Calibrating Star Formation Rates on the Galactic Mesoscale
Matthew S. Povich Assistant Professor, Department of Physics & Astronomy California State Polytechnic University, Pomona, CA USA Key Collaborators
Penn State University of University of Leisa Townsley Wisconsin Arizona Patrick Broos Edward Churchwell John Bieging Konstantin Getman Barbara Whitney Nathan Smith Eric Feigelson Marilyn Meade University of Brian Babler Mike Kuhn Exeter Michigan State Cal Poly Pomona Tim Naylor Laura Chomiuk Alex Rudolph * PhD student Remington Sexton*1 1 Now at UCR Max Planck Institute Nicole Sanchez*2 for Astronomy 2 Now at Fisk U. Alec Vinson*3 Thomas Robitaille 3 Now at UCLA Anoush Kazarians** ** Undergrad Some Definitions
• Microscale Star Formation - Local 500 pc volume, ~10 pc scale clouds, (e.g. Heiderman et al. 2010, Lada et al. 2010, 2012, 2013, Gutermuth et al. 2011, Evans et al. 2014). - Few O stars, ONC is most massive cluster. • Macroscale Star Formation — Extragalactic studies, including starbursts (e.g. Kennicutt 1998, Gao & Solomon 2004, Kennicutt et al. 2009) or parts of galaxies at 0.1-1 kpc scales (e.g. Calzetti et al. 2007, Faesi et al. 2014) • Mesoscale Star Formation - Case Study: The Carina Nebula Complex (Povich et al. 2011a,b) - Comparative Studies: Chomiuk & Povich (2011), MYStIX (+ MAGIX?) The Schmidt-Kennicutt “Law”
Schmidt (1959): N ∑SFR = A∑gas based on observations of stars and gas in the Solar neighborhood.
Kennicutt (1998): N = 1.4±0.15 (slope of line fit to data in plot) for a sample of normal, disk galaxies (filled circles, open circles for galaxy centers) and starburst galaxies (squares). Star formation rate (SFR) surface density Star formation
Gas surface density Mesoscale Case Study: The Chandra Carina Complex Project (CCCP) • Use wide-field, high-resolution, multiwavelength datasets to directly observe the young stellar population of the Great Nebula in Carina and measure its star formation rate (SFR). • Why Carina? – Nearest analog of extragalactic “starburst” regions. – Because we’re masochists…
Townsley et al. (2011a) + 15 other papers in an 19 October 2010 M. S. Povich • PSU Lunch ApJS Special Issue (volume5 196) Talk Hubble Space Telescope image of Herbig-Haro jets and pillars in the Carina Nebula
6 Hubble Space Telescope ~6´×12´ mosaic of the Great Nebula in Carina
7 Tr Tr14 14 Narrow-band visual images by John Gleason, D ~ 2.3 kpc, The Great Nebula http://jpgleason.zenfolio.com/ 10′ ~ 6.7 pc. ~2°x2° in Carina Bipolar, proto- • Carina is a “starburst superbubble! region,” an example of the large-scale star formation seen in starburst galaxies. • Carina contains at least 200 O and early-B stars, including the prototype O2 I star, +WRs +Eta Car.
Tr 14 Tr Tr14 14 Narrow-band visual images by John Gleason, D ~ 2.3 kpc, The Great Nebula http://jpgleason.zenfolio.com/ 10′ ~ 6.7 pc. ~2°x2° in Carina Bipolar, proto- • Carina is a “starburst superbubble! region,” an example of the large-scale star formation seen in starburst galaxies. • Carina contains at least 200 O and early-B stars, including the prototype O2 I star, +WRs +Eta Car.
Tr 14 The Chandra Carina Complex Project (CCCP) 0.50 – 0.70 keV 0.70 – 0.86 keV 0.86 – 0.96 keV
Townsley et al. (2011b) Pre-Main Sequence Stars: Magnetic reconnection flares produce hard (>2 keV) X-rays (e.g. Preibisch et al. 2005).
X-ray Luminosity Peaks 3.6 µm -59:00:00 1439 YSOs, 410
matched to CCCP Dec (J2000) Dec
10:00 sources: Trumpler 15 M > 3.1 Mʘ 3.1 > M > 2 Mʘ 20:00 M < 2 Mʘ
Trumpler 14 Trumpler 16 30:00 40:00 Treasure Chest 50:00
-60:00:00 South Bochum 11 Pillars
10:00 Contours: CCCP stellar density
20:00 (Feigelson et al. 2011)
30:00 Povich et al. (2011b) R.A. (J2000) 50:00.0 48:00.0 46:00.0 44:00.0 42:00.0 10:40:00.0 YSO Mass Function (YMF)
1439 YSOs detected, incomplete for m < 3.1 Mʘ
>20,000 YSOs predicted, with TOTAL mass >16,000 Mʘ, extrapolated to m ≥ 0.1 Mʘ
Present-Day SFR: >0.008 Mʘ/yr Black curve: Salpeter–Kroupa IMF (Kroupa 2001) Red curve: Best-fit power law to intermediate-mass YMF (Povich & Whitney 2010; Povich et al. 2011b) X-ray Luminosity Function (XLF) Scaling XLF from 840 stars Lightly-obscured Carina in the Orion Nebula Cluster Heavily-obscured Carina (ONC) to match Carina XLFs gives an ONC estimate of total stellar population
>38,000 diskless PMS stars predicted, extrapolated to Povich et al. (2011b) m ≥ 0.1 Mʘ Carina Nebula SFR from IR and X-ray “Star Counts”
• Global population: 5.8–7.4 × 104 stars, 4 containing 4.6–5.9 × 10 Mʘ total mass.
