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X-ray Emission from Primordial Starbursts

X-ray Emission from Primordial Starbursts. Antara Basu-Zych (NASA/GSFC & UMBC) Ann Hornschemeier Tassos Fragos Bret Lehmer Andy Ptak Panayiotis Tzanavaris Mihoko Yukita Andreas Zezas. X-ray Emission from Primordial Starbursts. Chandra image of M82. 0.3--1.1 keV 0.7--2.2 keV 2.2-6 keV.

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X-ray Emission from Primordial Starbursts

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  1. X-ray Emission from Primordial Starbursts • Antara Basu-Zych (NASA/GSFC & UMBC) • Ann Hornschemeier • Tassos Fragos • Bret Lehmer • Andy Ptak • Panayiotis Tzanavaris • Mihoko Yukita • Andreas Zezas

  2. X-ray Emission from Primordial Starbursts Chandra image of M82 0.3--1.1 keV 0.7--2.2 keV 2.2-6 keV Active galactic nuclei (AGN): -- centrally located point source -- accretion onto supermassive black hole Hot Gas: -- diffuse and spatially extended -- contributes to the soft X-ray band (0.5-2 keV) • X-ray Binaries: • unresolved point sources • dominates in the hard X-ray band (2-8 keV) • - accretion onto compact objects X-ray emission in galaxies...

  3. astronomynow.com Northwestern Low Mass X-ray Binaries (LMXBs) High Mass X-ray Binaries (HMXBs) • Massive O/B star (>8 M⊙) secondary feeding a compact object (neutron star or BH). • Massive/short-lived (~10−30 Myr) - trace recent star-formation. • Lower-mass star (<1.5 M⊙)evolves and swells to red giant feeding the compact object. • Old stars (>1 Gyr) - trace star-formation history and stellar mass of the galaxy.

  4. • To first-order, a physically-motivated scaling of LX will include both SFR and M★ to account for HMXBs and LMXBs: LX = LX(LMXBs)+LX(HMXBs) = α M★+ βSFR ⇒LX/SFR = α (SFR/M★)-1 + β Northwestern α = (9.05 ± 0.37) × 1028 erg s−1M⊙−1 β = (1.62 ± 0.22) × 1039 erg s−1 (M⊙ yr−1)−1 LX∝ SFR0.7 High Mass X-ray Binaries (HMXBs) LX∝ SFR0.9 Colbert et al. (2004) Iwasawa et al. (2009) Lehmer et al. (2010) Scatter ~ 0.5 dex Scatter ~ 0.3 dex X-ray Binaries in Nearby Galaxies: Local Scaling Relations

  5. X-ray Emissionfrom Primordial Starbursts SCREAMED THE DUST SPECK 1000.0 100.0 10.0 1.0 0.1 LIR/LFUV 109 1010 1011 1012 1013 Lbol = LIR + LUV Overzier et al, 2011 Overzier et al, 2010 Why do we care? What does this mean? • Primordial Mode of Star Formation: • dominated by recent star formation: high SFR/M★ • less chemically evolved: lower metallicities • and less dust attenuation • … compared to present-day (z=0) galaxies. z=0 Luminous IR galaxies z=0 SDSS local star-forming galaxies (contours) Normal z=0 star-forming galaxies z=2 galaxies (Reddy et al, 2010) z=2 (Erb et al, 2006) =SFR

  6. X-ray Emissionfrom Primordial Starbursts 1000.0 100.0 10.0 1.0 0.1 LIR/LFUV Why do we care? What does this mean? • X-ray binary formation and evolution • (White & Ghosh, 1998; Lehmer+2010; Cowie+2011, BZ+2013; Fragos+2013a, Kaaret2014) • Heating of the Intergalactic medium (IGM) • (Mesinger+2013; Fragos+2013b; Pacucci+2014) • Superwinds • (Strickland+2004,2009; Yukita+2012) z=0 Luminous IR galaxies z=0 SDSS local star-forming galaxies (contours) Normal z=0 star-forming galaxies z=2 galaxies (Reddy et al, 2010) z=2 (Erb et al, 2006) 109 1010 1011 1012 1013 Lbol = LIR + LUV =SFR Overzier et al, 2011 Overzier et al, 2010

