Extended tachyon field using form invariance symmetry

Abstract

In this work we illustrate how form-invariance transformations (FIT) can be used to construct phantom and complementary tachyon cosmologies from standard tachyon field universes. We show how these transformations act on the Hubble expansion rate, the energy density, and pressure of the tachyon field. The FIT generate new cosmologies from a known "seed" one, in particular from the ordinary tachyon field we obtain two types of tachyon species, denominated phantom and complementary tachyon. We see that the FIT allow us to pass from a non-stable cosmology to a stable one and vice-versa, as appeared in the literature. Finally, as an example, we apply the transformations to a cosmological fluid with an inverse square potential, V ∝ φ −2 , and generate the extended tachyon field.

Analysis cosmological tachyon and fermion model and observation data constraints

“…The large value χ 2 is critical in relation to the Akaike information criterion AIC = minχ 2 tot + 2N p . However, simultaneously, a decrease in the γ 0 parameter makes this model stable and provides the possibility of a theory with an ordinary tachyon according to the criterion [16]. The speed of sound for this model, which is confirmed by the observational data, is c 2 s = 1 − γ 0 = 0.992 > 1/5.…”

“…A tachyon field can play one of the leading roles in the modern accelerated expansion of the universe due to dark energy [1][2][3][4][5][6][7]. Also, it makes a big contribution to inflationary models [8][9][10][11] and brings a useful role in cosmology with different types of the tachyon potentials [12][13][14][15][16].…”

“…The complementary tachyon field always plays the role of matter [7,[18][19][20]. In the work [16] was illustrated, that a standard tachyon field, after applying a form invariance symmetry to it, can generate a complementary tachyon field and a phantom tachyon field. In [7] tachyonization of ΛCDM model was made for spatially flat, homogeneous and isotropic Friedman-Robertson-Walker (FRW) space-time.…”

Power spectra in extended tachyon cosmologies

“…Nevertheless there exists two new kinds of extended tachyon fields [23,26]. In the last of those references it is shown that these two new types of tachyons could be derived from the standard tachyon field (0 < γ < 1) by use of a symmetry argument [27].…”

“…In the recent years some attention to tachyon driven cosmologies was paid [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Some reasons are that such cosmologies may play an important role in inflationary models as well as in the present accelerated expansion, simulating the effect of the dark energy, [28][29][30][31][32][33][34][35], depending upon the form of the tachyon potential [28][29][30][36][37][38].…”