Anisotropy of the galaxy cluster X-ray luminosity–temperature relation

Migkas, K.; Reiprich, T. H.

doi:10.1051/0004-6361/201731222

Cited by 29 publications

(23 citation statements)

References 73 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In this work, we constructed and analyzed a new, large homogeneously selected X-ray galaxy cluster sample of 313 objects, with the purpose of probing the anisotropic behavior of the L X − T scaling relation as first found in Migkas & Reiprich (2018) (M18). Through the strong correlation between the Xray luminosity and temperature and the null hypothesis that the L X − T behavior must be similar throughout the sky, one can probe the existence of up-to-now unknown factors affecting the behavior of X-ray photons, galaxy clusters or both, for different sky directions.…”

Section: Discussionmentioning

confidence: 99%

“…Since the outcome of the search for a preferred cosmological direction remains ambiguous, new and independent methods for such tests should be introduced and applied to the latest data samples. In Migkas & Reiprich (2018) (hereafter M18), the use of the directional behavior of the galaxy cluster X-ray luminosity-temperature relation is described as a cosmological probe. It is well-known that galaxy clusters are the most massive gravitationally bound systems in the universe, strongly emitting X-ray photons due to the large amounts of hot gas they contain (∼ 10% of their total mass) in their intra-cluster medium (ICM).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Probing cosmic isotropy with a new X-ray galaxy cluster sample through theL_X–Tscaling relation

Migkas

Schellenberger

Reiprich

et al. 2020

A&A

190

148

View full text Add to dashboard Cite

The isotropy of the late Universe and consequently of the X-ray galaxy cluster scaling relations is an assumption greatly used in astronomy. However, within the last decade, many studies have reported deviations from isotropy when using various cosmological probes; a definitive conclusion has yet to be made. New, effective and independent methods to robustly test the cosmic isotropy are of crucial importance. In this work, we use such a method. Specifically, we investigate the directional behavior of the X-ray luminositytemperature (L X − T ) relation of galaxy clusters. A tight correlation is known to exist between the luminosity and temperature of the X-ray-emitting intracluster medium of galaxy clusters. While the measured luminosity depends on the underlying cosmology through the luminosity distance D L , the temperature can be determined without any cosmological assumptions. By exploiting this property and the homogeneous sky coverage of X-ray galaxy cluster samples, one can effectively test the isotropy of cosmological parameters over the full extragalactic sky, which is perfectly mirrored in the behavior of the normalization A of the L X − T relation. To do so, we used 313 homogeneously selected X-ray galaxy clusters from the Meta-Catalogue of X-ray detected Clusters of galaxies (MCXC). We thoroughly performed additional cleaning in the measured parameters and obtain core-excised temperature measurements for all of the 313 clusters. The behavior of the L X − T relation heavily depends on the direction of the sky, which is consistent with previous studies. Strong anisotropies are detected at a 4σ confidence level toward the Galactic coordinates (l, b) ∼ (280 • , −20 • ), which is roughly consistent with the results of other probes, such as Supernovae Ia. Several effects that could potentially explain these strong anisotropies were examined. Such effects are, for example, the X-ray absorption treatment, the effect of galaxy groups and low redshift clusters, core metallicities, and apparent correlations with other cluster properties, but none is able to explain the obtained results. Analyzing 10 5 bootstrap realizations confirms the large statistical significance of the anisotropic behavior of this sky region. Interestingly, the two cluster samples previously used in the literature for this test appear to have a similar behavior throughout the sky, while being fully independent of each other and of our sample. Combining all three samples results in 842 different galaxy clusters with luminosity and temperature measurements. Performing a joint analysis, the final anisotropy is further intensified (∼ 5σ), toward (l, b) ∼ (303 • , −27 • ), which is in very good agreement with other cosmological probes. The maximum variation of D L seems to be ∼ 16 ± 3% for different regions in the sky. This result demonstrates that X-ray studies that assume perfect isotropy in the properties of galaxy clusters and their scaling relations can produce strongly biased results whether the underlying reason is cosmological or related ...

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Probing cosmic isotropy with a new X-ray galaxy cluster sample through theL_X–Tscaling relation

Migkas

Schellenberger

Reiprich

et al. 2020

A&A

190

148

View full text Add to dashboard Cite

show abstract

“…More specifically, the cosmic isotropy can be investigated using such methods. In Migkas & Reiprich (2018) and in Migkas et al (2020) (hereafter M18 and M20 respectively) we performed such a test with very intriguing results. We studied the isotropy of the X-ray luminosity-temperature (L X − T ) relation, which we used as a potential tracer for the isotropy of the expansion of the local Universe.…”

Section: Introductionmentioning

confidence: 99%

Cosmological implications of the anisotropy of ten galaxy cluster scaling relations

