X‐Ray Emission from Rotating Elliptical Galaxies

Hanlan, Patricia C.; Bregman, Joel N.

doi:10.1086/308357

Cited by 13 publications

(18 citation statements)

References 34 publications

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“…If indeed the X‐ray properties of this central component are a property of the group rather than the galaxy itself, this would account for some of the observed scatter in the early‐type galaxy L X / L B relation. A group cooling flow could also explain the apparent lack of rotationally enhanced X‐ray ellipticity in the cooling flows of elliptical galaxies (Hanlan & Bregman 2000), and the correlation of X‐ray luminosity with the relative sizes of the X‐ray and optical emission (Mathews & Brighenti 1998), in that the most X‐ray overluminous galaxies should be found in the centre of bigger groups.…”

Section: Discussionmentioning

confidence: 99%

X-ray bright groups and their galaxies

Helsdon

Ponman

2003

Monthly Notices of the Royal Astronomical Society

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Combining X-ray data from the ROSAT PSPC and optical data drawn from the literature, we examine in detail the relationship between the X-ray and optical properties of X-ray bright galaxy groups. We find a relationship between optical luminosity and X-ray temperature consistent with that expected from self-similar scaling of galaxy systems, L_B \propto T^{1.6 +/- 0.2}. The self-similar form and continuity of the L_B : T relation from clusters to groups and the limited scatter seen in this relation, implies that the star formation efficiency is rather similar in all these systems. We find that the bright extended X-ray components associated with many central galaxies in groups appear to be more closely related to the group than the galaxy itself, and we suggest that these are group cooling flows rather than galaxy halos. In addition we find that the optical light in these groups appears to be more centrally concentrated than the light in clusters. We also use the optical and X-ray data to investigate whether early or late type galaxies are primarily responsible for preheating in groups. Using three different methods, we conclude that spiral galaxies appear to play a comparable role to early types in the preheating of the intragroup medium. This tends to favour models in which the preheating arises primarily from galaxy winds rather than AGN, and implies that spirals have played a significant role in the metal enrichment of the intragroup medium.Comment: 17 pages, accepted for publication in MNRA

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Section: Discussionmentioning

confidence: 99%

X-ray bright groups and their galaxies

Helsdon

Ponman

2003

Monthly Notices of the Royal Astronomical Society

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“…It would also explain the correlation of X‐ray luminosity with the relative sizes of the X‐ray and optical emission found by Mathews & Brighenti (1998): the most X‐ray overluminous galaxies should be found in the centre of bigger groups. In addition, the apparent lack of rotationally enhanced X‐ray ellipticity in the cooling flows of elliptical galaxies (Hanlan & Bregman 2000), may be explained if, the cooling flows are groups rather than galaxy cooling flows.…”

Section: Discussionmentioning

confidence: 99%

X-ray luminosities of galaxies in groups

Helsdon

Ponman

O’Sullivan

et al. 2001

Monthly Notices of the Royal Astronomical Society

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We have derived the X-ray luminosities of a sample of galaxies in groups, making careful allowance for contaminating intragroup emission. The L_X:L_B and L_X:L_{FIR} relations of spiral galaxies in groups appear to be indistinguishable from those in other environments, however the elliptical galaxies fall into two distinct classes. The first class is central-dominant group galaxies which are very X-ray luminous, and may be the focus of group cooling flows. All other early-type galaxies in groups belong to the second class, which populates an almost constant band of L_X/L_B over the range 9.8 < log L_B < 11.3. The X-ray emission from these galaxies can be explained by a superposition of discrete galactic X-ray sources together with a contribution from hot gas lost by stars, which varies a great deal from galaxy to galaxy. In the region where the optical luminosity of the non-central group galaxies overlaps with the dominant galaxies, the dominant galaxies are over an order of magnitude more luminous in X-rays. We also compared these group galaxies with a sample of isolated early-type galaxies, and used previously published work to derive L_X:L_B relations as a function of environment. The non-dominant group galaxies have mean L_X/L_B ratios very similar to that of isolated galaxies, and we see no significant correlation between L_X/L_B and environment. We suggest that previous findings of a steep L_X:L_B relation for early-type galaxies result largely from the inclusion of group-dominant galaxies in samples.Comment: 18 pages, 8 figures. Accepted for publication in MNRA

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“…In passing, we note that subsonic turbulence is a typical fea-ture in giant ellipticals (Werner et al 2009;de Plaa et al 2012;Ogorzalek et al 2017). Hanlan & Bregman (2000) studied a sample of 6 nearby objects with various rotational velocities and found that fast rotating elliptical galaxies have a smaller ellipticity in the X-rays than in the optical band. On the other hand, the lenticular galaxy NGC 6868 shows flattened X-ray isophotes (Machacek et al 2010), but it is currently also undergoing a merger.…”

Section: Shape Of the X-ray Halomentioning

confidence: 99%

“…This is most likely the result of the combined effect of the centrifugal barrier in the rotating atmosphere and the decreased depths of the effective gravitational potentials due to the rotational support. Apart from affecting the X-ray luminosities and shapes of the hot atmospheres (Brighenti & Mathews 1996, 1997Hanlan & Bregman 2000;Machacek et al 2010), rotation should also influence the conditions that govern thermal instabilities in the hot gas. Gaspari et al (2015) showed that the top-down multiphase condensation process -also known as chaotic cold accretion (CCA) -changes in rotation-dominated atmospheres.…”

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Cooling in the X-ray halo of the rotating, massive early-type galaxy NGC 7049

Juráňová

Werner

Gaspari

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The relative importance of the physical processes shaping the thermodynamics of the hot gas permeating rotating, massive early-type galaxies is expected to be different from that in non-rotating systems. Here, we report the results of the analysis of XMM-Newton data for the massive, lenticular galaxy NGC 7049. The galaxy harbours a dusty disc of cool gas and is surrounded by an extended hot X-ray emitting gaseous atmosphere with unusually high central entropy. The hot gas in the plane of rotation of the cool dusty disc has a multi-temperature structure, consistent with ongoing cooling. We conclude that the rotational support of the hot gas is likely capable of altering the multiphase condensation regardless of the t cool /t ff ratio, which is here relatively high, ∼ 40. However, the measured ratio of cooling time and eddy turnover time around unity (C-ratio ≈ 1) implies significant condensation, and at the same time, the constrained ratio of rotational velocity and the velocity dispersion (turbulent Taylor number) Ta t > 1 indicates that the condensing gas should follow non-radial orbits forming a disc instead of filaments. This is in agreement with hydrodynamical simulations of massive rotating galaxies predicting a similarly extended multiphase disc.

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X‐Ray Emission from Rotating Elliptical Galaxies

Cited by 13 publications

References 34 publications

X-ray bright groups and their galaxies

X-ray bright groups and their galaxies

X-ray luminosities of galaxies in groups

Cooling in the X-ray halo of the rotating, massive early-type galaxy NGC 7049

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