scholarly journals Probing the existence of a rich galaxy overdensity at z = 5.2

2021 ◽  
Author(s):  
Rosa Calvi ◽  
Helmut Dannerbauer ◽  
Pablo Arrabal Haro ◽  
José M Rodríguez Espinosa ◽  
Casiana Muñoz-Tuñón ◽  
...  
Keyword(s):  
Central Region ◽  
Clustering Analysis ◽  
Large Scale ◽  
Rest Frame ◽  
Physical Space ◽  
Far Infrared ◽  
Photometric Redshift ◽  
The Galaxy ◽  
Medium Band

Abstract We report the results of a pilot spectroscopic program of a region at z = 5.2 in the GOODS-N field containing an overdensity of galaxies around the well-known submillimeter galaxy HDF850.1. We have selected candidate cluster members from the optical 25 medium-band photometric catalog of the project SHARDS (Survey for High-z Absorption Red and Dead Sources). 17 rest-frame UV selected galaxies (LAEs and LBGs) with 5.15<zphot<5.27, candidates to be physically associated with the overdensity, have been observed with the instrument OSIRIS at the GranTeCan telescope. 13 out of these 17 (76 per cent) sources have secure spectroscopic confirmations via the Lyα line at the redshift of the galaxy protocluster PCl−HDF850.1, demonstrating the high reliabilty of our photometric redshift method. 10 out of 13 sources are newly confirmed members. Thus, we increase the number of confirmed members in this overdensity from 13 to 23 objects. In order to fully characterize this structure we combined our dataset with the sample from the literature. Beside the SMG HDF850.1, none of the 23 spectroscopically confirmed members are bright in the far-infrared/submm wavelength regime (SFRIR < few hundred M⊙ yr−1). The clustering analysis of the whole sample of 23 confirmed members reveals four distinct components in physical space in different evolutionary states, within Δz < 0.04 from the central region hosting SMG HDF850.1. The halo mass of the whole structure at z = 5.2, estimated by a variety of methods, range between 2 − 8 × 1012M⊙. The comparison with literature suggests a large scale assembly comparable to the formation of a central Virgo-like cluster at z=0 with several satellite components which will possibly be incorporated in a single halo if the protocluster is the progenitor of a more massive Coma-like cluster (>1015M⊙).

scholarly journals The rest-frame UV luminosity function at z ≃ 4: a significant contribution of AGNs to the bright end of the galaxy population

2020 ◽  
Vol 494 (2) ◽  
pp. 1771-1783 ◽  
Author(s):  
N J Adams ◽  
R A A Bowler ◽  
M J Jarvis ◽  
B Häußler ◽  
R J McLure ◽  
...  
Keyword(s):  
Power Law ◽  
Luminosity Function ◽  
Large Scale ◽  
Rest Frame ◽  
Galactic Nuclei ◽  
Absolute Magnitude ◽  
Photometric Redshift ◽  
Wide Range ◽  
The Galaxy ◽  
Galaxy Population

ABSTRACT We measure the rest-frame ultraviolet (UV) luminosity function (LF) at z ∼ 4 self-consistently over a wide range in absolute magnitude (−27 ≲ MUV ≲ −20). The LF is measured with 46 904 sources selected using a photometric redshift approach over ∼6 $\, {\rm deg}^2$ of the combined Cosmological Evolution Survey and XMM–Newton Large-Scale Structure fields. We simultaneously fit for both active galactic nuclei (AGNs) and galaxy LFs using a combination of Schechter or double power law (DPL) functions alongside a single power law for the faint-end slope of the AGN LF. We find a lack of evolution in the shape of the bright end of the Lyman-break galaxy (LBG) component when compared to other studies at z ≃ 5 and evolutionary recipes for the UV LF. Regardless of whether the LBG LF is fit with a Schechter function or DPL, AGNs are found to dominate at MUV < −23.5. We measure a steep faint-end slope of the AGN LF with $\alpha _{\mathrm{ AGN}} = -2.09^{+0.35}_{-0.38}$ ($-1.66^{+0.29}_{-0.58}$) when fit alongside a Schechter function (DPL) for the galaxies. Our results suggest that if AGNs are morphologically selected it results in a bias to lower number densities. Only by considering the full galaxy population over the transition region from AGN to LBG domination can an accurate measurement of the total LFs be attained.