• SFR: 0.009–0.012 Mʘ/yr, averaged over past 5 Myr, punctuated by more intense bursts that created the several massive clusters (e.g. Trumplers 15, 16, and 14). • Carina Nebula represents ~0.5% of the Galactic SFR (Chomiuk & Povich 2011). Povich et al. (2011b) What would the Carina H II region look like if viewed from a nearby, external galaxy? What would the NGC 1566 mid-IR Carina H II region d = 11.8 Mpc look like if viewed from a nearby, external galaxy? Extract IR flux densities for Galactic H II regions using large apertures on MSX and IRAS images. Then interpolate their IR SEDs to measure luminosities.
Plot SFR derived from the X-ray + IR “star counts” methods against equivalent Spitzer/MIPS 24 µm luminosity.
Note the significant, systematic discrepancy between this relation and the Calzetti et al. (2007) extragalactic calibration (dashed line). Chomiuk & Povich (2011) x2.7 (again?)
Range of CP11 SFRs
Lada et al. (2012) Gao & Solomon (2004) Improving CP11: Nebular SEDs
(B) PACS M17
MSX SPIRE (Jy)
i ground F IRAC based radio Planck
h(µm) Improving CP11: Ages on the Probabilistic H–R Diagram (pHRD)
b ! Main-sequence Stars
7 M
5.5 M
4 M
3 M
2 M
Background 1 M pHRD Stars? pMAD
SED modeling of 2376 pMAD: Transformation of pHRD into diskless, X-ray emitting stars Mass–Age model parameter space from CCCP Povich et al. (2014, in prep) 3.6 µm -59:00:00 1439 YSOs, 410
matched to CCCP Dec (J2000) Dec
10:00 sources: Trumpler 15 M > 3.1 Mʘ 3.1 > M > 2 Mʘ 20:00 M < 2 Mʘ
Trumpler 14 Trumpler 16 30:00 40:00 Treasure Chest 50:00
-60:00:00 South Bochum 11 Pillars
10:00 Contours: CCCP stellar density
20:00 (Feigelson et al. 2011)
30:00 Povich et al. (2011b) R.A. (J2000) 50:00.0 48:00.0 46:00.0 44:00.0 42:00.0 10:40:00.0 254 stars!
Tr 15 region
Vertical lines (pMADs): subcluster median AgeJX (Getman et al. 368 stars! 2014)
Tr 14 region 612 stars! Tr 16 region
Vertical lines (pMADs): subcluster median AgeJX (Getman et al. 2014) 322 stars!
South Pillars Massive Young star-forming complex Study in Infrared and X-rays (MYStIX) • 5-year program, funded by NASA Archival Data Analysis Program (ADAP) and NSF AST grants to Penn State (plus MSP’s NSF Postdoctoral Fellowship award) • 20 Galactic star-forming complexes, d = 0.4 to 3.7 kpc (Feigelson et al. 2013). • >20,000 X-ray sources + >10,000 IR excess sources classified. • First 8 technical/catalog papers published ApJS (2013–2014). Three additional science results papers (stellar ages, cluster structure) published in ApJ. Massive Star-forming regions Across the Galaxy in Infrared and X-rays (MAGIX): Pending NASA ADAP proposal to study 20 of the most massive Galactic complexes (multiple early O stars). MYStIX: Outer Galaxy “Prototype” Region
Stage 0/I YSO E Stage II/III YSO N Ambiguous
2.3 stage YSO Galactic latitude Galactic latitude 2.2 2.1 2.0
NGC 2264 1.9 d = 0.9±0.1 kpc Galactic longitude 03.6 203.5 203.4 203.3 203.2 203.1 203.0 202.9 202.8 202.7
Povich et al. (2013) 4.1 Figure 2. — 'PVSBEEJUJPOBM.:4U*9DPNQMFYFTXJUI 4.0 Serpens South 4QSPCBCMF of the .*3&4 20 :40 NFNCFSTMYStIX EJTQMBZFE Complexes PO N JNBHFT d = 0.26 kpc 3.9 (not in MYStIX) DPNNPOBOHVMBSTDBMF MIRES Catalog; Povich et al. (2013)
N
3.8 N 1.1
E E 3.7 1.0 W40 to scale
3.6 Stage 0/I YSO 0.9 Stage II/III YSO 3.5 Ambiguous 0.8
Galactic latitude Eagle 3.4 stage YSO 0.7 Nebula NGC 2264 to scale 3.3 0.6 (M16) 0.5
3.2 W40 d = 1.75 kpc Galactic latitude Galactic d = 0.5 kpc Galactic latitude 17.4 17.3 17.2 17.1 17.0 16.9 16.8 16.7 16.6 16.5 Galactic longitude 3.1 Galactic longitude 29.2 29.0 28.8 28.6 28.4 28.2 28.0 1. 1
-0.7 N N 1.0 -0.8 E E 0. 9 -0.9 0. 8
-1.0 W40 to scale 0. 7 -1.1 0. 6 -1.2 Galactic latitude 0. 5 Galactic latitude -1.3 Lagoon 0. 4
-1.4 Nebula 0. 3
-1.5 (M8) NGC 6357 d = 1.3 kpc 0. 2 -1.6 d = 1.7 kpc 0. 1 6.6 6.4 6.2 6.0 5.8 5.6 5.4 353.8 353.6 353.4 353.2 353.0 352.8 352.6 Galactic longitude Galactic longitude The Bottom Line...
• The combination of X-ray and IR observations of resolved young stellar populations provides a powerful tool for exploring mesoscale star formation the Milky Way. • We are now in a position to calibrate SFRs versus nebular emission tracers without invoking stellar population synthesis models. • Goal: bridge the orders-of-mag gulf in scales (spatial, temporal, luminosity) separating the detailed, local studies with extragalactic studies. Facilitate comparisons of theoretical “universal” SF laws to observations.