Large-scale clustering measurements with photometric redshifts: comparing the dark matter haloes of X-ray AGN, star-forming and passive galaxies at z ≈ 1

ABSTRACT We present evidence that active galactic nuclei (AGN) do not reside in ‘special’ environments, but instead show large-scale clustering determined by the properties of their host galaxies. Our study is based on an angular cross-correlation analysis applied to X-ray selected AGN in the COSMOS and UDS fields, spanning redshifts from $z$ ∼ 4.5 to $z$ ∼ 0.5. Consistent with previous studies, we find that AGN at all epochs are on average hosted by galaxies in dark matter haloes of 1012–1013 M⊙, intermediate between star-forming and passive galaxies. We find, however, that the same clustering signal can be produced by inactive (i.e. non-AGN) galaxies closely matched to the AGN in spectral class, stellar mass, and redshift. We therefore argue that the inferred bias for AGN lies in between the star-forming and passive galaxy populations because AGN host galaxies are comprised of a mixture of the two populations. Although AGN hosted by higher mass galaxies are more clustered than lower mass galaxies, this stellar mass dependence disappears when passive host galaxies are removed. The strength of clustering is also largely independent of AGN X-ray luminosity. We conclude that the most important property that determines the clustering in a given AGN population is the fraction of passive host galaxies. We also infer that AGN luminosity is likely not driven by environmental triggering, and further hypothesize that AGN may be a stochastic phenomenon without a strong dependence on environment.

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FORMATION OF DARK MATTER HALOES IN A HOMOGENEOUS DARK ENERGY UNIVERSE

International Journal of Modern Physics D ◽

10.1142/s0218271810017561 ◽

2010 ◽

Vol 19 (08n10) ◽

pp. 1397-1403

Author(s):

L. MARASSI

Keyword(s):

Dark Matter ◽

Dark Energy ◽

Large Scale ◽

State Parameter ◽

Mass Function ◽

Accelerated Expansion ◽

X Ray ◽

Energy Models ◽

Dark Energy Component ◽

Standard Press

Several independent cosmological tests have shown evidences that the energy density of the universe is dominated by a dark energy component, which causes the present accelerated expansion. The large scale structure formation can be used to probe dark energy models, and the mass function of dark matter haloes is one of the best statistical tools to perform this study. We present here a statistical analysis of mass functions of galaxies under a homogeneous dark energy model, proposed in the work of Percival (2005), using an observational flux-limited X-ray cluster survey, and CMB data from WMAP. We compare, in our analysis, the standard Press–Schechter (PS) approach (where a Gaussian distribution is used to describe the primordial density fluctuation field of the mass function), and the PL (power–law) mass function (where we apply a non-extensive q-statistical distribution to the primordial density field). We conclude that the PS mass function cannot explain at the same time the X-ray and the CMB data (even at 99% confidence level), and the PS best fit dark energy equation of state parameter is ω = -0.58, which is distant from the cosmological constant case. The PL mass function provides better fits to the HIFLUGCS X-ray galaxy data and the CMB data; we also note that the ω parameter is very sensible to modifications in the PL free parameter, q, suggesting that the PL mass function could be a powerful tool to constrain dark energy models.

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The XMM-Newton wide field survey in the COSMOS field: Clustering dependence of X-ray selected AGN on host galaxy properties

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935186 ◽

2019 ◽

Vol 629 ◽

pp. A14 ◽

Cited By ~ 1

Author(s):

A. Viitanen ◽

V. Allevato ◽

A. Finoguenov ◽

A. Bongiorno ◽

N. Cappelluti ◽

...

Keyword(s):

