output children of term

<?php wp_list_categories(‘orderby=name&taxonomy=taxonomy_name&show_count=10&use_desc_for_title=0&child_of=??????????????’);
?>

I want to output children categories of term’s page

e.g.

if I am on page
http://mysite.com/?taxonomy=yyy&term=aaa
to display children of term aaa
if
http://mysite.com/?taxonomy=yyy&term=bbb
to display children of term bbb

can someone help? please?