1 INTRODUCTION

2 BACKGROUND EVOLUTION WITH SCALAR FIELD COUPLED WITH DM

3 GROWTH OF MATTER FLUCTUATIONS IN THE LINEAR REGIME

4 THE REDSHIFTED 21 CM SIGNAL FROM THE POST-REIONIZATION EPOCH

5 RESULTS

6 THAWING VS TRACKER

7 FLUCTUATIONS IN THE SUPER-HORIZON SCALES

8 DISCUSSIONS