1. FRA 2015,July 29 - July 31,GuiYang WISE MIR properties of OHMs: Guide for future FAST OHM searching? JiangShui Zhang ( 张江水 ) GuangZhou University ( 广州大学 ) Collaborators ： Di Li @ NAOC JunZhi Wang @SHAO Qingfeng Zhu @USTC Juan Li @SHAO

2. FRA 2015,July 29 - July 31,GuiYang 1. Radio observations and theoretical studies of Pulsars 2. From atoms to stars: radio studies of ISM and star formation 3. Galaxy structure and evolution 4. Cosmology and dark mater 973 program: Frontiers in Radio Astronomy and FAST Early Science 6. Low-frequency multi-beam receivers and VLBI systems design 5. Radio spectroscopy and Masers Wang, Zhu, Zhang, Li

3. FRA 2015,July 29 - July 31,GuiYang FRA2015  Two works closely related to No. 5 subject WISE MIR properties of OH megamaser galaxies Guide for future FAST OHM searching? Zhang, Wang, Zhu et al. (2014), A&A, 570, A110 FAST maser studies Expectations: Detectability, OHMs Sky density… Zhang, Li, Wang, Zhu, Li, accepted, RAA special issue

4. FRA 2015,July 29 - July 31,GuiYang WISE MIR properties of OHMs  Introduction  OH megamaser & Non-masing Samples  WISE MIR properties  Hints for future FAST OHMs searching

5. FRA 2015,July 29 - July 31,GuiYang Introduction  Galactic OH masers:  First OH maser Weaver et al. (1965)  Widespread interstellar/circumstellar >3000 e.g., Mu et al. (2010)  Extragalactic OH masers  119 detections (published) Darling et al. (2002a,b), Fernandez et al. (2010), Willett (2012) the first: NGC253 (Whiteoak & Gardner 1974), Parkes the most luminous: IRAS14070+0525 (Baan+1992), Arecibo, z~0.265 the most distant: z~0.765, gravitation lens (Kanekar+2006),GBT > 106/119 L >10L ⊙ OH Megamaser (OHM)

6. FRA 2015,July 29 - July 31,GuiYang  OHMs different features Strong 1667MHz (weak 1665, a few in 1612,1720MHz) Broad line: 100~1000km/s (Galactic OHs: stronger 1665, ~ 1 km/s)  Same Pumping? Far-IR radiation Difference from line overlap Locket & Elitzur (2008) Introduction 1665 1667 Darling & Giovanelli 2002

7. FRA 2015,July 29 - July 31,GuiYang OHMs host galaxies : >> ULIRGs (35/106 ~1/3, L FIR >10 12 L ⊙ ) / LIRGs ( >10 11 L ⊙,102/106) associated with major galaxy merger-induced starbursts FIR radiation pumping e.g., Baan (1989); Darling & Giovanelli (2002) OHM detection rate ∝ L FIR,  1/3 for ULIRGs e.g., Darling & Giovanelli (2002); Baan (1991) Introduction

8. FRA 2015,July 29 - July 31,GuiYang OHM puzzle: Majority of (U)LIRGs without detection of OHM ！ Other factors besides FIR luminosity? OHM (U)LIRGs represent distinct population? Intrinsic properties? Lo (2005) Darling (2012) Introduction

9. FRA 2015,July 29 - July 31,GuiYang OHM v.s. Non-masing (U)LIRGs: Radio, optical and X-ray regimes : No systematic difference e.g., Lonsdale et al. 1998; Pihlström et al. 2005 Darling & Giovanelli 2006; Baan et al. 1998; Vignari et al. 2005 OHMs : high dense gas fraction Darling 2007  dense gas trigger for OHMs 6 cm H 2 CO line: Emission in OHM hosts Absorption in non-OHM hosts Mangum et al. (2008) Introduction

10. FRA 2015,July 29 - July 31,GuiYang Introduction Infrared properties: IRAS photometry data, OHMs: Color excesses at 25, 60μm Henkel et al. 1986 Larger far-IR spectral indices Chen et al. 2007 Spitzer spectroscopic data, OHMs: Deeper 10μm silicate dust absorption Steeper 15-30μm continuum slope Willett et al. (2011a,b) Wide-field Infrared Survey Explorer (WISE): Most sensitive One main goal: ULIRGs All-sky survey data released MIR properties of OHMs  Guide for future FAST OHMs searching Motivation: Details in Zhang et al. (2014)

