Perseus-Pisces Supercluster Research Articles

Updates on the Hotspot and the Perseus-Pisces supercluster Excess Observed by the Telescope Array Experiment

The Telescope Array (TA) experiment, the largest observatory studying ultra-high energy cosmic rays in the northern hemisphere, has reported evidence for two medium-scale anisotropies. The first, known as the TA hotspot, is an excess in the arrival direction distribution for events with energies greater than 5.7 × 1019 eV. More recently, an additional excess of events with energies greater than 1019.4 eV appearing in the direction of the Perseus-Pisces supercluster has been named the PPSC excess. In this presentation, we will update the status of the TA hotspot and the PPSC excess results using the most recent data measured by the TA surface detector array.

Infall Profiles for Supercluster-scale Filaments

We present theoretical expectations for infall toward supercluster-scale cosmological filaments, motivated by the Arecibo Pisces–Perseus Supercluster Survey (APPSS) to map the velocity field around the Pisces–Perseus Supercluster (PPS) filament. We use a minimum spanning tree applied to dark matter halos the size of galaxy clusters to identify 236 large filaments within the Millennium simulation. Stacking the filaments along their principal axes, we determine a well-defined, sharp-peaked velocity profile function that can be expressed in terms of the maximum infall rate V max and the distance ρ max between the location of maximum infall and the principal axis of the filament. This simple, two-parameter functional form is surprisingly universal across a wide range of linear mass densities. V max is positively correlated with the halo mass per length along the filament, and ρ max is negatively correlated with the degree to which the halos are concentrated along the principal axis. We also assess an alternative, single-parameter method using V 25, the infall rate at a distance of 25 Mpc from the axis of the filament. Filaments similar to the PPS have 116 km s−1, Mpc, and V 25 = 329 ± 68 km s−1. We create mock observations to model uncertainties associated with viewing angle, lack of three-dimensional velocity information, limited sample size, and distance uncertainties. Our results suggest that it would be especially useful to measure infall for a larger sample of filaments to test our predictions for the shape of the infall profile and the relationships among infall rates and filament properties.

The Cosmic Large-Scale Structure in X-rays (CLASSIX) Cluster Survey

It is important to map the large-scale matter distribution in the local Universe for cosmological studies, such as the tracing of the large-scale peculiar velocity flow, the characterisation of the environment for different astronomical objects, and for precision measurements of cosmological parameters. We used X-ray luminous clusters to map this matter distribution and find that about 51% of the groups and clusters are members of superclusters which occupy only a few percent of the volume. In this paper we provide a detailed description of these large-scale structures. With a friends-to-friends algorithm, we find eight superclusters with a cluster overdensity ratio of at least two with five or more galaxy group and cluster members in the cosmic volume out to z = 0.03. The four most prominent ones are the Perseus-Pisces, the Centaurus, the Coma, and the Hercules supercluster, with lengths from about 40 to over 100 Mpc and estimated masses of 0.6 − 2.2 × 1016 M⊙. The largest of these structures is the Perseus-Pisces supercluster. The four smaller superclusters include the Local and the Abell 400 supercluster and two superclusters in the constellations Sagittarius and Lacerta. We provide detailed maps, member catalogues, and physical descriptions of the eight superclusters. By constructing superclusters with a range of cluster sub-samples with different lower X-ray luminosity limits, we show that the main structures are always reliably recovered.

