X-Ray Binary Evolution Across Cosmic Time

Fragos, Tassos; Lehmer, Bret; Tremmel, Michael; Tzanavaris, P.; Basu-Zych, Antara; Belczyński, Krzysztof; Hornschemeier, A. E.; Jenkins, L. P.; Kalogera, V.; Ptak, Andrew; Zezas, A.

doi:10.1088/0004-637x/764/1/41

Cited by 277 publications

(342 citation statements)

References 80 publications

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“…At lower luminosities, the XLF of star-forming galaxies is comparable to, or even exceeds, the AGN XLF, in agreement with Vito et al (2016), who found that the X-ray emission in galaxies individually undetected in the 7 Ms CDF-S is mostly due to XRB. Similar conclusions are reached by scaling the star-formation rate functions (SFRF, i.e., the comoving space densities of galaxies per unit star-formation rate) from Smit et al (2012) and Gruppioni et al (2015), at z ≈ 3.5 and 4, respectively, into XLF using the best-fitting, redshift-dependent Fragos et al (2013) and Lehmer et al (2016) relations.…”

Section: The Agn Xlf At High Redshiftsupporting

confidence: 62%

High-redshift AGN in the Chandra Deep Fields: the obscured fraction and space density of the sub-L* population

Vito

Brandt

Yang

et al. 2017

Monthly Notices of the Royal Astronomical Society

164

184

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We investigate the population of high-redshift (3 z < 6) AGN selected in the two deepest X-ray surveys, the 7 Ms Chandra Deep Field-South and 2 Ms Chandra Deep Field-North. Their outstanding sensitivity and spectral characterization of faint sources allow us to focus on the sub-L * regime (logL X 44), poorly sampled by previous works using shallower data, and the obscured population. Taking fully into account the individual photometric-redshift probability distribution functions, the final sample consists of ≈ 102 X-ray selected AGN at 3 z < 6. The fraction of AGN obscured by column densities logN H > 23 is ∼ 0.6 − 0.8, once incompleteness effects are taken into account, with no strong dependence on redshift or luminosity. We derived the high-redshift AGN number counts down to F 0.5−2 keV = 7 × 10 −18 erg cm −2 s −1 , extending previous results to fainter fluxes, especially at z > 4. We put the tightest constraints to date on the low-luminosity end of AGN luminosity function at high redshift. The space-density, in particular, declines at z > 3 at all luminosities, with only a marginally steeper slope for low-luminosity AGN. By comparing the evolution of the AGN and galaxy densities, we suggest that such a decline at high luminosities is mainly driven by the underlying galaxy population, while at low luminosities there are hints of an intrinsic evolution of the parameters driving nuclear activity. Also, the black-hole accretion rate density and star-formation rate density, which are usually found to evolve similarly at z 3, appear to diverge at higher redshifts.

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Section: The Agn Xlf At High Redshiftsupporting

confidence: 62%

High-redshift AGN in the Chandra Deep Fields: the obscured fraction and space density of the sub-L* population

Vito

Brandt

Yang

et al. 2017

Monthly Notices of the Royal Astronomical Society

164

184

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“…These codes rely on precomputed grids of detailed stellar models and approximate treatments of the physical processes as described below. Despite the approximations, studies with this and similar codes based on the same philosophy have enabled insights into the many exotic phenomena resulting from lowand high-mass interacting binaries (e.g., recent work by Izzard et al 2004Izzard et al , 2006Izzard et al , 2009Ruiter et al 2009Ruiter et al , 2014Mennekens et al 2010;Abate et al 2013;de Mink et al 2013de Mink et al , 2014Fragos et al 2013;Vanbeveren et al 2013;Claeys et al 2014;Kochanek et al 2014;Mennekens & Vanbeveren 2014;Schneider et al 2014Schneider et al , 2015Toonen et al 2014).…”

Section: Methodsmentioning

confidence: 99%

Merger Rates of Double Neutron Stars and Stellar Origin Black Holes: The Impact of Initial Conditions on Binary Evolution Predictions