scholarly journals Void Hierarchy in the Northern Local Void

1999 ◽  
Vol 183 ◽  
pp. 185-190
Author(s):  
U. Lindner ◽  
K.J. Fricke ◽  
J. Einasto ◽  
M. Einasto
Keyword(s):  
Correlation Functions ◽  
Clustering Analysis ◽  
Large Scale ◽  
Empirical Studies ◽  
Large Scale Structure ◽  
Topological Methods ◽  
Probability Functions ◽  
Cluster Distribution ◽  
Luminous Matter ◽  
The Galaxy

Empirical studies of the Large–Scale Structure in the nearby Universe come in two complementary modes, namely the investigation of either the distribution of luminous matter or voids: (i) The description of the galaxy and cluster distribution employs correlation functions, clustering analysis, topological methods, et cetera. (ii) The investigation of the empty regions between systems of galaxies uses void probability functions, mean diameters of voids, the compilation of void catalogues, and so forth.

scholarly journals Resolving a dusty, star-forming SHiZELS galaxy at z = 2.2 with HST, ALMA and SINFONI on kiloparsec scales

2021 ◽  
Author(s):  
R K Cochrane ◽  
P N Best ◽  
I Smail ◽  
E Ibar ◽  
C Cheng ◽  
...  
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Rest Frame ◽  
Far Infrared ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Star Forming ◽  
Alpha Emission ◽  
The Galaxy ◽  
Dust Distribution

Abstract We present ∼0.15″ spatial resolution imaging of SHiZELS-14, a massive ($M_{*}\sim 10^{11}\, \rm {M_{\odot }}$), dusty, star-forming galaxy at z = 2.24. Our rest-frame $\sim 1\, \rm {kpc}$-scale, matched-resolution data comprise four different widely used tracers of star formation: the $\rm {H}\alpha$ emission line (from SINFONI/VLT), rest-frame UV continuum (from HST F606W imaging), the rest-frame far-infrared (from ALMA), and the radio continuum (from JVLA). Although originally identified by its modest $\rm {H}\alpha$ emission line flux, SHiZELS-14 appears to be a vigorously star-forming ($\rm {SFR}\sim 1000\, \rm {M_{\odot }\, yr^{-1}}$) example of a submillimeter galaxy, probably undergoing a merger. SHiZELS-14 displays a compact, dusty central starburst, as well as extended emission in $\rm {H}\alpha$ and the rest-frame optical and FIR. The UV emission is spatially offset from the peak of the dust continuum emission, and appears to trace holes in the dust distribution. We find that the dust attenuation varies across the spatial extent of the galaxy, reaching a peak of at least AHα ∼ 5 in the most dusty regions, although the extinction in the central starburst is likely to be much higher. Global star-formation rates inferred using standard calibrations for the different tracers vary from $\sim 10\!-\!1000\, \rm {M_{\odot }\, yr^{-1}}$, and are particularly discrepant in the galaxy’s dusty centre. This galaxy highlights the biased view of the evolution of star-forming galaxies provided by shorter wavelength data.

scholarly journals Dragging Force on Galaxies Due to Streaming Dark Matter

1990 ◽  
Vol 124 ◽  
pp. 645-649
Author(s):  
Tetsuya Hara ◽  
Shigeru Miyoshi
Keyword(s):  
Dark Matter ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Rest Frame ◽  
Background Radiation ◽  
Clusters Of Galaxies ◽  
Microwave Background ◽  
The Galaxy ◽  
Microwave Background Radiation ◽  
The Universe

