Revisiting the Cooling Flow Problem in Galaxies, Groups, and Clusters of Galaxies

Abstract

We present a study of 107 galaxies, groups, and clusters spanning ∼3 orders of magnitude in mass, ∼5 orders of magnitude in central galaxy star formation rate (SFR), ∼4 orders of magnitude in the classical cooling rate (Ṁ cool ≡ M gas (r < r cool )/t cool ) of the intracluster medium (ICM), and ∼5 orders of magnitude in the central black hole accretion rate. For each system in this sample we measure the ICM cooling rate,Ṁ cool , using archival Chandra X-ray data and acquire the SFR and systematic uncertainty in the SFR by combining over 330 estimates from dozens of literature sources. With these data, we estimate the efficiency with which the ICM cools and forms stars, finding ǫ cool ≡ SF R/Ṁ cool = 1.4 ± 0.4% for systems withṀ cool > 30 M ⊙ yr −1 . For these systems, we measure a slope in the SFR-Ṁ cool relation greater than unity, suggesting that the systems with the strongest cool cores are also cooling more efficiently. We propose that this may be related to, on average, higher black hole accretion rates in the strongest cool cores, which could influence the total amount (saturating near the Eddington rate) and dominant mode (mechanical vs radiative) of feedback. For systems withṀ cool < 30 M ⊙ yr −1 , we find that the SFR andṀ cool are uncorrelated, and show that this is consistent with star formation being fueled at a low (but dominant) level by recycled ISM gas in these systems. We find an intrinsic log-normal scatter in SFR at fixedṀ cool of 0.52 ± 0.06 dex (1σ RMS), suggesting that cooling is tightly self-regulated over very long timescales, but can vary dramatically on short timescales. There is weak evidence that this scatter may be related to the feedback mechanism, with the scatter being minimized (∼0.4 dex) for systems for which the mechanical feedback power is within a factor of two of the cooling luminosity.

Pressure Profiles and Mass Estimates Using High-resolution Sunyaev–Zel’dovich Effect Observations of Zwicky 3146 with MUSTANG-2

“…Edge et al (1994) estimate a pure cooling flow rate of 1250 M yr −1 . Subsequent reported rates vary between 300-1600 M yr −1 (Egami et al 2006b;Kausch et al 2007;McDonald et al 2018), Okabe & Smith (2016).…”

The X-Ray Halo Scaling Relations of Supermassive Black Holes

“…In the central regions of relaxed, coolcore (CC) systems, the plasma densities are such that the cooling time of the hot ICM/IGrM becomes much smaller than the Hubble time. Thus, a fraction of the hot gas 1 cools and condenses in the central galaxy, forming extended warm filaments detected in Hα and cold molecular clouds that fuel star formation (e.g., Fabian et al 2002;Peterson & Fabian 2006;Combes et al 2007;McDonald et al 2010McDonald et al , 2011McDonald et al , 2018Gaspari 2015;Molendi et al 2016;Temi et al 2018;Tremblay et al 2015Tremblay et al , 2018Nagai et al 2019). A portion of the cooling gas ignites the central AGN, which triggers the SMBH response via outflowing material that regulates the cooling flow of the macro-scale gaseous halo (e.g., Bîrzan et al 2004;Rafferty et al 2006;McNamara & Nulsen 2007;.…”

Inquiring into the nature of the Abell 2667 brightest cluster galaxy: physical properties from MUSE

“…These cosmologically rapidly cooling regions, are referred as 'cool cores' and today are believed to characterise roughly a third of all galaxy clusters (e.g. McDonald et al 2018), the so-called cool core clusters. According to their properties, cooling flows could drive to the BCG region starforming gas at huge rates.…”