11. FRA 2015,July 29 - July 31,GuiYang Samples OH maser galaxy sample: 119 OH maser galaxies 52 OHMs, from the advanced Arecibo survey Darling & Giovanelli (2002) Other OH masers, Willett (2012), Fernandez et al. (2010 ), Chen et al. (2007) Control sample: 259 non-detection ULIRGs in the survey For both samples, Cross-correlated to WISE All-Sky data  Magnitudes at W1,2,3,4 (3.4 μm, 4.6 μm, 12 μm, 22μm) WISE magnitudes  flux density: http://wise2.ipac.caltech.edu/docs/release/allsky/  luminosity:

12. FRA 2015,July 29 - July 31,GuiYang Results Luminosity difference All OHMs v.s. Non-OHMs (possible selection bias) Arecibo OHMs v.s. Nons (uniform criteria) OHMs  lower L Significant at 3.4 & 4.6 μm Arecibo OHMs All OHMs Non-OHMs

13. FRA 2015,July 29 - July 31,GuiYang Luminosity Difference (OHMs tend to lower L 1 & L 2 )  Low OHM fraction in high L 1 & L 2 Results

14. FRA 2015,July 29 - July 31,GuiYang Color-Color properties OHMs v.s. Non-OHMs: OHMs tend to have larger color values Significant Difference at W2-W3 & W3-W4 (between Arecibo samples) Results

15. Other OHMs Arecibo OHMs Non-OHMs Dashed line: Blackbody Solid: Power law Features: most far away from the blackbody line, Many of them follow the path described by the power-law model. AGN criteria : W1-W2>0.8, Stern et el. (2012 ) Similar AGN fraction ~40% for OHMs/Non-OHMs Color-Color properties

16. FRA 2015,July 29 - July 31,GuiYang WISE spectral indices Arecibo OHMs v.s. Non-OHMs OHMs  larger index Significant at α 43 & α 41 Steeper 15-30μm slope Willett+ (2001) Results

17. FRA 2015,July 29 - July 31,GuiYang OHMs fraction tends to increase with cooler MIR colors (larger color values, i.e., larger F 22μm / F 3.4μm ) W1-W4 9 50% MIR luminosity v.s.Colors OHMs fraction: very low in high L1 >10.5 1/18  W1 ( 3.4μm ) far away from FIR  pumping energy of OHMs High 3.4μm luminosity: a harder radiation environment, its strong UV radiation dissociate OH (Andersson & van Dishoeck 2008) Results

18. FRA 2015,July 29 - July 31,GuiYang R ising 22μm luminosity with increasing W1-W4 For Arecibo OHM sample: R~0.6 Arecibo OHMs mostly lie in a distinct region (within error ranges, dashed lines) Arecibo survey candidates ： IRAS galaxies with F 60μm >0.6Jy, Arecibo sky coverage ( 0º--37º) ， z~ 0.1--0.3 Detection rate increase ~25%, excluding those targets outside this region MIR luminosity v.s.Colors Other OHMs Arecibo OHMs Non-OHMs Results

19. FRA 2015,July 29 - July 31,GuiYang Maser v.s. MIR emission OHMs FIR pumping (Observations & Models) Martin et al.1988, Baan 1989, Kandalian 1996 Diamond et al. 1999, Darling&Giovanelli 2002 Maser-MIR correlation is nonsignificant after considering the Malmquist effect  Support indirectly OHMs FIR radiation pumping, e.g., 35μm or 53μm radiation (Skinner et al.1997, Lockett & Elitzur 2008)

20. FRA 2015,July 29 - July 31,GuiYang Guide for Future FAST OHMs searching? Hints on sample selections: ( U)LIRGs, excluding extreme luminous sources at short λ 3.4μm, 4.6 μm (U)LIRGs with Larger MIR spectral index: α 22-12μm α 22-3.4μm (cooler colors) Match correlation of L 22μm & (W1-W4)

21. FRA 2015,July 29 - July 31,GuiYang FRA2015  Two works closely related to No. 5 subject WISE MIR properties of OH megamaser galaxies Guide for future FAST OHM searching? Zhang, Wang, Zhu et al. (2014), A&A, 570, A110 FAST maser studies Expectations: Detectability, OHMs Sky density… Zhang, Li, Wang, Zhu, Li (2014), RAA special issue

