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| − | Here is my attempt at a proposal:
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| − | ABSTRACT
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| − | We propose to study galaxy clusters around “radio loud” AGN at a high redshift range of 0.7>z<1.2. We propose that in order to accomplish this we will utilize the datasets gathered by the “Spitzer Space Telescope” . In particular the investigative team will employ “snapshots” taken from the Spitzer High Red Shift Radio galaxy survey (SHzRG; Seymour et al. 2007, De Breuck et al. 2010. We propose to identify galaxy clusters by using simple IRAC color selection which has been found to be effective at unraveling high redshift galaxies (A. Galametz et al. 2011 ). Using a counts-in-cell analysis we will identify a field as being overdense if 15 or more IRAC sources are found within 1’ (ie. , 0.5 Mpc at 1<z<3) of the radio galaxy to the 5 sigma flux density limits of the IRAC data that was targeted. The number of our sample is 180 and we plan on both rediscovering previously known clusters and protoclusters as well as discovering new galaxy cluster candidates. The investigators further hope to create some statistical sampling which would further confirm suggestions that high redshift radio AGN’s with high radio luminosity lie in some of the densest regions in the Universe.
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| − | INTRODUCTION
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| − | While there exists a search technique for identifying galaxy clusters up to z=1 using x-ray emissions from the cluster’s intracluster medium moving past this redshift value has resulted in very insensitive cluster searches.
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| − | The launch of the Spitzer Space Telescope heralded a new beginning for astronomical research by carrying its coolant aloft which for the first time allowed us to measure objects in the 3.6 um flux density and above. For purposes of this research we will be examining AGN’s and their possible overdensities in the range of 0.7<z<2.5 . The instrument on board the Spitzer Telescope which our team will be using is IRAC (infrared array camera). It views objects in the 3.6,4.5,5.8, and 8 micron range. This is especially well suited for our research as we will be looking for evidence of the displaced SED (Spectral Energy Distribution) “bump” which has been displaced by the redshift. This “bump” has been shifted into the 3.0 to 5.0 micron range and therefore readily identified by IRAC1 and IRAC2. Given the fortuitous alignment of the SED with the Spitzer IRAC we would like to capitalize on this by investigating up to 180 “snapshots” of HzRG (high redshift radio galaxies) and determine if they in fact reside in overdensities as was suggested in A. Galametz et al.
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| − | We propose to use a counts-in-cell analysis to identify overdensities of red galaxies associated with HzRG’s . We will use the color selection method to identify overdensities in the same redshift range as the targeted AGN.
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| − | PROPOSED PROJECT
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| − | We propose to identify a new sample of galaxy clusters at z-1+- using IRAC “snapshots” of radio loud AGN. We hope to offer scientific conclusions based on our analysis of this data.
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| − | 1. The AGN Sample at z-1
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| − | Falder et al 2010 studied a large sample of high-redshift AGN at z-1. The sample was observed in the four IRAC bands. Of this sample, 75 are radio-loud quasars (RLQs) and 27 radio galaxies (RGs).The mixed sample of both types of AGN will give us an opportunity to AGN unification schemes.
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| − | A selection of excess 3.6 um sources within 300 kpc of the AGN as well as evidence for a positive correlation between source density and radio power. We propose here to refine the analysis of this unique dataset combining the powerof the four IRAC bands in order to isolate high-z galaxy clusters associated with our selected AGN population.
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| − | 2. Techniques to Analyze Data
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| − | As stated earlier we will use the counts- in- cell technique along with color selection to determine overdensities of red galaxies. It is anticipated that these overdensities (ie. approximately 15 or more galaxies will lie within a radius of .5 Mpc and possibly extend into the 1.0 Mpc range)will present themselves around the targeted AGN. We will derive our initial data from the Spitzer Wide-Infrared Extragalactic (SWIRE; Lonsdale et al. 2003) Once we have identified these overdensities then we will begin verifying same. We intend to use archived spectroscopy in order to filter out any point sources which might present themselves as candidates but are in fact objects which are in front of the targeted galaxy cluster. Some may even be behind. We will also make use of the Spitzer Deep,Wide-Field Survey (SDWFS; Ashby et al.2009) to determine cluster members.
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| − | POSSIBLE FINDINGS
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| − | 1. A correlation between HzRG ‘s and galactic overdensity . According to (A.Galametz et al 2011).
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| − | 2. We will look for a correlation of redshift range to AGN and overdensity. According to (A.Tomczak et al. 2010) “This suggests that F of AGN only increases at z>1.”
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| − | 3. We will further study the luminosity function (L500MHz> 10 to the 28.6 W Hz) and its correlation with galactic clusters.
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| − | 4. We will look at the form of the cluster to see if it is filamentary or clumped together.
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| − | 5. We will attempt to draw some conclusions regarding galaxy cluster formation in the redshift range of z>1.
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