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ABSTRACT We present the hot molecular and warm ionized gas kinematics for 33 nearby (0.001 ≲ z ≲ 0.056) X-ray selected active galaxies using the H$$_2\, 2.1218\, \mu$$m and Br γ emission lines observed in the K band with the Gemini near-infrared integral field spectrograph. The observations cover the inner 0.04–2 kpc of each active galactic nucleus at spatial resolutions of 4–250 pc with a velocity resolution of σinst ≈ 20 $${\rm km\, s^{-1}}$$. We find that 31 objects (94 per cent) present a kinematically disturbed region (KDR) seen in ionized gas, while such regions are observed in hot molecular gas for 25 galaxies (76 per cent). We interpret the KDR as being due to outflows with masses of 102–107 and 100–104 M⊙ for the ionized and hot molecular gas, respectively. The ranges of mass-outflow rates ($$\dot{M}_{\rm out}$$) and kinetic power ($$\dot{E}_{\rm K}$$) of the outflows are 10−3–101 M⊙ yr−1 and ∼1037–1043 erg s−1 for the ionized gas outflows, and 10−5–10−2 M⊙ yr−1 and 1035–1039 erg s−1 for the hot molecular gas outflows. The median coupling efficiency in our sample is $$\dot{E}_{\mathrm{K}}/L_{\rm bol}\approx 1.8\times 10^{-3}$$ and the estimated momentum fluxes of the outflows suggest they are produced by radiation-pressure in low-density environment, with possible contribution from shocks.
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Linking extended and plateau emissions of short gamma-ray bursts
ABSTRACT Some short gamma-ray bursts (SGRBs) show a longer lasting emission phase, called extended emission (EE) lasting $${\sim}10^{2\!-\!3}\, \rm s$$, as well as a plateau emission (PE) lasting $${\sim}10^{4\!-\!5}\, \rm s$$. Although a long-lasting activity of the central engines is a promising explanation for powering both emissions, their physical origin and their emission mechanisms are still uncertain. In this work, we study the properties of the EEs and their connection with the PEs. First, we constrain the minimal Lorentz factor Γ of the outflows powering EEs, using compactness arguments and find that the outflows should be relativistic, Γ ≳ 10. We propose a consistent scenario for the PEs, where the outflow eventually catches up with the jet responsible for the prompt emission, injecting energy into the forward shock formed by the prior jet, which naturally results in a PE. We also derive the radiation efficiency of EEs and the Lorentz factor of the outflow within our scenario for 10 well-observed SGRBs accompanied by both EE and PE. The efficiency has an average value of $${\sim}3\, {{\ \rm per\ cent}}$$ but shows a broad distribution ranging from ∼0.01 to $${\sim}100{{\ \rm per\ cent}}$$. The Lorentz factor is ∼20–30, consistent with the compactness arguments. These results suggest that EEs are produced by a slower outflow via more inefficient emission than the faster outflow that causes the prompt emission with a high radiation efficiency.
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- Award ID(s):
- 1908689
- PAR ID:
- 10186145
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 493
- Issue:
- 1
- ISSN:
- 0035-8711
- Page Range / eLocation ID:
- 783 to 791
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1093/mnras/staa305