22. Five-hundred-meter Aperture Spherical radio Telescope FAST maser studies

23. Frequency: 70M ~ 3GHz OH: 1612, 1665, 1667, 1720 MHz

24. Galactic OH masers Blind Sky survey ( long ago, 1970~80~90s) : Caswell et al., Parkes 64m 233 ◦ ≤ l≤ 2 ◦, | b |≤ 0.4 ◦ Johansson et al. Onsala 25.6m 18 ◦ ≤ l≤ 51 ◦, | b |≤ 1 ◦ 26 ◦ ≤ l≤ 36 ◦, | b |≤ 2 ◦ ； 30 ◦ ≤ l≤ 32 ◦, 2 ◦ ≤ | b |≤ 4 ◦ Turner et al., NRAO 42m 40 ◦ ≤ l≤ 270 ◦, 337 ◦ ≤ l≤ 40 ◦,| b |≤ 1.5 ◦ Bowers, 300 feet 12 ◦ ≤ l≤ 234 ◦, | b |≤ 2.5 ◦ Buad et al., Effelsberg 100m, Dwingeloo 25m 358 ◦ ≤ l≤ 15 ◦, | b |≤ 0.5 ◦ ; 10 ◦ ≤ l≤ 150 ◦, | b |≤ 4.2 ◦ Sevenster et al., 1993-95, ATCA, VLA, | l |≤ 45 ◦ | b |≤ 3 ◦ 。。。。 Selected-sample survey: Color-selected IRAS sample, e.g., Eder et al. 1988; Lewis 1990, 1997, Arecibo; te Lintel Hekkert 1991, Effelsberg & Parkes; SFRs, e.g., Szymczak et al. (2004), Nancay; Wouterloot et al. (1993), Effelsberg HMPSOs, e.g., Edris et al. (2007), Nançay & GBT 24

25. Relative sensitivity Galactic OH masers  Galactic plane Sky survey: much higher survey speed ~100 updated multi-beam L wide?  Sample-selection survey: IR catalogues, GLIMPS catalogue … FAST advantages: much better sensitivity one order more better than 1970s-80s-90s Good opportunity for maser survey (L wide receiver) Star formation Evolved stars Astrometry

26. OH Megamasers ~119 detections ( λ18cm ) Darling et al. (2002a,b), Chen et al. (2007), Fernandez et al. (2010) the first: IC4553 (Baan+1982), Arecibo the most luminous: IRAS14070+0525 (Baan+1992), Arecibo, z~0.265 the most distant: z~0.765, gravitation lens (Kanekar+2006),GBT Host galaxies : ULIRGs/LIRGs associated with major galaxy merger-induced starbursts High z OHM OHM  galaxy mergers Merger rate ~ (1+z) m e.g., Kim & Sanders (1998), Kau ff mann & Haehnelt (2000)

27. FRA 2015,July 29 - July 31,GuiYang FAST maser studies  Surveys: Arecibo 305m, NRAO 91m,JB MkIA 76m, Nancay 300m,Parkes 64m…  Arecibo survey IRAS f 60um > 0.6 Jy 0 ◦ <δ< 37 ◦, 0.1< z <0.3 ~200 hours 52 OHM/311 Darling et. (2000,2001,2002a,b) Φ ∝ L OH −0.6 Mpc −3 dex −1 IAU287 Dr. Wittlet+ 2012, GBT 9 new detections OHM Luminosity function

28. FAST maser studies FAST (ref. Arecibo) Nan et al. (2011, IJMPD, 20, 1) 2- 3 better raw sensitivity ~10 higher surveying speed 2-3 times sky coverage - 15 ◦ <δ< 65 ◦ (due to its innovative design of active primary surface)

29. Sky coverage FAST vs. Arecibo Sky coverage ZA 30 deg ZA 40 deg ZA 60 deg FAST Zenith ZA 56 deg Relative sensitivity

30. Expectations: Detectability v.s. sensitivity Zhang et al. accepted, RAA special FAST collecting area: ~3x Arecibo Expectation ： FAST, e.g., 12 minutes, 3σ ~ 0.7mJy z~1, most L OH >10 3 L ⊙ z~2, some L OH >10 3 L ⊙ z~4, all Giga-masers Black dots: Arecibo survey OHMs z

31. Expectations: OHM Sky density v.s. merger rate OHM  ULIRGs  galaxy mergers e.g., z 2000 FAST: -15º<δ <65º Ω: ~7.3 ster.  24000 deg 2 m=4 case, a few OHMs @z~2? Detectable OHM Sky density Merging rate ~ (1+z) m  More high z OHMs Zhang et al. accepted, RAA special z ~2.5

32. FRA 2015,July 29 - July 31,GuiYang Next ： OH megamasers searching ： Sample selection, application from Arecibo/GBT ？  FAST OH megamasers surveys (…experience…)

33. Thank you!