It has been reported that galaxies in large regions (~102Mpc), including some clusters of galaxies, may be streaming coherently with velocities up to 600km/sec or more with respect to the rest frame determined by the microwave background radiation.) On the other hand, it is suggested that the dominant mass component of the universe is dark matter. Because we can only speculate the motion of dark matter from the galaxy motions, much attention should be paid to the correlation of velocities between the observed galaxies and cold dark matter. So we investigate whether such coherent large-scale streaming velocities are due to dark matter or only to baryonic objects which may be formed by piling up of gases due to some explosive events.

scholarly journals Planetary nebulae in the central region of the Galaxy

1964 ◽  
Vol 20 ◽  
pp. 41-45 ◽  
Author(s):  
L. Perek
Keyword(s):  
Central Region ◽  
Surface Brightness ◽  
Large Scale ◽  
Direct Determination ◽  
Planetary Nebulae ◽  
Galactic Centre ◽  
Large Numbers ◽  
The Galaxy ◽  
Objective Prism

Planetary nebulae are convenient objects for studying the large-scale structure of the Galaxy. Firstly, they are easily recognized up to considerable distances on plates taken through an objective prism, and secondly, methods have been devised by various authors to determine their distances from two observable quantities: angular diameter and surface brightness. The importance of the subsystem of planetary nebulae has been accentuated especially by the discoveries by Minkowski and Haro of large numbers of planetaries in the direction of the galactic centre. The distribution of planetaries on the sphere suggests that they are connected with the galactic nucleus, but no direct determination of their distances, which would either confirm or contradict this statement, is available. The most serious obstacle in studying the subsystem of planetaries is the lack of observing data. The aim of the reported paper (Perek 1963) is to give a tentative outline of the distribution of planetaries in space based on extensive new observing material.

scholarly journals Cosmic distance determination from photometric redshift samples using BAO peaks only

2019 ◽  
Vol 488 (1) ◽  
pp. 295-305 ◽  
Author(s):  
Srivatsan Sridhar ◽  
Yong-Seon Song
Keyword(s):  
Large Scale ◽  
Distance Measures ◽  
Line Of Sight ◽  
Analysis Tool ◽  
Acoustic Oscillations ◽  
Distance Information ◽  
Photometric Redshift ◽  
Growth Functions ◽  
The Galaxy ◽  
Perpendicular Component

ABSTRACT The galaxy distributions along the line of sight are significantly contaminated by the uncertainty on redshift measurements obtained through multiband photometry, which makes it difficult to get cosmic distance information measured from baryon acoustic oscillations, or growth functions probed by redshift distortions. We investigate the propagation of the uncertainties into large-scale clustering by exploiting all known estimators, and propose the wedge approach as a promising analysis tool to extract cosmic distance information still remaining in the photometric galaxy samples. We test our method using simulated galaxy maps with photometric uncertainties of σ0 = (0.01, 0.02, 0.03). The measured anisotropy correlation function ξ is binned into the radial direction of s and the angular direction of μ, and the variations of $\xi (s,\mu)\,$with perpendicular and radial cosmic distance measures of DA and H−1 are theoretically estimated by an improved RSD model. Although the radial cosmic distance H−1 is unable to be probed from any of the three photometric galaxy samples, the perpendicular component of DA is verified to be accurately measured even after the full marginalization of H−1. We measure DA with approximately 6 per cent precision which is nearly equivalent to what we can expect from spectroscopic DR12 CMASS galaxy samples.

scholarly journals ALHAMBRA survey: morphological classification

2012 ◽  
Vol 10 (H16) ◽  
pp. 378-378
Author(s):  
M. Pović ◽  
M. Huertas-Company ◽  
I. Márquez ◽  
J. Masegosa ◽  
J. A. López Aguerri ◽  
...  
Keyword(s):  
Near Infrared ◽  
High Redshift ◽  
Morphological Properties ◽  
Support Vector ◽  
Late Type ◽  
Morphological Classification ◽  
Photometric Redshifts ◽  
Photometric Redshift ◽  
The Galaxy ◽  
Medium Band

