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Papers by Ariel Zandivarez
Se analizara la evolucion de la estructura en el Universo desde los puntos de vista numerico, est... more Se analizara la evolucion de la estructura en el Universo desde los puntos de vista numerico, estadistico y observacional dando una caracterizacion de las propiedades globales del Universo en Gran Escala. Para ello se analizaran los mayores catalogos de Galaxias existentes, nuevas observaciones y simulaciones numericas Cosmologicas de alta resolucion. Mediante la aplicacion de diferentes metodos capaces de proporcionar informacion util acerca de las propiedades del Universo, se pretende aportar significativamente a la comprension de la dinamica y la caracteristicas generales de Galaxias y sistemas de Galaxias.
VizieR Online Data Catalog, Apr 1, 2015
Boletin de la Asociacion Argentina de Astronomia La Plata Argentina, 2002
Monthly Notices of the Royal Astronomical Society, Feb 24, 2021
Boletin de la Asociacion Argentina de Astronomia La Plata Argentina, Jul 1, 2021
Summary: Treatment of boutonniere Dupuytren disease is rare and is resistant to treatment because... more Summary: Treatment of boutonniere Dupuytren disease is rare and is resistant to treatment because of altered tendon dynamics. The authors used a small dose of collagenase clostridium histolyticum for an enzymatic tenotomy of the distal interphalangeal joint and showed that hyperextension at the distal interphalangeal joint improved significantly. Fifteen patients with boutonniere Dupuytren disease with severe proximal interphalangeal joint contractures averaging -69 degrees of extension were included in the study. Ten patients had at least one previous intervention, including surgical fasciectomy, Digit Widget treatment, and needle aponeurotomy. Collagenase clostridium histolyticum enzymatic tenotomy was performed in-office as a wide-awake procedure. All patients received varying doses of collagenase clostridium histolyticum for volar Dupuytren disease enzymatic fasciotomy and 0.1 mg of collagenase clostridium histolyticum into the distal extensor tendon for tenotomy to treat boutonniere deformity at the same time. Collagenase clostridium histolyticum enzymatic tenotomy significantly improved total active motion of the finger by 41.0 degrees (p = 0.001). Loss of extension at both the metacarpophalangeal joint and the proximal interphalangeal joint also improved with gains of 11.7 (p = 0.04) and 20.7 degrees (p = 0.0005) of extension, respectively. The average distal interphalangeal joint hyperextension was improved from 29.7 degrees to 14.0 degrees (p = 0.002). The authors show that collagenase injection led to significant average improvement in joint contracture at all finger joints and significantly increased the arc of motion at the proximal interphalangeal joint and metacarpophalangeal joint. Although collagenase has been previously used for flexion contractures in Dupuytren disease, we believe it has a role in treating the distal interphalangeal joint hyperextension deformity associated with boutonniere deformity in Dupuytren disease as well. Clinical question/level of evidence: Therapeutic, IV.
We identify compact groups in the Sloan Digital Sky Survey (SDSS) using an algorithm similar to t... more We identify compact groups in the Sloan Digital Sky Survey (SDSS) using an algorithm similar to that developed by Lee et al. (2003, astro-ph 0312553). Given that some authors claim compact groups to be chance alignments of galaxies or diffuse galaxy groups cores (Zandivarez et al. 2003, MNRAS, 340, 1400), our intention is to make a statistical study of the
Monthly Notices of the Royal Astronomical Society
Compact groups of galaxies are devised as extreme environments where interactions may drive galax... more Compact groups of galaxies are devised as extreme environments where interactions may drive galaxy evolution. In this work, we analysed whether the luminosities of galaxies inhabiting compact groups differ from those of galaxies in loose galaxy groups. We computed the luminosity functions of galaxy populations inhabiting a new sample of 1412 Hickson-like compact groups of galaxies identified in the Sloan Digital Sky Survey Data Release 16. We observed a characteristic absolute magnitude for galaxies in compact groups brighter than that observed in the field or loose galaxy systems. We also observed a deficiency of faint galaxies in compact groups in comparison with loose systems. Our analysis showed that the brightening is mainly due to galaxies inhabiting the more massive compact groups. In contrast to what is observed in loose systems, where only the luminosities of Red (and Early) galaxies show a dependency with group mass, luminosities of Red and Blue (also Early and Late) galax...
