Write the IDs of the black holes as unsigned long long

src/black_holes/Default/black_holes_io.h

@@ -126,7 +126,7 @@ INLINE static void black_holes_write_particles(const struct bpart* bparts,
   list[2] = io_make_output_field("Masses", FLOAT, 1, UNIT_CONV_MASS, 0.f,
                                  bparts, mass, "Masses of the particles");
 
-  list[3] = io_make_output_field("ParticleIDs", LONGLONG, 1, UNIT_CONV_NO_UNITS,
+  list[3] = io_make_output_field("ParticleIDs", ULONGLONG, 1, UNIT_CONV_NO_UNITS,
                                  0.f, bparts, id, "Unique ID of the particles");
 
   list[4] = io_make_output_field(

src/black_holes/EAGLE/black_holes_io.h

@@ -130,7 +130,7 @@ INLINE static void black_holes_write_particles(const struct bpart* bparts,
       io_make_output_field("DynamicalMasses", FLOAT, 1, UNIT_CONV_MASS, 0.f,
                            bparts, mass, "Dynamical masses of the particles");
 
-  list[3] = io_make_output_field("ParticleIDs", LONGLONG, 1, UNIT_CONV_NO_UNITS,
+  list[3] = io_make_output_field("ParticleIDs", ULONGLONG, 1, UNIT_CONV_NO_UNITS,
                                  0.f, bparts, id, "Unique ID of the particles");
 
   list[4] = io_make_output_field(