[Show abstract][Hide abstract] ABSTRACT: In order to test if there is energy transfer between dark energy and dark
matter, we investigate cosmological constraints on two forms of nontrivial
interaction between the dark matter sector and the sector responsible for the
acceleration of the universe, in light of the newly revised observations
including OHD, CMB, BAO and SNe Ia. More precisely, we find the same tendencies
for both phenomenological forms of the interaction term $Q=3\gamma H\rho$,
i.e., the parameter $\gamma$ to be a small number, $|\gamma|\approx 10^{-2}$.
However, concerning the sign of the interaction parameter, we observe that
$\gamma>0$ when the interaction between dark sectors is proportional to the
energy density of dust matter, whereas the negative coupling ($\gamma<0$) is
preferred by observations when the interaction term is proportional to dark
energy density. We further discuss two possible explanations to this
incompatibility and apply a quantitative criteria to judge the severity of the
coincidence problem. Results suggest that the $\gamma_m$IDE model with a
positive coupling may alleviate the coincidence problem, since its coincidence
index $C$ is smaller than that for the $\gamma_d$IDE model, the interacting
quintessence and phantom models by four orders of magnitude.
International Journal of Modern Physics D 05/2011; 22(14). DOI:10.1142/S021827181350082X · 1.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this paper, we propose an accurate test of the distance-duality (DD)
relation, $\eta=D_{L}(z)(1+z)^{-2}/D_{A}(z)=1$ (where $D_{L}$ and $D_{A}$ are
the luminosity distances and angular diameter distances, respectively), with a
combination of cosmological observational data of Type Ia Supernave (SNe Ia)
from Union2 set and the galaxy cluster sample under an assumption of spherical
model. In order to avoid bias brought by redshift incoincidence between
observational data and to consider redshift error bars of both clusters and SNe
Ia in analysis, we carefully choose the SNe Ia points which have the minimum
acceptable redshift difference of the galaxy cluster sample ($|\Delta z|_{\rm
min} =\sigma_{z, \rm SN}+\sigma_{z, \rm cluster}$). By assuming $\eta$ a
constant and functions of the redshift parameterized by six different
expressions, we find that there exists no conceivable evidence for variations
in the DD relation concerning with observational data, since it is well
satisfied within $1\sigma$ confidence level for most cases. Further considering
different values of $\Delta z$ in constraining, we also find that the choosing
of $\Delta z$ may play an important role in this model-independent test of the
distance-duality relation for the spherical sample of galaxy clusters.
Research in Astronomy and Astrophysics 04/2011; 11(10). DOI:10.1088/1674-4527/11/10/008 · 1.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We propose a new consistent method to test of the distance-duality (DD)
relation which related angular diameter distances (DA) to the luminosity
distances (DL) in a cosmology-independent way. In order to avoid any bias
brought by redshift incoincidence between galaxy clusters and Type Ia Supernave
(SNe Ia), as well as to ensure the integrity of the galaxy clusters samples, we
obtain the luminosity distance of a certain SN Ia point at the same redshift of
the corresponding galaxy cluster by interpolating from the nearby SNe Ia. With
the observational data at the same redshifts of the angular diameter distances
from the complete 38 galaxy cluster sample for the spherical model and the
corrected luminosity distances interpolated from the Union2 set, we find that
$\eta \equiv {D_L}{(1+z)}^{-2}/{D_A}=1$ is satisfied within $2\sigma$
confidence level for various parameterizations of $\eta(z)$, which are more
stringent than previous testing results without considering redshift bias.