Monthly Notices of the Royal Astronomical Society, Feb 7, 2023
Monthly Notices of the Royal Astronomical Society, 2022
Many catalogues of isolated compact groups of galaxies (CGs) have been extracted using Hickson’s ... more Many catalogues of isolated compact groups of galaxies (CGs) have been extracted using Hickson’s criteria to identify isolated, dense systems of galaxies, with at least three or four galaxies concordant in magnitude and redshift. But is not clear to what extent the catalogues of CGs are complete and reliable, relative to 3D truly isolated, dense groups. Using five different semi-analytical models of galaxy formation (SAMs), we identify isolated dense groups in 3D real space, containing at least three galaxies. We then build mock redshift space galaxy catalogues and run a Hickson-like CG finder. We find that the Hickson-like algorithm in redshift space is poor at recovering 3D CGs of at least three galaxies, with a purity of sim10rmper,cent\sim 10{{\ \rm per \, cent}}sim10rmper,cent and a completeness of sim22rmper,cent\sim 22{{\ \rm per \, cent}}sim22rmper,cent. Among the sim90rmper,cent\sim 90{{\ \rm per \, cent}}sim90rmper,cent of spurious systems, typically 60rmpercent60{{\ \rm per\ cent}}60rmpercent are dense structures that failed the 3D isolation criteria, while the remaining $4...
Monthly Notices of the Royal Astronomical Society: Letters, 2011
Monthly Notices of the Royal Astronomical Society, 2019
Compact groups (CGs) of galaxies are defined as isolated and dense galaxy systems that appear to ... more Compact groups (CGs) of galaxies are defined as isolated and dense galaxy systems that appear to be a unique site of multiple galaxy interactions. Semi-analytical models (SAMs) of galaxy formation are a prime tool to understand CGs. We investigate how the frequency and the 3D nature of CGs depends on the SAM and its underlying cosmological parameters. Extracting nine light-cones of galaxies from five different SAMs and selecting CGs as in observed samples, we find that the frequency and nature of CGs depends strongly on the cosmological parameters. Moving from the WMAP1 to the WMAP7 and Planck cosmologies (increasing density of the Universe and decreasing normalization of the power spectrum), the space density of CGs is decreased by a factor 2.5, while the fraction of CGs that are physically dense falls from 50 to 35 per cent. The lower σ8 leads to fewer dense groups, while the higher Ωm causes more chance alignments. However, with increased mass and spatial resolution, the fraction...
We have analysed the distribution of galaxies in groups identified in the largest redshift survey... more We have analysed the distribution of galaxies in groups identified in the largest redshift surveys at the present: the final release of the 2dF Galaxy Redshift Survey and the first release of the Sloan Digital Sky Survey. Our work comprises the study of the galaxy density profiles and the fraction of galaxies per spectral type as a function of the group-centric distance. We have calculated the projected galaxy density profiles of galaxy groups using composite samples in order to increase the statistical significance of the results. Special cares have been taken in order to avoid possible biases in the group identification and the construction of the projected galaxy density profile estimator. The results show that the projected galaxy density profiles obtained for both redshift surveys are in agreement with a projected Navarro, Frenk & White predictions in the range 0.15< r/r_200 < 1, whereas a good fit for the measured profiles in the whole range of r/r_200 is given by a proj...
The goal of this work is to understand whether the extreme environment of compact groups can affe... more The goal of this work is to understand whether the extreme environment of compact groups can affect the distribution and abundance of faint galaxies around them. We performed an analysis of the faint galaxy population in the vicinity of compact groups and normal groups. We built a light-cone mock galaxy catalogue constructed from the Millennium Run Simulation II plus a semi-analytical model of galaxy formation. We identified a sample of compact groups in the mock catalogue as well as a control sample of normal galaxy groups and computed the projected number density profiles of faint galaxies around the first- and the second-ranked galaxies. We also compared the profiles obtained from the semi-analytical galaxies in compact groups with those obtained from observational data. In addition, we investigated whether the ranking or the luminosity of a galaxy is the most important parameter in the determination of the centre around which the clustering of faint galaxies occurs. There is no ...