Mink

Belczyński

2015

ApJ

Self Cite

202

151

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The initial mass function (IMF), binary fraction, and distributions of binary parameters (mass ratios, separations, and eccentricities) are indispensable inputs for simulations of stellar populations. It is often claimed that these are poorly constrained, significantly affecting evolutionary predictions. Recently, dedicated observing campaigns have provided new constraints on the initial conditions for massive stars. Findings include a larger close binary fraction and a stronger preference for very tight systems. We investigate the impact on the predicted merger rates of neutron stars and black holes. Despite the changes with previous assumptions, we only find an increase of less than a factor of 2 (insignificant compared with evolutionary uncertainties of typically a factor of 10-100). We further show that the uncertainties in the new initial binary properties do not significantly affect (within a factor of 2) our predictions of double compact object merger rates. An exception is the uncertainty in IMF (variations by a factor of 6 up and down). No significant changes in the distributions of final component masses, mass ratios, chirp masses, and delay times are found. We conclude that the predictions are, for practical purposes, robust against uncertainties in the initial conditions concerning binary parameters, with the exception of the IMF. This eliminates an important layer of the many uncertain assumptions affecting the predictions of merger detection rates with the gravitational wave detectors aLIGO/aVirgo.

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“…Furthermore, reduced wind mass losses in low-metallicity environments lead to reduced angular momentum losses and to overall tighter binary orbits, which in turn increase the ratio of Roche-lobe overflow versus wind-fed HMXBs. The former mass transfer mechanism is significantly more efficient, and produces a more luminous HMXB population (Fragos et al 2013b). Finally, low metallicity massive stars tend to expand later in their evolution compared to their high metallicity counterparts, thus interacting with their companions for the first time and entering the common envelope phase while having more massive cores and less bound envelopes that can be easily expelled.…”

Section: Mass-metallicity Relationmentioning

confidence: 99%

“…We have calculated the intrinsic (unabsorbed) spectral energy distribution (SED) of the global compact binary population following the prescriptions presented by Fragos et al (2013b), which treat separately neutron stars and black hole binaries in different spectral states -a high-soft state where the spectrum is dominated by the thermal emission from the disk, and a low-hard state where the spectrum is dominated by a power-law component. The transition between low-hard and high-soft states in both cases is observed to occur at a luminosity of about 5% L Edd ( (2010) compact binary RXTE samples are 0.63±0.09 and 0.51±0.13 for neutron stars and black hole binaries in the high-soft state, and 0.27 ± 0.09 and 0.33 ± 0.10 for neutron stars and black hole binaries in the low-hard state, respectively (Fragos et al 2013b).…”

Section: Mass-metallicity Relationmentioning

confidence: 99%

Radiation Backgrounds at Cosmic Dawn: X-Rays from Compact Binaries

Madau

Fragos

2017

ApJ

353

391

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We compute the expected X-ray diffuse background and radiative feedback on the intergalactic medium (IGM) from X-ray binaries prior and during the epoch of reionization. The cosmic evolution of compact binaries is followed using a population synthesis technique that treats separately neutron stars and black hole binaries in different spectral states and is calibrated to reproduce the observed X-ray properties of galaxies at z ∼ < 4. Together with an updated empirical determination of the cosmic history of star formation, recent modeling of the stellar mass-metallicity relation, and a scheme for absorption by the IGM that accounts for the presence of ionized H II bubbles during the epoch of reionization, our detailed calculations provide refined predictions of the X-ray volume emissivity and filtered radiation background from "normal" galaxies at z ∼ > 6. Radiative transfer effects modulate the background spectrum, which shows a characteristic peak between 1 and 2 keV. Because of the energy dependence of photoabsorption, soft X-ray photons are produced by local sources, while more energetic radiation arrives unattenuated from larger cosmological volumes. While the filtering of Xray radiation through the IGM slightly increases the mean excess energy per photoionization, it also weakens the radiation intensity below 1 keV, lowering the mean photoionization and heating rates. Numerical integration of the rate and energy equations shows that the contribution of X-ray binaries to the ionization of the bulk IGM is negligible, with the electron fraction never exceeding 1%. Direct He I photoionizations are the main source of IGM heating, and the temperature of the largely neutral medium in between H II cavities increases above the temperature of the cosmic microwave background (CMB) only at z ∼ < 10, when the volume filling factor of H II bubbles is already ∼ > 0.1. Therefore, in this scenario, it is only at relatively late epochs that neutral intergalactic hydrogen may be observable in 21-cm emission against the CMB.

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X-Ray Binary Evolution Across Cosmic Time

Cited by 277 publications

References 80 publications

High-redshift AGN in the Chandra Deep Fields: the obscured fraction and space density of the sub-L* population

High-redshift AGN in the Chandra Deep Fields: the obscured fraction and space density of the sub-L* population

Merger Rates of Double Neutron Stars and Stellar Origin Black Holes: The Impact of Initial Conditions on Binary Evolution Predictions

Radiation Backgrounds at Cosmic Dawn: X-Rays from Compact Binaries

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