The Cosmic Large-Scale Structure in X-rays (CLASSIX) Cluster Survey

The Perseus-Pisces supercluster is known as one of the largest structures in the nearby Universe that has been charted by the galaxy and galaxy cluster distributions. For the latter mostly clusters from the Abell catalogue have been used. Here we take a new approach to a quantitative characterisation of the Perseus-Pisces supercluster using a statistically complete sample of X-ray luminous galaxy groups and clusters from our CLASSIX galaxy cluster redshift survey. We used a friends-of-friends technique to construct the supercluster membership. We also studied the structure of the Southern Great Wall, which merges with the Perseus-Pisces supercluster with a slightly increased friends-of-friends linking length. In this work we discuss the geometric structure of the superclusters, compare the X-ray luminosity distribution of the members with that of the surroundings, and provide an estimate of the supercluster mass. These results establish Perseus-Pisces as the largest superstructure in the Universe at redshifts z ≤ 0.03. With the new data this supercluster extends through the zone of avoidance, which has also been indicated by some studies of the galaxy distribution by means of HI observations. We investigated whether the shapes of the member groups and clusters in X-rays are aligned with the major axis of the supercluster. We find no evidence for a pronounced alignment, except for the ellipticities of Perseus and AWM7, which are aligned with the separation vector of the two systems and weakly with the supercluster.

The Arecibo Pisces–Perseus Supercluster Survey. I. Harvesting ALFALFA

Abstract We report a multi-objective campaign of targeted 21 cm H i line observations of sources selected from the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) survey and galaxies identified by their morphological and photometric properties in the Sloan Digital Sky Survey. The aims of this program have been (1) to confirm the reality of some ALFALFA sources whose enigmatic nature suggest additional multiwavelength observations; (2) to probe the low signal-to-noise ratio (S/N) regime, below the ALFALFA reliability limit; and (3) to explore the feasibility of using optical morphology, color, and surface brightness to identify gas-rich objects in the region of the Pisces–Perseus Supercluster (PPS) whose H i fluxes are below the ALFALFA sensitivity limit at that distance. As expected, the reliability of ALFALFA detections depends strongly on the S/N of the H i line signal and its coincidence with a probable stellar counterpart identified by its optical properties, suggestive of ongoing star formation. The identification of low-mass, star-forming populations enables targeted H i line observations to detect galaxies with H i line fluxes below the ALFALFA sensitivity limits in fixed local volumes (D < 100 Mpc). The method explored here serves as the basis for extending the sample of gas-bearing objects as part of the ongoing Arecibo Pisces–Perseus Supercluster Survey (APPSS).

The Nançay H i Zone of Avoidance survey of 2MASS bright galaxies

To complement the 2MASS Redshift Survey (2MRS) and the 2MASS Tully-Fisher survey (2MTF) a search for 21cm HI line emission of 2MASS bright galaxy candidates has been pursued along the dust-obscured plane of the Milky Way with the 100m Nancay Radio Telescope. For our sample selection we adopted an isophotal extinction-corrected K-band magnitude limit of $K_s^o = 11.25$mag, corresponding to the first 2MRS data release and 2MTF, for which the 2MASX completeness level remains fairly constant deep into the Zone of Avoidance (ZoA). About one thousand galaxies without prior redshift measurement accessible from Nancay (Dec > -40\deg) were observed to an rms noise level of ~3 mJy for the velocity range -250 to 10'600 km/s. This resulted in 220 clear and 12 marginal detections of the target sample. Only few detections have redshifts above 8000 km/s due to recurring radio frequency interference (RFI). A further 29 detections and 6 marginals have their origin in non-target galaxies in the telescope beam. The newly detected galaxies are on average considerably more \HI-rich (mostly $10^9 - 10^{10}$M$_\odot$) compared to systematic (blind) HI surveys. The HI detections reveal various new filaments crossing the mostly uncharted northern ZoA (e.g. at $\ell \sim 90\deg, 130\deg, 160\deg$), whilst consolidating galaxy agglomerations in Monoceros and Puppis ($\ell \sim 220\deg, 240\deg$). Considerably new insight has been gained about the extent of the Perseus-Pisces Supercluster through the confirmation of a ridge ($\ell \sim 160\deg$) encompassing the 3C129 cluster that links Perseus-Pisces to Lynx, and the continuation of the second Perseus-Pisces arm ($\ell \sim 90\deg$) across the ZoA.

