ajax callback wp_query

<?php

function your_callback_to_return_content(){
    $cat = $_POST['category'];

    $args = array(
        'category_name'=> $cat,
        'posts_per_page' => -1
    );

    $slide = 0;
    $ajax_content = '';
    $my_post = new WP_Query($args);

    if($my_post->have_posts()) :

      $ajax_content .= '<div id="#whitepapersshow">';

        while ( $my_post->have_posts() ) :

        $my_post->the_post();

        $ajax_content .= '<h2><a href="'.get_the_permalink().'">'.get_the_title().'</a></h2>';

        endwhile;

      $ajax_content .= '</div>';

    endif;

    echo $ajax_content;
    die;
}
add_action('wp_ajax_my_action', 'your_callback_to_return_content');
add_action('wp_ajax_nopriv_my_action', 'your_callback_to_return_content');

// enqueue our ajax script file and passing ajaxurl value
function my_ajax_load_scripts() {
    // get our custom-script.js
    wp_enqueue_script('my-custom-script', get_template_directory_uri() . '/js/custom-script.js');
    // globalize admin-ajax.php url for ajax processing page
    wp_localize_script('my-custom-script', 'my_wp', array(
            'ajaxurl' => admin_url('admin-ajax.php')
        )
    );
}
add_action('wp_enqueue_scripts', 'my_ajax_load_scripts');


?>