Monthly Notices of the Royal Astronomical Society 04/2011; 436(2). DOI:10.1093/mnras/stt1589 · 5.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In order to test the possible interaction between dark energy and dark
matter, we investigate observational constraints on a phenomenological
scenario, in which the ratio between the dark energy and matter densities is
proportional to the power law case of the scale factor, $r\equiv
(\rho_X/\rho_m)\propto a^{\xi}$. By using the Markov chain Monte Carlo method,
we constrain the phenomenological interacting dark energy model with the newly
revised $H(z)$ data, as well as the cosmic microwave background (CMB)
observation from the 7-year Wilkinson Microwave Anisotropy Probe (WMAP7)
results, the baryonic acoustic oscillation (BAO) observation from the
spectroscopic Sloan Digital Sky Survey (SDSS) data release 7 (DR7) galaxy
sample and the type Ia supernovae (SNe Ia) from Union2 set. The best-fit values
of the model parameters are
$\Omega_{m0}=0.27_{-0.02}^{+0.02}(1\sigma)_{-0.03}^{+0.04}(2\sigma)$,
$\xi=3.15_{-0.50}^{+0.48}(1\sigma)_{-0.71}^{+0.72}(2\sigma)$, and
$w_X=-1.05_{-0.14}^{+0.15}(1\sigma)_{-0.21}^{+0.21}(2\sigma)$, which are more
stringent than previous results. These results show that the standard
$\Lambda$CDM model without any interaction remains a good fit to the recent
observational data; however, the interaction that the energy transferring from
dark matter to dark energy is slightly favored over the interaction from dark
energy to dark matter. It is also shown that the $H(z)$ data can give more
stringent constraints on the phenomenological interacting scenario when
combined to CMB and BAO observations, and the confidence regions of
$H(z)$+BAO+CMB, SNe+BAO+CMB, and $H(z)$+SNe+BAO+CMB combinations are consistent
with each other.
Monthly Notices of the Royal Astronomical Society 12/2010; 416(2). DOI:10.1111/j.1365-2966.2011.19105.x · 5.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The interacting dark matter (IDM) scenario allows for the acceleration of the
Universe without Dark Energy. We constrain the IDM model by using the newly
revised observational data including $H(z)$ data and Union2 SNe Ia via the
Markov chain Monte Carlo method. When mimicking the $\Lambda$CDM model, we
obtain a more stringent upper limit to the effective annihilation term at
$\kappa C_1\approx 10^{-3.4}\rm{Gyr}^{-1}$, and a tighter lower limit to the
relevant mass of Dark Matter particles at $M_x\approx 10^{-8.6}\rm{Gev}$. When
mimicking the $w$CDM model, we find that the effective equation of state of IDM
is consistent with the concordance $\Lambda$CDM model and appears to be most
consistent with the effective phantom model with a constant EoS for which
$w<-1$.
Astronomy and Astrophysics 11/2010; 529. DOI:10.1051/0004-6361/201016204 · 4.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We investigate observational constraints on the Dvali, Gabadadze and Porrati
(DGP) model with Gamma-ray bursts (GRBs) at high redshift obtained directly
from the Union2 Type Ia supernovae data (SNe Ia) set. With the
cosmology-independent GRBs, the Union2 set, as well as the cosmic microwave
background (CMB) observations from the WMAP7 result, the baryon acoustic
oscillation, the baryon mass fraction in clusters and the observed $H(z)$ data,
we obtain that the best-fit values of the DGP model are ${\Omega_{M0},
\Omega_{rc}} =\{0.235_{-0.014}^{+0.015},0.138_{-0.048}^{+0.051}\}$, which favor
a flat universe; and the transition redshift of the DGP model is
$z_T=0.67_{-0.04}^{+0.03}$. These results lead to more stringent constraints
than the previous results for the DGP model.