We present a new sample of galaxy groups identified in the Sloan Digital Sky Survey Data Release ... more We present a new sample of galaxy groups identified in the Sloan Digital Sky Survey Data Release 3. Following previous works we use the well tested friend-of-friend algorithm developed by Huchra & Geller which take into account the number density variation due to the apparent magnitude limit of the galaxy catalog. To improve the identification we implement a procedure to avoid the artificial merging of small systems in high density regions and then apply an iterative method to recompute the group centers position. As a result we obtain a new catalog with 10864 galaxy groups with at least four members. The final group sample has a mean redshift of 0.1 and a median velocity dispersion of 230 km s^-1.
We construct a galaxy groups catalogue from the public 100K data release of the 2dF galaxy redshi... more We construct a galaxy groups catalogue from the public 100K data release of the 2dF galaxy redshift survey. The group identification is carried out using a slightly modified version of the group finding algorithm developed by Huchra & Geller. Several tests using mock catalogues allow us to find the optimal conditions to increase the reliability of the final group sample. A minimum number of 4 members, an outer number density enhancement of 80 and a linking radial cutoff of 200 km sec^-1, are the best obtained values from the analysis. Using these parameters, approximately 90 real space have a redshift space counterpart. On the other hand the level of contamination in redshift space reaches to 30 artificial groups and ∼ 24 in real space. The final sample comprise 2209 galaxy groups covering the sky region described by Colless et al. spanning over the redshift range of 0.003 ≤ z ≤ 0.25 with a mean redshift of 0.1.
We compute the redshift space power spectrum of two X-ray cluster samples: the X-ray Brightest Ab... more We compute the redshift space power spectrum of two X-ray cluster samples: the X-ray Brightest Abell Cluster Sample (XBACS) and the Brightest Cluster Sample (BCS) using the method developed by Feldman, Kaiser & Peacock. The power spectrums derived for these samples are in agreement with determinations of other optical and X-ray cluster samples. For XBACS we find the largest power spectrum amplitude expected given the high richness of this sample (R > 2). In the range 0.05 < k < 0.4 the power spectrum shows a power law behavior P(k)∝ k^n with an index n≃-1.2. In a similar range 0.04 < k < 0.3 BCS power spectrum has a smaller amplitude with index n≃-1.0. We do not find significant evidence for a peak at k ≃ 0.05 suggesting that claims such of feature detections in some cluster samples could relay on artificial inhomogeneities of the data. We compare our results with power spectrum predictions derived by Moscardini et al. within current cosmological models (LCDM and OCDM...
... From the 3-D galaxy density profile we have estimated the 3-D fraction of galaxies per spectr... more ... From the 3-D galaxy density profile we have estimated the 3-D fraction of galaxies per spectral type. ... of galaxies computed using the projected profiles we observe a similar behavior of the galaxy spectral type ... for groups in the early data release of the 2dF Galaxy Redshift Survey ...
ABSTRACT We use the 2dF Galaxy Group Catalogue constructed by Merchán & Zandivarez to stu... more ABSTRACT We use the 2dF Galaxy Group Catalogue constructed by Merchán & Zandivarez to study the large scale structure of the Universe traced by galaxy groups. The resulting group power spectrum shows a similar shape to the galaxy power spectrum of the 2dF Galaxy Redshift Survey, but with a higher amplitude quantified by a relative bias in redshift space of bs(k) ˜ 1.5. The group two point correlation function ξ(s) for the total sample is well described by a power law with correlation length s0=8.9 ± 0.3 h-1 Mpc and slope γ=-1.6 ± 0.1. In order to study the dependence of the clustering properties on group mass we split the catalogue in four subsamples defined by different ranges of group virial masses finding that our results are consistent with a 40% increase of the correlation length s0. These computations allow a fair estimate of the relation described by s0 and the mean intergroup separation dc. An empirical scaling law s0=4.7 dc0.32 provides a very good fit to the results from this work, as well as to previous results obtained for groups and clusters of galaxies and for dark matter haloes in N-body simulations of ΛCDM models. We also study the redshift space distortions of galaxy groups, finding that the anisotropies in the clustering pattern of groups are consistent with gravitational instability, with a flattening of the ξ(s) contours in the direction of the line of sight and group pairwise velocities found for almost the whole sample of groups are consistent with < w2 >1/2 = (280+50-110)km/s, in agreement with ΛCDM cosmological simulations. The bias factor for the 2dF groups of moderate masses is consistent with the values predicted by the combination of a CDM model and the ellipsoidal collapse model for the formation of structures.
