Mapping the Most Massive Overdensity Through Hydrogen (Mammoth). I. Methodology

Cai, Zheng; Fan, Xiaohui; Peirani, Sébastien; Bian, Fuyan; Frye, Brenda; McGreer, Ian D.; Prochaska, J. Xavier; Lau, Marie Wingyee; Tejos, Nicolás; Ho, Shirley; Schneider, Donald P.

doi:10.3847/1538-4357/833/2/135

Cited by 89 publications

(93 citation statements)

References 104 publications

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“…In order to assess how well Ly-α absorption traces large scale, high density regions, we consider the correlation be- Figure 5. The relationship between δ m and δ τ eff on 15 h −1 cMpc scales (following Cai et al 2016). Left to right, the panels show the results from Sherwood, EAGLE and Illustris.…”

Section: Relationship Between Mass and Effective Optical Depth On 15 mentioning

confidence: 99%

“…Applying insight obtained from a 256 3 h −3 cMpc 3 collisionless dark matter simulation, Lee et al (2016) have used this method to successfully detect a galaxy overdensity at z = 2.44 in the COSMOS field, as well as cosmic voids at z ∼ 2.3 (Krolewski et al 2018). The second method -which we focus on in this work -is to search for the most massive overdensities at z = 2-4 from a large survey volume using strong, coherent Ly-α absorption along the line of sight (Cai et al 2016). This approach is more effective at redshifts where the density of bright background sources is too low for tomography.…”

Section: Introductionmentioning

confidence: 99%

“…Cai et al (2016) (hereafter C16) associate protoclusters with CoSLAs, defin-Probability distribution of δ m for 15h −1 cMpc volumes with an associated δ τ eff > 3.5 (i.e. CoSLAs) after removing all sight lines containing damped systems in Sherwood (blue), EAGLE (orange) and Illustris (brown).…”

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confidence: 99%

“…CoSLAs) after removing all sight lines containing damped systems in Sherwood (blue), EAGLE (orange) and Illustris (brown). The corresponding distribution from the analysis of a 1 h −3 cGpc 3 post-processed collisionless dark matter simulation byCai et al (2016) is displayed as a black dashed line. The total number of CoSLAs identified in each simulation is: Illustris (36), EAGLE (32), Sherwood (22).…”

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Searching for the shadows of giants: characterizing protoclusters with line of sight Lyman-α absorption

Miller

Bolton

Hatch

2019

Monthly Notices of the Royal Astronomical Society

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We use state of the art hydrodyamical simulations from the Sherwood, EAGLE and Illustris projects to examine the signature of M z=0 10 14 M protoclusters observed in Ly-α absorption at z 2.4. We find there is a weak correlation between the mass overdensity, δ m , and the Ly-α effective optical depth relative to the mean, δ τ eff , averaged over 15 h −1 cMpc scales, although scatter in the δ m -δ τ eff plane means it is not possible to uniquely identify large scale overdensities with strong Ly-α absorption. Although all protoclusters are associated with large scale mass overdensities, most sight lines through protoclusters in a ∼ 10 6 cMpc 3 volume probe the low column density Ly-α forest. A small subset of sight lines that pass through protoclusters exhibit coherent, strong Ly-α absorption on 15h −1 cMpc scales, although these correspond to a wide range in mass overdensity. Assuming perfect removal of contamination by Lyα absorbers with damping wings, more than half of the remaining sight lines with δ τ eff > 3.5 trace protoclusters. It is furthermore possible to identify a model dependent δ τ eff threshold that selects only protoclusters. However, such regions are rare: excluding absorption caused by damped systems, less than 0.1 per cent of sight lines that pass through a protocluster have δ τ eff > 3.5, meaning that any protocluster sample selected in this manner will also be highly incomplete. On the other hand, coherent regions of Ly-α absorption also provide a promising route for identifying and studying filamentary environments at high redshift.