ПРИСКОРЕННЯ ТА ПОШИРЕННЯ КОСМІЧНИХ ПРОМЕНІВ НАДВИСОКИХ ЕНЕРГІЙ У ЛОКАЛЬНОМУ ВСЕСВІТІ

Distribution of matter in the Local Universe (up to ~ 100 Mpc), especially in a Virgo Supercluster region (~20 Mpc) is strongly nonuniform and includes all elements of large scale structure: galaxies and their clusters, superclusters, filaments, sheets and voids. On its smallest scale, our Galaxy and its similar galaxy M31 (Andromeda Nebula) at a distance 770 kpc, together with dozens of dwarf galaxies, form the Local Group of Galaxies. Local group contained in Local Sheet – suchlike pancake concentration of galaxies with radius about 5 Mpc and thickness 1.5 Mpc. This structure is a part of Local Filament – cylindrical region with higher density of matter, that join us to more powerful filament, that concludes Virgo Supercluster and connects two highest matter concentrations in Local Universe – supercluster Great Attractor (70 Mpc) and Perseus-Pisces supercluster (60 Mpc). Extragalactic magnetic field (EGMF) distribution is expected to follow the baryonic matter density distribution. Ultra high energy cosmic rays (UHECRs, E>1018 eV) from extragalactic sources will undergo significant deviations in EGMF, which makes it difficult to search their sources. But for extremely high energy cosmic rays (EHECRs, E>5·1019 eV), that are on the top of cosmic rays energy spectrum (the biggest detected energy of cosmic rays is above 1020 eV), influence of EGMF can be negligible, and their arrival direction can correlate with source position. They carry an important information, about the physics of fundamental interactions beyond the standard model, but still unknown to their origins and mechanisms of acceleration. In addition, a flux of nuclear component of UHECRs decreases in result of nuclear photo-disintegration due to interaction with microwave and infrared background. These processes are significant for protons (hydrogen nuclei), for which the major losses are born of electron-positron pairs and photo-pions reactions. For multi nucleon nucleuses significant process of weakening is photo-disintegration with chemical composition change of main nuclei. In our work we estimate the influence of these factors on the propagation of the UHECRs from sources in the Local Universe, in particular we have investigated the mean free path and magnetic deflection of H(p), He, O, Si and Fe nuclei. For potential sources of UHECRs in the Local Universe, such as Virgo supercluster, Great Attractor and Perseus-Pisces supercluster, we have estimated types and energies of nuclei that can reach the Earth, and, in the same time, can save a connection of arrival directions with source position within 1 rad.

The WSRT ZoA Perseus-Pisces filament wide-field H i imaging survey – I. H i catalogue and atlas

We present results of a blind 21cm HI-line imaging survey of a galaxy overdensity located behind the Milky Way at $\ell,b$ $\approx$ 160 deg, 0.5 deg. The overdensity corresponds to a Zone-of-Avoidance crossing of the Perseus-Pisces Supercluster filament. Although it is known that this filament contains an X-ray galaxy cluster (3C129) hosting two strong radio galaxies, little is known about galaxies associated with this potentially rich cluster because of the high Galactic dust extinction. We mapped a sky area of $\sim$9.6 sq.deg using the Westerbork Synthesis Radio Telescope in a hexagonal mosaic of 35 pointings observed for 12 hours each, in the radial velocity range $cz = 2400 - 16600$ km/s. The survey has a sensitivity of 0.36 mJy/beam rms at a velocity resolution of 16.5 km/s. We detected 211 galaxies, 62% of which have a near-infrared counterpart in the UKIDSS Galactic Plane Survey. We present a catalogue of the HI properties and an HI atlas containing total intensity maps, position-velocity diagrams, global HI profiles and UKIDSS counterpart images. For the resolved galaxies we also present HI velocity fields and radial HI surface density profiles. A brief analysis of the structures outlined by these galaxies finds that 87 of them lie at the distance of the Perseus-Pisces Supercluster ($cz \sim 4000 - 8000$ km/s) and seem to form part of the 3C129 cluster. Further 72 detections trace an overdensity at a velocity of $cz \approx$ 10000 km/s and seem to coincide with a structure predicted from mass density reconstructions in the first 2MASS Redshift Survey.

