NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-20 T06:03:37 PDT
Help | Comment | NED Home

For refcode 2015ApJ...812..127K:
Retrieve 61 NED objects in this reference.
Please click here for ADS abstract

NED Abstract

Copyright by American Astronomical Society. Reproduced by permission
2015ApJ...812..127K X-Ray Scaling Relations of 'Core' and 'Coreless' E and S0 Galaxies Kim, Dong-Woo; Fabbiano, Giuseppina Abstract. We have re-examined the two X-ray scaling relations of early-type galaxies (ETGs), L_X,GAS_-L_K_ and L_X,GAS_-T_GAS_, using 61 ATLAS^3D^ E and S0 galaxies observed with Chandra (including ROSAT results for a few X-ray bright galaxies with extended hot gas). With this sample, which doubles the number of ETGs available for study we confirm the strong, steep correlations reported by Boroson et al. Moreover, the larger sample allows us to investigate the effect of structural and dynamical properties of ETGs in these relations. Using the sub-sample of 11 "genuine" E galaxies with central surface brightness cores, slow stellar rotations and old stellar populations, we find that the scatter of the correlations is strongly reduced, yielding an extremely tight relation of the form L_X,GAS_ ~ {{T}_{GAS_}}^4.5+/- 0.3^. The rms deviation is only 0.13 dex. For the gas-rich galaxies in this sample (L_X,GAS_ > 10^40^ erg s^-1^), this relation is consistent with recent simulations for velocity dispersion supported E galaxies. However, the tight L_X,GAS_-T_GAS_ relation of genuine E galaxies extends down into the L_X_ ~ 10^38^ erg s^-1^ range, where simulations predict the gas to be in outflow/wind state, with resulting L_X_ much lower than observed in our sample. The observed correlation may suggest the presence of small bound hot halos even in this low luminosity range. At the high luminosity end, the L_X,GAS_-T_GAS_ correlation of core elliptical galaxies is similar to that found in samples of cD galaxies and groups, but shifted down toward relatively lower L_X,GAS_ for a given T_GAS_. In particular cDs, central dominant galaxies sitting at the bottom of the potential well imposed by the group dark matter, have an order of magnitude higher L_X,GAS_ than our sample core galaxies for the same L_K_ and T_GAS_. We suggest that enhanced cooling in cDs, which have higher hot gas densities and lower entropies, could lower T_GAS_ to the range observed in giant Es; this conclusion is supported by the presence of extended cold gas in several cDs. Instead, in the sub-sample of coreless ETGs---these galaxies also tend to show stellar rotation, a flattened galaxy figure and rejuvenation of the stellar population---L_X,GAS_ and T_GAS_ are not correlated. The L_X_-T_GAS_ distribution of coreless ETGs is a scatter diagram clustered at L_X,GAS_ < 10^40^ erg s^-1^, similar to that reported for the hot interstellar medium (ISM) of spiral galaxies, suggesting that both the energy input from star formation and the effect of galactic rotation and flattening may disrupt the hot ISM. Key words: galaxies: elliptical and lenticular, cD, X-rays: galaxies
Retrieve 61 NED objects in this reference.
Please click here for ADS abstract

Back to NED Home