Extended Component Research Articles

Red wolf (Canis rufus) sperm quality and quantity is affected by semen collection method, extender components, and post-thaw holding temperature

Cryopreserving genetic resources is becoming increasingly important for species management. In the zoo-based red wolf (Canis rufus) population, inbreeding continues to increase in the absence of new founders. Through banking sperm, we preserve genetic diversity and create the ability to decrease inbreeding accumulation in the future. The quality and quantity of banked sperm can be affected by cryopreservation media and semen collection methods. This study's objectives were to further optimize semen extender used for red wolf sperm cryopreservation, investigate effects of post-thaw holding temperature, and to determine if urethral catheterization is an effective method for semen collection in this species. Semen collection via electroejaculation (EE) was performed on 39 adult red wolf males (ages 1 to 11) from 15 institutions. Urethral catheterization (UC) was attempted on a subset (n = 14) of those males, prior to EE. Thirteen different semen extenders were used for cryopreservation, which varied in osmolarity (HI or NORM), sugar source (glucose, fructose, or a combination), and cryoprotectant (glycerol or DMSO). Significant decreases in percent motility, forward progressive status (FPS), and acrosomal integrity were observed over time across all extenders (P < 0.0001). Among the extender components examined, post-thaw sperm motility and FPS were lower in DMSO versus glycerol based treatments (P < 0.005). Therefore, DMSO should be considered unsuitable as a cryoprotectant when freezing red wolf sperm. Effects of osmolarity and sugar source were minimal and temporally variable, however notably, a higher percentage of morphologically normal sperm were observed in the fructose-based extenders compared to glucose-based extenders post-thaw (P < 0.05). Additionally, post-thaw sperm motility and FPS declined more rapidly in samples maintained at 37 °C compared to samples held at room temperature (P < 0.05). Greater volumes of semen were collected using EE compared to UC (P = 0.041), and sperm samples collected using EE also had greater motility and FPS (P < 0.05). Additionally, though no gross morphological differences were observed, there were fewer sperm with intact acrosomes in the samples collected via UC (P = 0.0443). Thus, UC should not be considered sufficient for semen collection in red wolves when the desired fate of sperm is cryopreservation and/or AI. However, UC does provide an opportunity for a basic reproductive evaluation of a red wolf male.

Study of RCR Catalogue Radio Source Integral Spectra

We present the characteristics of the sources found on the averaged scans of the "Cold" experiment 1980--1999 surveys in the right-ascension interval $2^h$< RA <$7^h$. Thereby, a refinement of the parameters of the RC catalog sources (RATAN Cold) for this interval is complete. To date, the RCR catalog (RATAN Cold Refined) covers the right-ascension interval $2^h$< RA <$17^h$ and includes 830 sources. The spectra are built for them with the use of new data in the range of 70--230 MHz. The dependence between the spectral indices $\alpha_{0.5}$, $\alpha_{3.94}$ and integral flux density at the frequencies of 74 and 150 MHz, at 1.4, 3.94 and 4.85 GHz is discussed. We found that at 150 MHz in most sources the spectral index $\alpha_{0.5}$ gets steeper with increasing flux density. In general, the sources with flat spectra are weaker in terms of flux density than the sources with steep spectra, which especially differs at 150 MHz. We believe that this is due to the brightness of their extended components, which can be determined by the type of accretion and the neighborhood of the source.

1.4 GHz on the Fundamental Plane of black hole activity

The fundamental plane of black hole activity is an empirical relationship between the OIII/X-ray luminosity depicting the accretion power, the radio luminosity as a probe of the instantaneous jet power and the mass of the black hole. For the first time, we use the 1.4 GHz FIRST radio luminosities on the optical fundamental plane, to investigate whether or not FIRST fluxes can trace nuclear activity. We use a SDSS-FIRST cross-correlated sample of 10149 active galaxies and analyse their positioning on the optical fundamental plane. We focus on various reasons that can cause the discrepancy between the observed FIRST radio fluxes and the theoretically expected core radio fluxes, and show that that FIRST fluxes are heavily contaminated by non-nuclear, extended components and other environmental factors. We show that the subsample of 'compact sources', which should have negligible lobe contribution, statistically follow the fundamental plane when corrected for relativistic beaming, while all the other sources lie above the plane. The sample of LINERs, which should have negligible lobe and beaming contribution, also follow the fundamental plane. A combined fit of the low-luminosity AGN and the X-ray binaries, with the LINERs, results in the relation log L$_R$ = 0.77 log L$_{OIII}$ + 0.69 log M. Assuming that the original fundamental plane relation is correct, we conclude that 1.4 GHz FIRST fluxes do not trace the pure 'core' jet and instantaneous nuclear activity in the AGN, and one needs to be careful while using it on the fundamental plane of black hole activity.

