Studying Distant Galaxies: A Handbook Of Methods And Analyses

by Francois Hammer, Mathieu Peuch, Hector Flores, Myriam Rodrigues

Overview

Distant galaxies encapsulate the various stages of galaxy evolution and formation from over 95% of the development of the universe. As early as twenty-five years ago, little was known about them, however since the first systematic survey was completed in the 1990s, increasing amounts of resources have been devoted to their discovery and research. This book summarises for the first time the numerous techniques used for observing, analysing, and understanding the evolution and formation of these distant galaxies.In this rapidly expanding research field, this text is an every-day companion handbook for graduate students and active researchers. It provides guidelines in sample selection, imaging, integrated spectroscopy and 3D spectroscopy, which help to avoid the numerous pitfalls of observational and analysis techniques in use in extragalactic astronomy. It also paves the way for establishing relations between fundamental properties of distant galaxies. At each step, the reader is assisted with numerous practical examples and ready-to-use methodology to help understand and analyse research.François Hammer worked initially in general relativity and made the first modelling of gravitational lenses prior to their spectroscopic confirmation. Following this, he became co-leader of the first complete survey of distant galaxies, the Canada-France-Redshift Survey. This led to the discovery of the strong decrease of the cosmic star formation density measured from UV light as z=1, which, alongside Hector Flores, they confirmed as bolometric and dust independent. With Mathieu Puech, they then pioneered the 3D spectroscopy of distant galaxies, leading to a major increase of understanding of the dynamic state of distant galaxies evidenced by the scatter of the Tully-Fisher relation. This led them to propose, with the addition to the team of Myriam Rodrigues, that galactic disks may survive or be rebuilt in gas-rich mergers, a scenario that is consistent with contemporary cosmological simulations. Besides extensive observational experience, the authors have led, or are leading, several instruments implemented or to be implemented at the largest telescopes, including VLT/Giraffe, VLT/X-shooter, VLT/MOONS and E-ELT/MOSAIC. They have also developed several observational techniques in adaptive optics, and in sky subtraction for integral field units and fibre instruments.

Product Details

ISBN-13:	9781786341440
Publisher:	World Scientific Publishing Europe Ltd
Publication date:	01/13/2017
Series:	Advanced Textbooks In Physics
Pages:	400
Product dimensions:	6.00(w) x 9.00(h) x 0.80(d)

