인문학
사회과학
자연과학
공학
의약학
농수해양학
예술체육학
복합학
DBpia AI
AI 에이전트
AI 아이디어
AI 리더
AI 뷰어
Citeasy
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지원사업
학술연구/단체지원/교육 등 연구자 활동을 지속하도록 DBpia가 지원하고 있어요.
커뮤니티
연구자들이 자신의 연구와 전문성을 널리 알리고, 새로운 협력의 기회를 만들 수 있는 네트워킹 공간이에요.
초록·키워드
Context. Sources that leak Lyman continuum (LyC) photons and lead to the reionisation of the universe are an object of intense study using multiple observing facilities. Recently, the Low-redshift LyC Survey (LzLCS) has presented the first large sample of LyC emitting galaxies at low redshift ( z ∼ 0.3) with the Hubble Space Telescope Cosmic Origins Spectrograph. The LzLCS sample contains a robust estimate of the LyC escape fraction ( f esc LyC ) for 66 galaxies, spanning a wide range of f esc LyC values. Aims. Here, we aim to study the dependence of f esc LyC on the radio continuum (RC) properties of LzLCS sources. Overall, RC emission can provide unique insights into the role of supernova feedback, cosmic rays (CRs), and magnetic fields from its non-thermal emission component. RC emission is also a dust-free tracer of the star formation rate (SFR) in galaxies. Methods. In this study, we present Karl G. Jansky Very Large Array (VLA) RC observations of the LzLCS sources at gigahertz (GHz) frequencies. We performed VLA C (4−8 GHz) and S (2−4 GHz) band observations for a sample of 53 LzLCS sources. We also observed a sub-sample of 17 LzLCS sources in the L (1−2 GHz) band. We detected RC from both C - and S -bands in 24 sources for which we are able to estimate their radio spectral index across 3−6 GHz, denoted as α 6 GHz 3 GHz . We also used the RC luminosity to estimate their SFRs. Results. The radio spectral index of LzLCS sources spans a wide range, from flat (≥ − 0.1) to very steep (≤ − 1.0). They have a steeper mean α 6 GHz 3 GHz (≈ − 0.92) compared to that expected for normal star-forming galaxies ( α 6 GHz 3 GHz ≈ −0.64). They also show a larger scatter in α 6 GHz 3 GHz (∼0.71) compared to that of normal star-forming galaxies (∼0.15). The strongest leakers in our sample show flat α 6 GHz 3 GHz , weak leakers have α 6 GHz 3 GHz close to normal star-forming galaxies and non-leakers are characterized by steep α 6 GHz 3 GHz . We argue that a combination of young ages, free-free absorption, and a flat cosmic-ray energy spectrum can altogether lead to a flat α 6 GHz 3 GHz for strong leakers. Non-leakers are characterized by steep spectra which can arise due to break or cutoff at high frequencies. Such a cutoff in the spectrum can arise in a single injection model of CRs characteristic of galaxies which have recently stopped star-formation. The dependence of f esc LyC on α 6 GHz 3 GHz (which is orientation-independent) suggests that the escape of LyC photons is not highly direction-dependent at least to the first order. The radio-based SFRs (SFR RC ) of LzLCS sources show a large offset (∼0.59 dex) from the standard SFR RC calibration. We find that adding α 6 GHz 3 GHz as a second parameter helps us to calibrate the SFR RC with SFR UV and SFR H β within a scatter of ∼0.21 dex. Conclusions. For the first time, we have found a relation between α 6 GHz 3 GHz and f esc LyC . This hints at the interesting role of supernovae feedback, CRs, and magnetic fields in facilitating the escape (alternatively, and/or the lack) of LyC photons.
인공지능 문자 인식 모델을 통해 추출된 텍스트로, 일부 오타나 오류가 포함될 수 있으나 지속적으로 개선 중입니다.
오류를 발견하셨다면 해당 부분을 드래그한 후 ' 를 통해 신고해주세요.
오류를 발견하셨다면 해당 부분을 드래그한 후 ' 를 통해 신고해주세요.
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