Anillo de Cosmologa internal meeting, January 13th 2014

Deep I,V imaging with Warsaw telescope of the Extended Hubble Deep Field South (E-HDFS)

Carlos Hervas!Departamento de Astronoma, U. de Chile

Luis Campusano (U. de Chile), Gerry Williger (Louisville, Nice), Lutz Haberzettl, (Lousville), Roger Clowes (UCLan), Povilas Palunas (LCO), Ricardo Muoz (U. de Chile)

Introduction: Large Scale Structure of galaxies (LSS)

Structure formation theories predict size, characteristics of super-large structures : !

Scales of ~20-100 Mpc or bigger.!

Consequence of primordial density perturbation spectrum.!

Early 2000s onwards: Sloan Digital Sky Survey (SDSS): probe of Gpc scales out to z~0.3 (limited by photometry depth):!

More large structures and correlations on 20-100 Mpc scales found, enough to provide tests for structure formation theories.!

Need to extend LSS studies to higher redshifts: z > 0.3! Note that for z>0.3, quasars can be used to investigate the

LSS and in particular lo locate structures larger than superclusters even to z~2

Large Scale Structure: Extension to Z>0.3

1 degree in the sky at H0 = 70 km/s/Mpc, "=0.7 , "m = 0.3!!

Requires deep images on degree scales or larger.

z Local Mpc

Comov Mpc

m-M m(ML*)~-20

0.5 22 33 42.3 22.3

1.0 29 58 44.1 24.1

2.0 30 90 46.0 26.0

3.0 28 111 47.0 27.0

QSOs absorbers

The study LSS at higher redshifts (z>0.3) can be done through absorbers on QSOs lines of sight. Convenience of having many QSOs over a continuous area which needs to be 1-degree in size or larger.!

Large photometric surveys of deep fields are needed to characterize the galaxies that produce the QSOs absorbers, which in turn might be in groups or cluster of galaxies that can reveal LSS at particular redshifts.

Current wide deep fields

Up until recently, public wide deep fields have been limited! Extended Hubble Deep Field-N (EHDF-N), Chandra Deep Field South

(CDF-S), Groth Strip, COSMOS, SSA22, NOAO etc. (all typically ~

Case for use of E-HDFS

Only deep field accessible from Antarctic sites! South Pole Telescope (mm)! potential high resolution, thermal IR wide-field images and thermal IR

spectrographs! Optimal for new southern facilities!

SALT, ALMA, SKA, Giant Magellan Telescope! One of two deep fields in HST Continuous Viewing Zone (CVZ, doubles

observing efficiency)! Current data not uniform both in angular scale and frequency: ~45x45 optical;

~10x20 near-IR, GALEX (1 degree), some radio, South Pole Telescope (mm).

Further science with E-HDFS

Hints of large structures at z~0.5-0.6 from small amounts of galaxy spectroscopy in 10x20 near-IR survey field!

Further hints from GALEX-detected quasars, absorbers, up to degree scales! SCIENCE GOAL: EXPLORE GALAXY POPULATION OUT TO z~0.6-0.7, SEARCH

FOR LARGE STRUCTURES, COMPARE WITH KNOWN QUASARS, ABSORBERS! Attractive follow-up: HST COS spectroscopy exploiting CVZ to probe relationship

of absorbers with galaxies in large structures (doubly efficient compared to all other deep fields except EHDF-N) not possible in any other deep fields except EHDF-N!

EHDF-S has many more bright z~0.5-1.5 bright quasars than EHDF-N! Other science: investigate sources from SPT (mm), WISE (far-IR) e.g. Luminous IR

Galaxies or Ultra-luminous IR Galaxies (LIRGs/ULIRGs)

E-HDFS: Our Approach

Current coverage of E-HDFS, along with proposed observations of Warsaw telescope (larger square in black).!

Identified QSOs from GALEX slitless spectroscopy are the red circles.!

~100 other quasar candidates from 40x40 BTC subfield identified by multi-colour methods (Palunas et al. 2000, ApJ, 541, 61) our team has AAT multifibre spectra of many of them for confirmation/redshifts

The V, I Observations (sept 2012) at LCO

1.4 sq degrees field. Down to V~25 and I~24 in 3 nights.!

Three nights : sept 21,22 & 23, 2012. At Warsaw telescope in Las Campanas Observatory (LCO)!

Seeing between 1.3 and 1.6 . ! 0.26 /pixel scale. ! The camera is a wide field 32 chip array:

1d23m by 1d14m (maximum).! The observations were done by Palunas & C

Hervas

Collected Observations

Notice that field of view is as large as target field.! The strategy was dithering to cover column and

rows of gaps in between the chips. ! First, shallow exposures of 3 minutes were taken.

4 sets (in the corners) of 3 images. 12 for each filter.!

Then, deep exposures of 10 minutes were taken for the remaining of the observing time. Five runs, each E and W, five positions each.!

In total, 150 exposures and 4800 individual images.

Coverage

10 exposures were lost due to logistical problems. ! Out of 140, 72 are in I filter and 68 in V filter.! The maximum coverage for the center of the field is around 10 hours. ! There is a zone, roughly 1 sq degree, where the covereage is uniform.

Coverage Maps over the E-HDFS

These are the coverage maps, how many hours of integration per position in the field.! Red crosses are QSOs of interest.

Reductions (under supervision)

On multi-CCD pipeline THELI (Schirmer 2013).!

Calibration, background modelling, weighting, astrometry and coadding.!

We encountered some problems with the astrometry of the images, which was not good. ! This was solved by the use of

astrometry.net software.

Preliminary results

To test the astrometry, a subset of images (of the same area of the sky) were combined by using the SWARP software. !

This is a very rough coadding, only to test the astrometry. V filter, 0.3 x 0.55 degrees. Measured seeing ~1.6.

Current state and future

To present day, the images are calibrated. Also with astrometry. ! Masks for correcting random defects (cosmic rays, satellites tracks, etc.)

are done for V filter. Very slow process.! Working on background model step, where the defrindging takes place.! Once reduction of image is ready (soon), source extraction and

photometry.