AbstractThe Advanced Large Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA) survey is a photometric survey designed to study systematically cosmic evolution and cosmic variance (Moles et al.2008). It employs 20 continuous medium-band filters (3500 - 9700 Å), plus JHK near-infrared (NIR) bands, which enable measurements of photometric redshifts with good accuracy. ALHAMBRA covers > 4 deg2 in eight discontinuous regions (~ 0.5 deg2 per region), of theseseven fields overlap with other extragalactic, multiwavelength surveys (DEEP2, SDSS, COSMOS, HDF-N, Groth, ELAIS-N1). We detect > 600.000 sources, reaching the depth of R(AB) ~ 25.0, and photometric accuracy of 2-4% (Husillos et al., in prep.). Photometric redshifts are measured using the Bayesian Photometric Redshift (BPZ) code (Benítez et al.2000), reaching one of the best accuracies up to date of δz/z ≤ 1.2% (Molino et al., in prep.).To deal with the morphological classification of galaxies in the ALHAMBRA survey (Pović et al., in prep.), we used the galaxy Support Vector Machine code (galSVM; Huertas-Company 2008, 2009), one of the new non-parametric methods for morphological classification, specially useful when dealing with low resolution and high-redshift data. To test the accuracy of our morphological classification we used a sample of 3000 local, visually classified galaxies (Nair & Abraham 2010), moving them to conditions typical of our ALHAMBRA data (taking into account the background, redshift and magnitude distributions, etc.), and measuring their morphology using galSVM. Finally, we measured the morphology of ALHAMBRA galaxies, obtaining for each source seven morphological parameters (two concentration indexes, asymmetry, Gini, M20 moment of light, smoothness, and elongation), probability if the source belongs to early- or late-type, and its error. Comparing ALHAMBRA morph COSMOS/ACS morphology (obtained with the same method) we expect to have qualitative separation in two main morphological types for ~ 20.000 sources in 8 ALHAMBRA fields. For early-type galaxies we expect to recover ~ 70% and 30-40% up to magnitudes 20.0 and 21.5, respectively, having the contamination of late-types of < 7%. For late-type galaxies, we expect to recover ~ 70%, 60 - 70%, and ~ 30% of sources up to magnitudes 22.0, 22.5, and 23.0, respectively, having the contamination of early-types of ≤ 10%. These data will be used to study the evolution of active and non-active galaxies respect to morphology and morphological properties of galaxies in groups and clusters.

scholarly journals Properties of galaxies around the most massive SMBHs

2015 ◽  
Vol 11 (S319) ◽  
pp. 71-71
Author(s):  
Yuji Shirasaki ◽  
Yutaka Komiya ◽  
Masatoshi Ohishi ◽  
Yoshihiko Mizumoto
Keyword(s):  
Correlation Length ◽  
Clustering Analysis ◽  
Luminosity Function ◽  
Cross Correlation ◽  
Rest Frame ◽  
Length Increase ◽  
The Galaxy ◽  
Virial Mass ◽  
Halo Gas ◽  
Red Galaxies

AbstractWe present result of the clustering analysis performed between AGNs and galaxies. AGN samples with redshift 0.1–1.0 were extracted from AGN properties catalogs which contain virial mass estimates of SMBHs. Galaxy samples were extracted from SDSS DR8 catalog and UKIDSS DR9 LAS catalog. The catalogs of SDSS and UKIDSS were merged and used to estimate the IR-opt color and IR magnitude in the rest frame by SED fitting. As we had no redshift information on the galaxy samples, stacking method was applied. We investigated the BH mass dependence of cross correlation length, red galaxy fraction at their environment, and luminosity function of galaxies. We found that the cross correlation length increase above MBH ≥ 108.2M⊙, and red galaxies dominate the environment of AGNs with MBH ≥ 109M⊙. This result indicates that the most massive SMBHs are mainly fueled by accretion of hot halo gas.

scholarly journals Impact of photometric redshifts on the galaxy power spectrum and BAO scale in the LSST survey

