auto post with custom date php wordpress

When i upload the image from wp_media, this below code runs:

add_action('add_attachment', 'auto_post_after_image_upload'); // WordPress Hook

function auto_post_after_image_upload($attachId)
{
    $attachment = get_post($attachId);
    $image = wp_get_attachment_image_src( $attachId, 'large');
    $image_tag = '<p><img src="'.$image[0].'" /></p>';

    $postData = array(
        'post_title' => $attachment->post_title,
        'post_type' => 'post',
        'post_content' => $image_tag . $attachment->post_title,
        'post_category' => array('0'),
        'post_status' => 'publish',
        'post_date' => get_the_time()
    );

    $post_id = wp_insert_post($postData);

    // attach media to post
    wp_update_post(array(
        'ID' => $attachId,
        'post_parent' => $post_id,
    ));

    set_post_thumbnail($post_id, $attachId);

    return $attachId;
}

Now i want to put the date of the image when it was created and not the today’s date. How can i do that? get_the_time() returns the today date. I want the selected image created date.

<img src="https://i.stack.imgur.com/E7aYi.png" alt="Created date from image properties“>