Se analizara la evolucion de la estructura en el Universo desde los puntos de vista numerico, est... more Se analizara la evolucion de la estructura en el Universo desde los puntos de vista numerico, estadistico y observacional dando una caracterizacion de las propiedades globales del Universo en Gran Escala. Para ello se analizaran los mayores catalogos de Galaxias existentes, nuevas observaciones y simulaciones numericas Cosmologicas de alta resolucion. Mediante la aplicacion de diferentes metodos capaces de proporcionar informacion util acerca de las propiedades del Universo, se pretende aportar significativamente a la comprension de la dinamica y la caracteristicas generales de Galaxias y sistemas de Galaxias.
VizieR Online Data Catalog, Apr 1, 2015
Boletin de la Asociacion Argentina de Astronomia La Plata Argentina, 2002
Monthly Notices of the Royal Astronomical Society, Feb 24, 2021
Boletin de la Asociacion Argentina de Astronomia La Plata Argentina, Jul 1, 2021
Summary: Treatment of boutonniere Dupuytren disease is rare and is resistant to treatment because... more Summary: Treatment of boutonniere Dupuytren disease is rare and is resistant to treatment because of altered tendon dynamics. The authors used a small dose of collagenase clostridium histolyticum for an enzymatic tenotomy of the distal interphalangeal joint and showed that hyperextension at the distal interphalangeal joint improved significantly. Fifteen patients with boutonniere Dupuytren disease with severe proximal interphalangeal joint contractures averaging -69 degrees of extension were included in the study. Ten patients had at least one previous intervention, including surgical fasciectomy, Digit Widget treatment, and needle aponeurotomy. Collagenase clostridium histolyticum enzymatic tenotomy was performed in-office as a wide-awake procedure. All patients received varying doses of collagenase clostridium histolyticum for volar Dupuytren disease enzymatic fasciotomy and 0.1 mg of collagenase clostridium histolyticum into the distal extensor tendon for tenotomy to treat boutonniere deformity at the same time. Collagenase clostridium histolyticum enzymatic tenotomy significantly improved total active motion of the finger by 41.0 degrees (p = 0.001). Loss of extension at both the metacarpophalangeal joint and the proximal interphalangeal joint also improved with gains of 11.7 (p = 0.04) and 20.7 degrees (p = 0.0005) of extension, respectively. The average distal interphalangeal joint hyperextension was improved from 29.7 degrees to 14.0 degrees (p = 0.002). The authors show that collagenase injection led to significant average improvement in joint contracture at all finger joints and significantly increased the arc of motion at the proximal interphalangeal joint and metacarpophalangeal joint. Although collagenase has been previously used for flexion contractures in Dupuytren disease, we believe it has a role in treating the distal interphalangeal joint hyperextension deformity associated with boutonniere deformity in Dupuytren disease as well. Clinical question/level of evidence: Therapeutic, IV.
We identify compact groups in the Sloan Digital Sky Survey (SDSS) using an algorithm similar to t... more We identify compact groups in the Sloan Digital Sky Survey (SDSS) using an algorithm similar to that developed by Lee et al. (2003, astro-ph 0312553). Given that some authors claim compact groups to be chance alignments of galaxies or diffuse galaxy groups cores (Zandivarez et al. 2003, MNRAS, 340, 1400), our intention is to make a statistical study of the
Monthly Notices of the Royal Astronomical Society
Compact groups of galaxies are devised as extreme environments where interactions may drive galax... more Compact groups of galaxies are devised as extreme environments where interactions may drive galaxy evolution. In this work, we analysed whether the luminosities of galaxies inhabiting compact groups differ from those of galaxies in loose galaxy groups. We computed the luminosity functions of galaxy populations inhabiting a new sample of 1412 Hickson-like compact groups of galaxies identified in the Sloan Digital Sky Survey Data Release 16. We observed a characteristic absolute magnitude for galaxies in compact groups brighter than that observed in the field or loose galaxy systems. We also observed a deficiency of faint galaxies in compact groups in comparison with loose systems. Our analysis showed that the brightening is mainly due to galaxies inhabiting the more massive compact groups. In contrast to what is observed in loose systems, where only the luminosities of Red (and Early) galaxies show a dependency with group mass, luminosities of Red and Blue (also Early and Late) galax...