  7. X-ray Emissionfrom Primordial Starbursts 1000.0 100.0 10.0 1.0 0.1 • Lyman break analogs, LBAs LIR/LFUV 109 1010 1011 1012 1013 Lbol = LIR + LUV Overzier et al, 2011 • Our Focus: • X-ray binary evolution over cosmic time (driven by metallicity evolution?) using Chandra Deep Field-South data to study X-ray emission in galaxies between z=0—5 • X-ray binary populations within individual, nearby (z < 0.1) analogs of high-z (z > 2) Lyman break galaxies (low metallicity, low dust attenuation) Why do we care? What does this mean? • Primordial: galaxies from • the early Universe (z> 2) • high SFR per stellar mass • lower dust attenuations, • and lower metallicities • … compared to present-day (z=0) galaxies. z=0 Luminous IR galaxies z=0 SDSS local star-forming galaxies (contours) Normal z=0 star-forming galaxies z=2 galaxies (Reddy et al, 2010) z=2 (Erb et al, 2006) z~0.2 local analogs z~0.2 local analogs =SFR Overzier et al, 2010

  8. 4 Ms Chandra exposure 465 arcmin2 740 sources Hubble Ultradeep Field (Beckwith et al. 2006) Chandra Deep Field-South (Xue et al. 2011) Chandra Deep Field-South: Deepest X-ray View of the Universe! Chandra We love you! Within the Chandra Deep Field-South, the multiwavelength data (e.g., Hubble) have revealed there are many 10s of thousands of galaxies reaching back to when universe is <1 Gyr old! 7 Ms CDF-S Observations (additional 3 Ms) are almost completed: Expect to Be Galaxy-Dominated (vs. AGN) in Most Sensitive Regions. (see Lehmer et al., 2012)

  9. Hubble Chandra VLA Volume-averaged star formation rate for the Universe Spitzer VLT Herschel Deep-Field Galaxy Selection from Multiwavelength Data: Lyman break galaxies • Significance of LBGs: • Efficient technique for discovering high redshift (z>3) galaxies • Trace cosmic star formation history • Highest z galaxies? (possibly first galaxies) • Excellent sample for studying the average X-ray emission properties of galaxies over cosmic time

  10. High SFR Stacked LBGS High SFR Stacked LBGS Age of the Universe (Gyr) 13.5 9.0 6.7 5 4 3 2 Medium SFR Stacked LBGS Laird et al (2005) log LX/SFR (erg s-1 [M8 yr -1]-1) Lehmer et al (2010) Lehmer et al (2008) Laird et al (2006) Colbert et al (2004) Iwasawa et al (2009) Lehmer et al (2010) Colbert et al (2004) Iwasawa et al (2009) Lehmer et al (2010) Colbert et al (2004) Iwasawa et al (2009) Lehmer et al (2010) 0 1 2 3 4 Redshift (z) Does the local relation hold at higher redshifts? BZ+13 How does Lx/SFR evolve over cosmic time? log LX =A log(1 + z ) + B log SFR + C A = 0.93 +/- 0.07 B = 0.65 +/- 0.03 C = 39.80 +/- 0.03 (see also Cowie et al. 2011; Kaaret et al. (2014) LBG samples binned by Redshift and SFR: z=1.5, 1.9, 2.5, 3.0, 4.0, 5.0, ... (higher redshifts did not yield detections...) SFR/[M8yr-1]= 5 -15 & 15 -100 (<5 and >30 did not yield detections) Models from Fragos et al. (2012)

  11. Primordial Starbursts in our backyard Studying the X-ray emission within individual low-metallicity, high SFR galaxies: Sample of z~0.1 Lyman break analogs UV-selected: high SFRs, metal and dust poor resemble LBGs: metallicity, dust attenuations, SFRs, morphology, kinematics… (Heckman+2005, Hoopes+2007, Basu-Zych+2007,2009a, 2009b, Overzier+2008,2010,2011, Goncalves+2001) We use optical emission lines to screen against selecting AGN! z < 0.1 (LBAs) vs. z > 1.5 (LBGs) study in better details -- better spatial resolution, fainter features X-rays: study individual galaxies (vs. average properties) Mrk 54 Haro 11 J082355+280621 VV 114

  12. Basu-Zych et al. (2013) High SFR Stacked LBGS Medium SFR Stacked LBGS LBAS VV 114 Haro 11 Colbert et al (2004) Iwasawa et al (2009) Lehmer et al (2010) Fragos et al. (2013b) Studying X-ray emission within individual z< 0.1 LBAs What drives the elevated X-ray/SFR in UV-selected galaxies? Lower Metallicities? Theory: HMXBs in low metallicity environments are more luminous and UV-selected galaxies have lower metallicities compared to other higher SFR galaxies (LIRGs/ULIRGs). Observation: Current constraints indicate a negative correlation between LX/SFR and metallicity at the 99.2% confidence level.

