What's wrong with my e-mail to potential PhD supervisors? I recently sent some e-mails to potential supervisors asking information for a PhD with them, I obtained no answers. I share my doubts and then copy the standard mail I sent. 


I sent it to 5 different professors in different universities, is the sample too small to expect some answers? I know professors are flooded with e-mails so it could be normal not receiving answers.
Can you point out something I did wrong in my email such as: too long, too short, harsh, too many details, not many details, grammar mistakes (I'm not a native speaker), anything, to help me improve for future e-mails?
How do I have to take these silences? Should I solicit an answer or simply accept that they are not interested in answering?
I sent them on a sunday night, is this a bad moment to send such e-mails? if it is what are the best days and time to send them?
Feel free to give me any kind of advice you think could be helpful.


Here's a copy of my e-mail


  Dear professor XXX,
  I'm a student of XXX at the university of XXX thinking about applying for PhD in FIELD X, therefore your group at the university of YYY attracted my attention.
  I'd like to ask two questions about the possibility of being admitted at your university:
  
  1) Is there a good chance your group is going to look for PhD students in 2019/2020?
  
  2) Is the topic of the master's degree thesis fundamental for a strong application? For example, what are the chances that a student with a thesis in TOPIC Y would have his application taken very seriously into consideration by a group like yours?
  
  This is a very important question for me as it will have a great impact in my application strategy and maybe in the selection of the advisor for the thesis.
  
  Thank you in advance for your time and help if you decide to answer me.
  
  Best regards,
  
  ZZZZ


Addendum 1: as suggested by iayork I  have to be more precise and state that I'm European writing to professor in Europe and that I wasn't trying to bypass the application system by writing to them but instead following. As suggested I share the example of a  professor I didn't write to:
https://www.ics.uzh.ch/~jyoo/home.htm
In the section jobs he says he has to be contacted for information by possible PhD students. Another example from a university I didn't write to: http://www.en.physik.lmu.de/promotion/berechtigung/index.html
The point 1 is to find an advisor getting in touch with him/her

Addendum 2: Since it's creating a bit of confusion I have to precise that Topic Y in the letter is far from the research interests of the group contacted, I should have been more explicit in the mail and here explaining that the point of that question was to know if I had a chance even with such a thesis, and in case of negative answer I would change my master thesis advisor and topic to produce a thesis that allows me to have a chance to be taken in consideration by the group.

Thank you in advance for any help.
The statements


  what are the chances that a student with a thesis in TOPIC Y would have his application taken very seriously into consideration by a group like yours?


and 


  it will have a great impact in (sic) my application strategy and maybe in the selection of the advisor for the thesis


tell me you are not specifically interested in applying here. 

Are you interested in working with this prof or just shopping around? Giving general application advice to strangers isn't high on the list of the average professor's priorities.

(My direct experience is with German and Austrian universities. Programms with centralized admissions are becoming more frequent in continental Europe as well, but in general professors have more leeway here over whom to hire or take on as PhD students than in the US.)