We present a multi-wavelength study of the gravitational lens COSMOS J095930+023427 (Zl = 0.892), together with the associated galaxy group along the line of sight located at z 0.7, and the lensed background galax...We present a multi-wavelength study of the gravitational lens COSMOS J095930+023427 (Zl = 0.892), together with the associated galaxy group along the line of sight located at z 0.7, and the lensed background galaxy. The source redshift is currently unknown, but estimated to be at zs ~ 2. This analysis is based on publicly available HST, Subaru and Chandra imaging data, as well as VLT spectroscopy. The lensing system is an early-type galaxy showing a strong [OII] emission line, and pro- duces four bright images of the distant background source. It has an Einstein radius of 0.79", about four times larger than the effective radius. We perform a lensing anal- ysis using both a singular isothermal ellipsoid and a peudo-isothermal elliptical mass distribution for the lensing galaxy, and find that the final results on the total mass, the dark matter (DM) fraction within the Einstein radius and the external shear due to a foreground galaxy group are robust with respect to the choice of the parametric model and the source redshift (yet unknown). We measure the luminous mass from the pho- tometric data, and find the DM fraction within the Einstein radius fDM to be between 0.71 ~ 0.13 and 0.79 ~ 0.15, depending on the unknown source redshift. Meanwhile, the non-null external shear found in our lensing models supports the presence and structure of a galaxy group at z ~ 0.7, and an independent measurement of the 0.5- 2 keV X-ray luminosity within 20" around the X-ray centroid provides a group mass of M = (3 - 10) x 1013 Mo, in good agreement with the previous estimate derived through weak lensing analysis. Finally, by inverting the HST/ACS/814 image with the lensing equation, we obtain the reconstructed image of the magnified source galaxy, which has a scale of about 3.3 kpc at z~ = 2 (2.7 kpc at zs = 4) and the typical disturbed disk-like appearance observed in low-mass star-forming galaxies at z ~ 3. However, deep, spatially resolved spectroscopic data for similar lensed sources are still required to detect the first stage of galaxy evolution, since the available spectrum shows no clear features due to the background source.展开更多
In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting wh...In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-ray binaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellently suited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s.展开更多
基金supported by the National Natural Science Foundation of China under the Distinguished Young Scholar program(Grant Nos.10825313 and 11073005)the National Basic Research Program of China (973program,Grant No. 2012CB821804)+1 种基金the Fundamental Research Funds for the Central Universities and Scientific Research Foundation of Beijing Normal Universitythe Excellent Doctoral Dissertation of Beijing Normal University Engagement Fund
文摘We present a multi-wavelength study of the gravitational lens COSMOS J095930+023427 (Zl = 0.892), together with the associated galaxy group along the line of sight located at z 0.7, and the lensed background galaxy. The source redshift is currently unknown, but estimated to be at zs ~ 2. This analysis is based on publicly available HST, Subaru and Chandra imaging data, as well as VLT spectroscopy. The lensing system is an early-type galaxy showing a strong [OII] emission line, and pro- duces four bright images of the distant background source. It has an Einstein radius of 0.79", about four times larger than the effective radius. We perform a lensing anal- ysis using both a singular isothermal ellipsoid and a peudo-isothermal elliptical mass distribution for the lensing galaxy, and find that the final results on the total mass, the dark matter (DM) fraction within the Einstein radius and the external shear due to a foreground galaxy group are robust with respect to the choice of the parametric model and the source redshift (yet unknown). We measure the luminous mass from the pho- tometric data, and find the DM fraction within the Einstein radius fDM to be between 0.71 ~ 0.13 and 0.79 ~ 0.15, depending on the unknown source redshift. Meanwhile, the non-null external shear found in our lensing models supports the presence and structure of a galaxy group at z ~ 0.7, and an independent measurement of the 0.5- 2 keV X-ray luminosity within 20" around the X-ray centroid provides a group mass of M = (3 - 10) x 1013 Mo, in good agreement with the previous estimate derived through weak lensing analysis. Finally, by inverting the HST/ACS/814 image with the lensing equation, we obtain the reconstructed image of the magnified source galaxy, which has a scale of about 3.3 kpc at z~ = 2 (2.7 kpc at zs = 4) and the typical disturbed disk-like appearance observed in low-mass star-forming galaxies at z ~ 3. However, deep, spatially resolved spectroscopic data for similar lensed sources are still required to detect the first stage of galaxy evolution, since the available spectrum shows no clear features due to the background source.
基金supported by the Royal Society,ERC Starting(Grant No.639217)he European Union Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Global Fellowship(Grant No.703916)+10 种基金the National Natural Science Foundation of China(Grant Nos.11233001,11773014,11633007,11403074,11333005,11503008,and 11590781)the National Basic Research Program of China(Grant No.2015CB857100)NASA(Grant No.NNX13AD28A)an ARC Future Fellowship(Grant No.FT120100363)the National Science Foundation(Grant No.PHY-1430152)the Spanish MINECO(Grant No.AYA2016-76012-C3-1-P)the ICCUB(Unidad de Excelencia’Maria de Maeztu’)(Grant No.MDM-2014-0369)EU’s Horizon Programme through a Marie Sklodowska-Curie Fellowship(Grant No.702638)the Polish National Science Center(Grant Nos.2015/17/B/ST9/03422,2015/18/M/ST9/00541,2013/10/M/ST9/00729,and 2015/18/A/ST9/00746)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA15020100)the NWO Veni Fellowship(Grant No.639.041.647)
文摘In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-ray binaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellently suited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s.