  13. Basu-Zych et al. (2013) Z/Z◉ < 10% NULX/SFR Haro 11 VV 114 SINGS Fragos et al. (2013b) Mapelli et al. (2010) Prestwich et al. (2013) Brorby et al. (2014) Studying X-ray emission within individual z< 0.1 LBAs Basu-Zych et al. (2013) 12+log(O/H)=7.65 Observational evidence suggests that the X-ray binary populations per unit SFR are more luminous in low-metallicity galaxies (dwarfs and LBAs).

  14. 5’’ J082355+280621 Distribution of X-ray binaries within spatially-resolved LBAs Only the BRIGHT end of the luminosity distribution: LX > 1040 erg/s (ULXs) Contours: Chandra X-ray data 2-10 keV 0.5-10 keV VV 114 5’’ Haro 11

  15. VV114 5’’ simulated observed Haro11 Distribution of X-ray binaries within spatially-resolved LBAs Are the observed bright sources REALLY single ULXs? OR the result of multiple blended sources? Simulate the effects of source blending… 1. Draw random distributions ... 2. Marx ray tracing code HST images: Spatial distribution Produce simulated 2--10 keV Chandra images that match depth of actual observations Mineo et al. (2012) XLF: HMXB luminosity distribution + VV 114 5’’ Haro 11

  16. Basu-Zych et al. (2013) Distribution of X-ray binaries within spatially-resolved LBAs Are the observed bright sources REALLY single ULXs? OR the result of multiple blended sources? Simulate the effects of source blending… But include influence from metallicity this time! Renormalize the input luminosity function by the Lx/SFR enhancement due to low metallicity Haro11 VV114 Mineo+ 2012a Fragos+2013

  17. Summary & the exciting future... • Metallicity is an important factor for driving the formation and evolution of HMXBs, based on three different investigations of “primordial starbursts”: • X-ray stacking analyses for z < 4 LBGs (covering ∼90% of the universe’s history) using the 4 Ms Chandra Deep Field South data • Studies of individually-detected LBAs, with similarly low metallicities and elevated LX/SFR as LBGs • … and characterizing the bright end of the X-ray luminosity function within spatially-resolved LBAs Use upcoming Chandra Deep Field-South 7 Ms data to take this study deeper!

  18. Summary Next steps... • Due to their uniquely low metallicities, low dust attenuations and high SFRs in the local Universe, z~0.1 LBAs represent an important population for studying X-ray emission within galaxies similar to those in the early Universe (in primordial mode of star formation) & offer some advantages over studying high-z samples: • individually detected (vs. studying average properties) • higher spatial resolution NGC 3310 Mrk 54 J082355+280621 • Building up a larger sample of • low metallicity & high SFR galaxies • larger sample of LBAs • with deeper observations on other spatially resolved LBAs

  19. Athena Haro11 Summary & the exciting future... • Due to their uniquely low metallicities, low dust attenuations and high SFRs in the local Universe, z~0.1 LBAs represent an important population for studying X-ray emission within galaxies similar to those in the early Universe & offer some advantages over studying high-z samples: • Individually detected • Less biased towards the brightest galaxies • Higher spatial resolution Ne IX He α triplet Simulated spectrum for 25 ks with Athena XIFU FeXX, XXI • Possibility of studying the hot gas contribution Based on the average X-ray spectrum for 21 local star-forming galaxies, the hot gas component is well described by kT~ 0.3 keV (Mineo et al. 2012b) NOT accessible for z > 1 galaxies.

  20. Thanks!

  21. Conclusions & Next steps... • Based on X-ray stacking analyses for z < 4 LBGs (covering ∼90% of the universe’s history) using the 4Ms Chandra Deep Field South data, we find that the 2–10 keV X-ray luminosity evolves weakly with redshift (z) and SFR as • log LX = 0.93 log(1 + z) + 0.65 log SFR + 39.80. • Consistent with predictions from X-ray binary population synthesis models, the redshift evolution of LX/SFR appears to be largely driven by metallicity evolution in high mass X-ray binaries. • Based on X-ray emission studies of individually-detected Lyman break analogs, which have similarly low metallicities and elevated LX/SFR as high-z LBGs, we find that the relatively metal-poor, active mode of star formation in LBAs and distant z > 2 LBGs may yield higher total HMXB luminosity than found in typical galaxies in the local Universe. • Based on X-ray emission studies of individually detected Lyman break analogs, which have similarly low metallicities and elevated LX/SFR as high-z LBGs, the relatively metal-poor, active mode of star formation in LBAs and distant z > 2 LBGs may yield higher total HMXB luminosity than found in typical galaxies in the local Universe.

