pass member functions of a class with constructors to std::thread

I've defined a function in a class that takes a series of constructors and am trying to pass a function (fillgamma) to std::thread. the constructors themselves are quite large so I can't really pass them as parameters to the function every time I want to use it. I get a C3867 error when I try to compile which I'm pretty certain is due to the line marked bad line.

my project has gotten quite big so I've left off a load of the peripheral stuff but here's the class definition:

class gamma_threads
{
public:
    void fillgamma(int t, float &total);

    gamma_threads(std::vector<float> delpro, float Stau,float gamma0, int N);
    ~gamma_threads();

private:
    std::vector<float> delpro;
    const float Stau, gamma0;
    float gint=0;
    const int N;

};

And here's the body of the code attempting to implement the thread:

gamma_threads T(delpro, Stau, gammafbb[0], N); // vector, float, float, int

while (flag==1)
{
    std::thread th[8];
    for (int i = 0; i < 8; i++)
    { 
        if (!tlist.empty())  //tlist is a queue where I store the values to be fed to the threads
        {
            int temp_t = tlist.front();

            th[i] = std::thread((T.fillgamma, temp_t, gammafbb[temp_t])); // bad line
            if (temp_t + 8 <= tmax){ tlist.push(temp_t + 8); }
            else {  flag == 0; }
        }
    }
    for (int i = 0; i < 8; i++)
    {
        th[i].join();
    }
}

sorry if the code itself is offensively inefficient/ugly it's my first time with C++ so any other constructive criticism would be welcome too