Galaxy and Mass Assembly (GAMA): Optimal Tiling of Dense Surveys with a Multi-Object Spectrograph

AbstractA heuristic greedy algorithm is developed for efficiently tiling spatially dense redshift surveys. In its first application to the Galaxy and MassAssembly (GAMA) redshift survey we find it rapidly improves the spatial uniformity of our data, and naturally corrects for any spatial bias introduced by the 2dF multi-object spectrograph. We make conservative predictions for the final state of the GAMA redshift survey after our final allocation of time, and can be confident that even if worse than typical weather affects our observations, all of our main survey requirements will be met.

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PROBING COSMIC ACCELERATION WITH GALAXY REDSHIFT SURVEYS

International Journal of Modern Physics D ◽

10.1142/s0218271811020263 ◽

2011 ◽

Vol 20 (10) ◽

pp. 2109-2113

Author(s):

LUIGI GUZZO

Keyword(s):

Modern Science ◽

Short Review ◽

Cosmic Acceleration ◽

Acoustic Oscillations ◽

Redshift Surveys ◽

The Galaxy ◽

Type Ia ◽

Redshift Survey ◽

Alternative Scenarios ◽

Ia Supernovae

Redshift surveys of galaxies beyond the local Universe (z ≫ 0.1) are opening up new possibilities to understanding the observed acceleration of cosmic expansion, one of the greatest mysteries of modern science. Baryonic Acoustic Oscillations in the galaxy power spectrum (or correlation function), provide us with a standard rod to measure the expansion history H(z). At the same time, redshift-space distortions in the clustering pattern due to galaxy peculiar motions are a measure of the growth rate of structure f(z). The combination of these two quantities, allows us to distinguish whether cosmic acceleration is due to the existence of a "dark energy" in the cosmic budget, or rather requires a modification of General Relativity. These two radically alternative scenarios are degenerate when considering H(z) alone, as yielded, e.g. by the Hubble diagram of Type Ia supernovae. In this short review paper I will mostly concentrate on the latter measurement, whose potential importance in this context has been recently highlighted. Current results are consistent with the simplest GR-based cosmological constant scenario, but error bars are still large. Detailed forecasts show that next-generation deep surveys optimizing the combination of large volumes and good galaxy sampling will be able to use redshift distortions as a key tool to understand the physical origin of cosmic acceleration. Among these, I introduce the newly started VIMOS Public Extragalactic Redshift Survey (VIPERS) at the ESO VLT, which is building at [Formula: see text] a sample comparable to the local 2dFGRS. Expectations from even larger surveys planned from space-borne observatories such as EUCLID will also be mentioned.

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Direct Shear Mapping: Prospects for Weak Lensing Studies of Individual Galaxy–Galaxy Lensing Systems

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2015.39 ◽

2015 ◽

Vol 32 ◽

Author(s):

C. O. de Burgh-Day ◽

E. N. Taylor ◽

R. L. Webster ◽

A. M. Hopkins

Keyword(s):

Weak Lensing ◽

Mapping Technique ◽

Direct Shear ◽

Redshift Galaxy ◽

The Galaxy ◽

Redshift Survey ◽

Mass Assembly ◽

Using Data ◽

Spectrally Resolved ◽

Good Agreement

AbstractUsing both a theoretical and an empirical approach, we have investigated the frequency of low redshift galaxy-galaxy lensing systems in which the signature of 3D weak lensing might be directly detectable. We find good agreement between these two approaches. Using data from the Galaxy and Mass Assembly redshift survey we estimate the frequency of detectable weak lensing at low redshift. We find that below a redshift of z ~ 0.6, the probability of a galaxy being weakly lensed by γ ⩾ 0.02 is ~ 0.01. We have also investigated the feasibility of measuring the scatter in the M* − Mh relation using shear statistics. We estimate that for a shear measurement error of Δγ = 0.02 (consistent with the sensitivity of the Direct Shear Mapping technique), with a sample of ~$50,000 spatially and spectrally resolved galaxies, the scatter in the M* − Mh relation could be measured. While there are currently no existing IFU surveys of this size, there are upcoming surveys that will provide this data (e.g The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), surveys with Hector, and the Square Kilometre Array (SKA)).

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Optical Redshift Surveys

Highlights of Astronomy ◽

10.1017/s1539299600010030 ◽

1992 ◽

Vol 9 ◽

pp. 681-683

Author(s):

L. Nicolaci da Costa

Keyword(s):

Large Scale ◽

Current Status ◽

Redshift Surveys ◽

Galaxy Distribution ◽

The Galaxy ◽

Redshift Survey ◽

Different Depths ◽

Source Of Information ◽

The Universe

Redshift surveys of galaxies have been over the past decade the major source of information for studies of the large-scale structure of the Universe. Following the completion of the original CfA Redshift Survey, several groups have joined the endeavor, probing different regions of the sky to different depths in a remarkable long-term effort to study the nature of the galaxy distribution and its statistical properties at different scales. Here I summarize the current status of the ongoing surveys drawn from optical galaxy catalogs. The review is not intended to be complete but rather to demonstrate the vitality of the area and to point out that exciting new data should be forthcoming in the next few years.

