EVIDENCE FOR CO SHOCK EXCITATION IN NGC 6240 FROM HERSCHEL SPIRE SPECTROSCOPY

CORC > 紫金山天文台 > 中国科学院紫金山天文台 > 星系中的恒星形成研究团组

	EVIDENCE FOR CO SHOCK EXCITATION IN NGC 6240 FROM HERSCHEL SPIRE SPECTROSCOPY
	Meijerink, R.1,2; Kristensen, L. E.2; Weiss, A.3; van der Werf, P. P.2; Walter, F.4; Spaans, M.1; Loenen, A. F.2; Fischer, J.5; Israel, F. P.2; Isaak, K.6
刊名	ASTROPHYSICAL JOURNAL LETTERS
	2013-01-10
卷号	762 期号:2 页码:L16
关键词	galaxies: active galaxies: individual (NGC 6240) galaxies: nuclei galaxies: starburst infrared: galaxies
英文摘要	We present Herschel SPIRE FTS spectroscopy of the nearby luminous infrared galaxy NGC 6240. In total 20 lines are detected, including CO J = 4-3 through J = 13-12, 6 H2O rotational lines, and [C I] and [N II] fine-structure lines. The CO to continuum luminosity ratio is 10 times higher in NGC 6240 than Mrk 231. Although the CO ladders of NGC 6240 and Mrk 231 are very similar, UV and/or X-ray irradiation are unlikely to be responsible for the excitation of the gas in NGC 6240. We applied both C and J shock models to the H-2 v = 1-0 S(1) and v = 2-1 S(1) lines and the CO rotational ladder. The CO ladder is best reproduced by a model with shock velocity v(s) = 10 km s(-1) and a pre-shock density n(H) = 5 x 10(4) cm(-3). We find that the solution best fitting the H-2 lines is degenerate. The shock velocities and number densities range between v(s) = 17-47 km s(-1) and n(H) = 10(7)-5x10(4) cm(-3), respectively. The H-2 lines thus need a much more powerful shock than the CO lines. We deduce that most of the gas is currently moderately stirred up by slow (10 km s(-1)) shocks while only a small fraction (less than or similar to 1%) of the interstellar medium is exposed to the high-velocity shocks. This implies that the gas is rapidly losing its highly turbulent motions. We argue that a high CO line-to-continuum ratio is a key diagnostic for the presence of shocks.
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	LUMINOUS INFRARED GALAXIES ; MOLECULAR GAS ; STAR-FORMATION ; ARP 220 ; MARKARIAN 231 ; NGC-6240 ; DIAGNOSTICS ; NUCLEI ; DENSE ; ENVIRONMENTS
收录类别	SCI
语种	英语
WOS记录号	WOS:000325876300001
公开日期	2014-01-20
内容类型	期刊论文
源URL	[http://libir.pmo.ac.cn/handle/332002/10049]
专题	紫金山天文台_星系中的恒星形成研究团组
作者单位	1.Univ Groningen, Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands 2.Leiden Univ, Leiden Observ, NL-2300 RA Leiden, Netherlands 3.Max Planck Inst Radioastron, D-53121 Bonn, Germany 4.Max Planck Inst Astron, D-69117 Heidelberg, Germany 5.Naval Res Lab, Remote Sensing Div, Washington, DC 20375 USA 6.Estec, ESA Astrophys Miss Div, NL-2200 AG Noordwijk, Netherlands 7.Chalmers, Onsala Observ, Dept Radio & Space Sci, SE-43992 Onsala, Sweden 8.CALTECH, Spitzer Sci Ctr, Pasadena, CA 91125 USA 9.Univ Crete, Dept Phys, GR-71003 Iraklion, Greece 10.Observ Paris, LERMA CNRS UMR8112, F-75014 Paris, France
推荐引用方式 GB/T 7714	Meijerink, R.,Kristensen, L. E.,Weiss, A.,et al. EVIDENCE FOR CO SHOCK EXCITATION IN NGC 6240 FROM HERSCHEL SPIRE SPECTROSCOPY[J]. ASTROPHYSICAL JOURNAL LETTERS,2013,762(2):L16.
APA	Meijerink, R..,Kristensen, L. E..,Weiss, A..,van der Werf, P. P..,Walter, F..,...&Wiedner, M. C..(2013).EVIDENCE FOR CO SHOCK EXCITATION IN NGC 6240 FROM HERSCHEL SPIRE SPECTROSCOPY.ASTROPHYSICAL JOURNAL LETTERS,762(2),L16.
MLA	Meijerink, R.,et al."EVIDENCE FOR CO SHOCK EXCITATION IN NGC 6240 FROM HERSCHEL SPIRE SPECTROSCOPY".ASTROPHYSICAL JOURNAL LETTERS 762.2(2013):L16.