Thermal evolution of supernova iron in elliptical galaxies

被引:13
作者
Brighenti, F
Mathews, WG
机构
[1] Univ Calif Santa Cruz, Univ Calif Observ, Lick Observ, Dept Astron & Astrophys, Santa Cruz, CA 95064 USA
[2] Univ Bologna, Dipartimento Astron, I-40127 Bologna, Italy
关键词
cooling flows; diffusion; galaxies : elliptical and lenticular; cD; galaxies : ISM; supernova remnants; X-rays : galaxies : clusters;
D O I
10.1086/432042
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Interpretations of the spatial distribution, abundance ratios, and global masses of metals in the hot gas of galaxy clusters in terms of supernova enrichment have been problematical. For example, the abundance of iron and other elements occasionally declines toward the center just where the stellar and supernova densities are highest. Also, the mass of gas-phase iron per unit stellar mass or light is lower in elliptical galaxies and groups than in rich galaxy clusters. We discuss hypothetical scenarios in which these abundance anomalies can result from the preferential buoyant separation of metals. However, in this and all previous attempts to explain these metallicity observations it has been assumed that all metals created by supernovae are present in either visible stars or the hot gas. We discuss here the possibility that some of the iron expelled into the hot gas by Type Ia supernovae may have radiatively cooled, avoiding detection by X-ray and optical observers. Hydrodynamic models of Type Ia explosions in the hot gas inside elliptical galaxies create a gas of nearly pure iron that is several times hotter than the local interstellar gas. We describe the subsequent thermal evolution of the iron-rich gas as it radiates and thermally mixes with the surrounding gas. There is a critical time by which the iron ions must mix into the ambient gas to avoid rapid radiative cooling. We find that successful mixing is possible if the iron ions diffuse with large mean free paths, as in an unmagnetized plasma. However, the Larmor radii of the iron ions are exceptionally small in microgauss fields, so the field geometry must be highly tangled or radial to allow the iron to mix by diffusion faster than it cools by radiative losses. The possibility that some of the supernova iron cools cannot be easily discounted.
引用
收藏
页码:864 / 874
页数:11
相关论文
共 32 条
[1]   Intermediate-element abundances in galaxy clusters [J].
Baumgartner, WH ;
Loewenstein, M ;
Horner, DJ ;
Mushotzky, RF .
ASTROPHYSICAL JOURNAL, 2005, 620 (02) :680-696
[2]   Chandra observation of the cooling flow cluster Abell 2052 [J].
Blanton, EL ;
Sarazin, CL ;
McNamara, BR .
ASTROPHYSICAL JOURNAL, 2003, 585 (01) :227-243
[3]   A comparison of metal enrichment histories in rich clusters and individual luminous elliptical galaxies [J].
Brighenti, F ;
Mathews, WG .
ASTROPHYSICAL JOURNAL, 1999, 515 (02) :542-557
[4]   Ultralow iron abundances in the distant hot gas in galaxy groups [J].
Buote, DA ;
Brighenti, F ;
Mathews, WG .
ASTROPHYSICAL JOURNAL, 2004, 607 (02) :L91-L94
[5]   XMM-Newton and Chandra observations of the galaxy group NGC 5044.: II.: Metal abundances and supernova fraction [J].
Buote, DA ;
Lewis, AD ;
Brighenti, F ;
Mathews, WG .
ASTROPHYSICAL JOURNAL, 2003, 595 (01) :151-166
[6]  
Cappellaro E, 1999, ASTRON ASTROPHYS, V351, P459
[7]   Element segregation in giant galaxies and X-ray clusters [J].
Chuzhoy, L ;
Loeb, A .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2004, 349 (01) :L13-L17
[8]  
Dorfi EA, 1996, ASTRON ASTROPHYS, V307, P715
[9]  
DUPKE RA, 2000, APJ, V537, P13
[10]   Interaction of type Ia supernovae with their surroundings [J].
Dwarkadas, VV ;
Chevalier, RA .
ASTROPHYSICAL JOURNAL, 1998, 497 (02) :807-823