DISCOVERY OF AN ULTRA-DIFFUSE GALAXY IN THE PISCES-PERSEUS SUPERCLUSTER

ABSTRACT We report the discovery of DGSAT I, an ultra-diffuse, quenched galaxy located 10.°4 in projection from the Andromeda galaxy (M31). This low-surface brightness galaxy (μ V = 24.8 mag arcsec−2), found with a small amateur telescope, appears unresolved in sub-arcsecond archival Subaru/Suprime-Cam images, and hence has been missed by optical surveys relying on resolved star counts, in spite of its relatively large effective radius (R e (V) = 12″) and proximity (15′) to the well-known dwarf spheroidal galaxy And II. Its red color (V − I = 1.0), shallow Sérsic index (n V = 0.68), and the absence of detectable Hα emission are typical properties of dwarf spheroidal galaxies and suggest that it is mainly composed of old stars. Initially interpreted as an interesting case of an isolated dwarf spheroidal galaxy in the local universe, our radial velocity measurement obtained with the BTA 6 m telescope (V h = 5450 ± 40 km s−1) shows that this system is an M31-background galaxy associated with the filament of the Pisces-Perseus supercluster. At the distance of this cluster (∼78 Mpc), DGSAT I would have an R e ∼ 4.7 kpc and M V ∼ −16.3. Its properties resemble those of the ultra-diffuse galaxies (UDGs) recently discovered in the Coma cluster. DGSAT I is the first case of these rare UDGs found in this galaxy cluster. Unlike the UDGs associated with the Coma and Virgo clusters, DGSAT I is found in a much lower density environment, which provides a fresh constraint on the formation mechanisms for this intriguing class of galaxy.

Wide field polarimetry around the Perseus cluster at 350 MHz

This paper investigates the fascinating diffuse polarization structures at 350 MHz that have previously been tentatively attributed to the Perseus cluster and, more specifically, tries to find out whether the structures are located at (or near) the Perseus cluster, or in the Milky Way. A wide field, eight point Westerbork Synthesis Radio Telescope mosaic of the area around the Perseus cluster was observed in full polarization. The frequency range was 324 to 378 MHz and the resolution of the polarization maps was 2'x3'. The maps were processed using Faraday rotation measure synthesis to counter bandwidth depolarization. The RM-cube covers Faraday depths of -384 to +381 rad m^{-2} in steps of 3 rad m^{-2}. There is emission all over the field at Faraday depths between -50 and +100 rad m^{-2}. All previously observed structures were detected. However, no compelling evidence was found supporting association of those structures with either the Perseus cluster or large scale structure formation gas flows in the Perseus-Pisces super cluster. On the contrary, one of the structures is clearly associated with a Galactic depolarization canal at 1.41 GHz. Another large structure in polarized intensity, as well as Faraday depth at a Faraday depth of +30 rad m^{-2}, coincides with a dark object in WHAM H-alpha maps at a kinematic distance of 0.5 \pm 0.5 kpc. All diffuse polarized emission at 350 MHz towards the Perseus cluster is most likely located within 1 kpc from the Sun. The layers that emit the polarized radiation are less than 40 pc/B|| thick.

Delaunay Tessellation Field Estimator analysis of the PSCz local Universe: density field and cosmic flow