Table of Contents

Foreword v

List of Figures vii

List of Tables xi

List of Examples xiii

Glossary xvii

Introduction xxiii

1 Samples and Selection Effects 1

1.1 Introduction: which sample for which science goal? 1

1.1.1 General rules to optimize the scientific returns from a survey of distant galaxies 1

1.2 General rules for estimating magnitudes 5

1.2.1 Monochromatic and integrated magnitudes 5

1.2.2 Photometric systems 6

1.2.3 Total magnitudes and proxies 7

1.2.4 Absolute magnitudes 8

1.3 Pre-selection of a sample prior to redshift measurement 9

1.3.1 Photometric catalogs 9

1.3.2 Statistics: which size for a redshift survey? 9

1.3.3 Cosmological variance 11

1.3.4 Depth of the photometry and selection effects related to surface-brightness 11

1.3.5 Other selection effects: Malmquist bias, Eddington bias, and leasing effects 13

1.3.6 K-correction and choice of the selecting magnitude 17

1.4 Redshift surveys 21

1.4.1 Redshift measurements and spectroscopic selection effects 21

1.4.2 Determination of the LF, uncertainties and completeness tests 24

1.4.3 Examples of surveys (CFRS, DEEP2, VVDS, zCOSMOS, and WIGGLEZ) 30

1.5 Photometric redshifts 34

1.6 Selection of very distant galaxies at z >> 1 37

1.6.1 Lyman break galaxies (LBGs) 37

1.6.2 Balmer and 400mm break drop-out galaxies 40

1.6.3 Lyα emitters (LAEs) 41

1.6.4 Indirect probes: damped Lyα systems (DLAs) and gamma ray burst hosts 41

1.6.5 Dust-enshrouded galaxies 42

1.6.6 Towards an overview of the high-z galaxy population and a fair determination of the LFs 42

1.7 Relating distant and nearby galaxies 44

Bibliography 48

2 Imaging and Photometry 55

2.1 Introduction 55

2.2 Basic Elements of imaging and image analysis 57

2.2.1 Spatial resolution 57

2.2.2 Depth 62

2.2.3 Spectral Bandwidth 68

2.2.4 Observing with imagers 73

2.3 Data Reduction 75

2.3.1 Basic principles 75

2.3.2 Description of basic calibration frames 77

2.3.3 Reducing and calibrating images 78

2.3.4 S/N ratio 82

2.4 Galaxy Morphology 86

2.4.1 Morphological classifications 87

2.4.2 Characterizing morphology at high redshifts 89

2.1.3 Empirical methods - Eyeball classifications 92

2.4.3 Light decomposition using software 92

2.4.4 Automatic methods with two or more parameters 96

2.4.5 A pragmatic and conservative approach to classify distant galaxies 101

2.5 Multi-wavelength photometry 107

2.5.1 Cross-correlating images at different wavelengths 108

2.5.2 Aperture photometry 110

2.6 Spectral energy distributions (SEDs) 119

2.6.1 Impact of the stellar populations: which wavelength tells you what? 119

2.6.2 Impact of dust and gas 121

2.6.3 Estimating galaxy properties from an SED 126

2.6.4 Estimating stellar mass 130

2.6.5 Estimating galaxy SFRs 136

Bibliography 141

3 Integrated Spectroscopy 155

3.1 Introduction 155

3.1.1 Desiccating a galaxy spectrum 157

3.1.2 Integrated spectroscopy of distant targets 161

3.2 Basics of spectroscopy 162

3.2.1 Multi-object spectrographs 164

3.2.2 Slit-less grism spectrographs 165

3.2.3 NLR spectrographs 166

3.3 Preparing observations 166

3.3.1 The choice of spectral resolution 167

3.3.2 Optimization of the S/N ratio 168

3.3.3 Minimizing the impact of the sky background 172

3.4 Data reduction 178

3.4.1 Main steps 178

3.4.2 Characterize the quality of the data reduction 183

3.5 Emission lines 186

3.5.1 Emission line properties 186

3.5.2 Proper methods for measuring emission lines 188

3.5.3 Low S/N regime: measurement bias 193

3.6 Emission diagnostics of the ionized ISM 194

3.6.1 Dust extinction 195

3.6.2 Active galactic nuclei 203

3.6.3 Star formation rate (SFRs) 207

3.6.4 Direct measurement of the gas metallicity (T^e method) 210

3.6.5 Indirect metallicity estimates from strong line ratios 215

3.7 Absorption line diagnostics of ISM & IGM 219

3.7.1 Measuring absorption lines 220

3.7.2 Back-Illuminated neutral Hydrogen gas 224

3.7.3 Absorption dines from the ISM of distant starbursts 233

3.8 Properties of stellar populations 239

3.8.1 Spectral Evolution of SSPs 241

3.8.2 Lick indices 245

3.8.3 Full spectra fitting 248

3.8.4 Velocity dispersion 253

3.9 Conclusion 253

Bibliography 255

4 Integral Field Spectroscopy 267

4.1 Introduction 267

4.2 Basics of IFU instruments 271

4.2.1 Fiber instruments 272

4.2.2 Image slicer instruments 273

4.2.3 Compromise between resolutions and S/N 274

4.2.4 Spatial resolution 275

4.2.5 Spectral resolution and crosstalk 277

4.2.6 Observing with IFU instruments 280

4.3 Data reduction of IFU observations 281

4.3.1 Reduction of fiber data 282

4.3.2 Reduction of image sheer data 284

4.3.3 Correcting for atmospheric dispersion 285

4.3.4 Spatial, spectral smoothing, and binning 286

4.3.5 Optimizing sky subtraction with NIR IFUs 288

4.4 Mapping galaxy properties from a data cube 290

4.4.1 Measuring emission lines: methods and error budget 291

4.4.2 Mapping physical properties 294

4.4.3 Mapping the kinematics 295

4.5 Kinematics of distant galaxies 297

4.5.1 A fundamental reference: kinematics of nearby galaxies 297

4.5.2 Kinematics of distant galaxies and beam smearing 302

4.5.3 Classifications based on pure kinematics 308

4.5.4 The kinematic classification 313

4.5.5 The morpho-kinematie classification 317

4.6 Conclusion 318

Bibliography 318

5 Applications and Scaling Relations 323

5.1 Applications to different distant galaxy studies 323

5.2 Dissecting the properties of distant galaxies 324

5.2.1 An example of a multi-instrument and multi-wavelength survey 324

5.2.2 Description of a few individual distant galaxies 325

5.2.3 Spiral disk building and merger rate 330

5.3 Evolution of scaling relations 331

5.3.1 Tully-Fisher Relation 331

5.3.2 The evolution of the M Z relation 337

5.3.3 SFR-M^stellar diagram 342

5.4 Au important challenge: baryonic mass estimate 345

5.1.1 Stellar mass estimates 345

5.4.1 Gas mass estimates 347

Bibliography 349

Appendix A Most intense emission and absorption lines 355

Index 359