Introducing Soybean Oil in Semen Extenders of Awassi Rams

The aims of the study was to investigate the possibility of using an plant lecithin; commercial soybean oil (SO) directly in the components of semen extenders of Awassi rams, storage of semen in chilled technique and the effects of dilution, cooling and storage periods on semen quality. Semen was collected weekly from four Awassi rams by electro- ejaculator. Pooled samples were divided to six equal aliquots and diluted by Citrate egg yolk extender at 37˚C. Treatments were designed on the base of control extender containing 25% egg yolk and four treatments containing different addition of SO (12.5, 25, 37.5, and 50%) and combination treatment of 12.5% egg yolk + 12.5% SO. Treatment tubes were cooled to 5˚C and stored for three days. Semen was evaluated as raw, diluted, cooled and after storage in refrigerator (5˚C) for 1, 2 and 3 consecutive days. Results showed that there were no significant differences among all treatments in progressive motility, dead sperm %, abnormal sperm % and acrosome defect %, while pH were found to be significantly declined (p≤ 0.05) in control group. Significant effects of dilution, cooling, and storage period have been demonstrated with steadily significant deterioration (p≤ 0.05) for all studied characteristics when motility and pH declined while sperm abnormality, dead, and acrosome defect percentages increased. The results clearly indicated successful of using different levels of SO (plant source) as lecithin source instead of egg yolk (animal source of lecithin) without any impacts on the biological characteristics of Awassi ram semen and the process of dilution, cooling and storage periods have deterioration effects on semen quality.

The Highly Collimated Radio Jet of HH 80–81: Structure and Nonthermal Emission

Abstract Radio emission from protostellar jets is usually dominated by free–free emission from thermal electrons. However, in some cases, it has been proposed that nonthermal emission could also be present. This additional contribution from nonthermal emission has been inferred through negative spectral indices at centimeter wavelengths in some regions of the radio jets. In the case of HH 80–81, one of the most powerful protostellar jets known, linearly polarized emission has also been detected, revealing that the nonthermal emission is of synchrotron nature from a population of relativistic particles in the jet. This result implies that an acceleration mechanism should be taking place in some parts of the jet. Here, we present new high sensitivity and high angular resolution radio observations at several wavelengths (in the 3–20 cm range) of the HH 80–81 radio jet. These new observations represent an improvement in sensitivity and angular resolution by a factor of ∼10 with respect to previous observations. This allows us to resolve the morphology of the radio jet and to study the different emission mechanisms involved through spectral index maps. We conclude that synchrotron emission in this jet arises from an extended component detected at low frequencies and from the termination points of the jet, where strong shocks against the ambient medium can produce efficient particle acceleration.

The Second Galactic Center Black Hole? A Possible Detection of Ionized Gas Orbiting around an IMBH Embedded in the Galactic Center IRS13E Complex

Abstract The Galactic Center is the nuclear region of the nearest spiral galaxy, the Milky Way, and contains the supermassive black hole with , Sagittarius A* (Sgr A*). One of the basic questions about the Galactic Center is whether or not Sgr A* is the only “massive” black hole in the region. The IRS13E complex is a very intriguing infrared (IR) object that contains a large dark mass comparable to the mass of an intermediate mass black hole (IMBH) from the proper motions of the main member stars. However, the existence of the IMBH remains controversial. There are some objections to accepting the existence of the IMBH. In this study, we detected ionized gas with a very large velocity width ( km s−1) and a very compact size ( au) in the complex using the Atacama Large Millimeter/submillimeter Array (ALMA). We also found an extended component connecting with the compact ionized gas. The properties suggest that this is an ionized gas flow on the Keplerian orbit with high eccentricity. The enclosed mass is estimated to be by the analysis of the orbit. The mass does not conflict with the upper limit mass of the IMBH around Sgr A*, which is derived by the long-term astrometry with the Very Long Baseline Array (VLBA). In addition, the object probably has an X-ray counterpart. Consequently, a very fascinating possibility is that the detected ionized gas is rotating around an IMBH embedded in the IRS13E complex.