Large Scale ◽

Accretion Rate ◽

Spatial Clustering ◽

Distribution Functions ◽

Active Galaxies ◽

Host Galaxy ◽

Wide Field ◽

Photometric Redshifts ◽

X Ray ◽

Massive Halos

Aims. We study the spatial clustering of 632 (1130) XMM-COSMOS active galactic nuclei (AGNs) with known spectroscopic or photometric redshifts in the range z = [0.1–2.5] in order to measure the AGN bias and estimate the typical mass of the hosting dark matter (DM) halo as a function of AGN host galaxy properties. Methods. We created AGN subsamples in terms of stellar mass, M*, and specific black hole accretion rate, LX/M*, to study how AGN environment depends on these quantities. Further, we derived the M*−Mhalo relation for our sample of XMM-COSMOS AGNs and compared it to results in literature for normal non-active galaxies. We measured the projected two-point correlation function wp(rp) using both the classic and the generalized clustering estimator, based on photometric redshifts, as probability distribution functions in addition to any available spectroscopic redshifts. We measured the large-scale (rp ≳ 1 h−1 Mpc) linear bias b by comparing the clustering signal to that expected of the underlying DM distribution. The bias was then related to the typical mass of the hosting halo Mhalo of our AGN subsamples. Since M* and LX/M* are correlated, we matched the distribution in terms of one quantity and we split the distribution in the other. Results. For the full spectroscopic AGN sample, we measured a typical DM halo mass of log (Mhalo/h−1 M⊙) = 12.79−0.43+0.26, similar to galaxy group environments and in line with previous studies for moderate-luminosity X-ray selected AGN. We find no significant dependence on specific accretion rate LX/M*, with log (Mhalo/h−1 M⊙) = 13.06−0.38+0.23 and log (Mhalo/h−1 M⊙) = 12.97−1.26+0.39 for low and high LX/M* subsamples, respectively. We also find no difference in the hosting halos in terms of M* with log (Mhalo/h−1 M⊙) = 12.93−0.62+0.31 (low) and log (Mhalo/h−1 M⊙) = 12.90−0.62+0.30 (high). By comparing the M*−Mhalo relation derived for XMM-COSMOS AGN subsamples with what is expected for normal non-active galaxies by abundance matching and clustering results, we find that the typical DM halo mass of our high M* AGN subsample is similar to that of non-active galaxies. However, AGNs in our low M* subsample are found in more massive halos than non-active galaxies. By excluding AGNs in galaxy groups from the clustering analysis, we find evidence that the result for low M* may be due to larger fraction of AGNs as satellites in massive halos.

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GRB host galaxies: theoretical investigation

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312013312 ◽

2011 ◽

Vol 7 (S279) ◽

pp. 353-354

Author(s):

Jirong Mao

Keyword(s):

Dark Matter ◽

Star Formation ◽

Galaxy Evolution ◽

Gamma Ray ◽

Dark Matter Halo ◽

Host Galaxy ◽

Host Galaxies ◽

X Ray ◽

Star Forming ◽

Stellar Masses

AbstractLong gamma-ray bursts (GRBs) can be linked to the massive stars and their host galaxies are assumed to be the star-forming galaxies within small dark matter halos. We apply a galaxy evolution model, in which the star formation process inside the virialized dark matter halo at a given redshift is achieved. The star formation rates (SFRs) in the GRB host galaxies at different redshifts can be derived from our model. The related stellar masses, luminosities, and metalicities of these GRB host galaxies are estimated. We also calculate the X-ray and optical absorption of GRB afterglow emission. At higher redshift, the SFR of host galaxy is stronger, and the absorption in the X-ray and optical bands of GRB afterglow is stronger, when the dust and metal components are locally released, surrounding the GRB environment. These model predictions are compared with some observational data as well.

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X-ray clusters in a cold dark matter + lambda universe: A direct, large-scale, high-resolution, hydrodynamic simulation

The Astrophysical Journal ◽

10.1086/174297 ◽

1994 ◽

Vol 429 ◽

pp. 4 ◽

Cited By ~ 52

Author(s):

Renyue Cen ◽

Jeremiah P. Ostriker

Keyword(s):

Dark Matter ◽

High Resolution ◽

Large Scale ◽

Cold Dark Matter ◽

Hydrodynamic Simulation ◽

X Ray

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PhotoWeb redshift: boosting photometric redshift accuracy with large spectroscopic surveys

Astronomy and Astrophysics ◽

10.1051/0004-6361/201937382 ◽

2020 ◽

Vol 636 ◽

pp. A90 ◽

Cited By ~ 1

Author(s):

M. Shuntov ◽

J. Pasquet ◽

S. Arnouts ◽

O. Ilbert ◽

M. Treyer ◽

...

