The Alhambra Survey: A Large Area Multimedium-Band Optical and Near-Infrared Photometric Survey

Moles, M.; Benı́tez, N.; Aguerri, J. A. L.; Alfaro, E. J.; Broadhurst, Tom; Cabrera-Caño, J.; Castander, F. J.; Cepa, J.; Cerviño, M.; Cristóbal-Hornillos, D.; Fernández-Soto, A.; Delgado, R. M. González; Infante, L.; Márquez, I.; Martínez, V. J.; Masegosa, J.; Olmo, A. del; Perea, J.; Prada, Francisco; Quintana, J. M.; Sánchez, S. F.

doi:10.1088/0004-6256/136/3/1325

Cited by 154 publications

(190 citation statements)

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“…The Advanced Large, Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA 1 , Moles et al 2008) survey is a 20 narrow-band optical and three broad-band NIR (JHK) photometric survey imaged with the wide-field cameras LAICA and OMEGA-2000 respectively, at the Calar Alto Observatory (Spain) 2 .…”

Section: The Alhambra Surveymentioning

confidence: 99%

Galaxy clusters and groups in the ALHAMBRA survey

Ascaso

Benı́tez

Fernández-Soto

et al. 2015

Mon. Not. R. Astron. Soc.

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We present a catalogue of 348 galaxy clusters and groups with 0.2 < z < 1.2 selected in the 2.78 deg 2 ALHAMBRA Survey. The high precision of our photometric redshifts, close to 1%, and the wide spread of the seven ALHAMBRA pointings ensure that this catalogue has better mass sensitivity and is less affected by cosmic variance than comparable samples.The detection has been carried out with the Bayesian Cluster Finder (BCF), whose performance has been checked in ALHAMBRA-like light-cone mock catalogues. Great care has been taken to ensure that the observable properties of the mocks photometry accurately correspond to those of real catalogues. From our simulations, we expect to detect galaxy clusters and groups with both 70% completeness and purity down to dark matter halo masses of M h ∼ 3 × 10 13 M ⊙ for z < 0.85. Cluster redshifts are expected to be recovered with ∼ 0.6% precision for z < 1. We also expect to measure cluster masses with σ M h |M * CL ∼ 0.25 − 0.35 dex precision down to ∼ 3 × 10 13 M ⊙ , masses which are 50% smaller than those reached by similar work.We have compared these detections with previous optical, spectroscopic and Xrays work, finding an excellent agreement with the rates reported from the simulations. We have also explored the overall properties of these detections such as the presence of a colour-magnitude relation, the evolution of the photometric blue fraction and the clustering of these sources in the different ALHAMBRA fields. Despite the small numbers, we observe tentative evidence that, for a fixed stellar mass, the environment is playing a crucial role at lower redshifts (z<0.5).

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Section: The Alhambra Surveymentioning

confidence: 99%

Galaxy clusters and groups in the ALHAMBRA survey

Ascaso

Benı́tez

Fernández-Soto

et al. 2015

Mon. Not. R. Astron. Soc.

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“…The ALHAMBRA survey provides a photometric data set over 20 contiguous, equal-width (∼300 Å), non-overlapping, medium-band optical filters (3500 Å−9700 Å) plus 3 standard broad-band near-infrared (NIR) filters (J, H, and K s ) over 8 different regions of the northern sky (Moles et al 2008). The survey has the aim of understanding the evolution of galaxies throughout cosmic time by sampling a large enough cosmological fraction of the universe, for which reliable spectral energy distributions (SEDs) and precise photometric redshifts (z p ) are needed.…”

Section: The Alhambra Surveymentioning

confidence: 99%

“…The simulations of Benítez et al (2009), which relates the image depth and the accuracy of the photometric redshifts to the number of filters, have demonstrated that the filter set chosen for ALHAMBRA can achieve a photometric redshift precision that is three times better than a classical 4−5 optical broad-band filter set. The final survey parameters and scientific goals, as well as the technical properties of the filter set, were described by Moles et al (2008). The survey has collected its data for the 20+3 optical-NIR filters in the 3.5 m telescope at the Calar Alto observatory, using the wide-field camera LAICA (Large Area Imager for Calar Alto) in the optical and the OMEGA2000 camera in the NIR.…”

Section: The Alhambra Surveymentioning

confidence: 99%

“…should be different than those in number density studies. In the present paper, we take advantage of the unique design, depth, and photometric redshift accuracy of the ALHAMBRA 1 (Advanced, Large, Homogeneous Area, Medium-Band Redshift Astronomical) survey (Moles et al 2008) to estimate empirically, for the first time, the cosmic variance that affects close pair studies. The ALHAMBRA survey has observed eight separate regions of the northern sky, comprising 48 sub-fields of ∼180 arcmin 2 each that can be assumed as independent for our purposes.…”

Section: Introductionmentioning

confidence: 99%

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The ALHAMBRA survey: An empirical estimation of the cosmic variance for merger fraction studies based on close pairs

