Compound gravitational lensing as a probe of dark matter substructure within galaxy halos

被引:320
作者
Metcalf, RB
Madau, P
机构
[1] Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England
[2] Univ Calif Santa Cruz, Dept Astron & Astrophys, Santa Cruz, CA 95064 USA
关键词
cosmology : theory; dark matter; galaxies : formation; gravitational lensing;
D O I
10.1086/323695
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We show how observations of multiply imaged quasars at high redshift can be used as a probe of dark matter clumps (subhalos with masses less than or similar to 10(9) M-.) within the virialized extent of more massive lensing halos. A large abundance of such satellites is predicted by numerical simulations of galaxy formation in cold dark matter (CDM) cosmologies. Small-scale structure within galaxy halos affects the flux ratios of the images without appreciably changing their positions. We use numerical simulations to quantify the effect of dark matter substructure on the distribution of magnifications and find that the magnification ratio of a typical image pair will deviate significantly from the value predicted by a smooth lensing potential if, near the Einstein radius, only a few percent of the lens surface density is contained in subhalos. The angular size of the continuum source dictates the range of subclump masses that can have a detectable effect : to avoid confusion with gravitational microlensing caused by stars in the lens galaxy, the background source must be larger than the optical-continuum-emitting region of a QSO. We also find that substructure will cause distortions to images on milliarcsecond scales and bias the distribution of QSO magnification ratios-two other possible methods of detection.
引用
收藏
页码:9 / 20
页数:12
相关论文
共 36 条
[11]  
Flores RA, 1996, ASTROPHYS J, V457, pL5, DOI 10.1086/309879
[12]   Dark matter haloes within clusters [J].
Ghigna, S ;
Moore, B ;
Governato, F ;
Lake, G ;
Quinn, T ;
Stadel, J .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1998, 300 (01) :146-162
[13]   VLBI OBSERVATIONS OF THE GRAVITATIONAL LENS SYSTEM 0957+561 - STRUCTURE AND RELATIVE MAGNIFICATION OF THE A-IMAGES AND B-IMAGES [J].
GORENSTEIN, MV ;
COHEN, NL ;
SHAPIRO, II ;
ROGERS, AEE ;
BONOMETTI, RJ ;
FALCO, EE ;
BARTEL, N ;
MARCAIDE, JM .
ASTROPHYSICAL JOURNAL, 1988, 334 (01) :42-58
[14]   THE DISRUPTION OF THE SAGITTARIUS DWARF GALAXY [J].
JOHNSTON, KV ;
SPERGEL, DN ;
HERNQUIST, L .
ASTROPHYSICAL JOURNAL, 1995, 451 (02) :598-606
[15]   Lensing constraints on the cores of massive dark matter halos [J].
Keeton, CR ;
Madau, P .
ASTROPHYSICAL JOURNAL, 2001, 549 (01) :L25-L28
[16]  
Kembhavi A. K., 1999, QUASARS ACTIVE GALAC
[17]   Galaxies in N-body simulations:: Overcoming the overmerging problem [J].
Klypin, A ;
Gottlöber, S ;
Kravtsov, AV ;
Khokhlov, AM .
ASTROPHYSICAL JOURNAL, 1999, 516 (02) :530-551
[18]   Where are the missing galactic satellites? [J].
Klypin, A ;
Kravtsov, AV ;
Valenzuela, O ;
Prada, F .
ASTROPHYSICAL JOURNAL, 1999, 522 (01) :82-92
[19]   Resolving the structure of cold dark matter halos [J].
Klypin, A ;
Kravtsov, AV ;
Bullock, JS ;
Primack, JR .
ASTROPHYSICAL JOURNAL, 2001, 554 (02) :903-915
[20]  
LI LX, 2001, ASTROPH0010432