Jeltema T.E.,UCO Lick Observatories
AIP Conference Proceedings | Year: 2010
We use Chandra and XMM-Newton to study how the hot gas content in early-type galaxies varies with environment. We find that the L X-LK relationship is steeper for field galaxies than for comparable galaxies in groups and clusters. This suggests that internal processes such as supernovae driven winds or AGN feedback may expel hot gas from low mass field galaxies. Such mechanisms are less effective in groups and clusters where the presence of an intragroup or intracluster medium may confine outflowing material. © 2010 American Institute of Physics.
Mulchaey J.S.,Carnegie Institution for Science |
Jeltema T.E.,UCO Lick Observatories
Astrophysical Journal Letters | Year: 2010
We use Chandra and XMM-Newton to study the hot gas content in a sample of field early-type galaxies. We find that the LX-LK relationship is steeper for field galaxies than for comparable galaxies in groups and clusters. The low hot gas content of field galaxies with L KL* suggests that internal processes such as supernovae-driven winds or active galactic nucleus feedback expel hot gas from low-mass galaxies. Such mechanisms may be less effective in groups and clusters where the presence of an intragroup or intracluster medium can confine outflowing material. In addition, galaxies in groups and clusters may be able to accrete gas from the ambient medium. While there is a population of L KL* galaxies in groups and clusters that retain hot gas halos, some galaxies in these rich environments, including brighter galaxies, are largely devoid of hot gas. In these cases, the hot gas halos have likely been removed via ram pressure stripping. This suggests a very complex interplay between the intragroup/intracluster medium and hot gas halos of galaxies in rich environments, with the ambient medium helping to confine or even enhance the halos in some cases and acting to remove gas in others. In contrast, the hot gas content of more isolated galaxies is largely a function of the mass of the galaxy, with more massive galaxies able to maintain their halos, while in lower mass systems the hot gas escapes in outflowing winds. © 2010 The American Astronomical Society. All rights reserved.
Rasmussen J.,Copenhagen University |
Bai X.-N.,Princeton University |
Mulchaey J.S.,Carnegie Observatories |
Van Gorkom J.H.,Columbia University |
And 6 more authors.
Astrophysical Journal | Year: 2012
The role of environmentally induced gas stripping in driving galaxy evolution in groups remains poorly understood. Here we present extensive Chandra and Very Large Array mosaic observations of the hot and cold interstellar medium within the members of the nearby, X-ray bright NGC2563 group, a prime target for studies of the role of gas stripping and interactions in relatively small host halos. Our observations cover nearly all group members within a projected radius of 1.15Mpc (∼1.4 R vir) of the group center, down to a limiting X-ray luminosity and H I mass of 3 × 10 39ergs-1 and 2 × 108 M ⊙, respectively. The X-ray data are consistent with efficient ram pressure stripping of the hot gas halos of early-type galaxies near the group core, but no X-ray tails are seen and the limited statistics preclude strong conclusions. The H I results suggest moderate H I mass loss from the group members when compared to similar field galaxies. Six of the 20 H I-detected group members show H I evidence of ongoing interactions with other galaxies or with the intragroup medium. Suggestive evidence is further seen for galaxies with close neighbors in position-velocity space to show relatively low H I content, consistent with tidal removal of H I. The results thus indicate removal of both hot and cold gas from the group members via a combination of ram pressure stripping and tidal interactions. We also find that 16 of the 20 H I detections occur on one side of the group, reflecting an unusual morphological segregation whose origin remains unclear. © 2012. The American Astronomical Society. All rights reserved.
Hallman E.J.,University of Colorado at Boulder |
Hallman E.J.,Harvard - Smithsonian Center for Astrophysics |
Hallman E.J.,National Science Foundation |
Skillman S.W.,University of Colorado at Boulder |
And 5 more authors.
Astrophysical Journal | Year: 2010
We examine the incidence of cold fronts in a large sample of galaxy clusters extracted from a (512 h-1 Mpc) hydrodynamic/N-body cosmological simulation with adiabatic gas physics computed with the Enzo adaptive mesh refinement code. This simulation contains a sample of roughly 4000 galaxy clusters with M ≥ 1014M⊙ at z = 0. For each simulated galaxy cluster, we have created mock 0.3-8.0 keV X-ray observations and spectroscopic-like temperature maps. We have searched these maps with a new automated algorithm to identify the presence of cold fronts in projection. Using a threshold of a minimum of 10 cold front pixels in our images, corresponding to a total comoving length Lcf 156 h-1 kpc, we find that roughly 10%-12% of all projections in a mass-limited sample would be classified as cold front clusters. Interestingly, the fraction of clusters with extended cold front features in our synthetic maps of a mass-limited sample trends only weakly with redshift out to z = 1.0. However, when using different selection functions, including a simulated flux limit, the trending with redshift changes significantly. The likelihood of finding cold fronts in the simulated clusters in our sample is a strong function of cluster mass. In clusters with M ≥ 7.5 × 1014M⊙ the cold front fraction is 40%-50%. We also show that the presence of cold fronts is strongly correlated with disturbed morphology as measured by quantitative structure measures. Finally, we find that the incidence of cold fronts in the simulated cluster images is strongly dependent on baryonic physics. © 2010 The American Astronomical Society.
Simcoe R.A.,Massachusetts Institute of Technology |
Burgasser A.J.,University of California at San Diego |
Bochanski J.J.,Massachusetts Institute of Technology |
Schechter P.L.,Massachusetts Institute of Technology |
And 7 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010
We describe the construction and commissioning of FIRE, a new 0.8-2.5μm echelle spectrometer for the Magellan/ Baade 6.5 meter telescope. FIRE delivers continuous spectra over its full bandpass with nominal spectral resolution R = 6000. Additionally it offers a longslit mode dispersed by the prisms alone, covering the full z to K bands at R ∼ 350. FIRE was installed at Magellan in March 2010 and is now performing shared-risk science observations. It is delivering sharp image quality and its throughput is sufficient to allow early observations of high redshift quasars and faint brown dwarfs. This paper outlines several of the new or unique design choices we employed in FIRE's construction, as well as early returns from its on-sky performance. © 2010 Copyright SPIE - The International Society for Optical Engineering.