2019 ◽  
Vol 623 ◽  
pp. A76 ◽  
Author(s):  
Reza Ansari ◽  
Adeline Choyer ◽  
Farhang Habibi ◽  
Christophe Magneville ◽  
Marc Moniez ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
Near Infrared ◽  
Linear Part ◽  
Cosmological Parameters ◽  
Photometric Redshifts ◽  
Photometric Redshift ◽  
Near Ultraviolet ◽  
The Galaxy ◽  
The Impact

Context. The Large Synoptic Survey Telescope (LSST) survey will image billions of galaxies every few nights for ten years, and as such, should be a major contributor to precision cosmology in the 2020s. High precision photometric data will be available in six bands, from near-infrared to near-ultraviolet. The computation of precise, unbiased, photometric redshifts up to at least z = 2 is one of the main LSST challenges and its performance will have major impact on all extragalactic LSST sciences. Aims. We evaluate the efficiency of our photometric redshift reconstruction on mock galaxy catalogues up to z = 2.45 and estimate the impact of realistic photometric redshift (photo-z) reconstruction on the large-scale structures (LSS) power spectrum and the baryonic acoustic oscillation (BAO) scale determination for a LSST-like photometric survey. We study the effectiveness of the BAO scale as a cosmological probe in the LSST survey. Methods. We have performed a detailed modelling of the photo-z distribution as a function of galaxy type, redshift and absolute magnitude using our photo-z reconstruction code with a quality selection cut based on a boosted decision tree (BDT). We have simulated a catalogue of galaxies in the redshift range [0.2−2.45] using the Planck 2015 ΛCDM cosmological parameters over 10 000 square-degrees, in the six bands, assuming LSST photometric precision for a ten-year survey. The mock galaxy catalogues were produced with several redshift error models. The LSS power spectrum was then computed in several redshift ranges and for each error model. Finally we extracted the BAO scale and its uncertainty using only the linear part of the LSS spectrum. Results. We have computed the fractional error on the recovered power spectrum which is dominated by the shot noise at high redshift (z ≳ 1), for scales k ≳ 0.1, due to the photo-z damping. The BAO scale can be recovered with a percent or better accuracy level from z = 0.5 to z = 1.5 using realistic photo-z reconstruction. Conclusions. Reaching the LSST requirements for photo-z reconstruction is crucial to exploit the LSST potential in cosmology, in particular to measure the LSS power spectrum and its evolution with redshift. Although the BAO scale is not the most powerful cosmological probe in LSST, it can be used to check the consistency of the LSS measurement. Moreover we show that the impact of photo-z smearing on the recovered isotropic BAO scale in LSST should stay limited up to z ≈ 1.5, so as long as the galaxy number density balances the photo-z smoothing.

scholarly journals The ORELSE Survey

2006 ◽  
Vol 2 (S235) ◽  
pp. 165-166
Author(s):  
Roy Gal ◽  
L. M. Lubin ◽  
G. K. Squires
Keyword(s):  
Large Scale ◽  
Optical Data ◽  
Photometric Redshift ◽  
Near Ir ◽  
Galaxy Distribution ◽  
Early Results ◽  
The Galaxy ◽  
Dusty Galaxies ◽  
Multi Wavelength ◽  
Stellar Masses

AbstractThe ORELSE Survey (Observations of Redshift Evolution in Large Scale Environments) is a multi-wavelength program to study the large-scale structure around a sample of 20z>0.6 clusters, with the goal of understanding transformative processes affecting galaxies in a broad range of environments. The survey includes (1) deep optical imaging to map structure around the clusters; (2) optical spectroscopy to confirm redshifts, map the galaxy distribution, obtain cluster masses via dynamical estimates, and measure spectral properties; (3) ground-based K-band imaging, to better constrain galaxy stellar masses and improve photometric redshift estimates; (4) near-IR spectroscopy to study post-starburst galaxies and AGN; (5) HST imaging to obtain galaxy morphologies; (6) Spitzer IRAC and MIPS imaging to separate starburst and AGN populations, and examine dusty galaxies; and (7) Chandra and VLA mapping to find X-ray and radio-loud AGN that are not evident from optical data. We discuss here the motivation and some early results.

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