Research in Astronomy and Astrophysics 10/2010; 11(5). DOI:10.1088/1674-4527/11/5/001 · 1.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We investigate observational constraints on the generalized Chaplygin gas
(GCG) model including the gamma-ray bursts (GRBs) at high redshift obtained
directly from the Union2 type Ia supernovae (SNe Ia) set. By using the Markov
Chain Monte Carlo method, we constrain the GCG model with the
cosmology-independent GRBs, as well as the Union2 set, the cosmic microwave
background (CMB) observation from the Wilkinson Microwave Anisotropy Probe
(WMAP7) result, and the baryonic acoustic oscillation (BAO) observation from
the spectroscopic Sloan Digital Sky Survey (SDSS) data release 7 (DR7) galaxy
sample. The best-fit values of the GCG model parameters are
$A_S$=$0.7475_{-0.0539}^{+0.0556}(1\sigma)_{-0.0816}^{+0.0794}(2\sigma)$,
$\alpha$=$-0.0256_{-0.1326}^{+0.1760}(1\sigma)_{-0.1907}^{+0.2730}(2\sigma)$,
and the effective matter density
$\Omega_{m}=0.2629_{-0.0153}^{+0.0155}(1\sigma)_{-0.0223}^{+0.0236}(2\sigma)$,
which are more stringent than the previous results for constraining on GCG
model parameters.
Astronomy and Astrophysics 09/2010; 527(0004-6361). DOI:10.1051/0004-6361/201015919 · 4.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this paper, we constrain the Cardassian expansion models from the latest
observations including the updated Gamma-ray bursts (GRBs), which calibrated
cosmology-independently from the Union2 compilation of type Ia supernovae (SNe
Ia). By combining the GRB data to the joint observations with the Union2 SNe Ia
set, along with the Cosmic Microwave Background radiation observation from the
seven-year Wilkinson Microwave Anisotropy Probe result, the baryonic acoustic
oscillation observation from the spectroscopic Sloan Digital Sky Survey Data
Release galaxy sample, we find significant constraints on model parameters of
the original Cardassian model $\Omega_{{\rm M0}}=0.282_{-0.014}^{+0.015}$, $n=
0.03_{-0.05}^{+0.05}$; and $n= -0.16_{-3.26}^{+0.25}$,
$\beta=0.76_{-0.58}^{+0.34}$ of the modified polytropic Cardassian model, which
are consistent with the $\Lambda$CDM model in 1-$\sigma$ confidence region.
From the reconstruction of the deceleration parameter $q(z)$ in Cardassian
models, we obtain the transition redshift $z_{\rm T}=0.73\pm{0.04}$ for the
original Cardassian model, and $z_{\rm\rm T}=0.68\pm{0.04}$ for the modified
polytropic Cardassian model.
Research in Astronomy and Astrophysics 06/2010; 11(9). DOI:10.1088/1674-4527/11/9/002 · 1.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: For the use of Gamma-Ray Bursts (GRBs) to probe cosmology in a
cosmology-independent way, a new method has been proposed to obtain luminosity
distances of GRBs by interpolating directly from the Hubble diagram of SNe Ia,
and then calibrating GRB relations at high redshift. In this paper, following
the basic assumption in the interpolation method that objects at the same
redshift should have the same luminosity distance, we propose another approach
to calibrate GRB luminosity relations with cosmographic fitting directly from
SN Ia data. In cosmography, there is a well-known fitting formula which can
reflect the Hubble relation between luminosity distance and redshift with
cosmographic parameters which can be fitted from observation data. Using the
Cosmographic fitting results from the Union set of SNe Ia, we calibrate five
GRB relations using GRB sample at $z\leq1.4$ and deduce distance moduli of GRBs
at $1.4< z \leq 6.6$ by generalizing above calibrated relations at high
redshift. Finally, we constrain the dark energy parameterization models of the
Chevallier-Polarski-Linder (CPL) model, the Jassal-Bagla-Padmanabhan (JBP)
model and the Alam model with GRB data at high redshift, as well as with the
Cosmic Microwave Background radiation (CMB) and the baryonic acoustic
oscillation (BAO) observations, and we find the $\Lambda$CDM model is
consistent with the current data in 1-$\sigma$ confidence region.
