论文标题
HE II 1640发射星系在vandels中的X射线特性
X-ray properties of He II 1640 emitting galaxies in VANDELS
论文作者
论文摘要
我们探索了从Chandra Deep Field South的Vandels调查中Z〜2.3-3.6的18 He II 1640样品中的X射线发射，以对X射线源在为He II发射供电中的作用设置限制。我们发现4 He II发射器具有S/N〜2的暂定检测，并且具有X射线发光度，L_X = 1.5-4.9 x 10^41 ERG/s。所有18 He II发射器的堆叠光度为2.6 x 10^41 erg/s，13个狭窄的He II发射器（FHWM（HE II）<1000 km/s）的子集为3.1 x 10^41 erg/s。我们还通过匹配样品的引导测量非-He II发射器的堆叠L_X，并找到L_X = 2.5 x 10^41 ERG/s，这与He II发射器测得的L_X并没有显着差异。 He II发射器（log（l_x/sfr）〜40.0）和非发射器（log（l_x/sfr）〜39.9）的L_x每颗恒星形成率也可比较，并且与模型预测的红移进化和金属依赖性。由于有或没有HE II的星系中的X射线排放之间的差异无显着差异，我们得出的结论是，X射线二进制或弱或模糊的AGN不太可能成为Vandels恒星形成的星系中Z〜3的vandels恒星形成星系中的主流光子的主要生产者，鉴于Z〜3的机制。鉴于He II II的替代机制。可能需要探索低金属性恒星种群，流行的III星等。
We explore X-ray emission from a sample of 18 He II 1640 emitting star-forming galaxies at z ~ 2.3-3.6 from the VANDELS survey in the Chandra Deep Field South, to set constraints on the role of X-ray sources in powering the He II emission. We find that 4 He II emitters have tentative detections with S/N ~ 2 and have X-ray luminosities, L_X = 1.5-4.9 x 10^41 erg/s. The stacked luminosity of all 18 He II emitters is 2.6 x 10^41 erg/s, and that of a subset of 13 narrow He II emitters (FHWM(He II) < 1000 km/s) is 3.1 x 10^41 erg/s. We also measure stacked L_X for non-He II emitters through bootstrapping of matched samples, and find L_X = 2.5 x 10^41 erg/s, which is not significantly different from L_X measured for He II emitters. The L_X per star-formation rate for He II emitters (log (L_X/SFR) ~ 40.0) and non-emitters (log (L_X/SFR) ~ 39.9) are also comparable and in line with the redshift evolution and metallicity dependence predicted by models. Due to the non-significant difference between the X-ray emission from galaxies with and without He II, we conclude that X-ray binaries or weak or obscured AGNs are unlikely to be the dominant producers of He II ionising photons in VANDELS star-forming galaxies at z ~ 3. Given the comparable physical properties of both He II emitters and non-emitters reported previously, alternative He II ionising mechanisms such as localised low-metallicity stellar populations, Pop-III stars, etc. may need to be explored.