Keyword(s):

Large Scale ◽

Distribution Functions ◽

Distance Measurements ◽

Photometric Redshifts ◽

Star Forming ◽

Photometric Redshift ◽

Probability Distribution Functions ◽

Galaxy Sample ◽

New Generation ◽

Better Than

Improving distance measurements in large imaging surveys is a major challenge to better reveal the distribution of galaxies on a large scale and to link galaxy properties with their environments. As recently shown, photometric redshifts can be efficiently combined with the cosmic web extracted from overlapping spectroscopic surveys to improve their accuracy. In this paper we apply a similar method using a new generation of photometric redshifts based on a convolution neural network (CNN). The CNN is trained on the SDSS images with the main galaxy sample (SDSS-MGS, r ≤ 17.8) and the GAMA spectroscopic redshifts up to r ∼ 19.8. The mapping of the cosmic web is obtained with 680 000 spectroscopic redshifts from the MGS and BOSS surveys. The redshift probability distribution functions (PDF), which are well calibrated (unbiased and narrow, ≤120 Mpc), intercept a few cosmic web structures along the line of sight. Combining these PDFs with the density field distribution provides new photometric redshifts, zweb, whose accuracy is improved by a factor of two (i.e., σ ∼ 0.004(1 + z)) for galaxies with r ≤ 17.8. For half of them, the distance accuracy is better than 10 cMpc. The narrower the original PDF, the larger the boost in accuracy. No gain is observed for original PDFs wider than 0.03. The final zweb PDFs also appear well calibrated. The method performs slightly better for passive galaxies than star-forming ones, and for galaxies in massive groups since these populations better trace the underlying large-scale structure. Reducing the spectroscopic sampling by a factor of 8 still improves the photometric redshift accuracy by 25%. Finally, extending the method to galaxies fainter than the MGS limit still improves the redshift estimates for 70% of the galaxies, with a gain in accuracy of 20% at low z where the resolution of the cosmic web is the highest. As two competing factors contribute to the performance of the method, the photometric redshift accuracy and the resolution of the cosmic web, the benefit of combining cosmological imaging surveys with spectroscopic surveys at higher redshift remains to be evaluated.

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First results from XILO: XMM-Newton Investigations in the Lambda Orionis star forming region

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310011518 ◽

2009 ◽

Vol 5 (H15) ◽

pp. 768-768

Author(s):

B. Stelzer ◽

D. Barrado y Navascues ◽

N. Huelamo ◽

M. Morales-Calderon ◽

A. Bayo

Keyword(s):

Star Formation ◽

Large Scale ◽

Supernova Explosion ◽

Central Star ◽

Young Stars ◽

Data Set ◽

X Ray ◽

Star Forming ◽

First Results ◽

Low Mass

The λ Orionis star formation region (1-6 Myr, 400 pc) is a complex of star-forming clouds surrounded by a molecular ring with ~ 5° radius which was probably formed by a supernova explosion (Dolan & Mathieu 2002). For a complete picture of star formation, believed to be determined by the supernova blast, the large-scale distribution of the pre-main sequence population in λ Ori needs to be examined. We have embarked on a multi-wavelength study (XMM-Newton/X-ray, CFHT/optical, Spitzer/IR) of selected areas within this intriguing star-forming complex that enables us to identify young stars and brown dwarfs. Our study comprises various areas within the cloud complex as shown in Fig.1. This data set is among the most extended X-ray surveys carried out with XMM-Newton in a coherent star-forming environment. The XMM-Newton observations combined with optical and IR data reveal the low-mass stellar population down to ~ 0.4 M⊙. For this mass-limited sample, our preliminary analysis confirms the anomalously low disk-fraction of the central star cluster Coll 69, the Eastern extension of its low-mass population pointing towards B 35, and the concentration of young stars in front of B 35. The analysis of the ‘on-cloud field' of B 35 (white in the figure) will show if the cloud is currently forming stars. This will be crucial for determining the star-forming history in the whole λ Ori region.

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Triggering nuclear and galaxy activity in the Bullet cluster

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833601 ◽

2020 ◽

Vol 634 ◽

pp. A137

Author(s):

S. Puccetti ◽

F. Fiore ◽

A. Bongiorno ◽

K. Boutsia ◽

R. Fassbender ◽

...

