A search for warm/hot gas filaments between pairs of SDSS Luminous Red Galaxies

Abstract

We search the Planck data for a thermal Sunyaev-Zel'dovich (tSZ) signal due to gas filaments between pairs of Luminous Red Galaxies (LRG's) taken from the Sloan Digital Sky Survey Data Release 12 (SDSS/DR12). We identify ∼260,000 LRG pairs in the DR12 catalog that lie within 6-10 h −1 Mpc of each other in tangential direction and within 6 h −1 Mpc in radial direction. We stack pairs by rotating and scaling the angular positions of each LRG so they lie on a common reference frame, then we subtract a circularly symmetric halo from each member of the pair to search for a residual signal between the pair members. We find a statistically significant (5.3σ) signal between LRG pairs in the stacked data with a magnitude ∆y = (1.31 ± 0.25) × 10 −8 . The uncertainty is estimated from two Monte Carlo null tests which also establish the reliability of our analysis. Assuming a simple, isothermal, cylindrical filament model of electron over-density with a radial density profile proportional to r c /r (as determined from simulations), where r is the perpendicular distance from the cylinder axis and r c is the core radius of the density profile, we constrain the product of over-density and filament temperature to be δ c × (T e /10 7 K) × (r c /0.5h −1 Mpc) = 2.7 ± 0.5. To our knowledge, this is the first detection of filamentary gas at over-densities typical of cosmological largescale structure. We compare our result to the BAHAMAS suite of cosmological hydrodynamic simulations (McCarthy et al. 2017) and find a slightly lower, but marginally consistent Comptonization excess, ∆y = (0.84 ± 0.24) × 10 −8 .

The Physics of Galaxy Cluster Outskirts

“…As a comparison, the Planck SZ measurement of the massive cluster Abell 2319 (Ghirardini et al 2018a) is shown in the right hand panel of Figure 7. Also for comparison, the stacked Planck SZ measurement of the filamentary material between galaxies was found to be at a level of y ∼ 10 −8 (Tanimura et al 2017;de Graaff et al 2017), consistent with the pressure profile prediction at 6 × R 500 in Figure 7.…”

The abundance and physical properties of O vii and O viii X-ray absorption systems in the EAGLE simulations

“…For example, de Graaff et al (2019) used stacked massive galaxy pairs (mean stellar mass 10 11.3 M , virial mass ∼ 10 13 M h −1 ) to detect a filamentary thermal SZ signal. Tanimura et al (2019) similarly stacked luminous red galaxy pairs with stellar masses > 10 11.3 M , and found a filamentary thermal SZ signal larger than, but consistent with, predictions from the BAHAMAS simulations (Mc-Carthy et al 2017). Using the EAGLE simulations, Davies et al (2019) made theoretical predictions for the thermal SZ effect from the CGM at different halo masses.…”

Quantum mechanical look at the radioactive-like decay of metastable dark energy

“…In this place it should be noted that our analysis performed in this paper is free of this defect. Note also that Shafieloo et al [6] considered only the decays of the dark energy into dark components: dark matter and dark radiation, whereas we consider a general case (that is in our approach a decay of the dark energy into a visible baryonic matter is also admissible, which cannot be excluded in the light of the recently reported discovery of baryonic spindles linking galaxies [79][80][81]).…”