Migkas

Pacaud

Schellenberger

et al. 2021

A&A

View full text Add to dashboard Cite

The hypothesis that the late Universe is isotropic and homogeneous is adopted by most cosmological studies, including studies of galaxy clusters. The cosmic expansion rate H0 is thought to be spatially constant, while bulk flows are often presumed to be negligible compared to the Hubble expansion, even at local scales. The effects of bulk flows on the redshift–distance conversion are hence usually ignored. Any deviation from this consensus can strongly bias the results of such studies, and thus the importance of testing these assumptions cannot be understated. Scaling relations of galaxy clusters can be effectively used for this testing. In previous works, we observed strong anisotropies in cluster scaling relations, whose origins remain ambiguous. By measuring many different cluster properties, several scaling relations with different sensitivities can be built. Nearly independent tests of cosmic isotropy and large bulk flows are then feasible. In this work, we make use of up to 570 clusters with measured properties at X-ray, microwave, and infrared wavelengths to construct ten different cluster scaling relations and test the isotropy of the local Universe; to our knowedge, we present five of these scaling relations for the first time. Through rigorous and robust tests, we ensure that our analysis is not prone to generally known systematic biases and X-ray absorption issues. By combining all available information, we detect an apparent 9% spatial variation in the local H0 between (l, b)∼(280°−35°+35°, −15°−20°+20°) and the rest of the sky. The observed anisotropy has a nearly dipole form. Using isotropic Monte Carlo simulations, we assess the statistical significance of the anisotropy to be > 5σ. This result could also be attributed to a ∼900 km s−1 bulk flow, which seems to extend out to at least ∼500 Mpc. These two effects will be indistinguishable until more high-z clusters are observed by future all-sky surveys such as eROSITA.

show abstract

“…Besides the SNe Ia sample, galaxy [18][19][20]54], galaxy cluster [51][52][53], number counts of radio and mid-IR sources [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50], gamma-ray burst [13,66,108], gravitational wave [109], fast radio burst [109,110], and quasar [83,87] are also used to investigate the cosmic anisotropy. The UV and X-ray luminosity of quasars are used to test the cosmic anisotropy by Hu etc.…”

Section: Introductionmentioning

confidence: 99%

A tomographic test of cosmic anisotropy with the recently-released quasar sample

Zhao

Xia

2021

Eur. Phys. J. C

View full text Add to dashboard Cite

We test the cosmic anisotropy in the dipole-modulated $$\Lambda $$ Λ CDM model and Finslerian cosmological model with the recently-released quasar sample. Based on the redshift tomographic method, the quasar sample is divided into two subsets $$z \le z_{cut}$$ z ≤ z cut and $$z > z_{cut}$$ z > z cut by different cutting redshifts. The dipole amplitudes of the two cosmological models from the subsets $$z \le z_{cut}$$ z ≤ z cut are very weak. We find that quasars at a higher redshift range may provide more detailed information about the dipole amplitude $$A_D$$ A D . The dipole directions of each cosmological model from the subsets $$z \le 1.1$$ z ≤ 1.1 and $$z > 1.1$$ z > 1.1 are deviated by $$1\sigma $$ 1 σ level. The Pantheon sample is combined with the two subsets. The dipole amplitude from the two combined datasets is also very weak. In the dipole-modulated $$\Lambda $$ Λ CDM model, the dipole direction from the combined dataset quasar at $$z \le 1.1$$ z ≤ 1.1 and Pantheon sample is far away from the one given by the Pantheon sample. In the Finslerian cosmological model, the dipole directions from the two combined datasets are close to the one in the Pantheon sample.

show abstract

Anisotropy of the galaxy cluster X-ray luminosity–temperature relation

Cited by 29 publications

References 73 publications

Probing cosmic isotropy with a new X-ray galaxy cluster sample through theL_X–Tscaling relation

Probing cosmic isotropy with a new X-ray galaxy cluster sample through theL_X–Tscaling relation

Cosmological implications of the anisotropy of ten galaxy cluster scaling relations

A tomographic test of cosmic anisotropy with the recently-released quasar sample

Contact Info

Product

Resources

About

Anisotropy of the galaxy cluster X-ray luminosity–temperature relation

Cited by 29 publications

References 73 publications

Probing cosmic isotropy with a new X-ray galaxy cluster sample through theLX–Tscaling relation

Probing cosmic isotropy with a new X-ray galaxy cluster sample through theLX–Tscaling relation

Cosmological implications of the anisotropy of ten galaxy cluster scaling relations

A tomographic test of cosmic anisotropy with the recently-released quasar sample

Contact Info

Product

Resources

About

Probing cosmic isotropy with a new X-ray galaxy cluster sample through theL_X–Tscaling relation

Probing cosmic isotropy with a new X-ray galaxy cluster sample through theL_X–Tscaling relation