We apply the Delaunay Tessellation Field Estimator (DTFE) to reconstruct and analyse the matter distribution and cosmic velocity flows in the local Universe on the basis of the PSCz galaxy survey. The prime objective of this study is the production of optimal resolution 3D maps of the volume-weighted velocity and density fields throughout the nearby universe, the basis for a detailed study of the structure and dynamics of the cosmic web at each level probed by underlying galaxy sample. Fully volume-covering 3D maps of the density and (volume-weighted) velocity fields in the cosmic vicinity, out to a distance of 150 h(-1) Mpc, are presented. Based on the Voronoi and Delaunay tessellation defined by the spatial galaxy sample, DTFE involves the estimate of density values on the basis of the volume of the related Delaunay tetrahedra and the subsequent use of the Delaunay tessellation as natural multidimensional (linear) interpolation grid for the corresponding density and velocity fields throughout the sample volume. The linearized model of the spatial galaxy distribution and the corresponding peculiar velocities of the PSCz galaxy sample, produced by Branchini et al., forms the input sample for the DTFE study. The DTFE maps reproduce the high-density supercluster regions in optimal detail, both their internal structure as well as their elongated or flattened shape. The corresponding velocity flows trace the bulk and shear flows marking the region extending from the Pisces-Perseus supercluster, via the Local Superclusters, towards the Hydra-Centaurus and the Shapley concentration. The most outstanding and unique feature of the DTFE maps is the sharply defined radial outflow regions in and around underdense voids, marking the dynamical importance of voids in the local Universe. The maximum expansion rate of voids defines a sharp cut-off in the DTFE velocity divergence probability distribution function. We found that on the basis of this cut-off DTFE manages to consistently reproduce the value of Omega(m) approximate to 0.35 underlying the linearized velocity data set.

The Galaxy Distribution Function from the 2MASS Survey

We determine the spatial distribution function of galaxies from a wide range of samples in the 2MASS survey. The results agree very well with the form of the distribution predicted by the theory of cosmological gravitational many-body galaxy clustering. On large scales we find a value of the clustering parameter b = 0.867 +/- 0.026, in agreement with b = 0.83 +/- 0.05 found previously for the Pisces-Perseus supercluster. We measure b(theta) as a function of scale, since this is a powerful test of the applicability of computer simulations. The results suggest that when galaxies clustered they were usually surrounded by individual, rather than by communal haloes.

Spatial distribution of galaxies in the Puppis region

We determine the spatial distribution of the galaxies located behind the part of the zone of avoidance of the Milky Way defined by 220° < l < 260°, |b| < 20°, δ ≤ 0°, up to a distance of 8000 km s -1 . We use a sample of 369 galaxies with measured redshifts, of which 97 have been detected with the Nancay radio telescope. We show that our sample can be considered to be complete in apparent diameter down to 1.9 arcmin, a property that allows us to correct the density of galaxies for the loss of objects with distance. We then search for groups of galaxies using a companionship method and find 12 groups with at least five members, of which five are new. The members of one group are H I deficient by a factor of 1.6 on average. The method is then used to search for large structures and allows us to characterize the Puppis wall at 1400 < V 0 < 2600 km s -1 ; it is 30 Mpc long, with the main axis being parallel to the sky plane, and it connects the Antlia cluster to the Fornax cluster through the zone of avoidance. The density of galaxies in the wall is approximately 20 times the general density of galaxies, i.e. half that observed in the densest part of the Pisces-Perseus supercluster. No internal motions are found along the line of sight, indicating that the Puppis wall has not yet collapsed.

Constrained Simulations of the Real Universe: The Local Supercluster

We present cosmological simulations that closely mimic the real uiverse within ~100 Mpc of the Local Group. The simulations, called constrained simulations, reproduce the large-scale density field with major nearby structures, including the Local Group, the Coma and Virgo Clusters, the Great Attractor, the Perseus-Pisces Supercluster, and the Local Supercluster, in approximately correct locations. The MARK III survey of peculiar velocities of the observed structures inside an 80 h-1 Mpc sphere is used to constrain the initial conditions. Fourier modes on scales larger than a (Gaussian) resolution of ≈Rg = 5 h-1 Mpc are dominated by the constraints, while small-scale waves are essentially random. The main aim of this paper is the structure of the Local Supercluster region (LSC; ~30 h-1 Mpc around the Virgo Cluster) and the Local Group environment. We find that at the current epoch most of the mass (≈7.5 × 1014 h-1 M☉) of the LSC is located in a filament roughly centered on the Virgo Cluster and extending over ~40 h-1 Mpc. The simulated Local Group (LG) is located in an adjacent smaller filament, which is not a part of the main body of the LSC and has a peculiar velocity of ≈250 km s-1 toward the Virgo Cluster. The peculiar velocity field in the LSC region is complicated and is drastically different from the field assumed in the Virgocentric infall models. We find that the peculiar velocity flow in the vicinity of the LG in the simulation is relatively "cold": the peculiar line-of-sight velocity dispersion within 7 h-1 Mpc of the LG is ≲60 km s-1, comparable to the observed velocity dispersion of nearby galaxies.

