"Science, Faculty of"@en . "Physics and Astronomy, Department of"@en . "DSpace"@en . "UBCV"@en . "Sajina, Anna"@en . "2009-09-30T23:37:46Z"@en . "2002"@en . "Master of Science - MSc"@en . "University of British Columbia"@en . "We present results from sub-mm observations of sources selected from the ISO FIRBACK\r\n(Far IR BACKground) survey, along with UKIRT near-IR imaging of a sub-sample. This\r\ngives valuable insight to the brightest 10% of galaxies which contribute to the Cosmic\r\nInfrared Background (CIB). We estimate the photometric redshifts and luminosities of\r\nthese sources by fitting their Spectral Energy Distributions (SEDs). The data appear\r\nto show a bimodal galaxy distribution, with normal star-forming galaxies at z \u00E2\u0089\u0083 0, and\r\nthe z ~ 0.4-0.9 tail of a much more luminous population. These are similar to the\r\nultraluminous infrared galaxies which are found to evolve rapidly with redshift in other\r\nsurveys. We are biased away from much higher redshift objects by the detectability\r\nthreshold of FIRBACK. Nevertheless, the handful of z ~ 0.5 sources which we identify\r\nare likely to be the low-2 counterparts of the typically higher-2 sources found in blank field\r\nsub-mm observations. The sources we identify here have the virtue of being relatively\r\neasy to study in the optical. Hence their detailed investigation could help elucidate the\r\nnature of the sub-mm bright galaxies."@en . "https://circle.library.ubc.ca/rest/handle/2429/13439?expand=metadata"@en . "4278804 bytes"@en . "application/pdf"@en . "A multiwavelength study of 170/im selected sources by Anna Sajina B.Sc , The University of British Columbia, 2000 A THESIS S U B M I T T E D IN P A R T I A L F U L F I L M E N T OF T H E R E Q U I R E M E N T S F O R T H E D E G R E E OF M A S T E R OF SCIENCE in T H E F A C U L T Y OF G R A D U A T E STUDIES (Department of Physics and Astronomy) We accept this thesis as conforming to the required standard T H E U N I V E R S I T Y OF BRITISH C O L U M B I A October 9, 2002 \u00C2\u00A9 Anna Sajina, 2002 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of Physics and Astronomy The University Of British Columbia Vancouver, Canada 11 ABSTRACT We present results from sub-mm observations of sources selected from the ISO F I R B A C K (Far IR BACKground) survey, along with UKIRT near-IR imaging of a sub-sample. This gives valuable insight to the brightest 10% of galaxies which contribute to the Cosmic Infrared Background (CIB). We estimate the photometric redshifts and luminosities of these sources by fitting their Spectral Energy Distributions (SEDs). The data appear to show a bimodal galaxy distribution, with normal star-forming galaxies at z ~ 0, and the z ~ 0.4-0.9 tail of a much more luminous population. These are similar to the ultraluminous infrared galaxies which are found to evolve rapidly with redshift in other surveys. We are biased away from much higher redshift objects by the detectability threshold of F I R B A C K . Nevertheless, the handful of z ~ 0.5 sources which we identify are likely to be the low-2 counterparts of the typically higher-2 sources found in blank field sub-mm observations. The sources we identify here have the virtue of being relatively easy to study in the optical. Hence their detailed investigation could help elucidate the nature of the sub-mm bright galaxies. i i i C O N T E N T S Abstract i i Contents i i i List of Tables v List of Figures v i Acknowledgements x i i 1 Introduction 1 1.1 The Cosmic Infrared Background 1 1.2 The Multiwavelength Approach 5 2 T h e Data 8 2.1 Sample 8 2.2 The instrument 9 2.3 S C U B A sub-mm observations 13 2.4 S C U B A data reduction 16 2.5 U K I R T near-IR observations 21 3 Results & Analysis 25 3.1 Assembling the multiwavelength data 25 3.2 Linear Correlations 29 3.3 Sub-mm/Radio redshifts 37 3.4 Sub-mm vs. near-IR 38 3.5 SED fits 44 iv 3.6 Luminosity and SFR 46 4 A Model 53 5 Summary &: Discussion 63 5.1 Comparison with related studies 67 5.2 Bimodality 68 5.3 Comparison with evolutionary models 69 5.4 Future Direction 72 Bibliography 74 A Photometry with SCUBA 79 B Cosmology 83 V LIST OF TABLES 2.1 Source coordinates 22 2.1 continued 23 2.2 Calibration values 24 3.1 Multiwavelength data for our sample0 26 3.1 continued 27 3.2 Results for the linear fits to the data 31 3.3 The sub-mm/radio spectral indices and derived redshifts . . .