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Testing Cosmological Models with Clusters of Galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900132553 ◽

1999 ◽

Vol 183 ◽

pp. 221-228

Author(s):

S. Gottlöber ◽

J. Retzlaff ◽

A. Klypin

Keyword(s):

Statistical Tests ◽

Large Fraction ◽

Mass Scale ◽

Clusters Of Galaxies ◽

Matter Distribution ◽

Redshift Surveys ◽

The Galaxy ◽

Redshift Survey ◽

Formation And Evolution ◽

The Universe

Currently little is known about the mass distribution on intermediate scales between those probed by deep redshift surveys of galaxies and those probed by COBE. Catalogs of galaxy clusters reach depths of several hundred megaparsecs, and, thus, are very useful for those scales. Only the Las Campanas Redshift Survey (LCRS) is comparable with that depth. However, the LCRS samples only narrow slices whereas cluster catalogs cover a large fraction of the sky. Clusters seems to be the most suitable objects to fill the gap between scales probed by COBE and the galaxy samples. Moreover, clusters are advantageous over galaxies as probes of the matter distribution in the Universe because our understanding of its formation and evolution is better established than it is for galaxies. Clusters are high peaks (mass scaleM≃ 1015M⊙) in the density field, which have collapsed relatively recently. Because of that, it is easy to identify clusters in numerical simulations. But the number of clusters is much smaller than the number of galaxies, which makes the statistics of clusters noisier. Nevertheless, clusters are exceptionally useful objects for the investigation of the matter distribution on scales well above 100h–1Mpc. Thus, it is worth to apply different statistical tests to these objects.

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The Alignments of the Galaxy Spins with the Real‐Space Tidal Field Reconstructed from the 2MASS Redshift Survey

The Astrophysical Journal ◽

10.1086/523351 ◽

2007 ◽

Vol 671 (2) ◽

pp. 1248-1255 ◽

Cited By ~ 67

Author(s):

Jounghun Lee ◽

Pirin Erdogdu

Keyword(s):

Real Space ◽

The Real ◽

The Galaxy ◽

Redshift Survey

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The last breath of the Sagittarius dSph

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2114 ◽

2020 ◽

Vol 497 (4) ◽

pp. 4162-4182 ◽

Cited By ~ 3

Author(s):

Eugene Vasiliev ◽

Vasily Belokurov

Keyword(s):

Milky Way ◽

Dwarf Galaxy ◽

3D Structure ◽

Major Axis ◽

Final State ◽

Tidal Forces ◽

The Galaxy ◽

The Mean ◽

Red Clump ◽

Astrometric Data

ABSTRACT We use the astrometric and photometric data from Gaia Data Release 2 and line-of-sight velocities from various other surveys to study the 3D structure and kinematics of the Sagittarius dwarf galaxy. The combination of photometric and astrometric data makes it possible to obtain a very clean separation of Sgr member stars from the Milky Way foreground; our final catalogue contains 2.6 × 105 candidate members with magnitudes G < 18, more than half of them being red clump stars. We construct and analyse maps of the mean proper motion and its dispersion over the region ∼30 × 12 deg, which show a number of interesting features. The intrinsic 3D density distribution (orientation, thickness) is strongly constrained by kinematics; we find that the remnant is a prolate structure with the major axis pointing at ∼45° from the orbital velocity and extending up to ∼5 kpc, where it transitions into the stream. We perform a large suite of N-body simulations of a disrupting Sgr galaxy as it orbits the Milky Way over the past 2.5 Gyr, which are tailored to reproduce the observed properties of the remnant (not the stream). The richness of available constraints means that only a narrow range of parameters produce a final state consistent with observations. The total mass of the remnant is $\sim \!4\times 10^8\, \mathrm{M}_\odot$, of which roughly a quarter resides in stars. The galaxy is significantly out of equilibrium, and even its central density is below the limit required to withstand tidal forces. We conclude that the Sgr galaxy will likely be disrupted over the next Gyr.

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Galaxy And Mass Assembly (GAMA): assimilation of KiDS into the GAMA database

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1466 ◽

2020 ◽

Vol 496 (3) ◽

pp. 3235-3256 ◽

Cited By ~ 1

Author(s):

Sabine Bellstedt ◽

Simon P Driver ◽

Aaron S G Robotham ◽

Luke J M Davies ◽

Cameron R J Bogue ◽

...