Keyword(s):

Infrared Emission ◽

Point Sources ◽

Photometric Redshifts ◽

X Ray ◽

Cluster Galaxies ◽

Star Forming ◽

Multi Wavelength ◽

Cluster Environment ◽

Infrared Sources ◽

Trigger Mechanisms

The analysis of a cluster environment is a valuable instrument to investigate the origin of gas fuelling and trigger mechanisms in active galactic nuclei (AGN) and star-forming galaxies. To this purpose, we present a detailed analysis of the point-like X-ray sources in the Bullet cluster field. Based on ∼600 ks Chandra observations, we produced a catalogue of 381 X-ray point sources up to a distance of ∼1.5 virial radius and with flux limits ∼1 × 10−16 and ∼8 × 10−16 erg cm−2 s−1 in the 0.5–2 keV and 2–10 keV bands, respectively. We find a strong (up to a factor 1.5–2) and significant (≥4σ) over-density in the full region studied 0.3R200 < R < 1.5R200. We identified optical (R band) and infrared (Spitzer IRAC) counterparts for ∼84% and ∼48% of the X-ray sources, respectively. We obtained new spectroscopic redshifts for 106 X-ray sources and collected from the literature additional 13 spectroscopic and 8 photometric redshifts of X-ray sources. Twenty-nine X-ray sources turned out to be cluster members. Spectroscopic and photometric redshifts of optical and infrared sources were also collected, and these sources were used as ancillary samples. We used these multi-wavelength data to characterise the nature of the Bullet cluster X-ray point sources. We find that the over-density in the region 0.3R200 < R < R200 is likely due to X-ray AGN (mostly obscured) and star-forming galaxies associated with the cluster, while in the more external region this over-density is likely to be mostly due to background AGN. The fraction of cluster galaxies hosting an X-ray detected AGN is 1.0 ± 0.4%, which is nearly constant with the radius; this fraction is similar to that reported in other clusters of galaxies at similar redshift. The fraction of X-ray bright AGN (L2 − 10 keV > 1043 ergs s−1) in the region 0.3R200 < R < R200 is 0.5−0.2+0.6%, which is higher than that in other clusters at similar redshift and more similar to the AGN fraction in the field. Finally, the spatial distributions of AGN and star-forming galaxies, which we selected for their infrared emission, appear similar, thus suggesting that both are triggered by the same mechanism.

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Clusters of Galaxies in a Flat CHDM Universe

Symposium - International Astronomical Union ◽

10.1017/s0074180900115232 ◽

1998 ◽

Vol 188 ◽

pp. 299-299

Author(s):

A. Habe ◽

C. Hanyu ◽

S. Yachi

Keyword(s):

Dark Matter ◽

Large Scale ◽

Large Scale Structure ◽

Numerical Results ◽

Clusters Of Galaxies ◽

Statistical Features ◽

X Ray ◽

Numerical Resolution ◽

Radiative Processes ◽

The Universe

Cold and hot dark matter (CHDM) model is one of viable models which can reproduce the large scale structure of the universe. HDM may affect structure of clusters of galaxies in CHDM universe. Bryan et al. (1994) gave numerical results of CHDM model that explain some statistical features of X-ray clusters of galaxies, e.g. X-ray luminosiry-temperature realtion, L ∝~ T3.5, without considering radiative processes. However their numerical resolution is insufficient to resolve the cores of X-ray clusters. So, we simulate the formation of clusters in CHDM universe more carefully.

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High-energy processes in starburst-driven winds

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1720 ◽

2020 ◽

Vol 496 (2) ◽

pp. 2474-2481 ◽

Cited By ~ 1

Author(s):

Ana L Müller ◽

Gustavo E Romero ◽

Markus Roth

Keyword(s):

Cosmic Rays ◽

Power Law ◽

Large Scale ◽

Gamma Ray ◽

High Energy ◽

X Ray ◽

Star Forming ◽

Star Forming Regions ◽

Energy Processes ◽

Relativistic Particles

ABSTRACT Starburst galaxies generate large-scale winds powered by the activity in the star-forming regions located in the galactic discs. Fragmentation of the disc produced by the outbreak of the wind results in the formation of clouds. Bowshocks caused by the supersonic outflow appear around such clouds. In this paper, we discuss the acceleration of relativistic particles and the production of non-thermal radiation in such scenario. Cosmic rays accelerated at the bowshocks do not reach the highest energies, although the high-energy luminosity generated is significant. We show that up to ∼10 per cent of the gamma-ray emission in starbursts might come from these sources outside the galactic discs. Discrete X-ray sources with a power-law component are also expected.

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