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Section: Relationship Between Mass and Effective Optical Depth On 15 mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Searching for the shadows of giants: characterizing protoclusters with line of sight Lyman-α absorption

Miller

Bolton

Hatch

2019

Monthly Notices of the Royal Astronomical Society

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“…The optically selected quasar halo masses at z ∼ 1 − 3 are consistent with the typical halo mass of ∼ 10 12 M⊙ at that epoch Coil et al 2007;White et al 2012), suggesting they do not reside in very biased regions. In fact, recently, Cai et al (2016) found that the masses of protoclusters which are traced by Lyα forest absorption are much more massive than those of typical quasars at z ∼ 2 − 3. At higher redshift z > 3, Shen et al (2007) showed that optical quasar halo masses are more massive with M ∼ (4 − 6) × 10 12 h −1 M⊙, implying that almost all luminous quasars could be associated with cluster progenitors.…”

Section: Introductionmentioning

confidence: 99%

Luminous quasars do not live in the most overdense regions of galaxies at z ∼ 4

Uchiyama

Toshikawa

Kashikawa

et al. 2017

Publications of the Astronomical Society of Japan

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We present the cross-correlation between 151 luminous quasars (M UV < −26) and 179 protocluster candidates at z ∼ 3.8, extracted from the Wide imaging survey (∼ 121 deg 2 ) performed c 2014. Astronomical Society of Japan. 2Publications of the Astronomical Society of Japan, (2014), Vol. 00, No. 0 with a part of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). We find that only two out of 151 quasars reside in regions that are more overdense compared to the average field at > 4σ. The distributions of the distance between quasars and the nearest protoclusters and the significance of the overdensity at the position of quasars are statistically identical to those found for g-dropout galaxies, suggesting that quasars tend to reside in almost the same environment as star-forming galaxies at this redshift. Using stacking analysis, we find that the average density of g-dropout galaxies around quasars is slightly higher than that around g-dropout galaxies on 1.0 − 2.5 pMpc scales, while at < 0.5 pMpc that around quasars tends to be lower. We also find that quasars with higher UV-luminosity or with more massive black holes tend to avoid the most overdense regions, and that the quasar near zone sizes are anti-correlated with overdensity. These findings are consistent with a scenario in which the luminous quasar at z ∼ 4 resides in structures that are less massive than those expected for the progenitors of today's rich clusters of galaxies, and possibly that luminous quasars may be suppressing star formation in their close vicinity.

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The realm of the galaxy protoclusters

Overzier

2016

Astron Astrophys Rev

264

204

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The study of galaxy protoclusters is beginning to fill in unknown details of the important phase of the assembly of clusters and cluster galaxies. This review describes the current status of this field and highlights promising recent findings related to galaxy formation in the densest regions of the early universe. We discuss the main search techniques and the characteristic properties of protoclusters in observations and simulations, and show that protoclusters will have present-day masses similar to galaxy clusters when fully collapsed. We discuss the physical properties of galaxies in protoclusters, including (proto-)brightest cluster galaxies, and the forming red sequence. We highlight the fact that the most massive halos at high redshift are found in protoclusters, making these objects uniquely suited for testing important recent models of galaxy formation. We show that galaxies in protoclusters should be among the first galaxies at high redshift making the transition from a gas cooling regime dominated by cold streams to a regime dominated by hot intracluster gas, which could be tested observationally. We also discuss the possible connections between protoclusters and radio galaxies, quasars, and Ly-alpha blobs. Because of their early formation, large spatial sizes and high total star formation rates, protoclusters have also likely played a crucial role during the epoch of reionization, which can be tested with future experiments that will map the neutral and ionized cosmic web. Last, we review a number of promising observational projects that are expected to make significant impact in this growing, exciting field.Comment: Invited article for The Astronomy and Astrophysics Review (in press

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Mapping the Most Massive Overdensity Through Hydrogen (Mammoth). I. Methodology

Cited by 89 publications

References 104 publications

Searching for the shadows of giants: characterizing protoclusters with line of sight Lyman-α absorption

Searching for the shadows of giants: characterizing protoclusters with line of sight Lyman-α absorption

Luminous quasars do not live in the most overdense regions of galaxies at z ∼ 4

The realm of the galaxy protoclusters

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