Optical polarimetric and near-infrared photometric study of the RCW95 Galactic H ii region

We carried out an optical polarimetric study in the direction of the RCW95 star forming region in order to probe the sky-projected magnetic field structure by using the distribution of linear polarization segments which seem to be well aligned with the more extended cloud component. A mean polarization angle of $\theta=49.8^o\pm7.7^o$ was derived. Through the spectral dependence analysis of polarization it was possible to obtain the total-to-selective extinction ratio ($R_V$) by fitting the Serkowski function, resulting in a mean value of $R_V=2.93\pm0.47$. The foreground polarization component was estimated and is in agreement with previous studies in this direction of the Galaxy. Further, near-infrared images from Vista Variables in the Via L\'actea (VVV) survey were collected to improve the study of the stellar population associated with the HII region. The Automated Stellar Cluster Analysis (ASteCA) algorithm was employed to derive structural parameters for two clusters in the region, and a set of PAdova and TRieste Stellar Evolution Code (PARSEC) isochrones was superimposed on the decontaminated colour-magnitude diagrams (CMDs) to estimate an age of about 3 Myr for both clusters. Finally, from the near-infrared photometry study combined with spectra obtained with the Ohio State Infrared Imager and Spectrometer (OSIRIS) mounted at the Southern Astrophysics Research Telescope (SOAR) we derived the spectral classification of the main ionizing sources in the clusters associated with IRAS 15408$-$5356 and IRAS 15412$-$5359, both objects classified as O4 V stars.

A 85 kpc Hα tail behind 2MASX J11443212+2006238 in A1367

We report the detection of an Halpha trail of 85 kpc projected length behind galaxy 2MASX J11443212+2006238 in the nearby cluster of galaxies Abell 1367. This galaxy was discovered to possess an extended component in earlier, deeper H$\alpha$ observations carried out with the Subaru telescope. However, lying at the border of the Subaru field, the extended Halpha tail was cut out, preventing the determination of its full extent. We fully map this extent here, albeit the shallower exposure.

OISTER optical and near-infrared monitoring observations of peculiar radio-loud active galactic nucleus SDSS J110006.07+442144.3

Abstract We present monitoring campaign observations at optical and near-infrared (NIR) wavelengths for a radio-loud active galactic nucleus (AGN) at z = 0.840, SDSS J110006.07+442144.3 (hereafter, J1100+4421), which was identified during a flare phase in late 2014 February. The campaigns consist of three intensive observing runs from the discovery to 2015 March, mostly within the scheme of the OISTER collaboration. Optical–NIR light curves and simultaneous spectral energy distributions (SEDs) are obtained. Our measurements show the strongest brightening in 2015 March. We found that the optical–NIR SEDs of J1100+4421 show an almost steady shape despite the large and rapid intranight variability. This constant SED shape is confirmed to extend to ∼5 μm in the observed frame using the archival WISE data. Given the lack of absorption lines and the steep power-law spectrum of αν ∼ −1.4, where $f_{\nu }\propto \nu ^{\alpha _{\nu }}$, synchrotron radiation by a relativistic jet with no or small contributions from the host galaxy and the accretion disk seems most plausible as an optical–NIR emission mechanism. The steep optical–NIR spectral shape and the large amplitude of variability are consistent with this object being a low νpeak jet-dominated AGN. In addition, sub-arcsecond resolution optical imaging data taken with Subaru Hyper Suprime-Cam does not show a clear extended component and the spatial scales are significantly smaller than the large extensions detected at radio wavelengths. The optical spectrum of a possible faint companion galaxy does not show any emission lines at the same redshift, and hence a merging hypothesis for this AGN-related activity is not supported by our observations.

