The frequency of dwarf galaxy multiples at low redshift in SDSS versus cosmological expectations
The frequency of dwarf galaxy multiples at low redshift in SDSS versus cosmological expectations
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SDSS 中低红移处矮星系倍数的频率与宇宙学预期
DOI：
10.1093/mnras/sty2041
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发表时间：
2018
影响因子：
4.8
通讯作者：
Putman, Mary E.
中科院分区：
文献类型：
--
作者：
Besla, Gurtina;Patton, David R.;Stierwalt, Sabrina;Rodriguez-Gomez, Vicente;Patel, Ekta;Kallivayalil, Nitya J.;Johnson, Kelsey E.;Pearson, Sarah;Privon, George C.;Putman, Mary E.
我们量化了低红移（0.013 << 0.0252）矮星系（2 × 108 M <$<M星< 5 × 109 M <$）的伴星的频率，这些伴星是从SDSS中更大质量的星系中分离出来的，并与使用插图模拟观测的宇宙学预期进行了比较。矮多重星系是指两个或多个角距大于55角秒，投影距离小于150 kpc，相对视线速度小于150 km s−1的矮星系。虽然模拟星表预测的孤立矮星比SDSS中观测到的多两个，但每个矮星观测到的伴星的平均数量是Nc = 0.04，在考虑SDSS灵敏度极限时，与插图很好地吻合。在模拟星表中去除这些限制后，未来的巡天（LSST，DESI）的Nc = 0.06，将完成Mstar= 2 × 108 M。模拟矮多次波的3D分离揭示了投影效应观测中的2.40%的污染分数。大多数孤立的多重星系是成对的，三重星系是罕见的，在本研究所探讨的参数范围内，存在超过三个成员的束缚矮星群在宇宙学上是不可能的。我们发现，该领域中<1%的LMC类似物具有SMC类似物伴侣。矮“主要对”（恒星质量比>1：4）的比例随着主恒星质量的减少而稳步增加，而宇宙学的“主要合并率”（每Gyr）则有相反的行为。我们的结论是，宇宙学模拟可以可靠地用来限制跨宇宙时间的矮合并的分数。
We quantify the frequency of companions of low-redshift (0.013 << 0.0252) dwarf galaxies (2 × 108M⊙< Mstar< 5 × 109M⊙) that are isolated from more massive galaxies inSDSSand compare against cosmological expectations using mock observations of theIllustrissimulation. Dwarf multiples are defined as two or more dwarfs that have angular separations >55 arcsec, projected separationsrp< 150 kpc, and relative line-of-sight velocities ΔVLOS< 150 km s−1. While the mock catalogues predict a factor of two more isolated dwarfs than observed inSDSS, the mean number of observed companions per dwarf isNc∼ 0.04, in good agreement withIllustriswhen accounting forSDSSsensitivity limits. Removing these limits in the mock catalogues predictsNc∼ 0.06 for future surveys (LSST, DESI), which will be complete to Mstar= 2 × 108M⊙. The 3D separations of mock dwarf multiples reveal a contamination fraction of ∼40 per cent in observations from projection effects. Most isolated multiples are pairs; triples are rare and it is cosmologically improbable that bound groups of dwarfs with more than three members exist within the parameter range probed in this study. We find that <1 per cent of LMC-analogues in the field have an SMC-analogue companion. The fraction of dwarf “Major Pairs” (stellar mass ratio >1:4) steadily increases with decreasing Primary stellar mass, whereas the cosmological “Major Merger rate” (per Gyr) has the opposite behaviour. We conclude that cosmological simulations can be reliably used to constrain the fraction of dwarf mergers across cosmic time.
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影响因子：
4.8
作者：
L. Sales;Wenting Wang;S. White;J. Navarro
通讯作者：
J. Navarro
DOI：
10.1088/2041-8205/795/1/l5
发表时间：
2014
期刊：
The Astrophysical Journal Letters
影响因子：
--
作者：
K. Spekkens;N. Urbancic;B. Mason;B. Willman;J. Aguirre
通讯作者：
J. Aguirre
DOI：
10.1111/j.1365-2966.2009.15034.x
发表时间：
2008-08
影响因子：
4.8
作者：
K. Dolag;S. Borgani;S. Borgani;S. Borgani;G. Murante;V. Springel
通讯作者：
K. Dolag;S. Borgani;S. Borgani;S. Borgani;G. Murante;V. Springel
DOI：
10.1088/2041-8205/721/2/l97
发表时间：
2010-08
期刊：
The Astrophysical Journal Letters
影响因子：
--
作者：
G. Besla;N. Kallivayalil;L. Hernquist;R. V. D. Marel;T. J. Cox;D. Keres̆
通讯作者：
G. Besla;N. Kallivayalil;L. Hernquist;R. V. D. Marel;T. J. Cox;D. Keres̆
影响因子：
64.8
作者：
J. Wyithe;A. Loeb
通讯作者：
A. Loeb