The bulk motion of flat edge-on galaxies based on 2MASS photometry

We report the results of applying the 2MASS Tully-Fisher (TF) relations to study the galaxy bulk flows. For 1141 all-sky distributed flat RFGC galaxies we construct J, H, K_s TF relations and find that Kron $J_{fe}$ magnitudes show the smallest dispersion on the TF diagram. For the sample of 971 RFGC galaxies with V_{3K} < 18000 km/s we find a dispersion $\sigma_{TF}=0.42^m$ and an amplitude of bulk flow V= 199 +/-61 km/s, directed towards l=301 degr +/-18 degr, b=-2 degr +/-15 degr. Our determination of low-amplitude coherent flow is in good agreement with a set of recent data derived from EFAR, PSCz, SCI/SCII samples. The resultant two- dimensional smoothed peculiar velocity field traces well the large-scale density variations in the galaxy distributions. The regions of large positive peculiar velocities lie in the direction of the Great Attractor and Shapley concentration. A significant negative peculiar velocity is seen in the direction of Bootes and in the direction of the Local void. A small positive peculiar velocity (100 -- 150 km/s) is seen towards the Pisces-Perseus supercluster, as well as the Hercules - Coma - Corona Borealis supercluster regions.

Kinematics of the local universe

The matter distribution around the Perseus-Pisces (PP) supercluster is studied by comparing peculiar velocities given by the Kinematics of the local universe (KLUN) galaxy sample to those predicted by Tolman-Bondi (TB) models. To restrict the TB solutions we first solve the mass of the densest part of PP. This part is identified as a sphere at , Mpc having a radius of Mpc. This sphere surrounds the main part of the PP ridge and four most prominent clusters of the region. Using virial-like mass estimators we calculate the cluster masses and obtain the upper and lower limits for the mass inside the Mpc sphere: -. This corresponds to a mass overdensity , or -. Mass to light ratios of the clusters are 200 -600 , giving mass density ratio -0.3, if the value of is assumed to be representative elsewhere in the universe. We estimate a radial density distribution around the PP core using two toy models and a smoothed density distribution observed for IRAS galaxies. The cosmological density parameters and the PP mass are free parameters in the TB calculations. The KLUN velocities, obtained by Tully-Fisher relation and the normalized distance method, are adjusted by the Local Group (LG) infall velocity towards PP. Comparison of the TB velocities to KLUN data points indicates that the infall velocity km s-1. Allowing MPP to vary within the limits given above we get constraints for the value of ; -0.4 are prefered to the more extreme values, or 1. A choice of either or 0 do not cause any significant changes in the results. The validity of the TB model in complex environments is studied with an N-body simulation. There we see that the radially averaged velocity fields around simulated clusters are compatible with the corresponding TB velocities. This confirms the applicability of the TB model around large galaxy concentrations, providing that smoothed density and radially averaged velocity fields are used.