Very Large Array Multiband Monitoring Observations of M31*

Abstract The Andromeda galaxy (M31) hosts one of the nearest and most quiescent supermassive black holes, which provides a rare, but promising opportunity for studying the physics of black hole accretion at the lowest state. We have conducted a multifrequency, multi-epoch observing campaign, using the Karl G. Jansky Very Large Array (VLA) in its extended configurations in 2011–2012, to advance our knowledge of the still poorly known radio properties of M31*. For the first time, we detect M31* at 10, 15, and 20 GHz and measure its spectral index, α ≈ −0.45 ± 0.08 (S ν ∝ ν α ), over the frequency range of 5–20 GHz. The relatively steep spectrum suggests that the observed radio flux is dominated by the optically thin part of a putative jet, which is located at no more than a few thousand Schwarzschild radii from the black hole. On the other hand, our sensitive radio images show little evidence for an extended component, perhaps except for several parsec-scale “plumes,” the nature of which remains unclear. Our data also reveal significant (a few tens of percent) flux variation of M31* at 6 GHz, on timescales of hours to days. Furthermore, a curious decrease of the mean flux density, by ∼50%, is found between VLA observations taken during 2002–2005 and our new observations, which might be associated with a substantial increase in the mean X-ray flux of M31* starting in 2006.

Kiloparsec-scale emission in the narrow-line Seyfert 1 galaxy Mrk 783

We present the first results of a radio survey of 79 narrow-line Seyfert 1 (NLS1) carried out with the Karl G. Jansky Very Large Array (JVLA) at 5 GHz in A configuration aimed at studying the radio properties of these sources. We report the detection of extended emission in one object: Mrk 783. This is intriguing, since the radio-loudness parameter R of this object is close to the threshold between radio-quiet and radio-loud active galactic nuclei (AGN). The galaxy is one of the few NLS1 showing such an extended emission at z < 0.1. The radio emission is divided in a compact core component and an extended component, observed on both sides of the nucleus and extending from 14 kpc south-east to 12 kpc north-west. There is no sign of a collimated jet, and the shape of the extended component is similar to those of some Seyfert galaxies. The properties of the emission are compatible with a relic produced by the intermittent activity cycle of the AGN.

Effects of extended components of [O iii] on the correlation between the [O iii] luminosity and the power-law continuum luminosity for active galactic nuclei

In this manuscript, we check the well-known correlation between \oiii luminosity and continuum luminosity (\loiiicon) for AGN by a large sample of 1982 SDSS QSOs with $z<0.8$ and with high quality spectra. The strong correlation of \loiiicon can be found, similar as previous results for AGN. Moreover, among the 1982 QSOs, there are 708 QSOs with the [O~{\sc iii}]$\lambda$5007\AA\ described by two components: one core component plus one extended component. Based on the luminosity from the core components ($L_{\rm [O~\textsc{iii}],~narrow}$) and from the extended components ($L_{\rm [O~\textsc{iii}],~ext}$), we confirm that the correlation of $L_{{\rm [O~\textsc{iii}],~ext}}~-~L_{{\rm 5100\textsc{\AA}}}$ is more stronger and tighter than the correlations on the total \oiii luminosity and on the luminosity of the core components of the \oiii lines. Therefore, the luminosity of the extended components should be better applied to trace AGN intrinsic luminosity. Meanwhile, we have found strong line width correlation and line luminosity correlation between the core components and the extended components, indicating the extended components of the \oiii lines should be not due to commonly considered radial flows in the common \oiii line clouds. And virial effects due to gravity of central black holes naturally lead to the wider extended components from regions more nearer to central black holes. Finally, we can say that the reported correlation of $L_{{\rm [O~\textsc{iii}],~narrow}}~-~L_{{\rm 5100\textsc{\AA}}}$ on the core components of the \oiii lines should be more better to estimate AGN intrinsic luminosity in Type-2 narrow line AGN, because of totally/partly obscured extended components.

Inverse Compton emission from a cosmic-ray precursor in RX J1713.7−3946

Recently, the High Energy Stereoscopic System (H.E.S.S.) reported two new interesting results for a γ-ray emitting supernova remnant, RX J1713.7−3946 (G347.3−0.5). The first result is the establishment of a broken power-law spectrum of GeV–TeV γ-rays. The other is a more extended γ-ray spatial profile than the one in the X-ray band. In this paper, we show both of these results can be explained by inverse Compton emission from accelerated electrons. If the maximum energy of electrons being accelerated decreases with time, the broken power-law spectrum can be generated by accumulation. Furthermore, the extended component of γ-ray profile can be interpreted as a CR precursor of currently accelerated electrons.