- 39 3.3 continued 40 3.4 x 2 _ r a n g e occupancy for various /3 fits 45 3.5 Fit results for fi = 1.5 48 3.5 continued 49 3.6 Fit results for the higher-z sources\" 50 3.7 Estimating the Star Formation Rates\" 52 LIST OF FIGURES 1.1 This figure [58] is a compilation showing the different extragalactic back-grounds including the CIB (called FIB here for Far-Infrared Background). Notice in particular that the power output in the far-IR spectral region is comparable to that in the optical region 2.1 Shows the V L A coverage of the ELAIS-N1 field where our sample is lo-cated. Here the asterixes show the ISOPHOT pointings while the circles are ~30% sensitivity of their centers for the V L A pointings (the absolute radio sensistivity varies from region to region) [15] 2.2 This roughly estimates the selection cut off of the F I R B A C K survey in (L, z) space. The solid line is the 3cr limis (=135 mJy), the dashed line is the 4a limit (=180 mJy). The thin lines roughly estimate the region of influence of the radio selection. See text for details 2.3 Distribution of the S170/S1.4GHZ ratio. The solid histogram represents all the sources from the F I R B A C K catalogue which have been observed in the radio. The dashed histogram is our sample. The dotted line shows our high-z candidates (discussed in Chapter 3) 2.4 This shows the performance of the new S C U B A wide-band filters measured in the winter of 2000 compared to the old filters. Notice in particular the dramatic improvement in the 450 /im filter (30-40% depending on the weather). The black curve is the atmospheric transmission on Mauna Kea (1 mm PWV=precipitative water vapour). This figure was taken from the J C M T website. The filters were measured by D. Naylor and W. Holland. vii 2.5 The S C U B A arrays (courtesy of the J C M T website ). Here shown is both the physical scale of the arrays (~25mm) as well as the field of view (~2.3 arcmin). Note that the closely packed arrays shown here are misleading -the arrays are in fact highly undersampled. Using the basic jiggle mode of observing requires 64-point jiggles to create a fully sampled map in both bands(the spacing between 2 jiggle points is roughly 2\"). The photometry mode, that we use, involves a 9-point jiggle pattern with spacings of 1\". This is much more efficient at quickly reaching the desired SNR in a given bolometer, but the other bolometers produce a very undersampled map. . 15 2.6 Relations between optical depths derived from 26 skydip observations in 2001 (note the weighting towards grade 1 weather). The left hand panels show the entire range, while the right hand panels zoom to the grade 1 data (TCSO < 0.05) only. Here the dashed lines are the standard relations [1], while the solid lines are simple linear fits to our data (the same fit is shown in both columns). The two are sufficiently similar overall, considering the uneven weighting, and the inclusion of outliers. However, the relations with the CSO r seem to be shallower for the grade 1 data than the single slope relation, which may be due to the uncertainty in rcso 18 2.7 This shows the percentage error in the flux estimate as a function of optical depth r . Here crosses are 450 /im and stars are 850 jim. data. The airmass is 1.3 (i.e. y-axis scales as ~ A/1.3). The fit is y = -0.58+5.24r-6.97r 2 + 5.56T 3. Notice that our May 2001 data is off the scale here in 450 /im, and that with the above relation a r ~ 3 gives roughly 100% error. This figure is reproduced from [25] 19 3.1 The available U K I R T if-band images - centered on the radio positions. These images are about 15\" x 15\", or roughly one S C U B A F W H M 850 /an beam size. The exception is Nl-004 where the S C U B A beam is the white circle, as the galaxy itself is larger than this 28 viii 3.2 This figure is meant to illustrate, in their most obvious cases, the system-atic effects that must be kept in mind when trying to interpret the data at hand. Both images are roughly the size of ISO's beam. On the left is N1-004 with the S C U B A 850 /mi beam shown to the side (the 450 ftm one is about half of that). On the right is N1-008 with the positions of the two radio detections indicated. Our observation is for the stronger of the two - a 3.0 mjy radio source. Notice that the other radio detection (0.3 mjy) has a fainter near-IR counterpart which potentially could be a higher-2 source. We will explore this further with upcoming observations 30 3.3 The scatter plots with their fits and \u00C2\u00B1lcr scatter. The fit parameters are given in Table 3.2. Notice that the order here is: the first column is mainly sensitive to the location of the thermal peak, the second column to the sub-mm slope, and the third column to the trough between the thermal and non-thermal parts of the SED. The error bars are representative for our data 32 3.4 The histogram is the result of 1000 Monte Carlo simulations of the sub-mm fluxes of our sample. The dotted line shows the actual value of x2 for the observations. Only about ~ 2% of the simulations have a value this low (note that the binning is too crude to show that clearly) 34 3.5 The shows the best fit [/3,T/(l + z)\ combined from the 170/450 and 450/850 slopes, which is [1.5,31 K] along with the 68, 90, and 95% con-fidence levels. Notice that /3 is more poorly constrained. We exclude Nl-001, Nl-002, Nl-034, and Nl-059 from the fit due to their discrepant colours 36 ix 3.6 The sub-mm/radio spectral index as a redshift indicator. The thick solid line is the relation based on the SLUGS sample (104 galaxies - I R A S ' selected), with the dashed lines being its \u00C2\u00B1la envelope. The thin solid line is the standard C Y relation [8] (17 galaxies - IRAS and N R A O selection) with dotted \u00C2\u00B11 2