López-Sanjuan¹,

Cenarro²,

Hernández-Monteagudo³

et al. 2014

A&A

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Aims. Our goal is to estimate empirically the cosmic variance that affects merger fraction studies based on close pairs for the first time. Methods. We compute the merger fraction from photometric redshift close pairs with 10 h −1 kpc ≤ r p ≤ 50 h −1 kpc and Δv ≤ 500 km s −1 and measure it in the 48 sub-fields of the ALHAMBRA survey. We study the distribution of the measured merger fractions that follow a log-normal function and estimate the cosmic variance σ v as the intrinsic dispersion of the observed distribution. We develop a maximum likelihood estimator to measure a reliable σ v and avoid the dispersion due to the observational errors (including the Poisson shot noise term). Results. The cosmic variance σ v of the merger fraction depends mainly on (i) the number density of the populations under study for both the principal (n 1 ) and the companion (n 2 ) galaxy in the close pair and (ii) the probed cosmic volume V c . We do not find a significant dependence on either the search radius used to define close companions, the redshift, or the physical selection (luminosity or stellar mass) of the samples. Conclusions. We have estimated the cosmic variance that affects the measurement of the merger fraction by close pairs from observations. We provide a parametrisation of the cosmic variance with n 1 , n 2 , and V c , σ v ∝ n −0.54(n 2 /n 1 ) −0.37 . Thanks to this prescription, future merger fraction studies based on close pairs could properly account for the cosmic variance on their results.

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“…The ALHAMBRA 1 (Advanced, Large, Homogeneous Area, Medium-Band Redshift Astronomical) survey provides a photometric dataset over 20 contiguous, equal-width, nonoverlapping, medium-band optical filters (3500−9700 Å) plus 3 standard broad-band NIR filters J, H, and Ks over 8 different regions of the northern hemisphere (Moles et al 2008). The survey aims to understand the evolution of the structures and the different families of extragalactic sources throughout cosmic time by sampling a large enough cosmological fraction of the universe.…”

Section: Photometric Data: the Alhambra Surveymentioning

confidence: 99%

Quasi-stellar objects in the ALHAMBRA survey

Matute

Márquez

Masegosa

et al. 2012

A&A

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Context. Even the spectroscopic capabilities of today's ground and space-based observatories can not keep up with the enormous flow of detections (>10 5 deg −2 ) unveiled in modern cosmological surveys as: i) would be required enormous telescope time to perform the spectroscopic follow-ups and ii) spectra remain unattainable for the fainter detected population. In the past decade, the typical accuracy of photometric redshift (photo-z) determination has drastically improved. Nowdays, it has become a perfect complement to spectroscopy, closing the gap between photometric surveys and their spectroscopic follow-ups. The photo-z precision for active galactic nuclei (AGN) has always lagged behind that for the galaxy population owing to the lack of proper templates and their intrinsic variability. Aims. Our goal is to characterize the ability of the Advanced Large, Homogeneous Area Medium-Band Redshift Astronomical (ALHAMBRA) survey in assigning accurate photo-z's to broad-line AGN (BLAGN) and quasi-stellar objects (QSOs) based on their ALHAMBRA very-low-resolution optical-near-infrared (NIR) spectroscopy. This will serve as a benchmark for any future compilation of ALHAMBRA selected QSOs and the basis for the statistical analysis required to derive luminosity functions up to z ∼ 5. Methods. We selected a sample of spectroscopically identified BLAGN and QSOs and used a library of templates (including the SEDs of AGN and both normal and starburst galaxies, as well as stars) to fit the 23 photometric data points provided by ALHAMBRA in the optical and NIR (20 medium-band optical filters plus the standard JHKs). Results. We find that the ALHAMBRA photometry is able to provide an accurate photo-z and spectral classification for ∼88% of the 170 spectroscopically identified BLAGN/QSOs over 2.5 deg 2 in different areas of the survey and brighter than m 678 = 23.5 (equivalent to r SLOAN ∼ 24.0). The derived photo-z accuracy is below 1% and is comparable to the most recent results in other cosmological fields that use photometric information over a wider wavelength range. The fraction of outliers (∼12%) is mainly caused by the larger photometric errors for the faintest sources and the intrinsic variability of the BLAGN/QSO population. A small fraction of outliers may have an incorrectly assigned spectroscopic redshift. Conclusions. The definition of the ALHAMBRA survey in terms of the number of filters, filter properties, areal coverage, and depth is able to provide photometric redshifts for BLAGN/QSOs with a precision similar to any previous survey that makes use of mediumband optical photometry. In agreement with previous literature results, our analysis also reveals that, in the 0 < z < 4 redshift interval, very accurate photo-z can be obtained without the use of NIR broadband photometry at the expense of a slight increase in the outliers. The importance of NIR data is expected to increase at higher z (z > 4). These results are relevant for the design of future optical follow-ups of surveys containing a large fractio...

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The Alhambra Survey: A Large Area Multimedium-Band Optical and Near-Infrared Photometric Survey

Cited by 154 publications

References 64 publications

Galaxy clusters and groups in the ALHAMBRA survey

Galaxy clusters and groups in the ALHAMBRA survey

The ALHAMBRA survey: An empirical estimation of the cosmic variance for merger fraction studies based on close pairs

Quasi-stellar objects in the ALHAMBRA survey

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