Monthly Notices of the Royal Astronomical Society, Feb 7, 2023
Monthly Notices of the Royal Astronomical Society, 2022
Many catalogues of isolated compact groups of galaxies (CGs) have been extracted using Hickson’s ... more Many catalogues of isolated compact groups of galaxies (CGs) have been extracted using Hickson’s criteria to identify isolated, dense systems of galaxies, with at least three or four galaxies concordant in magnitude and redshift. But is not clear to what extent the catalogues of CGs are complete and reliable, relative to 3D truly isolated, dense groups. Using five different semi-analytical models of galaxy formation (SAMs), we identify isolated dense groups in 3D real space, containing at least three galaxies. We then build mock redshift space galaxy catalogues and run a Hickson-like CG finder. We find that the Hickson-like algorithm in redshift space is poor at recovering 3D CGs of at least three galaxies, with a purity of sim10rmper,cent\sim 10{{\ \rm per \, cent}}sim10rmper,cent and a completeness of sim22rmper,cent\sim 22{{\ \rm per \, cent}}sim22rmper,cent. Among the sim90rmper,cent\sim 90{{\ \rm per \, cent}}sim90rmper,cent of spurious systems, typically 60rmpercent60{{\ \rm per\ cent}}60rmpercent are dense structures that failed the 3D isolation criteria, while the remaining $4...
Monthly Notices of the Royal Astronomical Society: Letters, 2011
Monthly Notices of the Royal Astronomical Society, 2019
Compact groups (CGs) of galaxies are defined as isolated and dense galaxy systems that appear to ... more Compact groups (CGs) of galaxies are defined as isolated and dense galaxy systems that appear to be a unique site of multiple galaxy interactions. Semi-analytical models (SAMs) of galaxy formation are a prime tool to understand CGs. We investigate how the frequency and the 3D nature of CGs depends on the SAM and its underlying cosmological parameters. Extracting nine light-cones of galaxies from five different SAMs and selecting CGs as in observed samples, we find that the frequency and nature of CGs depends strongly on the cosmological parameters. Moving from the WMAP1 to the WMAP7 and Planck cosmologies (increasing density of the Universe and decreasing normalization of the power spectrum), the space density of CGs is decreased by a factor 2.5, while the fraction of CGs that are physically dense falls from 50 to 35 per cent. The lower σ8 leads to fewer dense groups, while the higher Ωm causes more chance alignments. However, with increased mass and spatial resolution, the fraction...
We have analysed the distribution of galaxies in groups identified in the largest redshift survey... more We have analysed the distribution of galaxies in groups identified in the largest redshift surveys at the present: the final release of the 2dF Galaxy Redshift Survey and the first release of the Sloan Digital Sky Survey. Our work comprises the study of the galaxy density profiles and the fraction of galaxies per spectral type as a function of the group-centric distance. We have calculated the projected galaxy density profiles of galaxy groups using composite samples in order to increase the statistical significance of the results. Special cares have been taken in order to avoid possible biases in the group identification and the construction of the projected galaxy density profile estimator. The results show that the projected galaxy density profiles obtained for both redshift surveys are in agreement with a projected Navarro, Frenk & White predictions in the range 0.15< r/r_200 < 1, whereas a good fit for the measured profiles in the whole range of r/r_200 is given by a proj...
The goal of this work is to understand whether the extreme environment of compact groups can affe... more The goal of this work is to understand whether the extreme environment of compact groups can affect the distribution and abundance of faint galaxies around them. We performed an analysis of the faint galaxy population in the vicinity of compact groups and normal groups. We built a light-cone mock galaxy catalogue constructed from the Millennium Run Simulation II plus a semi-analytical model of galaxy formation. We identified a sample of compact groups in the mock catalogue as well as a control sample of normal galaxy groups and computed the projected number density profiles of faint galaxies around the first- and the second-ranked galaxies. We also compared the profiles obtained from the semi-analytical galaxies in compact groups with those obtained from observational data. In addition, we investigated whether the ranking or the luminosity of a galaxy is the most important parameter in the determination of the centre around which the clustering of faint galaxies occurs. There is no ...