Molecular Outflows in Local ULIRGs: Energetics from Multitransition OH Analysis

Abstract We report on the energetics of molecular outflows in 14 local ultraluminous infrared galaxies (ULIRGs) that show unambiguous outflow signatures (P Cygni profiles or high-velocity absorption wings) in the far-infrared lines of OH measured with the Herschel/PACS spectrometer. All sample galaxies are gas-rich mergers at various stages of the merging process. Detection of both ground-state (at 119 and 79 μm) and one or more radiatively excited (at 65 and 84 μm) lines allows us to model the nuclear gas (≲300 pc) and the more extended components using spherically symmetric radiative transfer models. Reliable models and the corresponding energetics are found in 12 of the 14 sources. The highest molecular outflow velocities are found in buried sources, in which slower but massive expansion of the nuclear gas is also observed. With the exception of a few outliers, the outflows have momentum fluxes of (2–5) × L IR/c and mechanical luminosities of (0.1–0.3)% of L IR. The moderate momentum boosts in these sources (≲3) suggest that the outflows are mostly momentum driven by the combined effects of active galactic nuclei (AGNs) and nuclear starbursts, as a result of radiation pressure, winds, and supernova remnants. In some sources (∼20%), however, powerful (1010.5–11 L ⊙) AGN feedback and (partially) energy-conserving phases are required, with momentum boosts in the range of 3–20. These outflows appear to be stochastic, strong AGN feedback events that occur throughout the merging process. In a few sources, the outflow activity in the innermost regions has subsided in the past ∼1 Myr. While OH traces the molecular outflows at subkiloparsec scales, comparison of the masses traced by OH with those previously inferred from tracers of more extended outflowing gas suggests that most mass is loaded (with loading factors of ) from the central galactic cores (a few × 100 pc), qualitatively consistent with an ongoing inside-out quenching of star formation. Outflow depletion timescales are &lt;108 yr, shorter than the gas consumption timescales by factors of 1.1–15, and are anticorrelated with the AGN luminosity.

Connecting the new H.E.S.S. diffuse emission at the Galactic Center with the Fermi GeV excess: A combination of millisecond pulsars and heavy dark matter?

The H.E.S.S. collaboration has reported a high-energy spherically symmetric diffuse gamma-ray emission in the inner 50 pc of the Milky Way, up to ~ 50 TeV. Here we propose a leptonic model which provides an alternative to the hadronic scenario presented by the H.E.S.S. collaboration, and connects the newly reported TeV emission to the Fermi-LAT Galactic center GeV excess. Our model relies on a combination of inverse Compton emission from a population of millisecond pulsars---which can account for the GeV excess---and a supermassive black hole-induced spike of heavy (~ 60 TeV) dark matter particles annihilating into electrons with a sub-thermal cross-section. With an up-to-date interstellar radiation field, as well as a standard magnetic field and diffusion set-up, our model accounts for the spectral morphology of the detected emission. Moreover, we show that the dark matter induced emission reproduces the spatial morphology of the H.E.S.S. signal above ~ 10 TeV, while we obtain a slightly more extended component from pulsars at lower energies, which could be used as a prediction for future H.E.S.S. observations.

TRACING INFALL AND ROTATION ALONG THE OUTFLOW CAVITY WALLS OF THE L483 PROTOSTELLAR ENVELOPE

ABSTRACT Single-dish observations in CS(7–6) reveal emission extending out to thousands of au along the outflow axis of low-mass protostars and having a velocity gradient in the opposite direction to that of their outflows. This emission has been attributed to dense and warm gas flowing outward along the walls of bipolar outflow cavities. Here, we present combined single-dish and interferometric CS(7–6) maps for the low-mass protostar L483, revealing a newly discovered compact central component (radius ≲800 au) and previously unknown features in its extended component (visible out to ∼4000 au). The velocity gradient and skewed (toward the redshifted side) brightness distribution of the extended component are detectable out to a radius of ∼2000 au, but not beyond. The compact central component exhibits a velocity gradient in the same direction as, but which is steeper than that of, the extended component. Furthermore, both components exhibit a velocity gradient with an approximately constant magnitude across the outflow axis, apparent in the extended component not just through but also away from the center out to 2000 au. We point out contradictions between our results and model predictions for outflowing gas and propose a new model in which all of the aforementioned emission can be qualitatively explained by gas inflowing along the outflow cavity walls of a rigidly rotating envelope. Our model also can explain the extended CS(7–6) emission observed around other low-mass protostars.

