Redshift ◽  
Large Field ◽  
Very Large Telescope ◽  
Wide Range ◽  
The Galaxy ◽  
Integral Field Spectrograph ◽  
Galaxy Luminosity Function ◽  
Very High ◽  
Integral Field

AbstractStrong gravitational magnification in the core of lensing clusters allows to probe the faint-end of the galaxy luminosity function up to very high redshift. In particular, the Frontier Fields have allowed us to identify a large number of faint dropouts and constrain the Lyman-break luminosity function at z~5-7. I present here the results of an ongoing program with MUSE, a new integral field spectrograph on the Very Large Telescope having a large field of view (1 arcmin2), to confirm these candidate high redshift dropouts through Lyman-α emission and identify additional emitters with high equivalent width, fainter than the depth of the Frontier Fields Hubble images. Combined with similar deep exposures taken with MUSE in blank fields, this gives us the best opportunity to probe the Lyman-α luminosity function over a wide range in luminosity.

scholarly journals Linear bias forecasts for emission line cosmological surveys

2019 ◽  
Vol 486 (4) ◽  
pp. 5737-5765 ◽  
Author(s):  
Alexander Merson ◽  
Alex Smith ◽  
Andrew Benson ◽  
Yun Wang ◽  
Carlton Baugh
Keyword(s):  
Galaxy Formation ◽  
Luminosity Function ◽  
High Redshift ◽  
Dark Matter Halo ◽  
Cumulative Number ◽  
Formation Model ◽  
Single Scale ◽  
Halo Masses ◽  
Dust Attenuation ◽  
Number Counts

Abstract We forecast the linear bias for  Hα-emitting galaxies at high redshift. To simulate a Euclid-like and a WFIRST-like survey, we place galaxies into a large-volume dark matter halo lightcone by sampling a library of luminosity-dependent halo occupation distributions (HODs), which is constructed using a physically motivated galaxy formation model. We calibrate the dust attenuation in the lightcones such that they are able to reproduce the  Hα luminosity function or the  Hα cumulative number counts. The angle-averaged galaxy correlation function is computed for each survey in redshift slices of width Δ z = 0.2. In each redshift bin the linear bias can be fitted with a single, scale-independent value that increases with increasing redshift. Fitting for the evolution of linear bias with redshift, we find that our Euclid-like and WFIRST-like surveys are both consistent within error with the relation b(z) = 0.7z + 0.7. Our bias forecasts are consistent with bias measurements from the HiZELS survey. We find that the Euclid-like and WFIRST-like surveys yield linear biases that are broadly consistent within error, most likely due to the HOD for the WFIRST-like survey having a steeper power-law slope towards larger halo masses.

scholarly journals QSO obscuration at high redshift (z ≳ 7): predictions from the bluetides simulation

2020 ◽  
Vol 495 (2) ◽  
pp. 2135-2151 ◽  
Author(s):  
Yueying Ni ◽  
Tiziana Di Matteo ◽  
Roberto Gilli ◽  
Rupert A C Croft ◽  
Yu Feng ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Column Density ◽  
Luminosity Function ◽  
High Redshift ◽  
Formation Rate ◽  
Host Galaxy ◽  
Clear Trend ◽  
A Minor ◽  
Host Properties ◽  
High Column

ABSTRACT High-$z$ AGNs hosted in gas-rich galaxies are expected to grow through significantly obscured accretion phases. This may limit or bias their observability. In this work, we use bluetides, a large volume cosmological simulation of galaxy formation to examine quasar obscuration for the highest redshift ($z$ ≥ 7) supermassive black holes residing in the centre of galaxies. We find that for the bright quasars, most of the high-column density gas ($\rm {\gt} 90 {\rm {per\ cent}}$) resides in the innermost regions of the host galaxy (typically within &lt;10 ckpc), while the gas in the outskirts is a minor contributor to the NH. The brightest quasars can have large angular variations in galactic obscuration, over 2 orders of magnitude (ranging from column density $N_\mathrm{H} \sim 10^{21.5 \!-\! 24}\, \rm {cm}^{-2}$), where the lines of sight with the lowest obscuration are those formed via strong gas outflows driven by AGN feedback. The obscured fraction P(NH &gt; 1023 cm−2) typically ranges from 0.6 to 1.0 for increasing LX (with $L_\mathrm{ X} \gt 10^{43} \, \rm {erg\, s}^{-1}$), with no clear trend of redshift evolution. Due to the angular variation in NH, all relations between NH and LX, MBH, and galaxy host properties (global M*, $M_{\rm H_2}$, and star formation rate) show appreciable scatter. The dust optical depth in the UV band τUV has tight positive correlation with NH. Our dust-extincted UV luminosity function (UVLF) is about 1.5 dex lower than the intrinsic UVLF, implying that more than 99 per cent of the $z$ ∼ 7 AGNs are heavily dust extincted and therefore would be missed by the UV-band observation.

scholarly journals Simulating the effect of photoheating feedback during reionization

2019 ◽  
Vol 488 (1) ◽  
pp. 419-437 ◽  
Author(s):  
Xiaohan Wu ◽  
Rahul Kannan ◽  
Federico Marinacci ◽  
Mark Vogelsberger ◽  
Lars Hernquist
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Luminosity Function ◽  
High Redshift ◽  
Formation Rate ◽  
Mass Function ◽  
Stellar Mass ◽  
Microwave Background ◽  
Stellar Feedback ◽  
Stellar Sources

Abstract We present self-consistent radiation hydrodynamic simulations of hydrogen reionization performed with arepo-rt complemented by a state-of-the-art galaxy formation model. We examine how photoheating feedback, due to reionization, shapes the galaxies properties. Our fiducial model completes reionization by z ≈ 6 and matches observations of the Ly α forest, the cosmic microwave background electron scattering optical depth, the high-redshift ultraviolet (UV) luminosity function, and stellar mass function. Contrary to previous works, photoheating suppresses star formation rates by more than $50{{\ \rm per\ cent}}$ only in haloes less massive than ∼108.4 M⊙ (∼108.8 M⊙) at z = 6 (z = 5), suggesting inefficient photoheating feedback from photons within galaxies. The use of a uniform UV background that heats up the gas at z ≈ 10.7 generates an earlier onset of suppression of star formation compared to our fiducial model. This discrepancy can be mitigated by adopting a UV background model with a more realistic reionization history. In the absence of stellar feedback, photoheating alone is only able to quench haloes less massive than ∼109 M⊙ at z ≳ 5, implying that photoheating feedback is sub-dominant in regulating star formation. In addition, stellar feedback, implemented as a non-local galactic wind scheme in the simulations, weakens the strength of photoheating feedback by reducing the amount of stellar sources. Most importantly, photoheating does not leave observable imprints in the UV luminosity function, stellar mass function, or the cosmic star formation rate density. The feasibility of using these observables to detect imprints of reionization therefore requires further investigation.

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