The Beta Problem: A Study of Abell 262

We present an investigation of the dynamical state of the cluster A262. Existing optical line-of-sight velocities for select cluster galaxies have been augmented by new data obtained with the Automated Multi-Object Spectrograph at Lick Observatory. We find evidence for a virialized early-type population distinct from a late-type population infalling from the Pisces-Perseus supercluster ridge. We also report on a tertiary population of low-luminosity galaxies the velocity dispersion of which distinguishes them from both the early- and late-type galaxies. We supplement our investigation with an analysis of archival X-ray data. A temperature is determined using ASCA GIS data, and a gas profile is derived from ROSAT HRI data. The increased statistics of our sample results in a picture of A262 with significant differences from earlier work. A previously proposed solution to the "β-problem" in A262 in which the gas temperature is significantly higher than the galaxy temperature is shown to result from using too low a velocity dispersion for the early-type galaxies. Our data present a consistent picture of A262 in which there is no "β-problem," and the gas and galaxy temperature are roughly comparable. There is no longer any requirement for extensive galaxy-gas feedback to drastically overheat the gas with respect to the galaxies. We also demonstrate that entropy floor models can explain the recent discovery that the β values determined by cluster gas and the cluster core radii are correlated.

Signatures in a Giant Radio Galaxy of a Cosmological Shock Wave at Intersecting Filaments of Galaxies

Sensitive images of low-level, Mpc-sized radio cocoons offer new opportunities to probe large scale intergalactic gas flows outside clusters of galaxies. New radio images of high surface brightness sensitivity at strategically chosen wavelengths of the giant radio galaxy NGC 315 (Mack et al. 1997,1998) reveal significant asymmetries and particularities in the morphology, radio spectrum and polarization of the ejected radio plasma. We argue that the combination of these signatures provides a sensitive probe of an environmental shock wave. Analysis of optical redshifts in NGC 315 vicinity confirms its location to be near, or at a site of large-scale flow collisions in the 100 Mpc sized Pisces-Perseus Supercluster region. NGC 315 resides at the intersection of several galaxy filaments, and its radio plasma serves there as a `weather station' (Burns 1998) probing the flow of the elusive and previously invisible IGM gas. If our interpretation is correct, this is the first indication for a shock wave in flows caused by the cosmological large scale structure formation, which is located in a filament of galaxies. The possibility that the putative shock wave is a source of gamma-rays and ultra high energy cosmic rays is briefly discussed.

Evidence for dark matter on different scales from the KLUN galaxy sample

The KLUN (Kinematics of the Local UNiverse) sample of 6600 spiral galaxies is used in studying dark matter on different scales: •The Morphological Type dependence of the zero-point of the Tully-Fisher relation indicates mass to light ratio M/L ≈ 9 − 16 on galactic scales.•Preliminary results from a study of selection effects influencing double galaxies give a larger value M/L ≈ 30 − 50.•Study of the Perseus-Pisces supercluster, using Malmquist bias corrected TF distances and Tolman-Bondi solutions indicates M/L ≈ 200 − 600 for large clusters. Similar results were obtained in our previous work on Virgo galaxies.•Application of a modified version of Sandage-Tammann-Hardy test of the linearity of Hubble law inside the observed hierarchical (fractal) galaxy distribution up to 200 Mpc suggests that either Ω0 is very small (0.01) or the major part of the matter is uniformly distributed dark matter.

The CfA Redshift Survey: Data for the South Galactic Cap

We present redshifts for a sample of 4391 galaxies with magnitude mB(0) ≤ 15.5 covering 20h ≤ α ≤ 4h in right ascension and -25 ≤ δ ≤ 90° in declination. This sample is complete for all galaxies in the merge of the Zwicky et al. and Nilson catalogs in the south Galactic cap. Redshifts for 2964 of these were measured as part of the second CfA Redshift Survey. The data reveal large voids in the foreground and background of the Perseus-Pisces Supercluster. The largest of these voids lies at a mean velocity ~8000 km s-1, has diameter ~5000 km s-1, and is enclosed by a complex of dense structures. The large structure known as the Perseus-Pisces Supercluster forms the near side of this complex. On the far side of this large void, at a mean velocity ~12,000 km s-1, there is another coherent dense wall. The structures in this survey support the view that galaxies generally lie on surfaces surrounding or nearly surrounding low-density regions or voids.