Radio recombination lines: the synergy between a big dish and - - PowerPoint PPT Presentation
Radio recombination lines: the synergy between a big dish and dipoles Pedro Salas The Big Impact of a Big Dish: Science with the Effelsberg 100-m telescope Bonn, Germany, 20 February 2018 With support from RadioNet and NWO Assembly of
Pedro Salas
The Big Impact of a Big Dish: Science with the Effelsberg 100-m telescope Bonn, Germany, 20 February 2018
With support from RadioNet and NWO
Moriarty-Schieven
ESA/Herschel/PACS/SPIRE/HOBYS Consortium
−0.004 −0.002 0.000
78 MHz Cα(438)
τα (Optical depth units) Radio velocity (km s−1)
−0.004 −0.002 0.000
73 MHz Cα(448)
τα (Optical depth units) Radio velocity (km s−1)
−0.004 −0.002 0.000
68 MHz Cα(459)
τα (Optical depth units) Radio velocity (km s−1)
−0.004 −0.002 0.000
64 MHz Cα(467)
τα (Optical depth units) Radio velocity (km s−1)
−0.004 −0.002 0.000
60 MHz Cα(477)
τα (Optical depth units) Radio velocity (km s−1)
−50 50 −0.004 −0.002 0.000
57 MHz Cα(485)
τα (Optical depth units) Radio velocity (km s−1)
54 MHz Cα(496)
τα (Optical depth units) Radio velocity (km s−1)
49 MHz Cα(510)
τα (Optical depth units) Radio velocity (km s−1)
45 MHz Cα(527)
τα (Optical depth units) Radio velocity (km s−1)
41 MHz Cα(542)
τα (Optical depth units) Radio velocity (km s−1)
38 MHz Cα(559)
τα (Optical depth units) Radio velocity (km s−1)
−80 80
35 MHz Cα(575)
τα (Optical depth units) Radio velocity (km s−1)
30 MHz Cα(601)
τα (Optical depth units) Radio velocity (km s−1)
24 MHz Cα(645)
τα (Optical depth units) Radio velocity (km s−1)
20 MHz Cα(689)
τα (Optical depth units) Radio velocity (km s−1)
17 MHz Cα(731)
τα (Optical depth units) Radio velocity (km s−1)
14 MHz Cα(782)
τα (Optical depth units) Radio velocity (km s−1)
−250 0 250 500
11 MHz Cα(843)
τα (Optical depth units) Radio velocity (km s−1)
◮ Mainly from carbon and hydrogen. ◮ Change in line properties with frequency
constrains the gas physical properties.
◮ Low frequency emission from carbon
traces cold diffuse gas (nH ∼ 100 cm−3, T ∼ 100 K).
◮ Hydrogen traces warm ionized gas.
200 300 400 500 600 700 800 −15 −10 −5 5 10 15
Te = 85 K ne = 0.04 cm−3 Te = 85 K ne = 0.05 cm−3 Te = 85 K ne = 0.03 cm−3
816.0 242.0 102.0 52.0 30.0 19.0 13.0 Cα frequency (MHz)
Integrated optical depth (Hz) Principal quantum number
25% variation in ne.
Oonk+2017
200 300 400 500 600 700 800 −15 −10 −5 5 10 15
Te = 85 K ne = 0.04 cm−3 Te = 105 K ne = 0.04 cm−3 Te = 65 K ne = 0.04 cm−3
816.0 242.0 102.0 52.0 30.0 19.0 13.0 Cα frequency (MHz)
Integrated optical depth (Hz) Principal quantum number
25% variation in Te.
Oonk+2017
−2.5 0.0 2.5 −2.5 0.0 2.5 −2.5 0.0 2.5 −2.5 0.0 2.5 −2.5 0.0 2.5 −2.5 0.0 2.5 −2.5 0.0 2.5 −2.5 0.0 2.5 −2.5 0.0 2.5 −2.5 0.0 2.5
12CO(2-1)
∆δ (arcmin) ∆α (arcmin) 300 350 400 450 500 550 600 0.0 0.2 0.4 0.6 0.8 1.0 1.2 HPBW 4.6 5.4 6.1 6.9 7.7 8.4 9.2
Projected distance on the sky @3.16 kpc (pc)
12CO(2 − 1)
18 cm-OH C268α C539α
Normalized optical depth/intensity Distance along slice (arcsec)
Salas+2018
ESA/Herschel/PACS/SPIRE/HOBYS Consortium
Sensitive observations with a 100 m single dish
100 200 Radio velocity w.r.t. C166α (km s−1) 0.000 0.001 0.002 0.003 0.004 Optical depth C166α H166α −200 −100 Radio velocity w.r.t. H166α (km s−1)
−40 40 −40 40 −40 40 −40 40 −40 40 −40 40
∆δ (arcmin) ∆α (arcmin)
Thanks to B. Winkel
The LOFAR perspective
−1◦ 0◦ 1◦ 2◦ 3◦ 76◦ 78◦ 80◦ 82◦ −1◦ 0◦ 1◦ 2◦ 3◦ 76◦ 78◦ 80◦ 82◦
Oonk+in prep.
The LOFAR perspective
−1◦ 0◦ 1◦ 2◦ 3◦ 76◦ 78◦ 80◦ 82◦ −1◦ 0◦ 1◦ 2◦ 3◦ 76◦ 78◦ 80◦ 82◦
Oonk+in prep.
200 300 400 500 600 700 −3 −2 −1 1 2 Absorption Emission Te = 95 K ne = 0.03 cm−3 Te = 10 K ne = 0.1 cm−3 816.0 242.0 102.0 52.0 30.0 19.0 Cα frequency (MHz)
Integrated optical depth (Hz) Principal quantum number
◮ The ISM is a complex system, and observations across
the electromagnetic spectrum are needed in order to understand it.
◮ RRLs at different frequencies can be used to study the
density structure of the ISM.
◮ A combination of Effelsberg and LOFAR allows for an
accurate determination of the gas physical conditions.