The Astrophysical Journal is the foremost research journal in the world devoted to recent developments, discoveries, and theories in astronomy and astrophysics. Many of the classic discoveries of the twentieth century have first been reported in the Journal.
All American Astronomical Society research journals published with IOP Publishing are now electronic only and no longer print paper editions.
Our online author services system makes it easy to submit an article to the ApJ. All you need to do is upload and approve your manuscript and the peer-review process will start immediately.
The Astrophysical Journal Letters is a peer-reviewed express scientific journal that allows astrophysicists to rapidly publish short notices of significant original research. Submit an article to the ApJL.
The Astrophysical Journal Supplement publishes significant papers containing extensive data or calculations, or of very specialized interest. The Supplement contains many of the most frequently cited papers in the astronomical literature.
Submit an article to the ApJ Supplement.
These are the latest articles published in The Astrophysical Journal.
H. M. Foster et al. 2015 ApJ 805 94
We analyze 3 yr of nearly continuous Kepler spacecraft short cadence observations of the pulsating subdwarf B (sdB) star KIC 3527751. We detect a total of 251 periodicities, most in the g-mode domain, but some where p-modes occur, confirming that KIC 3527751 is a hybrid pulsator. We apply seismic tools to the periodicities to characterize the properties of KIC 3527751. Techniques to identify modes include asymptotic period spacing relationships, frequency multiplets, and the separation of multiplet splittings. These techniques allow for 189 (75%) of the 251 periods to be associated with pulsation modes. Included in these are three sets of ℓ = 4 multiplets and possibly an ℓ = 9 multiplet. Period spacing sequences indicate ℓ = 1 and 2 overtone spacings of 266.4 ± 0.2 and 153.2 ± 0.2 s, respectively. We also calculate reduced periods, from which we find evidence of trapped pulsations. Such mode trappings can be used to constrain the core/atmosphere transition layers. Interestingly, frequency multiplets in the g-mode region, which sample deep into the star, indicate a rotation period of 42.6 ± 3.4 days while p-mode multiplets, which sample the outer envelope, indicate a rotation period of 15.3 ± 0.7 days. We interpret this as differential rotation in the radial direction with the core rotating more slowly. This is the first example of differential rotation for a sdB star.
Yue Shen et al. 2015 ApJ 805 96
We present host stellar velocity dispersion measurements for a sample of 88 broad-line quasars at (46 at ) from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project. High signal-to-noise ratio coadded spectra (average per 69 pixel) from SDSS-RM allowed for the decomposition of the host and quasar spectra and for measurements of the host stellar velocity dispersions and black hole (BH) masses using the single-epoch (SE) virial method. The large sample size and dynamic range in luminosity ( ) lead to the first clear detection of a correlation between SE virial BH mass and host stellar velocity dispersion far beyond the local universe. However, the observed correlation is significantly flatter than the local relation, suggesting that there are selection biases in high- z luminosity-threshold quasar samples for such studies. Our uniform sample and analysis enable an investigation of the redshift evolution of the relation relatively free of caveats by comparing different samples/analyses at disjoint redshifts. We do not observe evolution of the relation in our sample up to , but there is an indication that the relation flattens toward higher redshifts. Coupled with the increasing threshold luminosity with redshift in our sample, this again suggests that certain selection biases are at work, and simple simulations demonstrate that a constant relation is favored to . Our results highlight the scientific potential of deep coadded spectroscopy from quasar monitoring programs, and offer a new path to probe the co-evolution of BHs and galaxies at earlier times.
Zhen Yan and Wenfei Yu 2015 ApJ 805 87
We have performed a statistical study of the properties of 110 bright X-ray outbursts in 36 low-mass X-ray binary transients (LMXBTs) seen with the All-Sky Monitor (2–12 keV) on board the Rossi X-ray Timing Explorer ( RXTE) in 1996–2011. We have measured a number of outburst properties, including peak X-ray luminosity, rate of change of luminosity on a daily timescale, e-folding rise and decay timescales, outburst duration, and total radiated energy. We found that the average properties, such as peak X-ray luminosity, rise and decay timescales, outburst duration, and total radiated energy of black hole LMXBTs, are at least two times larger than those of neutron star LMXBTs, implying that the measurements of these properties may provide preliminary clues to the nature of the compact object of a newly discovered LMXBT. We also found that the outburst peak X-ray luminosity is correlated with the rate of change of X-ray luminosity in both the rise and decay phases, which is consistent with our previous studies. Positive correlations between total radiated energy and peak X-ray luminosity, and between total radiated energy and the e-folding rise or decay timescale, are also found in the outbursts. These correlations suggest that the mass stored in the disk before an outburst is the primary initial condition that sets up the outburst properties seen later. We also found that the outbursts of two transient stellar-mass ultraluminous X-ray sources in M31 also roughly follow the correlations, which indicate that the same outburst mechanism works for the brighter outbursts of these two sources in M31 that reached the Eddington luminosity.
Chao-Wei Tsai et al. 2015 ApJ 805 90
We present 20 Wide-field Infrared Survey Explorer ( WISE)-selected galaxies with bolometric luminosities L bol > 10 14 L ☉, including five with infrared luminosities L IR ≡ L (rest 8–1000 μm) > 10 14 L ☉. These “extremely luminous infrared galaxies,” or ELIRGs, were discovered using the “ W1 W2-dropout” selection criteria which requires marginal or non-detections at 3.4 and 4.6 μm ( W1 and W2, respectively) but strong detections at 12 and 22 μm in the WISE survey. Their spectral energy distributions are dominated by emission at rest-frame 4–10 μm, suggesting that hot dust with T d ∼ 450 K is responsible for the high luminosities. These galaxies are likely powered by highly obscured active galactic nuclei (AGNs), and there is no evidence suggesting these systems are beamed or lensed. We compare this WISE-selected sample with 116 optically selected quasars that reach the same L bol level, corresponding to the most luminous unobscured quasars in the literature. We find that the rest-frame 5.8 and 7.8 μm luminosities of the WISE-selected ELIRGs can be 30%–80% higher than that of the unobscured quasars. The existence of AGNs with L bol > 10 14 L ☉ at z > 3 suggests that these supermassive black holes are born with large mass, or have very rapid mass assembly. For black hole seed masses ∼10 3 M ☉, either sustained super-Eddington accretion is needed, or the radiative efficiency must be <15%, implying a black hole with slow spin, possibly due to chaotic accretion.
E. Sonbas et al. 2015 ApJ 805 86
For a sample of Swift and Fermi gamma-ray bursts, we show that the minimum variability timescale and the spectral lag of the prompt emission is related to the bulk Lorentz factor in a complex manner. For small Γ's, the variability timescale exhibits a shallow (plateau) region. For large Γ's, the variability timescale declines steeply as a function of Γ ( ). Evidence is also presented for an intriguing correlation between the peak times, t p , of the afterglow emission and the prompt emission variability timescale.