Keyword(s):

Near Infrared ◽

Data Set ◽

The Galaxy ◽

Analysis Package ◽

Selection For ◽

Mass Assembly ◽

A New Technique ◽

Source Extraction ◽

Homogeneous Data

ABSTRACT The Galaxy And Mass Assembly Survey (GAMA) covers five fields with highly complete spectroscopic coverage (>95 per cent) to intermediate depths (r < 19.8 or i < 19.0 mag), and collectively spans 250 deg2 of equatorial or southern sky. Four of the GAMA fields (G09, G12, G15, and G23) reside in the European Southern Observatory (ESO) VST KiDS and ESO VISTA VIKING survey footprints, which combined with our GALEX, WISE, and Herschel data provide deep uniform imaging in the $FUV/NUV/u/g/r/i/Z/Y/J/H/K_s/W1/W2/W3/W4/P100/P160/S250/S350/S500$ bands. Following the release of KiDS DR4, we describe the process by which we ingest the KiDS data into GAMA (replacing the SDSS data previously used for G09, G12, and G15), and redefine our core optical and near-infrared (NIR) catalogues to provide a complete and homogeneous data set. The source extraction and analysis is based on the new ProFound image analysis package, providing matched-segment photometry across all bands. The data are classified into stars, galaxies, artefacts, and ambiguous objects, and objects are linked to the GAMA spectroscopic target catalogue. Additionally, a new technique is employed utilizing ProFound to extract photometry in the unresolved MIR–FIR regime. The catalogues including the full FUV–FIR photometry are described and will be fully available as part of GAMA DR4. They are intended for both standalone science, selection for targeted follow-up with 4MOST, as well as an accompaniment to the upcoming and ongoing radio arrays now studying the GAMA 23h field.

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N-body Simulations to Test the Reliability of Two-point Correlation Functions of Galaxies

Highlights of Astronomy ◽

10.1017/s1539299600010108 ◽

1992 ◽

Vol 9 ◽

pp. 703-704

Author(s):

Yasushi Suto

Keyword(s):

Correlation Functions ◽

Large Scale ◽

Sample Volume ◽

Limited Data ◽

Observable Universe ◽

Large N ◽

The Galaxy ◽

Point Correlation ◽

Systematic Biases ◽

Redshift Survey

The shape and amplitude of the galaxy – galaxy correlation functions, ξgg(r), are among the most widely used measures of the large-scale structure in the universe (Totsuji & Kihara 1969). The estimates, however, might be seriously affected by the limited size of the sample volume, or equivalently, the limited number of available galaxies. In fact, while the observable universe extends c/H0 ~ 3000h-1Mpc, most observational works to map the distribution of galaxies so far have been mainly applied to samples within ~ 100h-1Mpc from us. Thus a CfA redshift survey slice, for example, of 8h < α < 17h, 26.5° < δ < 32.5°, and cz ≾ 15000km/sec (de Lapparent et al. 1986, 1988) represents merely ~ 2 x 10-5 of the total volume of the observable universe. This clearly illustrates the importance of examining possible systematic biases and variations in the estimates of two-point correlation functions from instrinsically limited data. We studied such sample-to-sample variations by analysing subsamples extracted from large N-body simulation data.

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Probing the Redshift Desert Using the Gemini Deep Deep Survey: Observing Galaxy Mass Assembly at z > 1

Symposium - International Astronomical Union ◽

10.1017/s0074180900196822 ◽

2005 ◽

Vol 216 ◽

pp. 390-397

Author(s):

Karl Glazebrook ◽

Keyword(s):

Spectroscopic Studies ◽

Star Forming ◽

Hubble Sequence ◽

First Results ◽

Deep Survey ◽

Redshift Survey ◽

Mass Assembly ◽

Galaxy Assembly ◽

First Time ◽

The Universe

The aim of the Gemini Deep Deep Survey is to push spectroscopic studies of complete galaxy samples (both red and blue objects) significantly beyond z = 1; this is the redshift where the current Hubble sequence of ellipticals and spirals is already extant. In the Universe at z = 2 the only currently spectroscopically confirmed galaxies are blue, star-forming and of fragmented morphology. Exploring this transition means filling the ‘redshift desert’ 1 < z < 2 where there is a dearth of spectroscopic measurements. To do this we need to secure redshifts of the oldest, reddest galaxies (candidate ellipticals) beyond z > 1 which has led us to carry out the longest exposure redshift survey ever done: 100 ksec spectroscopic MOS exposures with GMOS on Gemini North. We have developed an implementation of the CCD “nod & shuffle” technique to ensure precise sky-subtraction in these ultra-deep exposures. At the halfway mark the GDDS now has ∼ 36 galaxies in the redshift desert 1.2 < z < 2 extending up to z = 1.97 and I < 24.5 with secure redshifts based on weak rest-frame UV absorption features complete for both red, old objects and young, blue objects. The peak epoch of galaxy assembly is now being probed by direct spectroscopic investigation for the first time. on behalf of the GDDS team I present our first results on the properties of galaxies in the ‘redshift desert’.

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