  22. UVLG : LFUV ≥ 2 x 1010 L Lyman break analogs (LBAs) : IFUV ≥ 109 L kpc-2 LBGs/ LBAs LBA Overview: z~0.1-0.3 rare (at z<1 = 10-5/Mpc3) but dominate UV emission at z>3 compact : half light radii = 1-2 kpc) high SFRs : 1-100 M⊙/yr high sSFR: SFR/M⊙~10-9 - 10-8 Hoopes et al. (2007)

  23. X-ray Emission from Primordial Starbursts Chandra image of M82 0.5-2 keV Total Emission 2-10 keV X-ray Binaries Hot Gas 0.3--1.1 keV 0.7--2.2 keV 2.2-6 keV Average X-ray spectrum for 21 local star-forming galaxies (Mineo et al. 2012a,b) is described well by models of: bremsstrahlung (hot gas; kT ~ 0.3 keV) plus power-law due to X-ray binaries (Γ ~ 1.8) X-ray emission in galaxies... Mineo et al. (2012a,b) At higher redshifts, the X-ray binary contribution dominates.

  24. 4 Ms Chandra exposure 465 arcmin2 740 sources S−1.5 S−2.2 Hubble Ultradeep Field (Beckwith et al. 2006) Chandra Deep Field-South (Xuey et al. 2011) Chandra Deep Field-South: Deepest X-ray View of the Universe! • At 4 Ms depth, we estimate number counts to ~5 × 10−18 erg cm−2 s−1 (0.5−2 keV) and obtain source densities of ~28,000 deg−2. Lehmer et al. (2012) • At the 0.5−2 keV flux limit, AGNs and galaxies provide comparable contributions to number counts: AGNs − 14,900 deg−2 (560 sources) galaxies − 12,700 deg−2 (170 sources) • Relatively sharp slope of normal galaxy counts (dN/dS ∝ S−2.2) indicate that we will soon be in a galaxy dominated regime. Chandra We love you! Within the Chandra Deep Field-South, the multiwavelength data (e.g., Hubble) have revealed there are many 10s of thousands of galaxies, but only ~170 galaxies are individually detected by Chandra. 7 Ms CDF-S Observations (additional 3 Ms) are almost completed: Expect to Be Galaxy-Dominated in Most Sensitive Regions.

  25. Un G R Shapley et al, 2003 Selecting Lyman break galaxies Color selection at z=3: (Un - G) ≥ 1+(G-R) (Un -G) ≥ 1.6 (G-R) ≤ 1.2

  26. HMXBs detected in spatially-resolved LBAs

  27. Haro 11:Using VLT XShooter data, knot C appears to be associated with luminous blue variable stars Ages for Knots B and C are <10Myr (Guseva+2012)

  28. Implications... -- Heating of the Intergalactic Medium -- * First galaxies at z=10-20 * XRBs dominate over AGN (Fragos+2013) * Lx/SFR does not follow the local relation, but evolves with metallicity evolution of the Universe, as predicted by XRB population synthesis models... Summary • Based on three different investigations: • X-ray stacking analyses for z < 4 LBGs (covering ∼90% of the universe’s history) using the 4Ms Chandra Deep Field South data • Studies of individually-detected LBAs, with similarly low metallicities and elevated LX/SFR as LBGs • … and characterizing the bright end of the X-ray luminosity function within spatially-resolved LBAs • we find that metallicity is an important factor driving the formation and evolution of HMXBs within low-metallicity and high SFR galaxies (“primordial starbursts”).

  29. Total Emission 0.5-2 keV 2-10 keV X-ray Binaries Hot Gas Average X-ray spectrum for 21 local star-forming galaxies (Mineo et al. 2012a,b) is described well by models of: bremsstrahlung (hot gas; kT ~ 0.3 keV) plus power-law due to X-ray binaries (Γ ~ 1.8) At higher redshifts, the X-ray binary contribution dominates, and hot gas component is not easy to study! Mineo et al. (2012a,b) At z=0, the hot gas component and XRB component are nearly equal at E=0.5-2keV

  30. Lehmer et al. in-prep Next steps with Chandra 7 Ms Deep Field Data • Based on three different investigations: • X-ray stacking analyses for z < 4 LBGs (covering ∼90% of the universe’s history) using the 4Ms Chandra Deep Field South data • Studies of individually-detected LBAs, with similarly low metallicities and elevated LX/SFR as LBGs • … and characterizing the bright end of the X-ray luminosity function within spatially-resolved LBAs • we find that metallicity is an important factor driving the formation and evolution of HMXBs within low-metallicity and high SFR galaxies (“primordial starbursts”). SFRs from IR and UV. SFRs from extinction-corrected UV only.

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