International Journal of Modern Physics D 03/2010; 21(2). DOI:10.1142/S0218271812500162 · 1.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Constraints on the original Cardassian model and the modified polytropic Cardassian model are examined from the recently derived
42 gamma-ray bursts (GRBs) data calibrated with the method that can avoid the circularity problem. The results show that GRBs
can be an optional observation to constrain the Cardassian models. Combining the GRBs data with the newly derived size of
baryonic acoustic oscillation peak from the Sloan Digital Sky Survey (SDSS), and the position of the first acoustic peak of
the Cosmic Microwave Background radiation (CMB) from Wilkinson Microwave Anisotropy Probe (WMAP), we find Ω
mo = 0.27−0.02+0.02, n = 0.06−0.08+0.07 (1σ for the original Cardassian model, and Ω
mo = 0.27−0.02+0.03, n = −0.09−1.91+0.23
β = 0.82−0.62+2.10 (1 σ) for the modified polytropic Cardassian model.
KeywordsCardassian-Gamma ray burst-Cosmic Microwave Background-baryonic acoustic oscillation
[Show abstract][Hide abstract] ABSTRACT: We investigate the cosmological evolution of a two-field model of dark energy, where one is a dilaton field with canonical kinetic energy and the other is a phantom field with a negative kinetic energy term. Phase-plane analysis shows that the ``phantom"-dominated scaling solution is the stable late-time attractor of this type of model. We find that during the evolution of the universe, the equation of state w changes from w > -1 to w < -1, which is consistent with recent observations.
Chinese Physics Letters 01/2009; 26(6). DOI:10.1088/0256-307X/26/6/069501 · 0.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This report is an update and extension of our paper accepted for publication in ApJ (arXiv:0802.4262). Since objects at the same redshift should have the same luminosity distance and the distance moduli of type Ia supernovae (SNe Ia) obtained directly from observations are completely cosmology independent, we obtain the distance modulus of a gamma-ray burst (GRB) at a given redshift by interpolating or iterating from the Hubble diagram of SNe Ia. Then we calibrate five GRB relations without assuming a particular cosmological model, from different regression methods, and construct the GRB Hubble diagram to constrain cosmological parameters. Based upon these relations we list the cosmology-independent distance moduli of 42 GRBs between redshift of 1.44 and 6.60, with the 1-$\sigma$ uncertainties of 1-3%. Comment: 6 pages, 2 figures, 3 tables. To appear in the proceedings of "2008 Nanjing GRB conference", Nanjing, 23-27 June 2008
[Show abstract][Hide abstract] ABSTRACT: An important concern in the application of gamma-ray bursts (GRBs) to cosmology is that the calibration of GRB luminosity/energy relations depends on the cosmological model, due to the lack of a sufficient low-redshift GRB sample. In this paper, we present a new method to calibrate GRB relations in a cosmology-independent way. Since objects at the same redshift should have the same luminosity distance and since the distance moduli of Type Ia supernovae (SNe Ia) obtained directly from observations are completely cosmology independent, we obtain the distance modulus of a GRB at a given redshift by interpolating from the Hubble diagram of SNe Ia. Then we calibrate seven GRB relations without assuming a particular cosmological model and construct a GRB Hubble diagram to constrain cosmological parameters. From the 42 GRBs at $1.4<z\le6.6$, we obtain $\Omega_{\rm M}=0.25_{-0.05}^{+0.04}$, $\Omega_{\Lambda}=0.75_{-0.04}^{+0.05}$ for the flat $\Lambda$CDM model, and for the dark energy model with a constant equation of state $w_0=-1.05_{-0.40}^{+0.27}$, which is consistent with the concordance model in a 1-$\sigma$ confidence region. Comment: 7 pages, 3 figures, 1 table, now matches the editorially revised version; accepted for publication in ApJ (vol 685);
The Astrophysical Journal 02/2008; 685(1). DOI:10.1086/590903 · 5.99 Impact Factor