We present a new sample of galaxy groups identified in the Sloan Digital Sky Survey Data Release ... more We present a new sample of galaxy groups identified in the Sloan Digital Sky Survey Data Release 3. Following previous works we use the well tested friend-of-friend algorithm developed by Huchra & Geller which take into account the number density variation due to the apparent magnitude limit of the galaxy catalog. To improve the identification we implement a procedure to avoid the artificial merging of small systems in high density regions and then apply an iterative method to recompute the group centers position. As a result we obtain a new catalog with 10864 galaxy groups with at least four members. The final group sample has a mean redshift of 0.1 and a median velocity dispersion of 230 km s^-1.
We construct a galaxy groups catalogue from the public 100K data release of the 2dF galaxy redshi... more We construct a galaxy groups catalogue from the public 100K data release of the 2dF galaxy redshift survey. The group identification is carried out using a slightly modified version of the group finding algorithm developed by Huchra & Geller. Several tests using mock catalogues allow us to find the optimal conditions to increase the reliability of the final group sample. A minimum number of 4 members, an outer number density enhancement of 80 and a linking radial cutoff of 200 km sec^-1, are the best obtained values from the analysis. Using these parameters, approximately 90 real space have a redshift space counterpart. On the other hand the level of contamination in redshift space reaches to 30 artificial groups and ∼ 24 in real space. The final sample comprise 2209 galaxy groups covering the sky region described by Colless et al. spanning over the redshift range of 0.003 ≤ z ≤ 0.25 with a mean redshift of 0.1.
We compute the redshift space power spectrum of two X-ray cluster samples: the X-ray Brightest Ab... more We compute the redshift space power spectrum of two X-ray cluster samples: the X-ray Brightest Abell Cluster Sample (XBACS) and the Brightest Cluster Sample (BCS) using the method developed by Feldman, Kaiser & Peacock. The power spectrums derived for these samples are in agreement with determinations of other optical and X-ray cluster samples. For XBACS we find the largest power spectrum amplitude expected given the high richness of this sample (R > 2). In the range 0.05 < k < 0.4 the power spectrum shows a power law behavior P(k)∝ k^n with an index n≃-1.2. In a similar range 0.04 < k < 0.3 BCS power spectrum has a smaller amplitude with index n≃-1.0. We do not find significant evidence for a peak at k ≃ 0.05 suggesting that claims such of feature detections in some cluster samples could relay on artificial inhomogeneities of the data. We compare our results with power spectrum predictions derived by Moscardini et al. within current cosmological models (LCDM and OCDM...
... From the 3-D galaxy density profile we have estimated the 3-D fraction of galaxies per spectr... more ... From the 3-D galaxy density profile we have estimated the 3-D fraction of galaxies per spectral type. ... of galaxies computed using the projected profiles we observe a similar behavior of the galaxy spectral type ... for groups in the early data release of the 2dF Galaxy Redshift Survey ...
ABSTRACT We use the 2dF Galaxy Group Catalogue constructed by Merchán & Zandivarez to stu... more ABSTRACT We use the 2dF Galaxy Group Catalogue constructed by Merchán & Zandivarez to study the large scale structure of the Universe traced by galaxy groups. The resulting group power spectrum shows a similar shape to the galaxy power spectrum of the 2dF Galaxy Redshift Survey, but with a higher amplitude quantified by a relative bias in redshift space of bs(k) ˜ 1.5. The group two point correlation function ξ(s) for the total sample is well described by a power law with correlation length s0=8.9 ± 0.3 h-1 Mpc and slope γ=-1.6 ± 0.1. In order to study the dependence of the clustering properties on group mass we split the catalogue in four subsamples defined by different ranges of group virial masses finding that our results are consistent with a 40% increase of the correlation length s0. These computations allow a fair estimate of the relation described by s0 and the mean intergroup separation dc. An empirical scaling law s0=4.7 dc0.32 provides a very good fit to the results from this work, as well as to previous results obtained for groups and clusters of galaxies and for dark matter haloes in N-body simulations of ΛCDM models. We also study the redshift space distortions of galaxy groups, finding that the anisotropies in the clustering pattern of groups are consistent with gravitational instability, with a flattening of the ξ(s) contours in the direction of the line of sight and group pairwise velocities found for almost the whole sample of groups are consistent with < w2 >1/2 = (280+50-110)km/s, in agreement with ΛCDM cosmological simulations. The bias factor for the 2dF groups of moderate masses is consistent with the values predicted by the combination of a CDM model and the ellipsoidal collapse model for the formation of structures.