Constraints on the dark matter annihilation from Fermi-LAT observation of M31

Gamma-ray is a good probe of dark matter (DM) particles in the Universe. We search for the DM annihilation signals in the direction of the Andromeda galaxy (M31) using 7.5 year Fermi-LAT pass 8 data. Similar to Pshirkov et al. (2016), we find that there is residual excess emission from the direction of M31 if only the galactic disk as traced by the far infrared emission is considered. Adding a point-like source will improve the fitting effectively, although additional slight improvements can be found if an extended component such as a uniform disk or two bubbles is added instead. Taking the far infrared disk plus a point source as the background model, we search for the DM annihilation signals in the data. We find that there is strong degeneracy between the emission from the galaxy and that from 10s GeV mass DM annihilation in the main halo with quark final state. However, the required DM annihilation cross section is about 10−25–10−24 cm3s−1, orders of magnitude larger than the constraints from observations of dwarf spheroidal galaxies, indicating a non-DM origin of the emission. If DM subhalos are taken into account, the degeneracy is broken. When considering the enhancement from DM subhalos, the constraints on DM model parameters are comparable to (or slightly weaker than) those from the population of dwarf spheroidal galaxies. We also discuss the inverse Compton scattering component from DM annihilation induced electrons/positrons. For the first time we include an energy dependent template of the inverse Compton emission (i.e., a template cube) in the data analysis to take into account the effect of diffusion of charged particles. We find a significant improvement of the constraints in the high mass range of DM particles after considering the inverse Compton emission.

DISCOVERY OF A HOT CORINO IN THE BOK GLOBULE B335

ABSTRACT We report the first evidence of a hot corino in a Bok globule. This is based on ALMA observations in the 1.2 mm band toward the low-mass Class 0 protostar IRAS 19347+0727 in B335. Saturated complex organic molecules (COMs), CH3CHO, HCOOCH3, and NH2CHO, are detected in a compact region within a few 10 au around the protostar. Additionally, CH3OCH3, C2H5OH, C2H5CN, and CH3COCH3 are tentatively detected. Carbon-chain related molecules, CCH and c-C3H2, are also found in this source, whose distributions are extended over a scale of a few 100 au. On the other hand, sulfur-bearing molecules CS, SO, and SO2 have both compact and extended components. Fractional abundances of the COMs relative to H2 are found to be comparable to those in known hot corino sources. Though the COMs lines are as broad as 5–8 km s−1, they do not show obvious rotation motion in the present observation. Thus, the COMs mainly exist in a structure whose distribution is much smaller than the synthesized beam (0.″58 × 0.″52).

Construction of time‐invariant rate‐compatible‐low‐density parity‐check convolutional codes

In this study, a family of time-invariant rate-compatible (RC) low-density parity-check (LDPC) convolutional codes with algebraic construction is developed based on the graph-extension method over a given positive integer m, which is considered as the given encoding memory. The base code of this family is first obtained by modifying a given construction of a time-invariant LDPC convolutional code. Afterwards, the authors derive the other extended component codes by successively adding extra information bits into the base code. In particular, each component code in the family not only enables the property of fast encoding that can dramatically reduce the implementation complexity, but has the given encoding memory m for each parity-check bit that can remarkably improve the error performance as well. They also demonstrate that the Tanner graph for all the codes in the family is free of girth 4. Simulation results indicate that the proposed family of RC-LDPC convolutional codes collectively offers a desirable performance improvement as compared with the existing counterparts over the binary-input additive Gaussian noise channels under BP decoding.

Jamming and Attraction of Interacting Run-and-Tumble Random Walkers.

We study a model of bacterial dynamics where two interacting random walkers perform run-and-tumble motion on a one-dimensional lattice under mutual exclusion and find an exact expression for the probability distribution in the steady state. This stationary distribution has a rich structure comprising three components: a jammed component, where the particles are adjacent and block each other; an attractive component, where the probability distribution for the distance between particles decays exponentially; and an extended component in which the distance between particles is uniformly distributed. The attraction between the particles is sufficiently strong that even in the limit where continuous space is recovered for a finite system, the two walkers spend a finite fraction of time in a jammed configuration. Our results potentially provide a route to understanding the motility-induced phase separation characteristic of active matter from a microscopic perspective.